pic: 6Wheel Drive Sheet Metal



After a wonderful 2012 season, and my first year attending champs (even if it was only for Saturday) I learned a ton of useful things at champs and over this build season! One thing we did this year was got our first ever batch of sheet metal water jetted and we really enjoyed it! After seeing some robots at champs and talking to some teams I realized how great it would be to run a full drive on gears, and how easy it would be with the sheet metal resource! So this is my FIRST iteration of a versatile geared drive, what makes it so versatile is that the pattern for the axles allows you to have a set up for 6" and 8", 6wd and 8wd in both sizes (The middle 3 axles are dropped). Our team is very lucky to have an industrial strength 3d printer coming in during this moth sometime, so hopefully we could 3d print some gears for this drive, because the gears we found were almost perfect but would cost us something like 250$ per gear, so if any one has a place to get Large gears at a decent price, please PM me or put it in the comments!! And question and comments are always welcomed!

Do you know the make/model of the 3D printer you are getting?

While 3D printing literally anything you can CAD is awesome, it has its limitations. And one of those limitations is that with currently available technology 3D printed gears are unlikely to survive for very long in a torque-transmitting application in a FRC robot drive train*. And depending on what model of 3D printer and what material you are printing with, it may actually be more expensive to print plastic gears that large than it would be to purchase COTS metal gears. Some high-strength 3D printed parts cost several dollars per gram in raw material and support.

  • However, 3D printed parts work great for making gears/couplers for encoders and potentiometers.

I may be looking at the picture wrong, but it appears that you have two idler gears between each wheel. This would make the middle wheels spin the opposite direction of the outer wheels.

Consider this:
http://blog.iamjvn.com/2011/02/inside-raptor-plate-gears.html

My team hasn’t done this yet, but could be a much cheaper alternative.

  • T

We’ve done this after seeing 148/973 do this to great success. Its a very cool way of making virtually any gear size you want. We’ve done this for window/pg71 motors to make the proper spline.

A fellow team did something like this (Thanks Andrew!)

Using gears from WCP, we offer a 60T that would help cover the area/decently large gear.

-RC

From what I can see you have 4 unnecessary idler gears. We do a 6 wheel drive with six inch wheels and direct drive from 5 inch steel gears for a total of 10 gears. The gears that we purchase are from Boston gear, we than machine the thickness down to save some weight. Next year we will be most likely going to 8 inch wheels and increasing our gear size. If you need more specs on the gears let me know or pictures I can get them for you.

JB

This

Matt,

If you have access to a press brake you can add bends along the edges to make the sheet metal stiff. Your design is using flat pieces of sheet metal. Think of it like a piece of paper. In the flat the paper flops but if you add a bend in the paper suddenly the paper is stiff and can support weight.

Designing the sheet metal to locate and interlock the various pieces is what makes the sheet metal medium a great way to build a robot.

Don’t forget your belly pan, mounting points for your manipulator and the bumper brackets. One piece bumpers are the rage.

Here is a shot of our 2012 frame. It’s only 3 pieces. Very light and stiff. We use a cnc punch press to make the parts. Takes only 10 minutes to punch all the parts for two frames.

https://picasaweb.google.com/104549320706687649408/2012971RoySPhotoS#5732818256773910530

There is a very obvious gap between the center gear and the next gear that would fit a small pinion nicely, the .75" hole with 10 clearance holes at 2" diameter show a CIM would mount there. One CIM per side, two total.

Pretty cool setup, and very light (especially if those gears are pocketed).

This drive is actually based off of y’alls robot haha but could you give me the link to those gears yall get from boston? that would help a ton!

Matt,

If you have access to a press brake you can add bends along the edges to make the sheet metal stiff. Your design is using flat pieces of sheet metal. Think of it like a piece of paper. In the flat the paper flops but if you add a bend in the paper suddenly the paper is stiff and can support weight.

Designing the sheet metal to locate and interlock the various pieces is what makes the sheet metal medium a great way to build a robot.

Don’t forget your belly pan, mounting points for your manipulator and the bumper brackets. One piece bumpers are the rage.

Here is a shot of our 2012 frame. It’s only 3 pieces. Very light and stiff. We use a cnc punch press to make the parts. Takes only 10 minutes to punch all the parts for two frames.

Yes… In know, I actually tried to put in bends at the end but mates were already made and I got ALOT off errors… Plus this is only the first iteration :wink: Yes I have seen y’alls drive base!! I loved what i have seen from the pictures, I tried to stop by y’alls pit at champs, to get a closer look, but I was only there for a day :frowning:

I may be looking at the picture wrong, but it appears that you have two idler gears between each wheel. This would make the middle wheels spin the opposite direction of the outer wheels.

Sigh… I can’t believe I didn’t catch this… I feel kinda bad now haha. (But hey it would work with and 8WD)

Ill update it and post a picture response! thanks for all the suggestions.

Pretty awesome! You should implement some sort of handles on the sides, so it doesn’t slice through someone’s hand.