Not trying to hijack your thread mate but rather than spam the forum with another one, I've read about HDPE sometimes warping is there any way to avoid this? Also would say 12mm of HDPE hold up well as a base and what else could I use for the same kind of weight, I guess 3.2mm of hardox would be a fair bit heavier for say a 300mmx200mm size base? Alu?
Aluminium seems to be around 3 times the density of HDPE and Hardox 3 times the density of Aluminium roughly
so a 12mm sheet of hdpe weighs the same as a 4mm sheet of aluminium
a 4mm sheet of aluminium weighs about the same as a 1.3mm sheet of Hardox.
(I think that's correct)
Righto cheers.
1.3mm of hardox seems very thin.. im guessing I should go a bit thicker if I go with HDPE, maybe 16mm?
Density
HDPE 0.95kg dm³
Aluminium. Between 2.7 and 2.9 kg dm³, depending on alloy. (better to err on the heavy side, Always pleasant to have some weight left after building)
Steel (hardox is low alloy steel) 7.9kg dm³
HDPE warping? Yes, it will always try to get into the original shape.
Very surprising to see a crooked wheel go straigth after a few days of rest.
1.3mm Hardox is rare as hens teeth. 3.2 is not rare , and 4mm is easely sourced.
You could do what we did for Perun. Take a big, thick sheet and mill it out to fit everything in.
Last edited by maddox10; 9th August 2016 at 16:18.
Just to say I was only giving you relative densities. Hardness has more variables than you can explain on an internet forum. Usually you need some pretty swanky software to analyse stress.
So HDPE is lighter than I expected, very good thickness to weight ratio. Whats the best way to go about fixing HDPE? My design involves angled bits for those nasty spinners - no 90 degree angles lol. So brackets? Tapping it for the shape I need would be a pain I think, but if it would be better tapped I'll put some time into it (Maybe a combo of tapping a few bolts for the bulkheads into the base along with brackets and brackets for the outer armour.)
That is also a great idea maddox, that base must be bombproof! And cheers higgeh I just was hoping to get an idea of how tried and tested HDPE as a base is for a feather thats all.
I fix HDPE with about any means possible. Ranging from wood screws to bending and welding.
From Ranglebox nutstrips to selfmade barrelnuts. Even Titanium brackets with rivnuts and bolts.
I've been going M6 barrel nuts and tee nuts all the way with my design. Right pain in the arse to get the two right-angled holes aligned properly though. XD I didn't know you could weld HDPE? What do you melt it with?
HDPE is a thermoplastic material, and it's commonly welded with a hot air gun and a specialised nozzle to feed the filler material.
I use the same hot air gun (not the cheap paintstripper stuff, but a fully adjustable Leinster) to bend HDPE.
I thought about using thick and coarse woodscrews, stronger than you'd think I imagine? Interesting about the welding, does the heat not make it warp though?
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