ABRASIVES COMPARISON - multiple types, grits compared by 4 testers

Over the last several weeks I have accumulated a stash of different abrasive brands and grits and these have been sent out to three other testers, as well as myself. There are 25 discs in all to be compared from 80 to 1500 grit. The four sets didn't quite match up 100% as there was a shortfall on a few discs, and my set was the one the copped most of those shortfalls. This was because I am quite familiar with the missing discs (hence why they are missing :;).

A few things to observe before I get to my results:

• The testers were all required to have a Festool ETS 150 sander because the discs that I procured were in the Festool 17 hole pattern, and I wasn't prepared to spend my life's savings on acquiring all manner of DE hole patterns to get some variety happening. This should have no reflection on the results (either an abrasive is good at cutting, or it's not). All of the discs to be tested are 150mm.
• Two of the other testers are professionals, and another is a gifted amateur with a scientific background.
• I have my sander hooked up to a 36mm hose which results in much better extraction than the standard 27mm hose. I mention this because none of the abrasives so far have left any detectable dust on the job.
  
• I am very familiar with two of the brands tested, Jöst and Festool Rubin 2, having used both of them extensively for the past 2+ years. In that time I have developed a preference for the Jöst discs with one exception, the 60g. I have found this particular grit to be not as aggressive as I would have thought, and needs replacing more often than I'd like.
• In particular I have found the finer grits of Jöst (400 and up) to be ridiculously durable. It seems that the finer they get the longer they last (up to 3000). The Festool Rubin 2 range finishes at 220g, so from there up to 500 I have been using the Granat range and have been somewhat underwhelmed by them. I have never used the Festool Platin very fine grits as they are just too expensive by comparison (local RRP is $4.60 per disc compared to the Jöst equivalent "SG2" at around $2.00 including freight from Germany).
• The other discs included are two different types of Klingspor, and Abrasives Industrial, a Perth based company that imports jumbo abrasive rolls from China and processes them here into the various shapes and hole patterns. There were only two types of Klingspor included in the 80g range.
• Also, in the 80g range only there were two types of Jöst - the standard Superpad (yellow) and the newer Abrafilm (and I was omitted from both of these due to short supply).
• I will not supply the various pricings just at the moment until the rest of the results are in.

Some notes and observations on the individual brands and types (and sequenced in the order that I tested them, for want of a better reason):

JÖST

• These abrasives are made in Germany and have to be specifically imported (i.e they are not sold in Australia).
• They have a patented DE hole pattern that suits any sander's holes. They achieve this by covering the disc with hundreds of 2mm holes rather than 9 to 17 larger holes. This means that the holes don't necessarily line up very numerously with the sander's holes. It also results in some dust staying on the back of the disc, and this is no big deal - it does not affect the general extraction at all and in my extensive use of them I have noted that the amount of dust left on the job is the same as the Festool 17 hole pattern - nil that I can wipe off with my fingers.
• The range of grits is from 40 and 60 in Red, 80 to 600 in Yellow, and these are all known as Superpad. The range then goes on from 800 to 4000 in "SG2" and these are on a 3mm thick sponge substrate with no DE holes at all, as the dust is fine enough to be sucked through the sponge at these grits. The same applies to the Festool Platin discs.
• Very occasionally I get some little tears just at the edges of the discs, depending upon what I am sanding. This has never been a problem for me, and doesn't seem to affect performance or leave undue scratch marks.
• The second Jöst range is Abrafilm, and as the name implies, they are a film substrate rather than paper. This significantly increase the strength of the substrate. In the 40 to (I think) 150 range the abrasive is Aluminium Zirconia, and from there up to 3000 the abrasive is a ceramic. Caveat - I need to check the crossover point, and get a better description of the "ceramic".

ABRASIVES INDUSTRIAL

• This company imports large rolls of abrasives from China and cuts them to size in Perth.
• They have two ranges of abrasives. The range we tested is an Aluminium Oxide grit on film substrate, with a grit range 40 to 1200. The other range is a more expensive ceramic grit on film substrate, grit range 40 to 2000.
• The die that has been used for punching the 17 hole pattern has deformed the coarser grits to the point where they will not stick properly to the sanding pad - the hole edges are raised up by up to 2mm which prevents the rest of the disc making proper contact. Care had to be taken to ensure as much contact as possible, so that the disc didn't fly off. Having said that, I did not experience any problems because of this improperly formed hole (on the only grit tested so far - 80g), but this deformity needs to be addressed. It remains to be seen how it affects the more delicate fine grits (the hole deformation is different).

KLINGSPOR AlOx range

• This range is locally available, as Klingspor have an Australian distributor (or branch). I brought my testing discs in from the USA because I had a source and also a box of other goods to be despatched, so it was convenient at the time.
• Manufactured in Poland.
• Grit range is 60 to 1500and available in packs of 10 or 50.
• Stearate coated
• Very large range of sizes, shapes and hole patterns

FESTOOL RUBIN 2

• Limited to shapes, sizes and hole patterns to suit Festool Sanders
• Grit range 40 to 220 (can then switch to Granat, and then to Platin 2 to go up to 4000)
• Probably manufactured in Finland

KLINGSPOR Aluminia Zirconia range

• This is a heavier duty range, which has a coraser grit range of 36 to 220
• 50 packs only
• Stearate coated
• Not sure if they are available locally yet.
• Discs only, with a good range of hole patterns

Ok, that will do for this post. I will post my results once the others have told me they are finished. As the proponent of this testing cycle I feel obliged to do as thorough a job as possible, and as empirically as I can. However, I do not have the required instruments to do a thoroughly scientific job (or the knowledge :roll:). Nor do I expect that the testers will go to quite the same lengths.

So far, I have sanded 1.8 kilometres, that's right 1800 metres, 1000 strokes of 930mm up and back of 115mm wide hardwood. :D

I have gotten past the 80 grit discs yet. :doh:

Brett, if you're going to do this, do it right.

