Anyone here work with Polystyrene or High Density Foam

[Grumpy John]

I recently purchased a backpack off eBay to carry my drone around in. The trouble is the insert shown in the photo is not included. I have complained and been offered a refund, but the cost of returning the backpack is not worth it.

Does anyone here have any suggestions on the best way to make an insert?

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[FenceFurniture]

Kaizen foam (https://www.timbecon.com.au/site-shop-accessories/general-shop-accessories/kaizen-foam-organizer)?

[elanjacobs]

It'd need hours of machine time to mill those, let alone model them. You could make something less detailed with foam sheets and glue. If you're lucky you might find a styrofoam box that's the right size to start from

[Grumpy John]

I was thinking of going to Clark Rubber and buying sheets of 20mm thick high density foam, or polystyrene and cutting and layering to suit.

I still have the original cardboard packaging that fits in the bag. Would I be able to use this as a mould and cast an insert using something like expanda foam?

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[Chris Parks]

Perhaps they could just send the insert?

[Grumpy John]

Perhaps they could just send the insert?

Already asked, they don't sell the insert, it's just for demo purposes.
I left a bad feedback and comment for them.

[chambezio]

John, I would be using the original paper mashe as a "template" and cut and join foam to make the packing. To make a mould and mess around doing something else would be slow going. High density as well as low density foam and a box cutting knife and a couple of hours and you are away. Use spray on Contact glue where necessary to get the desired layout

[FenceFurniture]

Rightio, I'm gonna go totally left field here.

Would it be possible to reinforce the original cardboard in the same way that pen turners stabilise timber? Put it in a pressure pot or summink? Maybe worth a post in the pens forum to find out. I can't see why it may not work - after all, cardboard used to be timber so they will have the same sort of cell structure.

[Grumpy John]

I'm a lefty, so I like your thinking Brett.
Maybe fibreglass over the cardboard form to build it up on the outside, This would give it strength and make it fit better in the backpack.

[FenceFurniture]

I was thinking resin infusion or similar, but I think you're right in that the outside walls are the main part in need of reinforcing. If they can be made stiff (say with fibreglass) then that will be more than half the battle to keep it in shape.

Perhaps the inside moulding could be painted with epoxy in the right form?

[Chris Parks]

Perhaps spray it with Polyurethane then use (very carefully) a two part expanding foam to fill the voids?

[derekcohen]

All this seems a lot of work for the original cost of the backpack. But ...

I would build a frame out of balsa, not polystyrene. Balsa would be as light and much easier to work with. Round the outside corners. Fibreglass both sides (one layer should be sufficient) and use West Systems epoxy resin.

Regards from Perth

Derek

[Grumpy John]

All this seems a lot of work for the original cost if the backpack. But ...

.................................................

Regards from Perth

Derek

I agree totally Derek, but I like a challenge

Stay tuned, WIP to follow.

[old1955]

I agree totally Derek, but I like a challenge.

And a challenge you have....

Ross

[Chief Tiff]

Try casting an insert using a spray can of insulating foam...

1: Build a cardboard box that will fit in the backpack, cut off a piece for the lid on the bandsaw.

2: Cover the drone, controller etc in Gladwrap. Then cover them again, just to make sure. Two layers minimum.

3: Spray a layer of insulation foam into the bottom of the box, allow to go tacky. Press your drone into the slightly firm foam so that it sinks into it but doesn't overflow or cover any part. Allow to harden. Once hard, any foam that has flowed over the drone can be snapped or carved off.

4: Now cover the hardened foam surface and the drone with more Gladwrap, two layers minimum. Spray a layer of foam into the lid, invert and place the lid in position on top of the box. Add a bit of weight to keep the lid down, don't be scared of a bit of squeeze out.

5: Remove the lid and peel off all the Gladwrap, carve off any squeeze out. You now have a perfectly moulded foam box with lid.

Many manufacturers supply components in packing crates where instead of carefully fitting wooden chocks to hold the item in place, they now just fill polythene bags with expanding foam and jam them between the item and the crate sides. Cheap and very effective!

[q9]

Why not just use expands foam on the reverse of you cardboard packaging? Would add strength and rigidity and simplify everything down to about 3 min of work.

[Grumpy John]

I ended up gluing some 5m coreflute to the cardboard insert and then filled the voids with expanda foam. A bit of trimming and good to go.
It's pretty rough, but it will do the job short term.
I'm going to buy another backpack, this time I'll read the description all the way to the end, including the fine print. I need to remember - "If it sounds too good to be true, it probably is"

Thanks to all for your helpful suggestions.


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[q9]

Perfect! At least the bag is the right size.

I have seen a drone pack for sale in one of the camera stores, it is about $400+...so maybe your bodge job is ok for the money...

[FenceFurniture]

It's pretty rough, but it will do the job short term.
I'm going to buy another backpack, I think you might be surprised how long the cardboard will last now GJ. It will only suffer abrasion, not dinging, I should think. I'd be holding off on buying another backpack for a while yet ..........unless you have enough drones to start a bee hive, that is :D.

Edit: it may still be worthwhile giving it a lick of resin or maybe even CA.

[Grumpy John]

I was thinking of giving it a coat of PVA, I've go 5 litres of it in the shed:D.