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Unread 25-05-2010, 17:11
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Garret Garret is offline
Standing on the Shoulders of Giants
AKA: Garret Smalley
FRC #0691 (Hart District Robotics)
Team Role: Mentor
 
Join Date: Dec 2009
Rookie Year: 2008
Location: Goleta, CA (UCSB)
Posts: 203
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Re: pic: Prototype Drivetrain

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It looks like you only have 2 CIMS powering your drivetrain. Did you do this to save weight, or do you have another purpose for them? I'm of the belief that there are enough motors available in the KOP that 4 CIMs (or at least a CIM and a FP) should be used on any drive train (with 2K9 being an anomaly).
My team uses only two CIMs on our drive train in general so that we free up the rest to use on manipulators. depending on what we plan to do with the robot I may or may not add the additional CIMs.
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Replace all the 1/16th wall aluminum with 0.035" wall 4130 steel square tubing. You'll improve chassis strength, stiffness, maintain the same weight, and your welder will have an easier time
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The reason I used the materials I did is because my team has a very, very, very low off season budget and all the materials are scrap from this year's robot.
In terms of welding we have a sponsor who will weld our aluminum for us and they really do not have a problem welding it.

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Are you using Riv-nuts to hold on the axle pillow blocks?
We are using 1/4-20 bolts and nylock nuts. I just didn't drill the holes because Inventor crashed.

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Instead of using washers to lower your middle wheels, try drilling the holes in all 16 pillow blocks off center by 1/16", and flip the middle ones over so the axel ends up being 1/8" lower than the outside axels. Adding washers isn't as clean/sturdy.

Also, to lower your CG (which is ALWAYS important), you might want to mount the pillow blocks on the top side of your lower frame members, that way the whole frame is lowered a total of 2 inches. And try mounting your electronics (Battery/CRio/etc) on the lower frame level, not the upper one. This will lower your CG and give the manipulator teams more area to work with. Win Win.
I would not have thought of drilling holes off center. In general we have used washers and other spacers because we really don't have access to precision machine tools due to the fact we build out of one of the team members garages.
The battery, compressor, and speed controllers are all below the top of the frame, I put the CRIO on top for easier access. There will be a cover over it. I left the front Area pretty open and thought that that was enough space for the manipulators.

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whereas welded 6061 aluminum will be total garbage, around 8-10KSI.
I have never had an aluminum weld break on me. We also use a professional welder on our frame.

How strong are the brunner connectors and 80/20 quickframe system. How much do they cost?

I appreciate the suggestions greatly and will try to implement them where possible.
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