pic: Off-Season Drive Project

[Akash Rastogi]

Originally Posted by sanddrag

That is a thing of beauty. I can't believe I haven't seen it before. What's the part number on those wheels, and do you have a link to any more pictures?

I don't think there are build season photos on the team website yet, but you can find some random pictures of the drive on the team facebook page.

Here's one, and there should be more if you keep clicking next https://www.facebook.com/photo.php?f...type=3&theater

If there's anything in particular you want to see, just ask!

[AdamHeard]

Using a bolt to retain the wheels and take up all slop is a bad idea as it will preload the bearings. It's also more likely to loosen the fastener.

[Chris is me]

Originally Posted by AdamHeard

Using a bolt to retain the wheels and take up all slop is a bad idea as it will preload the bearings. It's also more likely to loosen the fastener.

Compared to two snap rings, etc. it's definitely sub-optimal, but with regular maintenance (check the bolts before a match) and some Loctite, it's a decent enough solution that will retain wheels and account for manufacturing tolerances. Just don't over-tighten the bolts as the tighter they are, the more preloaded your bearings are, and hex bearings seem to be particularly temperamental in FRC.

By the way, the wheels in 11's photo are 2" wide black Colsons.

I'll third the notion of not using thin polycarbonate as a structural belly pan. Polycarbonate is great for some applications but in this one the thickness you need for polycarbonate to be sufficiently rigid makes it a poor choice compared to thinner sections of other materials, such as garolite. We still use an un-lightened 1/16th aluminium belly pan though this is suboptimal.

[Andrew Remmers]

Kind of reminds me of an old 179 drive.

http://www.chiefdelphi.com/media/img...67e7a6da_l.jpg

http://www.chiefdelphi.com/media/img...87d7b504_l.jpg

[IndySam]

Originally Posted by AdamHeard

Using a bolt to retain the wheels and take up all slop is a bad idea as it will preload the bearings. It's also more likely to loosen the fastener.

We have used a bolt to retain wheels for three years and have never had a single problem. We do not take up slop with them, we always leave a little slop just like you would with a retaining clip.

[AdamHeard]

Originally Posted by IndySam

We have used a bolt to retain wheels for three years and have never had a single problem. We do not take up slop with them, we always leave a little slop just like you would with a retaining clip.

That is what I was recommending. As opposed to clamping the bearings.

I still prefer snap rings for reliability, fabrication time and swap out speed. They're easier to do than people think.

[Brandon_L]

Originally Posted by EricDrost

Is there a reason that thread locking screws aren't used in that situation more commonly? We ran them this year on our wheel axles, with e-clips on the inside and we've never had to adjust them and never had any issues. We use them pretty frequently on other assemblies as well and I love them.

[Aren Siekmeier]

Originally Posted by Brandon_L

Is there a reason that thread locking screws aren't used in that situation more commonly? We ran them this year on our wheel axles, with e-clips on the inside and we've never had to adjust them and never had any issues. We use them pretty frequently on other assemblies as well and I love them.

How many uses is the nylon good for? We remove wheels all the time, not just for wheel maintenance, but also for shaft maintenance and if they got in the way of something else because our design was too constrained... We've used bolts, washers, and loctite in the past because drilling and tapping the hole seemed like the easier way to go, rather than machining a groove, but in the interest of maintenance, we'll definitely check out snap rings for the future. If you bother to machine the grooves and have the right tools, it seems far more convenient.

[AdamHeard]

Originally Posted by compwiztobe

How many uses is the nylon good for? We remove wheels all the time, not just for wheel maintenance, but also for shaft maintenance and if they got in the way of something else because our design was too constrained... We've used bolts, washers, and loctite in the past because drilling and tapping the hole seemed like the easier way to go, rather than machining a groove, but in the interest of maintenance, we'll definitely check out snap rings for the future. If you bother to machine the grooves and have the right tools, it seems far more convenient.

If you have people with basic lathe skills, the snap ring groove is actually a faster operation than drilling + tapping.

If the shaft was predilled (already had a hole in it), it'd become comparable but I still think the groove is a tad less tedious to machine than tapping once the skillset is obtained.

Also, the tolerances for the groove width and depth are are like +.003/-0.0 and +/-.002 but we've been fine in situations where we've botched that by quite a bit. So it isn't as daunting as that makes it seem. The width tolerance is set by your insert too, so you don't even deal with that.

[Aren Siekmeier]

Originally Posted by AdamHeard

If you have people with basic lathe skills, the snap ring groove is actually a faster operation than drilling + tapping.

If the shaft was predilled (already had a hole in it), it'd become comparable but I still think the groove is a tad less tedious to machine than tapping once the skillset is obtained.

Also, the tolerances for the groove width and depth are are like +.003/-0.0 and +/-.002 but we've been fine in situations where we've botched that by quite a bit. So it isn't as daunting as that makes it seem. The width tolerance is set by your insert too, so you don't even deal with that.

So there's another point for snap rings and against bolts

Lathe and mill work is relatively new on our team, so we are still figuring out the do's and don't's and can's and cannot's on our machines. Good to hear how it can really be a "snap"