Mounting Sprockets to the Rover Wheels
 

Hey,

So I was mounting some AndyMark aluminum sprockets to the rover wheels and I noticed that the holes in the wheels are smaller than those in the sprockets. How have other teams been dealing with this? I ended up using machine screws that fit through the wheel mounting holes, but because they're smaller than the holes on the sprocket, it shifts around.

Any suggestions?

Re: Mounting Sprockets to the Rover Wheels
 

we just gave them a little tap with the rubber mallet

8/32 bolts with lock nuts and locktite

Re: Mounting Sprockets to the Rover Wheels
 

Someone in this thread said that locktite dissolved the plastic on the wheels. I would not recommend using lockite in that case. We decided right away that tapping the holes and screwing steel bolts into plastic was not a good idea (even though it was suggested in the intructions for putting the chassis together) so we drilled the holes out bigger and got longer bolts and bolted the sprockets all the way through with some nylon lock nuts on the other side.

Re: Mounting Sprockets to the Rover Wheels
 

locktite does NOT dissolve plastic at all

Re: Mounting Sprockets to the Rover Wheels
 

I haven't seen it happen, but there have been many, many reports that locktited plastic parts break.

I know my team (used to) simply tap the holes of the AM wheels and put the screws in.

Re: Mounting Sprockets to the Rover Wheels
 

from the locktite website

"Threadlockers should only be used on metal-to-metal applications, because the Threadlocker turns into a plastic-like substance."

which is probobly the cause.....

Re: Mounting Sprockets to the Rover Wheels
 

The holes are intentionally small. AndyMark included instructions for tapping and connecting the sprockets to the wheels in the KOP. These instructions are available via a video at the AM website here: http://lib.store.yahoo.net/lib/yhst-.../AM09WNick.mp4

Re: Mounting Sprockets to the Rover Wheels
 

This is somewhat incorrect.

Depending on the type of loctite and the type of plastic it can craze and crack plastics. The general suggestion is to test the loctite product on a small, non critical, portion of the plastic to see if there is a reaction.

And if you don't believe me, try Loctite 496 on a piece of polycarbonate ;)

Re: Mounting Sprockets to the Rover Wheels
 

locktite meaning, threadlocker blue,green and red....

Re: Mounting Sprockets to the Rover Wheels
 

Yes, that sort of thing. Try it first on a non-critical area.

Re: Mounting Sprockets to the Rover Wheels
 

we've always used it, its kinda too late now:D

i doubt it could though,

and not just on the wheels......

Re: Mounting Sprockets to the Rover Wheels
 

Well, I hate to contradict you, but 811 unfortunately knows better. :eek:

Re: Mounting Sprockets to the Rover Wheels
 

i read this, it seems they just poured it in the holes?

if it was the blue threadlocker, then alot of people are in for some troblue:ahh:

and we put our everything together with it:ahh:
maybe thats why it says to use it on only metal to metal applications

i still doubt this though,

Re: Mounting Sprockets to the Rover Wheels
 

Follow the instructions on Andy Marks Website, it explains what size screw to use, and how to tap the holes on the wheels!

Re: Mounting Sprockets to the Rover Wheels
 

We put a 10-32 tap into the old DeWalt cordless and power tapped the holes in the wheel. It seemed to work fine. Then I started worrying about someone over tightening the screws and stripping the threads. We went ahead and drilled clearance holes and put lock nuts on.

Re: Mounting Sprockets to the Rover Wheels
 

I like to use a 10-32 bolt that puts about 1 inch into the wheel. we run a tap in about .75 inch. The last .25 without threads makes it nice and tight.
I have just run them in without tapping but then they can't be disassembled without the threads getting screwed up.

Re: Mounting Sprockets to the Rover Wheels
 

We ended up just drilling out the holes in the AM wheels and putting 10-32 bolts through with aircraft nuts.

And yes, Loctite DOES melt certain thermoplastics! I'm not sure if the wheels are thermoplastic, but team 811 is not gonna risk it (again!)

Re: Mounting Sprockets to the Rover Wheels
 

The wheel hubs are black polycarbonate.

Loctite dissolves polycarbonate.

Therefore, if you use Loctite to mount sprockets or hubs to the wheels, you will dissolve the plastic.

Use nylock nuts or split lock washers instead.

Re: Mounting Sprockets to the Rover Wheels
 

With the thickness of the spacer and sprocket, a 3/4" bolt would not penetrate very far into the hub. As many have pointed out it's best to either put a bolt all the way through and use nuts or use long enough bolts to almost go thru and tap them in. When the robots are on carpet and they take a side impact, the stress is distributed to all the wheels. With drifting this year the robot can hit the carpet with only 1 or 2 wheels taking the impact.
Beware of the carpet.

Re: Mounting Sprockets to the Rover Wheels
 

have you ever experienced this first-hand?

I would like to see some pictures,(besides this one, http://www.chiefdelphi.com/media/photos/17114)

nothing on the loctite website says it does(at least from what i can find)
http://www.loctiteproducts.com/

Re: Mounting Sprockets to the Rover Wheels
 

Try looking here

Re: Mounting Sprockets to the Rover Wheels
 

Greetings,

Please - so much strange information posted here. I am a plastics engineer and I have never heard of using Locktite on plastic - not because it will melt the polymer. Because locktite does not do much good with plastic. locktite is a chemical bond used with iron based metals. Other grades can be used to prep aluminum so that it can be bonded - but do not use with plastic as superglue would do just as well....... Good luck.

Re: Mounting Sprockets to the Rover Wheels
 

We tapped ours 10-32 with a cordless drill, and it works just fine. Not worried about cracking or stripping anything.