Quote:
Originally Posted by flameout
Okay, so it sounds like they won't wear too fast (we won't run on asphalt bad enough to cause horrible control issues).
However, since it sounds like we'll have to replace them about once per year, do people have recommendations for how to replace the rollers? AndyMark sells them for $3-4 apiece, which is too much for us to spend each year (we have no problem buying replacements -- I would like to get the yearly maintenance cost down to $20 or less, which necessitates cheap roller replacements).
We've talked about fashioning rollers out of PVC ourselves, but I fear that it is too slick, negating the mecanum effect (by sliding just as easily along the axis of rotation as it rotates around that axis). Is there a less expensive way for us to make our own rollers (I know other teams have used urethane, but I recall that being above our budget)?
It sounds like the best option would be to buy a set of AM mecanums (or other COTS mecanums) and replace the rollers with something cheaper than AM's rollers each year -- does anyone disagree?
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if you buy a full set of 12 rollers (for 8 inch wheels) it only costs $40 times 4 wheels means it would cost $160 per year IF you used AM rollers. To build new replacements for 12.5% of the cost of COTS rollers might be difficult, but there are other options that might be cheaper:
1) protect the rollers when driving on rough ground
Either lay out something to cover the ground or cover the individual rollers with a sleeve of some sort, the former is easy and quick, but a ground cover sturdy enough to drive on might need a lot of storage space. The latter would likely be time consuming and trying to keep the roller covers in place would be challenging, and performance might be affected.
2) have a different set of more durable rollers for driving on rough ground
Skateboard wheels come to mind, put 2 or three on an axle and shape them to the approximate contour of the mecanum rollers (the sponsors with machining capabilities might be able to help). Just switch the rollers when you switch surfaces.
3) instead of replacing the rollers, maybe new rollers could be cast over the old ones
This saves money on urethane, but the layered structure might fail, which wouldn't be good
4) this one is like number three, but the rollers are cast over PVC cores, this allows for more control over the structure of the wheel so that the rollers are more uniform, every time the rollers wear out, remove the remaining tread and cast a new one over the core.
I think the even numbered ones sound like they might work better, but if you could find rollers within your budget, that might be even better.