Re: Check Out Our New Custom Frame!
 

Even though you may not want to use a bumper/outside rail. I would extremely recommend it. My team uses ifi tract. wheels and without proper protection they are easily bent/broken, last thing you want is a smashed wheel out on the field. Besides that i like the concept. Though adding an outside rail would also provide a place to mount the other end of the axle, thus making it stronger and lessing the need for such big bearing blocks.

Re: Check Out Our New Custom Frame!
 

I can't speak for the new IFI traction wheels, but if you were to run last year's version outside the frame like that, they'd last maybe 3-4 matches. You definitely want to protect them somehow.

As to snaprings, you can use them to space your sprockets and such. Make sure you leave yourself some wiggle room between the groove and the sprocket, or else the snapring will not properly seat itself. In the past we've just machined nylon/aluminum tube to the proper length and slid it over the shaft.

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Its a good start but... I think you would be happier with a couple more cross frames to help keep things straight. Just my 2 cents worth....

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I witnessed this, and it was particularly nasty. Im not claiming to know the workings of their robot, however simply put, if they shortened the width of the chasis by about 2 inches, they would have room to put stock across the axles as a sort of guard.

But after seeing how succesful that chassis was, it is only a small detail.


To address the poster, you have a good chasis on your hands. However have you considered some sort of shifting tranny? If you use them, they can give you a big advantage as far as driving goes.

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Why shorten the width? You can get stock up to at least 10' and cut it to length.

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One of the big advantages to having exposed wheels (such as also in the design central to this thread) is the ability to quickly replace your wheels. This is especially true on live axles (as also in this frame design). Reportedly 968 could switch an individual wheel in around 1 minute (or less) with their exposed, cantilevered, live axle design last year. Whether some sort of guard or bumper mount that is quickly and easily removable (or doesn't inhibit replacing wheels) can be added is a challenge left up to the individual team.

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How often do teams typically change wheels throughout a season? I've never had occasion to replace a wheel, but my teams often don't use the popular traction materials that wear down with time.

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Approximately 2-3 times per competition for us.

We generally leave the tread on the bot that we tested with before ship, change it on Thursday night, change it on Friday night, and before the finals.

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We used SBR Roughtop on a 3/4" wide wheel and it held up fine throughout VCU on a primarily defensive 'bot, very little wear although it did leave black lines on the carpet when we got into tough pushing matches. (Or reversed direction quickly) However, I understand the Wedgetop 968 used wears a little quicker, and their wheel width might be smaller, and I know their wheels were smaller diameter, so the wear couldn't be spread out as much.

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Like I said, I dont know their robot. Im just assuming it was already at max witdh.

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I can think of a way off the top of my head to make a guard with 2 nuts holding it on.


Remove one, and swing it out of the way.

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With a system like 968's they could replace them whenever they wanted. Before the 2nd match of the Finals on Einstein, they apparently replaced one so they could drive slightly better.

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Just to clarify, we could easily replace all 6 wheels in under a minute and I do believe we did so before that last match. By new wheels, I mean wheels with new tread. As Cory mentioned, both teams had two sets of wheels so that at any given time we could be replacing tread while the robot was still on the field.

The new tread helped us drive straighter which was very helpful during autonomous mode. We had a gyro to keep us going straight and encoders to tell us when to stop, but new tread always seemed to add consistency and lessen the error/drift.

In regards to the OP, I agree with most everyone that you should add some sort of protection for the wheels. It is something we will be doing this year for sure, one way or another.