pic: Manually machinable one-speed gearbox

[cxcad]

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[cxcad]

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[asid61]

Looks solid. What are the two small holes in the center for? How is the gearbox mounted?

[cxcad]

The two center holes are for the encoder plate, which mounts on the motor side. This is mounted to the frame by using the bolts that go through the spacers.

[asid61]

Originally Posted by cxcad

The two center holes are for the encoder plate, which mounts on the motor side. This is mounted to the frame by using the bolts that go through the spacers.

Thsoe bolts look like they're more than 2" apart vertically, so it's difficult to mount to 2x1 with that.
How is the encoder attached to the shaft?

[bkahl]

Originally Posted by asid61

Thsoe bolts look like they're more than 2" apart vertically, so it's difficult to mount to 2x1 with that.

Almost impossible to do chain in tube in 2x1 anyway. It's probably designed for 3x1 or larger.

[cxcad]

I meant the horizontal bolts. The encoders are mounted to the GB by an adaptor plate. The shaft is mounted to the encoder by either a shaft coupler or the surgical tubing method

[asid61]

Originally Posted by bkahl

Almost impossible to do chain in tube in 2x1 anyway. It's probably designed for 3x1.

I think it's possible. We were planning on converting our competition bot to it in the offseason.
Using something like versablocks as bearing blocks allows for more than ample space in the 2x1 for 2 16t #25 sprockets side-by-side.

So this is mounted using the bolts along the bottom? I feel like that could cause the gearbox to flex back, but I could be wrong (something like that happened to our 2012 robot, although it was a slightly different situation).

[cxcad]

The bottom bolts. I don't flex should be an issue, because motor load isn't that cantilevered

[Gregor]

It looks like you're trying to direct drive a wheel with this. 11:64 is far too fast unless your wheel diameter is significantly smaller than 4".

[asid61]

Originally Posted by Gregor

It looks like you're trying to direct drive a wheel with this. 11:64 is far too fast unless your wheel diameter is significantly smaller than 4".

~16fps free speed according to JVN calc. We ran that last year.

[Knufire]

Originally Posted by bkahl

Almost impossible to do chain in tube in 2x1 anyway. It's probably designed for 3x1 or larger.

Actually a COTS product: http://www.team221.com/viewproduct.php?id=133

[Munchskull]

Could some one explain how you get the chain in the tub. To me it seems like it would be a complex process.

[Knufire]

Originally Posted by Munchskull

Could some one explain how you get the chain in the tub. To me it seems like it would be a complex process.

Originally Posted by Brendan Browne

Sprocket layout:
Back wheel = Sprocket 1A
Center assemble= Sprocket 1B & 2B
Front wheel= Sprocket 2A
Chains were slightly loose which allowed for easy line up (once its in there the chains rub on the top/bottom wall but they can't go anywhere.
Spacers were round OD so the only hex profile you needed to worry about was lining up the hex axle and hex sprockets. Super glue only held the sprockets in for assembly.

Step 1: Cut Chains to length and assemble the loops (no master link)

Step 2: Super Glue spacers to sprockets creating your internal assembly (118 uses double sprockets with build in extrusions on the side for a single assembly) Double sprockets were not glued together.

Step 3: Press bearings into tube

Step 4: Put sprocket 1A on your back chain and drop through the end of the tube. Used a magnet to help slide the assembly down the tube. Spacers were undersized so it was easier to drop between the edges of the bearings. Used long small screwdrivers to help line it up. Once in line, axle gets put through.

Step 5: Using a machined pocket above the middle assembly, drop the first half of the sprocket assembly into the middle (pairing with the chain you just put in). Throw an axle/rod through to hold the 1B for the next step.

Step 6: Repeat step 4 but this time using sprocket 2A and the second chain.

Step 7: Drop sprocket 2B into the center assembly and slide the axle through both gears.

Now all 4 sprockets, 3 axles, and 2 chains are assembled. Move on to mounting the gearbox and wheel assemblies.

tl;dr, it's not easy.

[asid61]

Originally Posted by Knufire

tl;dr, it's not easy.

That is one way to do it. I talked to a couple teams at champs (can't remember which) and from what I heard from them it was a largely painless process after the initial installation. Could be something to start a thread about.
I'm sure that no matter which way you do initial installation it's going to be harder than traditional WCD, but the upkeep should be simple.