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Questions-Thoughts/Input On First Drivetrain Design
Recently our team has "revived" an old (but new) CNC Router
I've had a chance to get the CNC figured out and thought it'd be good to get started on working out the kinks on Designing and Building these things before build season. Notes/Features: *The Drive Plates are constructed out of 2 sheets of Aluminium, with 1"x1" C-Frame wedged in-between the sheets. This is because be don't have a very reliable Break at our school and therefore I can't do complex flanges. *It features Andy Mark Shifters. I don't have any experience with them so I'm not sure what the configuration is on how to mount them to the Assembly. *It features 0.050" Sheet Aluminum. I've done some reading on this but still am unsure about the "normal" of what teams are using. Input would be nice to have if you have experience with them *Also, so far on sheet metal projects i've been using 3/16" Aluminium rivets ![]() ![]() ![]() Any input (positive or negative) would be appreciated on the Design :) |
Re: Questions-Thoughts/Input On First Drivetrain Design
Overall, that is a solid chassis. I do have a few suggestions, however.
Right now, your AM Shifters are relying on the bellypan for all support. You can easily fix this by lowering the height of the frame such that it lines up with the top of the shifters and flanging it over, allowing the frame to rivet into the shifters from top and bottom. Your pocketing isn't as efficient as it can be. Based on the style that you seem to be using, you may want to try a 118-esque Isogrid. You could also go with the ever popular (254+1323+233+ many other teams) diamond style bellypan pocketing. Other than that, it looks like a solid start to a drivetrain. Good luck! |
Re: Questions-Thoughts/Input On First Drivetrain Design
I think it would be just fine with 1/3 the amount of rivets.
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Re: Questions-Thoughts/Input On First Drivetrain Design
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sanddrag, I wasn't sure what the correct spacing was for rivets, so I figured i put in a lot and then remove later if necessary |
Re: Questions-Thoughts/Input On First Drivetrain Design
Thanks msimon785, I'll definitely try out the diamond belly pan and the AM shifter mounting. Thanks
sanddrag, i wasn't sure about spacing between rivets so I put a lot and remove later id needed. Thanks |
Re: Questions-Thoughts/Input On First Drivetrain Design
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Also, add some fillets to your pocketing patterns as well. It definitely helps the end mill for the router to eliminate the precise corners that you have going on there. Even more so, if you ran this, it will still have the mill's OD in each corner of your triangles. I would advise you make the fillets to your the mills exact OD or higher; never under. Also, the normal/nominal thickness I have seen over the past years for sheet is a variance between .090" and 1/8". 1/8" for the beefier parts that require much of the static loads to be held and .090" for manipulation systems. (Correct me if I'm wrong guys haha) Aside, it looks like a pretty decent sheet chassis. |
Re: Questions-Thoughts/Input On First Drivetrain Design
We used .125 on our drivetrain this year IIRC, but I've heard of teams using .090. .063 is the thinnest sheet we use on our robot, and I doubt it would ever be on the drivetrain. Make it thicker just to play it safe.
Concerning gearbox placement, you'll definitely want to direct drive one wheel on each side to avoid losing an entire side of your drivetrain to chain failure. Also, lay off the rivets. :) |
Re: Questions-Thoughts/Input On First Drivetrain Design
I'm not quite sure how you are using the AM Shifters. These do not have an output shaft but have two internal sprockets on the output shaft for chain runs.
If you want an output shaft you should be using an AM Super Shifter. |
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Also thanks to everyone for giving input, it's going to help me immensely |
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Riveting tip: if you are riveting into tubing, make sure that there is a hole for the mandril tips to exit. This will help you avoid the "rainstick effect" :D All in all, sweet drivetrain. Do you have plans for tensioning the chains? |
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Re: Questions-Thoughts/Input On First Drivetrain Design
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For the other six chains you can calculate the runs down the the link, and place your wheels accordingly. Then tension the chain as it stretches using something like these from AM http://www.andymark.com/product-p/am-0286.htm If you prefer to manufacture in house, I am currently working on a more student machinist friendly version of the product shown above and I can share the files with you. |
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No, for something that cheap im sure it wouldn't be a problem to buy. I agree with driving one wheel directly, and wanted to do it, but im not sure on how to go about doing it. Especially with the AM Shifter's without experience. |
Re: Questions-Thoughts/Input On First Drivetrain Design
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If you design the flanges and structure correctly, and pick the right alloy, you really don't need very much thickness. All of the waterjet pieces of this robot are 0.063" except the gearbox plates (they are 0.090"). |
Re: Questions-Thoughts/Input On First Drivetrain Design
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Situate the wheels where you want them, then rotate the supershifters around their output shafts until you find a suitable mounting position. With the design of your frame, you will probably be mounting to the face of the supershifter. This year, ours wound up rotated about 45 degrees and mounted to the frame using L brackets. If you want an example, I can provide a CAD model and pictures. |
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