1. All grits should be compared, the fact that you have knowledge of some is irrelevant to this comparison.
2. What are you comparing and what are you comparing to? You should have a reference set of grits.
3. Have you got a reference method and a reference set of grits.
4. Are you using the same board or set of boards for each tester?
5. I believe you should;
a) exclude yourself from the comparison as you bring Jost into Australia and therefore have a vested interest.
b) have a neutral person evaluate the result for the same reason.
6. What is your means of comparison
7. What units do you use to compare results
8. Have you spoken to the testers at all about your opinion of the grits? If so, you may have inadvertently skewed results already.

Show your scientific mate and see what he says. Without proper rigor in the testing, your comparison is merely "he said, she said"


I've just reread your notes and you have clearly stated a preference for Jost pads, your results are already biased.
In addition, you have selectively chosen grits based on price. You are excluding information that may affect the outcome.

You got it wrong again. I won't comment on this evaluation any more. One, because I have a system of sanding which gives me reproducible consistent results using Festool pads and secondly, because the results of this "comparison" are already biased.


LGS

Such passion about sandpaper!

I agree with FF. This isnt supposed to be some rigorous scientific test. Its four dudes who use a lot of sandpaper and seeing if they can drive better value, results or duration from a disk.

If they evaluate and find Jost, or Festool, or Bunnings Generic Crap is better (god forbid!) then this is OK with me. Its all subjective anyway... just like asking the guy at the tool store which is the best drill. Of course he is going to point to the 5 he has in stock - knowing you really need a WhizzBang 9000 from his competitor.

There is a small pile of mostly used Festool disks here I really know I should throw out, but all I see is money... $1 a disk... It makes me sad. Its a false economy, but if I get just one more blatt out of one... horray!

FF has made no secret of his preference for Jost. They sound very cool. A fine mesh, so holes are irrelevant (reduce inventory, therefore price), long (or good) duration and a good price. Importing is not a problem. This sounds like a winner.

If he has put the thumb on the scale a bit by not being strictly-scientifically-impartial, again, no problem. He has clearly stated he is not a scientist and the methods may be deemed to be arbitrary. BUT THATS THE POINT. All here have purchased things based upon the arbitrary opinion of those we have deemed to trust (sometimes very expensive things, my Laguna SUV is such an example) . There might even be a few shills here who spruik on behalf of products or companies...this is part of the modern dangers of The Internet... things are Not What They Seem sometimes.

Be reasonable, prudent and a little cynical and it should be good. FF has stated he likes Jost and stated clearly why. I don't think he's going to poison the chalice for the simple reason there are 3 other testers. Im sure they will be just as reasonable and come back with results that might reflect their preferences, experiences and tools. Again, this is the point.

Personally, I would have loved to try Jost. I love the Festool types I use (Brilliant, Rubin and Rubin2) and feel its the best sandpaper I've even used. If it can be "beaten", excellent, I know then where to acquire it.

The good thing about this forum is that unlike some of the "tests" posted on blogs the methodology.opinion/results of tester can be challenged. Testers should try to take this in a positive light and use the ideas presented to improve their testing if they wish.

Subjective testing is perfectly fine as long as it is clearly identified as such and I think that FF has sort of done that when we already know he's and fan of Jost and he says

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As the proponent of this testing cycle I feel obliged to do as thorough a job as possible, and as empirically as I can. However, I do not have the required instruments to do a thoroughly scientific job (or the knowledge http://d1r5wj36adg1sk.cloudfront.net...es/rolleye.gif). Nor do I expect that the testers will go to quite the same lengths.

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One aspect that would be essential for a an objective evaluation is for the products being tested to be be completely de-identified, so logos, labels and any colours or textures should not identify the product. This may not be possible so no matter what else is done these types of test will always be susceptible to bias whether it's intended or not.

All that aside it's not clear to me what is being tested.
Is it, rate of stock removal, longevity of abrasive, consistency of finisih, smoothness of finish, . . . . . . ??????

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Originally Posted by BobL

All that aside it's not clear to me what is being tested.
Is it, rate of stock removal, longevity of abrasive, consistency of finisih, smoothness of finish, . . . . . . ??????

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That will become clearer when I put up my results Bob. I've just finished my report on the 80g jobbies and the headings are:
Dust left on the surface
Clogging of the abrasive face
Dust left on the back of the discs
Sharpness to touch after each cycle of 50 strokes, compared to a new disc of each type
Surface finish left on the timber
# of strokes to remove the pencil line
Material removed from the board – thickness reduction


and some of those sections will have photographs.

The ultimate aim is to determine which of them gives the best bang for buck. If a 50% more expensive abrasive lasts twice as long then it's a better buy. However, for a low volume user if they are only available in quantities of 50 or 100 then they are probably cost prohibitive.

The same sort of logic applies to speed of material removal, but this is far more relevant to a pro where time is money.

There are various aspects of the results that may appeal to people in different ways. One little quirky thing, for example, is that the Jöst discs are much easier and quicker (for me) to attach. This is because one doesn't bother trying to line up as many of the little holes as possible with the DE holes. One just whacks it on, and it works, and will work just the same even if it is a bit eccentric. With the 17 hole discsneed to be pretty much smack on, and I have found that the most accurate way of lining up all those 17 holes is to insert three 6mm dowels into three holes and drop it over them. Easy enough but just an extra little PITA every disc change.

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Originally Posted by BobL

....the methodology.opinion/results of tester can be challenged. Testers should try to take this in a positive light and use the ideas presented to improve their testing if they wish.

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Indeed Bob, indeed. I'm all for getting the best possible/most accurate results and if others can contribute some ideas in a courteous manner, then let's go and it will be taken on board.

However, when someone is just not capable of being courteous when it comes to anything I might have to say (because I exist), and will go to any lengths to score an imaginary point in some imaginary war they are waging, even when, as we have seen, the substance has not yet been revealed, then they can only be seen as deliberately inflammatory for the hell of it. As such, they will never be taken seriously, or have their suggestions heeded.

