Quote:
Originally Posted by brennerator
1) Our axils jut out 2.25 inches. With the force of the chain, will our axils bend?
2) Note the front and rear axils and that they have only one sprocket and that we have to use a spacer. What would be a good spacer to use?
3) Our wheels are exposed and we are using a 1/2 inch keyed shaft. Our wheels are high traction wheels from IFI Robotics In what ways could the wheels be damaged and are there any ways to prevent this besides putting a beam or bumpers on the outside.
4) can use use e-clips or spacers?
5) Any other flaws with our robot that we should know about before we go on and CAD it?
Thank you very much for your responses. They've been really helpful thus far.
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What sort of manufacturing capability is available to your team and to what extent are you proficient at using it? There are no photos of your past work in the gallery that allow us to get an idea of what experience your team has had in the past.
Some questions and concerns I have based on your CAD model:
- It appears as if your gearbox is driving the center axle through one chain, while a second chain connects all three wheels. As shown, that second chain engages the center sprocket across a very small arc along its bottom. I believe that, without additional wrap around the center sprocket, you'll find that the chain will not remain positively engaged at all times, resulting in complete loss of power transmission to the outer wheels. What's worse is that wrap is along the bottom side, meaning that the introduction of any slack in the chain will immediately find its way to the bottom. Don't underestimate the nuisance of gravity
- It's difficult to discern what components are custom-made and which are off-the-shelf. Is there particular use or reason behind the elaborate pillow blocks? They're complex to machine and their length through bore seems excessive, making the cantilevered load on each axle much further from the frame than it need be.
- Again, it's difficult to tell based upon only the rendering (and I don't have Inventor installed, so I can't open the files you linked to), but are the hubs meant to hold the wheels custom made? I think custom-made is the way to go here so that you can make certain the length through bore is equal to or greater than that of the IFI traction wheel you order. The off-the-shelf hub available from AndyMark is too short and has a diameter too small for the IFI wheels and would result in part of the wheel being completely unsupported.
- It looks like there's no provision for tensioning chain built in. Consider placing slots to allow the pillow blocks to be moved and locked down rather than discrete holes at fixed distances.
I think what you have is a good start, but that it needs refinement. Some of the other questions you've asked -- about spacers and e-clips and the like -- suggest to me that, overall, you might not be ready to tackle a drivetrain as resource and design intensive as this. It would make a fantastic project for the summer or off-season, though, and allow your team to gain a lot more experience and perspective on what it takes to thoughtfully design and build a custom drivetrain and frame.
Edit: I split the discussion about this drivetrain from the thread titled "Standard vs. Custom Frame". All discussion about this design should happen here from now onward.