Hi guys!
Greenblitz 4590 from Israel here
In the past we’ve built a WCD chassis using (the equivilent of) 2" x 1" x 0.1" aluminum extrusion. (It’s actually 50mm x 25mm x 3mm). Which still works fine.
For this year we’re thinking about using a 50mm x 20mm x 2mm aluminum extrusion, but we’re a bit uncertain if we should be concerned about the strength of the extrusion.
Wondering if anyone had any experience with using something close to a 2" x 0.75" x 0.075" alu extrusion for a WCD robot?
No experience running 2 x 0.75 but the wall thickness definitely won’t be and issue, I know plenty of team including us have used 2 x 1 x 0.0625 without issue. The only thing to note is that the wall will be too thin to hold a bearing by itself but if your using clamping bearing blocks that’s not an issue.
I don’t see any inherent issue with this kind of setup, especially with bearing blocks. As long as you feel you have enough surface to mount stuff, I guess you’re good. But in terms of strength, I don’t see a reason to be concerned. Keep in mind a lot of COTS components are geared towards mounting to 1" or 2" faces, so you might have some challenges there if you’re going with majority COTS parts.
We ran our 8wd WCD in 2020/2021 using Clamping Versablocks and 2" x 1" x 0.0625" wall aluminum. No issues over two years of practice, at home challenges, and seven days on a real field. Would run again.
The only difference with your .75" extrusion would be the bearings will be closer together on the shaft by 1/4" overall. Shouldn’t be an issue. Using the Versablocks you are getting an actual spacing above an 1". Many teams have run WCDs in 2"x1"x.125" or .1" wall extrusion with bearings pressed into the tubing & no bearing blocks. Your’s have the benefit of being in a thick Versablock for additional support.
Unless its a cheap grade of aluminum & like @Akash_Rastogi points out some COTS parts might not like .75" overall thickness. You should be fine.
I would be much more concerned with the specific aluminum alloy. Stick with 6061 – the only time we had anything bend was when I picked up 2x1 extrusion at the local metal store but didn’t specify the alloy and came back with 6063.
We ran WCD with 2mm wall the past few years. I think we used 50x25 but basically the same strength. I wouldn’t be worried about the strength as long as you have bearing blocks to support the wheel axles.