Thanks for the info FF and good on for giving this a go even if it is subjective.

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Originally Posted by FenceFurniture

That will become clearer when I put up my results Bob. I've just finished my report on the 80g jobbies and the headings are:
Dust left on the surface
Clogging of the abrasive face
Dust left on the back of the discs
Sharpness to touch after each cycle of 50 strokes, compared to a new disc of each type
Surface finish left on the timber
# of strokes to remove the pencil line
Material removed from the board – thickness reduction

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Of these
- The first and 3rd are too dependent on other variables and machinery being used (In particular the DC system being used) to worry about and they certainly wouldn't be significant to me about whether I choose one abrasive over another.
- the second may be worth knowing but is also bound up with machinery. How do proposed to asses that. I would use weight gain by the disc see my comment on #7. I usually don't worry about clogging unless it compromises stock removal rate or smoothness.
- the 4th one is too subjective and like the second one, does it really matter, if the abrasive is clogged or blunt but still rapidly removing stock in a smooth way?
- #5 is fine but how will you quantify it
- #6 us a really good one provided you can generate the same pressure pencil line across the wood. I'd suggest drilling a hole in a piece of wood and jamming the pencil in the hole and then dragging that across the piece of wood being marked. That way you will get the same downward force each time
- #7 is the one I would be most interested in. I doubt you can measure that evenly enough across a piece of wood with a standard calliper. Even if you had a deep throated calliper you would have to measure many points and then get a true average i.e. a lot of work. The way I would do it is by weight. If a 300 x 15 x 12 mm board of density of 0.5 g/cc is used this would weigh ~270g - using a 300g balance that can measure to 0.01g ($10 on ebay) a true average thickness reduction of 0.01/270*12 or 0.00044mm could be rapidly detected. If nothing else this would save a heap of time.

The sort of info that I would be mostly interested in is'
When new, how quickly does the abrasive remove stock
After X square m or Y minutes use, how quickly does the abrasive reduce stock.
Repeat pervious Z times to show trend over time.
To avoid operator the pressure on the sander needs to be applied in a way that is not directly influenced by the operator. Perhaps a weight could be added to the sander and the operator is only permitted to move it side to side.
I would be interested to know this for hard and soft wood and also on clean and abrasive wood.

Going back to #5, the smoothness and consistency of the finish is something I'd be interested in
The average smoothness can be semi quantitatively assessed using friction tests.
There are standardised tests for this invoking a devices called a "turtle"
Basically it measures the force needed to drag a piece of a "standard material" across the surface being assessed.
Place a block of wood on the surface and connect that to a length of string and through a pulley fixed to the end of the surface being assessed.
Then on the end of the string add weights until the block of wood starts to move.
It's a tad more complicated than this but at least its quantitative and largely removes the experimenter from the picture.

I hope you can get some useful ideas from this.

Yeah I agree that some of those headings a pretty irrelevant (and I concur with your thoughts actually, on which are and which aren't), but they are the observations that I made throughout the process. If they were left out then there would be criticism from somewhere. Two years ago when some Jöst papers were sent out, one tester seemed to think that dust on the back of the disc was a problem and was somewhat critical of them for this, but didn't specify why it mattered.

Some, such as sharpness are very subjective.

As far as I'm concerned there are really only two parameters that really matter - material removal and durability verses cost. One can expect that DE would be the same across the 17 hole papers (why would it be different), and that the surface finish from the same grits would be pretty much the same. However, there are some variations in that second one.

Hey, I'd love to have, or have access to, the proper instruments that can measure these things with accuracy and relevance, but I don't, so I can only give it my best shot. If it was a report for a magazine then it would have to be done with those sort of instruments. All those variables that you correctly speak of can be pretty much ironed out with averaging, which is one of the reasons why I did them all in cycles of 50, repeat, repeat, repeat.

I believe that once the results and opinions of the four testers are up, then people will be able to make up their own minds, particularly if there is more concurrence than not. If my results are consistently at odds with others (bearing in mind that there are another 5 grits for me to test) then I'd say that a claim of bias could be substantiated.

Btw, the most obvious way to measure material removal is to weight the board after each cycle (think you might have said that), but the problem is having a set of scales that will weigh to a tenth of a gram (which is probably the level required), but also be able to weigh a ten kilo board or whatever the one I used is. I have both types of scales, but not as one unit. My little gemmologist's scales will weigh to a tenth gram, but only up to 100 grams or similar.

So, I'm stuck with measuring thickness.

I can see that any criticism of the test at the moment is premature. Clearly it is an appetite whetner at this stage with the all testers still to submit their results. I can see where laboratory conditions and equipment would be ideal, but reasonably speaking these are not available to us.

So I think we should be content with a general appraisal for the range of abrasives. That in itself is much more than has been commonly available until now. We may have to accept that it is not ideal. I quite like people stating their prejudices. It means they themselves have an awareness they are biased and equally everybody is aware of the same thing and can make allowances if they think it neccessary.

I don't believe Brett's self-confessed bias will prevent him prefering an alternative brand if he finds one to be better. In fact I have a prejudice against at least one of the brands Brett has identified for testing, but it is certainly not my place to mention it at this stage. Indeed, it may be me that is the problem (bad workmen blame their tools etc.etc).

For me, I welcome these evaluations as at worst it provides more information than was previously available and at best it introduces a whole new range of options.

I trust this will be a comparrison of abrasives and not an abrasive comparison. It is up to us.

Holding my breath (in a series of short bursts) for the outcome.

Regards
Paul

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Originally Posted by Bushmiller

I trust this will be a comparrison of abrasives and not an abrasive comparison. It is up to us.
l

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10/10 for the joke and the sentiments. :2tsup:

I agree we are not all experts at testing and experiments but there are often very simple tests that can be done to quantify performance.
I think I have said this before but I will say it again. Before folks launch into spending a lot of time testing, it might, and I will stress "might" be useful to run the proposed tests past the forums to get some simple ideas for better quantifying testing.

