It's worrying that NST can crack a 22mm Nylon bulkhead!
HDPE comes in several grades but is generally very soft..... Impressive impact resistance so swings and roundabouts I guess. Our plan for BitzaMk3 is thick HDPE bulkhead so we'll let you know how we get on.
HDPE wouldn't be likely to crack in the same way that the Nylon did, but I would still choose Nylon over it for areas such as spinner bulkheads. It's harder-wearing so can stand up to the forces and revolutions of spinning weapons, whereas with HDPE being softer, although it has a tendency to absorb and spring back from spinner impacts, it's more likely to wear over time and lose its trueness (if that's even a word) potentially resulting in misaligned spinning shafts and such. That in itself can result in more friction in the setup which reduces the potency of the weapon and can exacerbate the situation.
I think the cracking just highlights the amount of power contained in NST's weapon. Whether that was just the one hit or whether the previous hits had partially weakened that area, I don't know. But I think some bracing/beefing up at the front of Drumroll is in order after seeing this :P
HDPE is indeed softer, but it's not that soft. A bit of our bulkhead was cleanly cracked off at MMM. It's not chewed and twisted, it was a clean separation of two pieces. That's the white stuff, though, it might have different properties to the others. Point being it's flexible but isn't beyond use for bulkheads, it seems.
Also I believe Intertia XL's spinner uprights are HDPE?
I personally prefer Nylon as I've found over the years that compared to HDPE, it's better for load-bearing and structural parts as well as for wear resistance. But that's not to say that HDPE can't be used, your two cases of Tormenta 2 and Inertial XL being examples of HDPE serving well.
Ultimately choosing between the two can also come down to personal factors. HDPE is cheaper, lighter and easier to work with than Nylon so it can often boil down to what suits the budget best.
the clue is in boil
I think the secret sauce is in the joining of the materials
I've found HDPE too soft if trying to tap threads into it. I know other roboteers use wood screws which can be cheap and effective.
Personally I prefer to join by using things like angle iron and bolting through the HDPE. Just about everything except the HDPE joins broke on Spur using this method
Boil it
Bolt or screw either some 8mm HDPE or wood to the outside of the bulkheads. On the older chassis with boner/drumroll the HDPE panels on the outside were good at taking the knocks. Nylon was then protected. Or just go for some hardox or titanium, always a good middle ground
I use several systems at once to connect HDPE pannels.Originally Posted by shakesc
Draw out the armor is as little as possible parts. CAD is my favorite here (Cardboard Aided Design)
Take the HDPE sheet, put the CAD on it, and have a go at it with the cutting instrument of choise After that, I bend the pieces using hot air so it folds together. Joints and inserts get screwed together with coarse, long narrow woodscrews (these ain't strength parts, but ease of manufacturing assists).
Then I weld up the joints with the hot air welder.
These welds tend to be brittle. So I strengthen those welds with braces I screw and weld on crosswise to the first welds.
For removable pannels, I use ali blocks I bolt inside the armor, and drill and tap thread in the ali, so the threads have enough meat to do the job. The bolting does the rest.
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