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We have a sanding challenge to solve. We’re after advice on how we can automate sanding of our bamboo laminated bike handlebars. Here they go www.passchier.co.nz.
The bars vary in diameter from 22.2mm to 29.95mm to 22.2mm, from the end to middle to end…with varying diameter in between. The bar length is up to 760mm long.
Any advice to speed up this process would be much appreciated
Attachment 501390
Best idea gets a set of Passchier Gumps.
Cheers..Dirk
how are you currently doing it and what tools do you have and how much actual sanding is required?
my first thought would be get a few of these with varying degree of grits. at least it would wrap around at least half of the round section and doesn't worry
DETROIT 1300W Pipe Belt Sander DETPBS1300 | Total Tools
Attachment 501413
If the handlebars are not too rough to begin with then sanding mops could be an option. I use 150mm Klingsor mops extensively on rattan poles with good results, in grits from #80 to #400.
They have the advantage that they can handle curved shapes well without needing to be precisely positioned in relation to the item being shaped.
In terms of automation that probably depends on just how automated you are hoping to get. I normally move the rattan by hand back and forth across a mop fixed in a drill press and rotate the rattan a bit each pass to sand all 360°.
To automate things you might move up to a molding sander which is just a really wide sanding mop, and somehow move the handlebar back and forth through it whilst rotating it, or move the sander back and forth whilst rotating the handlebar. A large enough diameter mop could deal with the fact that the handlebars aren't totally straight too.
Good luck in your quest.
P.S. I couldn't open the Attachment 501390 link. Does it contain additional information on related to your question?
Cool handlebars.
I’ve recently acquired an ebike and being geriatric have put bars with an 80mm rise on them.
Re your sanding
I guess the bars are routed or spindle moulded round after sawing the pressings to shape.
I made a batch of Teak chairs for a steam yacht a few decades back and rigged up a gadget to sand the legs.
Turned up an MDF disc with the form on the perimeter which I covered in flexible backed abrasive. This was run on a bobbin sander with the up & down oscillation disabled.
Wonder if you made similar and mounted it on a spindle it might be a starting point.
A few further discs with various grits could be rigged up to sand and push the bars thru at the same time. I’m suggesting sanding with the grain not across it and the end machine being something you just feed the bars in one end and out pops a sanded bar at the other.
Thinking about this whilst writing a few flap wheels in the mix would be nice or if not too much sanding flap wheels for sanding and MDF for moving the bars past them?Attachment 501462
Still have the disc in the junk stash so here’s a photo.
H.
Hi DirkQuote:
Originally Posted by Dirk J
My initial thoughts to speed up the sanding process is to use an industrial robot -- companies in various parts of the world will rent a suitable robot to small scale users like yourself so you are not faced with the upfront capital cost. To use the sanding robot I'd suggest adopting a batch sanding approach. Do all of a batch of bamboo bars using the same grit of paper, change to a finer grit and sand again. Repeat till you get the finish you require.
The sanding robot could be a small footprint (say 900 x 600) 4-axis variable speed CNC machine fitted with either a spiral bit (the finish off the spiral bit may not require sanding) or a sanding bobbin slightly smaller than the smallest radius you need to sand.
Don't forget to include dust collection !!
My next thought is to keep with the batch sanding process, but use a large (say 6 or 9 in) linisher. Do the sanding by hand using the roller at the end of the linisher. BUT hand sanding might introduce too much variability in the dimensional tolerance you are trying to achieve through the centre of each bar.
Again, don't forget the dust collection.
Being in NZ, as a response to Covid initiative, your government might even have a grant program that would cover most of the initial cost of purchasing a suitable machine outright. Worth investigating.
BTW
how are the bamboo bars being sanded at present?
Thank you for your reply. I have seen these sanding machines. i use same technique but by hand this does not make for a perfect round bar. it takes 20 to 30 minutes using half round plastic pipe with grit 80 to 240 grit sandpaper and constant measuring to get round.
Thank you for your response. the bars are CNC machined to o.25mm of tolarance then using a 100mm long half plastic pipe of simalar size with 80 to 240 grit sand paper inside and hand sanding . This takes to much effort and a lot of measuring. A sanding robot sounds perfect but no idea what that would look like.
Thank you .That was awesome never seen a sanding mop used before love you tube. i could use that on some parts of the bar but i dont think it would work on the perfectly 22.2 grips area that i need to achive. thank you
thank you great ideas . Yes the bars are CNC machine to about 0.3mm of actual size and sanded by hand with sandpaper inside 100mm long half pipe of simalar size. and lots of measuring.
Quote:
Originally Posted by Dirk J
Dirk,Quote:
Originally Posted by Dirk J
can you possibly rethink your process.
I understand why the centre of the bar needs to be a very particular size (29.95 mm, though I thought most bike components were metric and that a 29.95 bar diameter would be an undersize to fit in the stem clamp)
But more importantly, why does the rest of the bar need to be round to such a close tolerance?
Would any of your customers notice if the bars were ovoid -- say 22.15 x 22.25 -- at the grip end??
Would any of them notice if the bar between the stem clamp and the bar grips was ever so slightly not a mirror image?
and most importantly, apart from where the stem clamp grips the bar, do the bars even need to be "nearly round". Would a distinct ovoid shape give the bike rider a better feel?
What I'm wondering is, with your bamboo bars, are you chasing the precision of a metal component when do don't need to
i'd also question if the machine finish is that bad that you need to start at 80 grit?
I'd talk to the machinist (if you're not doing it your self) to see what can be done tooling and speed wise to have the machine finish the product for you to a better quality. This may cost a bit more but sounds like the savings in sanding time could be much more beneficial if you only have to sand it slightly with the 240.
What I'm wondering is, with your bamboo bars, are you chasing the precision of a metal component when do don't need to[/QUOTE]
The brake and gear levers etc have to clamp on the bars.
Plus the grips are round.
That being said I’ve fitted ergonomic grips to my peddlies to stop numb hands.
So an oval shape out there could be interesting.
H.
On my peddlies there is enough tolerance in the clamps used to hold the brake levers and gear shifters to accommodate a slightly ovoid bar and/or a bar where the left hand end is not a mirror image of the right hand one.Quote:
Originally Posted by clear out
I have a pneumatic drum sander and a series of flap sanders which leave a beautiful finish on compound curve work. Doing piece work by hand can be very quick and accurate once you get it set up and have a bit of practice. I would be very wary of trying to set up automated machinery unless you are doing well over ten thousand pieces.