Some folks on the forum know how to do this naturally, and there are others that have been especially trained and spent many years of their working lives as quantitative testers of some sort or another, should be able suggested ways of quantitative testing that don't necessarily require a "laboratory" or expensive "lab apparatus". We are not usually afraid to ask questions about tools and machines so I can't see why questions can't be asked about ways of testing.

The rate of stock removal I have suggested can be improved significantly simply by using a balance, and the degree of smoothness can be assessed with a friction plate and a few weights.
The degrees of smoothness test using a friction plate is quite time consuming and requires some finessing but is not out of the question for a DIY.
While the results obtained with a friction plate are not as definitive as the stock removal test it still provides a numerical result that can be used for comparison between testers and for punters to make more informed judgements.

Just got off the phone from Klingspor Australia. Very helpful chap called Paul Hoye. He's going to send me some sample abrasives from the other wood ranges, including some film substrates. These will be in the same grits as the ones to be tested, so depending on how many he sends and the timing I may be able to spin these out to the other three.

So, I have a small conundrum, for the next stage of testing. For me this comes in two parts, as I regard the 80g as a stock remover and it is usually my starting point for "hogging off". Grits above that I just regard as the next grit in getting to the final grit.

That means there are two different sets of values to consider:
1. Pure stock removal (80 grit)
2. Surface condition (all other grits)

and therefore two different test sets. Obviously with both test sets the durability of the disc is critically important (this is all about bang for buck with a good finish :B).

So, what I have in mind for the second round of >80grit discs is the following:

• Put the board back through the thicknesser, to get a fresh flat face.
• Before testing each disc, go over the face of the board with enough strokes of the grit underneath the one to be tested to replicate the next stage in sanding. That is to say, before testing the 120g I would go over the board with a 100g disc to leave a 100g scratch pattern and see how long it takes to get it out.
• Put the pencil mark over the top of the 100g (or whatever it is for the grit in question - 320g tests would be preceded by 240g each time etc). My thinking here is that when the pencil mark is removed then that probably coincides with when the scratch pattern from the preceding grit is removed.
• Then see how many times each disc can do the same thing in a satisfactory time to assess durability. That would probably be when the number of strokes required is 25% more than when the disc was new. Maybe a slightly higher % but I can play that by ear and adjust accordingly.

I'll do a bit of a test later to see how well the pencil line removal coincides with when I think I would go up to the next grit in the process.

Of course, when we are sanding a job under non-testing circumstances it is indeed very subjective as to when we proceed to the next grit. We would move up when we think it "feels about right" to. Nothing particularly quantitative about that.

To get a consistent pressure with the pencil I can insert it into a board with a weight on it to maintain the same pressure, and just guide it over the board to be sanded. O'course the pencil will need to be revolved around to keep the line at a reasonably consistent width. The one I have been using is a massive 5mm thick jobbie. The 0.5mm one will scribe to fine a line I believe. I may have a slightly thicker one in the drawer.

So, what say the brains trust?

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Originally Posted by FenceFurniture

ABRASIVES INDUSTRIAL

• The die that has been used for punching the 17 hole pattern has deformed the coarser grits to the point where they will not stick properly to the sanding pad - the hole edges are raised up by up to 2mm which prevents the rest of the disc making proper contact. Care had to be taken to ensure as much contact as possible, so that the disc didn't fly off. Having said that, I did not experience any problems because of this improperly formed hole (on the only grit tested so far - 80g), but this deformity needs to be addressed. It remains to be seen how it affects the more delicate fine grits (the hole deformation is different).

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This is what I mean about the holes being raised up:

https://www.woodworkforums.com/attach...9&d=1409130943


This is how they should be:

https://www.woodworkforums.com/attach...8&d=1409130938

The Pencil method will give some quantitative information which is will be useful provided some way of determining if there is any pencil mark left can be worked out.

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Originally Posted by FenceFurniture

Of course, when we are sanding a job under non-testing circumstances it is indeed very subjective as to when we proceed to the next grit. We would move up when we think it "feels about right" to. Nothing particularly quantitative about that.

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This is where the friction plate would be really useful because it will measure surface friction The sanding would then be performed until the surface reached a constant friction - further sanding just removes stock and will not improve the so this give the point at which the next grit should be used. The measurements could be a bit tedious.

To be quantitative the testing should be done on the same piece of wood and sanded back to the same surface friction using one brand of paper, otherwise the effect of the previous paper will impact on the result for the next paper. If you want to test the range of grits out as a complete system then that would be a separate test - maybe this is what you are trying to test?

t

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Originally Posted by BobL

The Pencil method will give some quantitative information which is will be useful provided some way of determining if there is any pencil mark left can be worked out.

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Visual will have to do - it's what we would normally do if there was a mark there. If you can't see it but there are traces of it there then it wouldn't matter anyway.

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Originally Posted by BobL

This is where the friction plate would be really useful because it will measure surface friction The sanding would then be performed until the surface reached a constant friction - further sanding just removes stock and will not improve the so this give the point at which the next grit should be used. The measurements could be a bit tedious.

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I reckon they would be very tedious. A little earlier I tried the pencil method using a new 120g on a surface sanded previously by a new 100g. It only took four strokes to visually remove it. That means that going through the cycles enough times to find out where the papers are starting to be less useful is going be extremely tedious in itself. I suppose I could speed that up by seeing how long it takes to remove the pencil mark after a cycle of 50 strokes (as there is a reasonable expectation the you'd get 50 strokes out of any disc worth it's salt, regardless of how fine it is).

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Originally Posted by BobL

To be quantitative the testing should be done on the same piece of wood and sanded back to the same surface friction using one brand of paper, otherwise the effect of the previous paper will impact on the result for the next paper. If you want to test the range of grits out as a complete system then that would be a separate test - maybe this is what you are trying to test?

