pic: New gearbox CAD
 

Re: pic: New gearbox CAD
 

That is quite beautiful. However, I have one question...how are you mounting the cims to the plate. It doesn't look like you have any corresponding holes for it.

Re: pic: New gearbox CAD
 

CIM's have 4 holes, two filled with bolts that hold the housing together. That's what you're seeing. The other two are used to hold the gearbox together and to the frame of the bot.

Re: pic: New gearbox CAD
 

I still don't understand though. Are you running extra long bolts through the transmission and into the CIM? If so aren't they really small bolts?

Re: pic: New gearbox CAD
 

Pretty sweet. I love elaborate cutouts. (IN CAD)

Re: pic: New gearbox CAD
 

Well if you get it cut on a waterjet or laser its not too bad in real life either:D

Re: pic: New gearbox CAD
 

They're #10-32 bolts. Four of them will be more than strong enough to support the gearbox. If my stress tests indicate otherwise, I may add another set of standoffs. We shall see.

Re: pic: New gearbox CAD
 

So the holes on a cim are threaded for 10-32? That certainly changes things for the better.

Re: pic: New gearbox CAD
 

Yep. I remember one year we accidentally used #10-24 on our gearboxes... And I kept wondering why it stripped out all the time.

Re: pic: New gearbox CAD
 

HAHA thats never good. Maybe I'll have to integrate that into one of my transmissions.

Re: pic: New gearbox CAD
 

Whats the estimated output speed of the output shaft?

Re: pic: New gearbox CAD
 

Under load, it's calculated to be around 550rpm. When put to a 4 inch wheel, top speed is calculated at 9.67. I'm assuming 2 inch wide roughtop wheels for this system, but this gearbox could be mated to quite a few different systems.

By the way, if anyone wants the CAD for this, feel free to PM me. It wasn't too difficult to make, so I'd have no problems handing the CAD out.

Re: pic: New gearbox CAD
 

I'd bet you could get another pound out of it in those gears if you wanted to, but overall, nice work.

Re: pic: New gearbox CAD
 

What is the advantage over the toughbox?

I like the CIM mounts. That's a very compact way to do it.

Re: pic: New gearbox CAD
 

I guess It would be the weight savings.

I'm not really a fan of the same 4 bolts holding the gearbox together, the motors on and the gearbox to whatever structure it is mounted to. No matter what, that is going to make assembly and mounting a much bigger pain that it needs to be. I'll agree it cuts down on parts and weight, but I don't think it's worth it.

Re: pic: New gearbox CAD
 

No, actually. The gears are heavily "dished" out on the other side, in order to keep those components to a single lathe process. There's practically no weight I can save by removing materials, only adding material.

The advantage it has over the toughbox is custom ratio, massively lighter, more stylish, more precise, and better bragging rights.

It would be a bit of a pain to assemble. However, depending on what kind of drive system that it would mate to, two of the mounting bolts may be countersunk. That would aid a bit in assembly.

Re: pic: New gearbox CAD
 

A straight-forward single-speed gearbox--simple in its mechanical design, but the weight savings and sideplate design make it very elegant...something defintely to brag about if this is on your robot!

And yes, "elegant" can be used to describe a gearbox...ask the Germans!!

Re: pic: New gearbox CAD
 

Craig,
I like it.
mike d

Re: pic: New gearbox CAD
 

It does look like much more of a hassle to mount, but thinking of the end product with those gearboxes mounted nicely would make it worth it. Pain for Beauty. :P

Countersinking would aid in assembly but it still would be more complicated to assemble than needed. Very interesting design though, kudos.

Re: pic: New gearbox CAD
 

The weight savings and more custom ratios.

A big difference is one is made for mass production and one is made to build a few of. The cost to mass produce something like this would be quite a bit greater then the price of the Toughbox (e.g. more machining).

Re: pic: New gearbox CAD
 

What did you use for the weight of the motors (ie what is the real weight of the gearbox).

Re: pic: New gearbox CAD
 

while you are making your own gearbox you could take a hint from 968/254 and add a FP motor :).

Re: pic: New gearbox CAD
 

And then take another hint from 968/254 and take them out after the first regional ;).

They didn't even notice they were gone (I misheard something a while back, they noticed [like Cory says below]), and with the Big CIMs out of the kop, the FPs are better suited for a mechanism than added power in the drive (for most games)

Re: pic: New gearbox CAD
 

I wouldn't say that's entirely accurate--we were definitely noticeably less speedy. it took a bit longer to accelerate to top speed.

The benefit we got out of putting the FP's elsewhere more than made up for the slightly slower acceleration.

Re: pic: New gearbox CAD
 

How much do the CIMs weigh anyways? I've always wanted to know that :o

According to the AM website the toughboxes weigh 2.5 lbs. without motors. The only reason they weigh more than the Craig's is b/c they don't have any lightening patters on the gears (which as Kyle pointed out would make them more expensive).

Re: pic: New gearbox CAD
 

2.75 lbs

Re: pic: New gearbox CAD
 

Really?

So the gearbox weighs 1.6 oz.!!!?? Screw the toughboxes :D I know what I'm using next year :D

Re: pic: New gearbox CAD
 

Just weighed one a little while ago to check and see.

Re: pic: New gearbox CAD
 

Yeap.

I always set up my CIMs to be 2.8 lbs (each) in Inventor. He must be using the default material on inventor.

Looks good, I would also like to know how much it weights with out the motors.

Re: pic: New gearbox CAD
 

dude thats freaking sweet!

Re: pic: New gearbox CAD
 

...Woah, I guess I've been using an incorrect model for my CIM's. Thanks for pointing that out! I'm at work right now, but I'll update the model and fill you all in on how much it ACTUALLY weighs when I get home.


EDIT: After a materials update, the gearbox comes out to 7 pounds even with motors.

Re: pic: New gearbox CAD
 

I second that. Very elegant, very nice design. If you use this gearbox... you should make a couple extra side plates and chrome plate them for explanation-to-judges purposes at regionals. We had a really cool frame system on our 2006 robot and did something similar... we had extra aluminum frame components that we polished to a high gloss shine for explanation purposes.

Everybody likes bling... even FIRST judges. :D

Great job!

-q