Armour /chassis material

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tomboys
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Armour /chassis material

Post by tomboys » Tue Jan 01, 2019 11:44 am

Hello, I have a few questions about making the main body of my robot now I've done the electronics:

I've heard about some of the strengths and weaknesses of using hdpe and polycarbonate, but if you were making the chassis/Armour combined out of them, what are the best ways to connect them?

I've heard about bending hdpe and connecting polycarbonate with nuts and screws. How easy is it to bend polycarbonate?

Has anyone tried these? https://www.fingertechrobotics.com/prod ... d=nutstrip

I don't really have access to 3d printing.
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MarkR
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Re: Armour /chassis material

Post by MarkR » Tue Jan 01, 2019 5:39 pm

About connecting - I use M2 nuts and bolts and they're awful, don't do that :)

If you want to use nuts and bolts, use at least M2.5.

Nylon nuts & bolts are weak but easily replaced and bolts cut to length. Steel bolts are harder to cut down to size (I use a belt sander, it's really tricky to do because the bolt gets very hot very quickly and it's tricky to hold. A dremel grinder also works somewhat.)

Some people seem to use self-tapping screws and small blocks inside, or a 3d printed chassis.

Small pop-rivets also work.

PC is quite easy to bend at room temperature and mostly stays put. Other plastics don't do that so easily and will require heat or an alternative process.

HDPE is a pain to work with in every respect, I've given up using it because it's too tricky and heavy (I notice, watching Bugglebots, that it seems very popular in Beetleweights)
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Charlie_Foxtrot
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Re: Armour /chassis material

Post by Charlie_Foxtrot » Sun Mar 03, 2019 1:08 pm

I would disagree that polycarb is easy to bend and stays put at room temp, as I have found 1mm PC to be quite difficult to bend (at least, without proper equipment), and also quite springy (it won't go back to being flat, but it won't hold a 90 degree bend). If you want to bend PC, I'd recommend either using a heat gun (it doesn't quite melt, but it does become much more malleable above a certain temperature), or a hot wire though I only have some experience with the former.

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Shakey
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Re: Armour /chassis material

Post by Shakey » Wed Mar 06, 2019 8:09 pm

Charlie_Foxtrot wrote:
Sun Mar 03, 2019 1:08 pm
I would disagree that polycarb is easy to bend and stays put at room temp, as I have found 1mm PC to be quite difficult to bend (at least, without proper equipment), and also quite springy (it won't go back to being flat, but it won't hold a 90 degree bend).
As with cold bending nearly all materials you have to 'over bend' it. ie to get it to stay at a 90 degree bend you might have to bend it to 120 and then it springs back to 90 (essentially the balance between elastic and inelastic deformation). I frequetly bend polycarb and once the angle is set it stays there pretty permanently. Bending the polycarb is done easily enough with a vice (can pick them up super cheap) or simply clamping a bit of wood one side of the bend. Smaller bends you might be able to get away with just some pliers.
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