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That's what I said I would be doing in the previous post. No, not trying to find the best suite of grits, just the best performer in each grit. However, I think one could reasonably expect that this may well be the same brand over the different grits in the second range of testing. I mean, it would hardly be a surprise to find that the same brand is consistently the best performer.

One problem I see with the testing, in fact any testing, is that is is besides being relatively tedious it is also very demanding on time. It is why there are probably relatively few instances of extensive testing being performed outside of commercial or sponsored studies.

It is for that reason I am quite happy to encourage anybody prepared to commit time to such activities. It seems to me they get relatively little out of it compared to the rest of us, who tend to sit back and criticise. Such tests can be expensive as well as time consuming. There is another factor that is too easily forgotten and it is that in a forum such as this there is much more transparency than say a company commissioning a test. If it doesn't suit them, they don't have to publish. It didn't come up with a result that suits their agenda so that is the last that is heard.

Now having said all that I am going to make an observation (I hesitate to call it criticism) and it as to the use of the pencil and the length of time it take to sand a pencil mark away.

The pressure exerted on the pencil is critical to my mind: In fact more so than the sanding pressure on the ROS. Any pressure on an ROS beyond the weight of the machine will be detrimental to the life of the sandpaper. consequently I would suggest that merely the ROS weight is utilised. It will be constant and allows just for sideways motion. If you have to exert pressure the sanding disc has lost it's cutting power.

So back to the pencil mark. If pressure is exerted, the pencil will leave a deep mark in the timber with more sanding required to erase it. Consequently a consistent method of marking the timber is required. I don't see that a hole in a piece of timber will work to hold it at a constant height as the pencil point will be worn down as you go. Clearly the pressure at the point will change. I don't think the width of pencil matters much other than to slow down the wearing down of the point. On that basis a carpenter's pencil would probably be better.

I don't know the solution: Only the problem.

Regards
Paul

It's starting to sound like it may not be a good idea to publish the results.

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Originally Posted by Bushmiller

One problem I see with the testing, in fact any testing, is that is is besides being relatively tedious it is also very demanding on time.

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So far I have spent:

• researching abrasives and their availability, about 6-8 hours
• Purchasing, organising freight (including one lost package for two weeks, and the time involved in tracking it down), assembling the various packages to go to the testers, emails of general instructions, liaising with another supplier and getting them to produce a 17 hole die for an even playing field about 6 hours
• Preparing spreadsheets, preparing timber about 1½ hours
• Sanding with just one grit in the range, taking about 50 different photographs, about 6 hours and significant fatigue to go with it (sanding 1.8 kilometres is pretty taxing)
• Writing the report on just that one grit, uploading photos to the computer, cropping, resizing etc in Photoshop, uploading to the forum about 9-10 hours
• Writing posts about 3 hours

So that's a total of about 33 hours, and there are 5 grits to go. I have tested 5 out of 23 discs, but there may be a few more to arrive from Klingspor following my conversation today (sounds like about 6-8 different discs).

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Originally Posted by Bushmiller

Such tests can be expensive as well as time consuming.

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So far I have spent about $140 on purchases and postage. I will have some discs leftover from that.

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Originally Posted by Bushmiller

It seems to me they (the testers) get relatively little out of it compared to the rest of us, who tend to sit back and criticise.

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There is absolutely nil benefit to me in publishing these results on the forum. None whatsoever. I started this thread thinking that the results might be useful to those who are capable of reading without prejudice, and who may have enjoyed the spirit that the thread was started in.

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Originally Posted by Bushmiller

Any pressure on an ROS beyond the weight of the machine will be detrimental to the life of the sandpaper. consequently I would suggest that merely the ROS weight is utilised.

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This is already going to take long enough by exerting the usual amount of pressure that I would on a sander (which is apparently about 9kgs, for coarse work anyway). Maybe I need a lesson on how to sand. Using only the weight of the sander will add a prohibitive amount of time and strokes, and as such, is not going to happen.


There is a reason why I have pointed these things out, and I'll come back to that.


So far, there is one poster that just wants to criticise for the sake of it, and tell me how wrong (again) and biased the whole exercise is. This is to be expected. There are two other occasions where methodology suggestions have been made, that have already been put in place (using the same piece of timber, and a larger pencil). I had previously stated that I was going to be using the same piece of timber, and that the pencil I used for marking was 5mm thick (and that's a cylinder, btw).

My point is that people are already not taking in the detail that has been provided, and suggesting I do what has already been done. If this is the way that it is before any results have even been published, what is it going to be like when all the test data has to be digested and comprehended? Should I really set myself up for that???

Given that there is no benefit to me in publishing the results here, and given that I am quite clearly just going to open myself up to whatever grief in whatever form it may come, and given that the spirit of this thread is already tainted, I think the prudent thing to do will be to keep the results private.

I'll sleep on that and make a decision tomorrow.

Brett

I hope that after a sleep you will feel it is worthwhile to continue:Personally I think it is important that you continue. As I mentioned before, it will provide a good supply of hitherto unavailable information. Sanding is a big part of woodworking but arguably does not carry the "glory" of some other operations (planing, cutting etc).

From my previous post:

"It is for that reason I am quite happy to encourage anybody prepared to commit time to such activities. It seems to me they get relatively little out of it compared to the rest of us, who tend to sit back and criticise. "

The work you put in is appreciated both in this thread and others such as the saw files, which was/is an epic. There is always a detractor somewhere, but plenty of others who appreciate the effort and the results.

Go for it!

Regards
Paul

Paul, to be clear the testing will continue - it's a matter of whether or not I put the results up here, for the reasons described. It may be that I'll leave it at if someone wants to see the report then they can send me a PM and request it.

