So currently my teams shooter hood is not working as intended. The code is fine everything works except for the physical hood. We found out that the gear we were using was rubbing too much on our hood because of the four bolts that are put through one side of the gear and out of the other side of the hood(it’s a custom 3d printed gear so that’s why there are bolts through it). There are slots for these bolts so that they move with the hood but these cause way too much friction and will not let the hood move properly. If we remove these bolts the hood is then not kept in place. If anyone has ideas on reducing friction that would be great or if you need more details I can give them.
A couple of photos would probably help.
Pics please
here you go
sorry its bad quality i can take another if you want
We need a photo of the whole thing to help… Better quality would help too
let me see if I have one
if this doesn’t help i’ll try my best to find another sorry
Better photos are always better.
From what I can see, I think I understand the problem. Rectifying it may be fairly easy, or may require a good deal of rework. Without having a hand on the device and being able to feel it and better understand where the friction lays its hard to say.
First step; You can try using a plastic washer between the bolt heads and hood plate. A first pass with mcmaster found me these: McMaster-Carr , but a better part may be possible knowing your bolt size and what sort of clearances you have.
A more involved step would be to redesign using shoulder bolts, like this: McMaster-Carr
These bolts have a shank that is very well ground to size and surface finish. That alone may be enough improvement in the slots to free up movement. If not, you can also add a rolling plastic sleeve to the shoulder.
The core problem is likely that you have two competing factors in this design. On one hand you need those screws to be tight enough to hold things together, but also slide in their channels. Because of tolerance stack up those channels will never be perfectly coradial, and some ‘slop’ has to be accepted, and the amount of slot needed to allow the screws to slide in their channel may be too much to keep gears meshed. Make sense?
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I does thank you, we are using 10/32 bolts with the slots being just wide enough to fit them.
Yeah, these sorts of ‘bolts in a slot’ mechanisms never really seem to satisfy. It’s really hard to manage the stack up across multiple features and still have a fit that both controls the motion of the device and allows for low friction. In FRC you’re also usually dealing with a steel fastener in aluminum or plastic slots and things don’t age well.
There are ‘track followers’, which are basically roller bearings on a threaded stud, that are made to do this sort of work. They’re really industrial parts and come with a matching price tag and size. I’d probably opt for a shoulder bolt and plastic sleeve before I sent you in that direction.
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Okay, thanks for the help, I’ll try these things asap.
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