pic: 816's 2011 Off-Season Teaser

[thefro526]

Originally Posted by AdamHeard

A double sprocket before the teeth are hobbed, and the cylinder is likely a wheel hub to be press/cast into a plastic wheel.

Dang it.

You're right, though I hoped that it'd take a little longer to figure out.

The part on the left is a blank for a 22T double sprocket, made from 7075 Aluminum. It's been broached before the sprocket cutting to make things a little easier for the mill operator.

The part on the right is a 'plug' for a 2" wide colson wheel, made from 6061 AL. Preliminary testing shows that the press is good to at least 80 foot-pounds of torque.

(I'll have to bug you on FB for a shipping address once the stickers are made.)

[rcmolloy]

Originally Posted by thefro526

The part on the right is a 'plug' for a 2" wide colson wheel, made from 6061 AL.

Oh I see where you're going with this one Dustin. The topic that we were discussing about makes sense then.

Originally Posted by thefro526

(I'll have to bug you on FB for a shipping address once the stickers are made.)

...Or just give them to me for hand delivery dude. We don't live that far away.

[Andrew Schreiber]

Originally Posted by rcmolloy

Oh I see where you're going with this one Dustin. The topic that we were discussing about makes sense then.



...Or just give them to me for hand delivery dude. We don't live that far away.

If you guys can wait until Madera I can hand deliver them as long as they go next to the "Powered by..." sticker on your bot

[roystur44]

Drain plug to keep the water out and a small anchor???

[rsisk]

Originally Posted by Andrew Schreiber

If you guys can wait until Madera I can hand deliver them as long as they go next to the "Powered by..." sticker on your bot

Why do I get the feeling there is going to be a heck of a good time had at Madera?

[Brandon Holley]

Originally Posted by thefro526

The part on the right is a 'plug' for a 2" wide colson wheel, made from 6061 AL. Preliminary testing shows that the press is good to at least 80 foot-pounds of torque.

I've been making a variation of the press-fit Colson hub since 05 using the same principle. If I'm seeing the hub correctly, it looks like its knurled which is something I've had great success with as well.

Looking good.

-Brando

[AdamHeard]

For season I see the resources used to make the double sprockets better used elsewhere, and instead just purchase off the shelf sprockets.

[thefro526]

Originally Posted by rcmolloy

Oh I see where you're going with this one Dustin. The topic that we were discussing about makes sense then.



...Or just give them to me for hand delivery dude. We don't live that far away.

Hehehehe. I don't know if you're fully aware of how ridiculous our current project is.

Originally Posted by Brandon Holley

I've been making a variation of the press-fit Colson hub since 05 using the same principle. If I'm seeing the hub correctly, it looks like its knurled which is something I've had great success with as well.

Looking good.

-Brando

Brando, Technically the hubs aren't knurled. The grooving that is visible in the picture was done by running a tool at a relatively high rate across each plug. Technically, it's not the right way to create a strong press because the cuts are in the same direction as the wheels would see force but I'm very happy with the results so we'll probably just stick with this method since it's easy for our Lathe guy to knock out - and it's pretty easy to replicate in house with minimal skill/effort.

Originally Posted by AdamHeard

For season I see the resources used to make the double sprockets better used elsewhere, and instead just purchase off the shelf sprockets.

Adam, you're right on the money with this. I doubt we'll do a run of double sprockets again unless they're absolutely needed or it makes sense to do so.

This entire project is heavily influenced by a few factors:

-We wanted to try some new construction methods.
-We wanted to build a lighter more competitive drive than what we used in 2008.
-We wanted to move to an 'assembly' style build method.
-The shop foreman at our machine shop told me to design something 'interesting' for his guys to make - one thing lead to another and yeah....

Here are some more pictures for those of you that are interested:

[Brandon Holley]

Originally Posted by thefro526

Brando, Technically the hubs aren't knurled. The grooving that is visible in the picture was done by running a tool at a relatively high rate across each plug. Technically, it's not the right way to create a strong press because the cuts are in the same direction as the wheels would see force but I'm very happy with the results so we'll probably just stick with this method since it's easy for our Lathe guy to knock out - and it's pretty easy to replicate in house with minimal skill/effort.

Ah- yes the mental picture popped into place. Knurling is really REALLY simple (and pretty cool). It could be something you guys experiment with now, especially since you already have the lathe, etc.

The gearbox plate looks good. I assume bearings will be pressed into it. I'd be curious to see what results you get as far as the tolerance on the press fit from a waterjet. We've had access to a waterjet for a while, and we use it for a lot of things. One thing I've always been wary about is bearing holes though. We usually will cut out almost the entire part and then go back to correct the bearing holes with a secondary process.

-Brando

[thefro526]

Originally Posted by Brandon Holley

Ah- yes the mental picture popped into place. Knurling is really REALLY simple (and pretty cool). It could be something you guys experiment with now, especially since you already have the lathe, etc.

The gearbox plate looks good. I assume bearings will be pressed into it. I'd be curious to see what results you get as far as the tolerance on the press fit from a waterjet. We've had access to a waterjet for a while, and we use it for a lot of things. One thing I've always been wary about is bearing holes though. We usually will cut out almost the entire part and then go back to correct the bearing holes with a secondary process.

-Brando

We might experiment with knurling in house before build, but we have about a dozen other parts that are on the priority list first. Our sponsor can knurl if we absolutely needed it too.

The bearings are more of a tight slip fit then a true press. I can get a good measure on the bore when I go to the shop tonight. We have originally intended to ream the holes under the assumption that they'd run under, but they came out of the waterjet just right it seems.

Got one of the finished Sprockets:

[ttldomination]

Originally Posted by AdamHeard

For season I see the resources used to make the double sprockets better used elsewhere, and instead just purchase off the shelf sprockets.

Where do you guys go for your off the shelf double sprockets?

- Sunny G.

[AdamHeard]

We just use two single sprockets. Makes all of our drive sprockets the exact same.

Originally Posted by ttldomination

Where do you guys go for your off the shelf double sprockets?

- Sunny G.

[craigboez]

Originally Posted by ttldomination

Where do you guys go for your off the shelf double sprockets?

- Sunny G.

AndyMark has a few
http://www.andymark.com/SearchResult...ouble+sprocket

[waialua359]

Team 2348 has been making our double sprockets for the past 5 seasons for our "West Coast" bicycle chain drive.
As suggested, we should instead just buy them if possible. A lot of time, energy and round stock is used.

[craigboez]

Originally Posted by thefro526

The part on the right is a 'plug' for a 2" wide colson wheel, made from 6061 AL. Preliminary testing shows that the press is good to at least 80 foot-pounds of torque.

I assume your hex broach goes all the way thru the ~2" wide Colson hub. Did you have any issues hex broaching that length? The Dumont literature states the max length of cut is 1-3/8" but that is based on mild steel. I'm curious what it can do in aluminum.