RE: Time and effort needed to do testing.
Welcome to the world of testing :D

All the testing I have done (both as part of my old day job and associated with this forum) has been " time wise" in a similar vein.
I now only do it because I'm interested and post what I think some folks might find useful
Constructive criticism (not all seen by the tester as constructive) can be very irritating but is an essential part of the process because it does improve things.
Non-constructive criticism is inevitable and can drive experimenters around the bend so it's far easier to ignore than to fight it - that is if you want to stay sane. :)
It can get so bad that you can spend all of your time dealing with critics and get little else done.
just draw a line somewhere and don't cross it and get back to testing. :2tsup:

Quote:

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Originally Posted by BobL

It can get so bad that you can spend all of your time dealing with critics and get little else done.

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And I have little interest in dealing with critics when they are ctitical of a technique that they have either read incorrectly or are suggesting it be done a certain way, when it already has. Unfortunately though, the effect of this unfounded criticism is unknown upon other readers, and one doesn't know if it's just a waste of time. Then there is the wasted time correcting the critics unfounded criticism, which also just clogs up the thread.

Quote:

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Originally Posted by BobL

just draw a line somewhere and don't cross it and get back to testing. :2tsup:

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And that line could be getting the report sent in private with the caveat that the tests have been done to the best standard can manage with the non-lab equipment available. The readers could either accept that the tests have been conducted in good faith, and for example the pressure on the pencil is reasonably consistent, and averaged over several repetitions to iron out any inconsistencies, or not.

At least that way the prospect of a public spectacle is obviated, and currently it's difficult to see this not turning into a spectacle.

Brett
Keep going there is probely a tone of us reading this and not saying much.
But enjoying it and gaining from your hard work.And thank you.
In my own business 95% of my clients are fantastic
5% of my clients take up quite a bit off time
I focus on the 95 percent the five percent I as a rule generally only work for once.
At a guess I would say 95% percent off us here can't wait for the finally conclusion
We all know how it's being done
And we can then decide what we think.
Keep up the great sanding
Matt

Here are some things that might help.

1. Pencil mark and scratches

It was my experience in setting up a protocol for hard burnishing, that it was better to run a set of sanding strokes rather than sand to "what felt right".
I use 10 up and back strokes (20 total) with each pad, then move to the next. It may be better to use something like this in your study.
Define an area of the board, say 1 metre x (x) width and keep your answers to the results you get from this area.
For scratches and pencil line, you can award a point system.
Mark 1 for no change from one grit to the other, 2 for some removal of scratches and 3 for total removal of scratches. By using 10 up and backs, you can display results as % efficiency by comparing the grit's value against the mean. It is important not to deliberately focus on areas which show severe scratching or try to erase the pencil mark.

While you are doing this stock removal, you can set a Vernier Caliper to the starting depth of the piece of timber, then measure the final depth for each grit you use and record it. Repeat for each grit.

I think that each users normal routine for sanding should be adequate for a study like this. You can include these as "acceptable" normal variations. The same is true also for how the sander is passed over the surface. (Though any serious outliers from the means you generate should be seriously questioned)

To make for consistent measuring, reset the vernier for each grit. You can then add the values for each run and define a mean. Anything that looks way out should not be used to establish the mean. Once you have the mean you can derive a % varianace from the mean. Either that or you can graph the mean versus the value of the stock removed and directly compare efficiency.

You may be able to measure longevity of the pads by running each again after the initial run and measuring again the amount of stock removed and quality of the finish.

It is very important that you all use the same timber, preferably from the one board. If you can't do that, then set the type of timber to be used. I would suggest either "Tas" Oak or radiata Pine. You will get more data probably using the pine (it would probably show greater variation between operators too.)

Values for dust produced and where it lands don't really have a place in this study. What they tell you is really how efficient your D/E is.

What ever way you decide to go FF, kudos for giving it a go. Sounds like a lot of hard work and I would be very appreciative of knowing how things pan out.

I have come to a conclusion on publishing the results, and have taken a few things into consideration to arrive at this conclusion:

1. The other testers don't seem to have concluded (not even sure if they have started), and I wouldn't publish any of the results until they are all finished
2. There are some people who would like to see the results, and I already have some results from my testing, and should have finished in about 36 hours.
3. As I have previously described, in my opinion there are two test sets: one for the coarse starting grit, which in this case is 80 (and is also my normal starting grit), and another test set for the grits finer than 80. The first test set revolves around sheer material removal (not particularly interested in surface finish), and the second is purely refinement of finish (not particularly interested in material removal quantity).
4. I do not wish this thread to degenerate as some other threads have, in terms of "it should have been done this way" or "this is rubbish because everything you do is rubbish in my opinion, regardless of how good it is, or how useful it might be to other people". And that second one is pretty damn common from one quarter. That means that the report will not necessarily be made available to everyone who asks.

So, with all that in mind, I am going to make the report available to people who request it by PM.

The report on 80g is finished, and BobL has already read it two days ago. Therefore there can be no changes to that report, and there certainly won't be any changes to the methodology.

Whether or not the final report (with all tester's notes) is published on the forum remains to be seen, and so that decision can be made later. The testers may simply decide to publish their reports on here, and that is most certainly their prerogative if they wish to.

As for my methodology, the readers can make up their own minds as to whether there is any bias or incompetence. Bob is most welcome to post his thoughts on the competence of the methodology and the fairness of the 80g report.

For those who receive the report: you are welcome to comment in general in the thread at this stage, but remember that the other testers have not finished so don't spill the results in your posts.

At the moment the 80g report is in a word document with BBcodes, ready for posting on to here, so it will take me a little while (tomorrow) to replace the BBcodes with the actual images, and then turn it into a PDF. The people who are on my email list will receive this report in due course anyway (at the end of all testing), but you may wish to have a look sooner than that, so send a PM.

