First time chassis help

[Samjw]

Ive been on here for a fair few years, always having the intention of actually getting stuck in band building one. After how ridiculous 2020 has been i though Now’s as good of a time as any!

Ive mocked up a design, drawn out wiring diagrams, and just about got my head around what I’m doing with that side of things.

I don’t plan on ever actually fighting it, (but never say never) so I’ve chosen to make it out of HDPE, however I’m struggling of what to make the actual chassis out of. Originally i thought I’d build it entirely out of HDPE, but I’ve chosen 5mm and 10mm cheer, and I’m thinking its going to be almost impossible to join the two together being so thin, with no internal frame.

Can anyone suggest either a fixing method for 5 and 10mm HDPE, or a material to add some sort of frame work to the inside?

[Mr Manuva27]

Congrats on taking the first step!

First question, which weight class are you planning on building? If you're looking at Beetleweight then 5-10mm HDPE is appropriate. If you are planning on Featherweight, then 10-20mm is probably better suited.

With regards to working with/fixing HDPE, it machines very similar to wood. Wood screws are pretty standard, but worth noting that HDPE doesn't hold a thread well, so if you're planning on undoing certain panels frequently then you will need threaded inserts or barrel bolts. If you're still finding it is too thin, then nutstrip and angle brackets will work too.

Would you mind sharing some pictures of the design you had in mind? May give some idea on how best to mount it.

[Ocracoke]

As Andrew mentions, threaded inserts are your friend here with HDPE but simply bolting through things together is a more robust connection. Depending on your design, you could bend the 5mm HDPE to bolt through that and the 10mm HDPE for a secure fixing. Threaded inserts I would only use on the lid for a BW (or in short, anything you intend on removing regularly).

I don’t plan on ever actually fighting it, (but never say never) so I’ve chosen to make it out of HDPE, however I’m struggling of what to make the actual chassis out of.

I've used HDPE as a chassis for my FWs in the past without much issue (I did try PVC once with my first BW, Shu!... don't use that :P). My current BW, The Honey Badger 4.0, has pine wooden chassis members running across the width of the shell which is what holds it all together. In the FW class, it held up sort of OK but in the BW class its doing fine so far. This is where the threaded inserts go in on that.

[Samjw]

Thank you both for the advice!

I had a play around with things yesterday, And I feel a lot more comfortable with the HDPE now!


I managed to cobble together something that moved around, with a working lifter, and it’s massively helped me get my head around things, also just seeing something I’d made actually function has given me a huge boost!


ive run into a few more issues that I’m trying to figure out.

right now I’m using a 2s lipo to power everything. The 7.4v is obviously underpowered for the 2 x 12v motors. But the esc’s and the receiver can’t handle anything larger. How do I provide more power to the motors, without drying the esc or receiver?


ive also read about people hooking the servo straight to the battery, rather than being powered by the receiver, but again 7.4v is higher than the voltage it would recieve when it’s powered from the receiver?


Although I’ve become even more aware about how much I don’t know, I’m taking huge positives from yesterday’s accomplishment!

[Ocracoke]

Glad to hear some progress is being made!

right now I’m using a 2s lipo to power everything. The 7.4v is obviously underpowered for the 2 x 12v motors. But the esc’s and the receiver can’t handle anything larger. How do I provide more power to the motors, without drying the esc or receiver?

The ESCs often provide power to the receiver through the radio wires at a reduced voltage. So you end up powering the ESC from the battery and it, in turn, powers the receiver. However, this can still overload the receiver so what you may need to do is cut the positive red wire on one of the ESCs to prevent that ESC delivering more voltage to the receiver than it needs.

ive also read about people hooking the servo straight to the battery, rather than being powered by the receiver, but again 7.4v is higher than the voltage it would recieve when it’s powered from the receiver?

If the servo is attached to the receiver (as it sounds like in your case), this may not be a problem. Some servos are marked as HV (high voltage), which one have you got?

[Samjw]

I may try adding a second 2s lipo then, I don’t think that it’s a HV servo, it has been powered from the receiver so far