I believe I have solved the consistent pressure problem for the pencil line in the second group of tests. Following Bob's suggestion I mounted (glued into a hole) a pencil in a small block and then dragged that in a wave motion down the board with the heel of the block always in contact with the main board (i.e. not lifting the heel which would vary the pressure), and noted how many strokes it took to remove it. I purchased a 0.7 mechanical clutch pencil with some 2B leads. I would have preferred a 1mm lead pencil but there was not one available.

As it turns out, the 0.7 is absolutely ok, and is producing results consistent with predictions*. Furthermore it is consistent with the results I got from the 80g test where I was drawing the wave freehand. When the lead becomes too short it is simply a matter of a click on the button to show some new lead. My original concern with this technique turned out to be quite unfounded - I thought that a fine pencil might dig in to form a scratch. Using this type of pencil ensures that a consistent diameter of graphite is in contact with the board.

*There was one aspect the went exactly the opposite of what I had thought, but when I thought about it, it made perfect sense. That is, I had figured that the number of sanding strokes to remove the line would increase as the grits got finer (because the grits are becoming less aggressive). Exactly the opposite was the case, which created a furrowed brow and narrowed eyes until I figured out why. Pretty simple really. For this second round of tests where I am really only interested in how long it takes to get the finish of the board up to the next level of smoothness, I am preceding each different disc with 10 strokes of the grit below it. That is too say that for testing each of the four disc in the 120g range, i do 10 strokes with a 100g disc before each new disc. For 180g they are preceded by a 150g disc, and so on.

Well of course the surface that I apply the pencil line to is smoother than it used to be, and so the graphite doesn't have as many hills and craters to be erased from. Thus, the number of strokes to remove the line becomes less as the grits get finer because the surface is smoother to start with.

Furthermore, this notion was vindicated when I noticed that the given protrusion of lead between clicks was laster longer as I moved up to finer grits. Obviously the smoother surface of the timber does not abrade the graphite as much.



As for using the same species of timber for all the testers, and preferably from the same board: I disagree. As long as each tester uses the same piece of timber (as I have) then that is all that is required. If the species vary from tester to tester then that just gives us a better idea of how the same abrasives perform on different species, and that of course is very worthwhile information. If there are wild variations in the results, from wildly different species (hardness, abrasion) then we may have to figure out why that might be, but it most certainly WILL NOT be because of bias.

Quite frankly, I think it's an affront to suggest that someone would be biased, particularly as that claim was made before even the methodology had been revealed or reported, let alone the results.

I think many people will also appreciate subjective experience ... may even filter out all the details about attempted fairness of comparisons.

I think some people might respond to, eg ... FF's opinions were XYZ. I've seen the sort of work he's interested in ... or I can search back and check some of it out ... and if he thinks ABC is pretty good then that's ok by me.

I assume people would also take into consideration any commercial interest that might or might not exist ... Youtube videos are like that. There are people you get to know over time ... they voice their opinions and we evaluate the opinions based on what we have seen of them as a person. If they work for a company, or benefit from a product we tae that into account ... we've all seen infomercial stuff that would have you saying "Hang on, hang on ..."

I'm all for carefully measured results ... but sometimes a "rough evaluation" (not labelling this effort as that) is quick and sufficient to come up with some indications pretty painlessly. eg we don't need a microscope to tell an aardvark from an artichoke.

In fact you might well possibly think ... if the difference requires careful measurement to detect ... then for many people it would be sufficient to say there is little difference. I think Bob's instinct is to try to be certain there really is little difference, or there really is a large difference ... but you can also modify the aims to suit the methodology ... vs modifying the methodology to suit the aims.

Cheers,
Paul

That's well said Paul.

Quantifying is important for determining small differences, isolating one aspect that may be the determining factor, and vindicating a previously held "gut" feel. It is also important for determining the relevance of certain observations and whether is worth continuing to note them.

The two different test sets have highlighted much of this, and should help to disparage any prejudices to a fair minded person. In the first test set I made note of everything i could observe, and as others have said, some of them weren't relevant, such as the dust left on the job. Some of these observations were dropped for the second test set to a) de-clutter the reading of the results (which can be tedious for many people, particularly those who have little tolerance for minor detail - that's not a criticism - some just want to cut to the chase) and b) speed up the process.

As I have mentioned before, and this won't give anything away, there has previously been criticism of Jöst from a couple of other people because dust gathers on the back of the disc. Had I not made note of the dust left on the job and showed the pics of the disc backs then those people would no doubt have been baying for blood that I did not take observations of this and would have remained convinced that the dust on the job must be an issue because it can't look like that on the back and have been effective at removing dust from the job.

My observations have now proved that it is just not an issue, although I very much doubt that will be convincing enough for at least one of those people (who has, by the way, never responded to an opportunity to sample the discs for himself - he would rather maintain the prejudice in ignorance - perhaps because he didn't want to run the risk of being proved wrong).

Another very relevant example is starting to emerge from the second test set: one disc is the quickest at removing the pencil, but curiously it also yields the smoothest finish. "How can that be?" one could quite rightly ask. The answer is "I dunno, but them's the facts". It would seem completely counter-intuitive that the smoothest surface comes from the disc that gets the smooth surface quickest, but that's the way it is.

In the first test set I didn't need any measurements at all to work out which was the best disc - the difference was stark, but the numbers will back up my comments.

The 80 grit report is ready now for those who would like it.

I've thought of some other things that may help with the evaluation
1. Are all the Festool 150's the same? i.e. Are they all 150/3's or are there 5's and 3' mixed together. One would hope that a larger stroke would give a result different to a smaller stroke.
2. Are all operators operating at the same speed. If you are reviewing this data, you might want to check that. If you operate at a different speed, the results may not apply to your situation.
3. Since each operator seems to be using a different timber rather than a standard piece of wood, how will you achieve a test of reproducibilty? Also, one timber will probably affect the sanding pad differently to another. How can you compare apples to oranges?

That's enough for now I think.

It's not an attempt to get identical data from each tester, nor is it a laboratory test - it's all about what four different testers think of the different abrasives, and why they think that.

After all, woodworkers operate in different ways, with different timbers, with different sanders, to different levels of finish, with different pressures on the sanders, with different dust extractions systems, and so it goes on. BUT the abrasive manufacturer would like to sell their abrasives to as many different woodworkers as possible.

To follow your line of logic the tests would have to be done by (say) four different testers, on each of (say) six different sanders, on each of (say) four different species. That's a total of 96 different testers.

If someone wants to fund and organise all that, and then collate the data (kee-rist that would be a job) then they are very welcome to.

Just within my own testing (now ready to start the 320 grit stage) I'm seeing patterns emerge, some more definite than others, and where the patterns are closer together there are other factors which separate the different discs, such as purchase price and smoothness of operation. What I mean by that is that a consumer has to make one only choice when buying a brand of grit. They may choose to have different brands across the range in different grits (as I will) but i think it highly unlikely that an amateur woodworker would have two brands of 120, 2x180 and so on, just to suit subtle nuances. A handyman, on the other hand, may well have two types in the same grit - one open coat abrasive for paint, varnish etc, and a closed coat for timber. They never know what they are coming up against. They may even have a third type for metals for all I know.

There may be one or two exceptions to that at the ends of the grit range - e.g. I may end up stocking two types of 80g for two different hogging off purposes, and certainly at the very fine end I could very well end up stocking two brands of the same grits (in 800 upwards). This will depend on tomorrow's round of testing, but the Jöst "SG2" very fine grits are the same as the Platin 2 in that they are on 3mm sponge. You would be aware that this soft sponge will cause a very slight rounding over of edges even when used with a hard pad, which is sometimes not desirable. The other brands of very fine grits (including the Jöst ceramic on film range) don't have the sponge and I would anticipate that the sharp edge of the board will be retained.

So, all in all, there is other very useful information that is coming out of this testing, as well as the original goal of finding which are the durable brands in a price v performance situation.

I don't know about you, but I find the "jagging" (where the sander just wants to zip off in another direction - constant push and pull) of the 17 hole disc very fatiguing on a long sanding job. Towards the end of the job I find it downright aggravating (and have just done another 2.4 kilometres this arvo). That would be another separating factor, along with price.

EDIT: meant to say that there is one 17 hole disc brand where this jagging, although still present, as vastly reduced compared to two of the other brands. I don't understand it, I'm afraid.

Well said!

Quote:

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Originally Posted by LGS

Well said!

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¿Que?

Quote:

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Originally Posted by FenceFurniture

I don't know about you, but I find the "jagging" (where the sander just wants to zip off in another direction - constant push and pull) of the 17 hole disc very fatiguing on a long sanding job. Towards the end of the job I find it downright aggravating (and have just done another 2.4 kilometres this arvo). That would be another separating factor, along with price.

EDIT: meant to say that there is one 17 hole disc brand where this jagging, although still present, as vastly reduced compared to two of the other brands. I don't understand it, I'm afraid.

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What's your experience of this phenomenon?

I think it's worth remembering here...

We're talking about sanding discs. The testing isn't on relative merits of expensive gear.

Accept the parameters of the testing, understand that it's not an exhaustive test performed in a lab environment, realise that it's going to be a least a bit subjective, take the information in good faith and move on.

If you've got good ideas about the testing practices, share them but seriously, if someone doing this testing rubs you up the wrong way.

Buy your own sandpaper and do the test yourself.

I for one, am very interested in the results.

So, I dropped in on Brett t'other day for a beer and a story... and of course I had to poke around in his disks and take some for a test drive.

I think it's an understatement to say that I was favourably impressed with the results from some of the disks we played with. "Wow" is probably closer to the mark.

The end surface of the piece we were playing with ended up with a close to mirror finish using what, to me, was a ridiculously low grit. To achieve the same with my el-cheapo paper I'd have been up into my automotive wet'n'drys. Probably somewhere between 8k and 12k (depending on the timber, of course!)

I, for one, am definitely interested in Brett's final results. I thought there'd be some differences, of course, but this much? :oo:

Skew, I insist on accuracy in this thread.




It was 2 beers. :D

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Originally Posted by FenceFurniture

Skew, I insist on accuracy in this thread.




It was 2 beers. :D

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only 2?

Hah

anyway

to the testers undertaking this process - thankyou

http://d1r5wj36adg1sk.cloudfront.net...cons/icon1.png Time to change sanding disk brands

Brett kindly sent me his first review. Very informative and interesting. It may be subjective and not 100% scientific as one poster said but so is wine tasting and its all useful information and good enough for mehttp://d1r5wj36adg1sk.cloudfront.net...rd/biggrin.gif. Keep up the testing, very useful.From the information already, I will be changing over from my stock standard product from the Green Shed and going "up market" Happy to pay twice as much if the disks last three times as long. It has long been a source of annoyance to me that the disks I have been purchasing have to be changed every few minutes to keep the sanding process going at a reasonable pace. A little off topic, butI have been doing a little side reading on the health risks of dust and this tells me I should be using perforated disks and attach the vacuum hose!! I didn't even know that there are specific nasal cancers caused by wood dust inhalationhttp://d1r5wj36adg1sk.cloudfront.net...andard/mad.gif. Duh, obvious when I think about it. With the amount of dust I have inhaled over the years its lucky I don't smoke. Time to be sensible.
Keep up the good work, I look forward to the next instalment

Quote:

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Originally Posted by kikuyu

...I should be using perforated disks and attach the vacuum hose!!

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Absolutely! You'll also find that the same type of abrasive discs will last considerably longer with DE happening. It prevents clogging of the abrasive face which creates unnecessary heat (which exacerbates the clogging even more, which creates more heat), and the clogging can prevent the abrasive being in contact with the surface to be sanded.

Also much quicker to clean up, tools and workshop don't get covered in dust.

Oh yeah, and you'll live longer!