pic: Vex Face Bearing Gusset Gearbox

[aldaeron]

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[aldaeron]

STEP is here

Thanks asid61!

[Cash4587]

The gusseting looks a bit overkill to me. This is a cool Idea though.

[asid61]

Originally Posted by aldaeron

Trying to attach the STEP file and cannot seem to find the attach button I am looking for. Help please?

You can only attach certain formats, and even then only up to 2MB. Uploading to Drive or GrabCAD first helps. I recommend the latter because it has infinite file storage and revision control for free.

Looks pretty neat. What gusset does this use again? What size gears can you use?

[AdamHeard]

Originally Posted by aldaeron

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1.125" OD x .75" ID bushings are available on mcmaster. I'm assuming the goal is to pilot the CIM in a 1.125" bore?

[s_forbes]

Pretty clever! I'm hoping vexpro will come out with a transmission that attaches to a 1x2 tube in a similar fashion in the future. They have lots of cool gearboxes, but they don't seem to bolt on to tubular frames very easily.

Originally Posted by asid61

What gusset does this use again? What size gears can you use?

Versaframe face gusset. Here's a drawing. Hole spacing is for 84 total teeth.

[aldaeron]

Originally Posted by asid61

You can only attach certain formats, and even then only up to 2MB. Uploading to Drive or GrabCAD first helps. I recommend the latter because it has infinite file storage and revision control for free.

I knew one of the many gearbox designers would know how to help. Added link to the STEP above.

Originally Posted by asid61

Looks pretty neat. What gusset does this use again? What size gears can you use?

It is the .090 sheet metal Vex Face Bearing Gusset. It is sized for 84 Tooth 20 DP gears (C-C is 2.103). Vex Drawing is here.

Basically you get two gear reduction pairs of any two hex bore 20 DP gears that add to 84 teeth. The largest reduction is 66:18 (3.67).

It may not be as reuseable as other gearboxes and does take some assembly work, but is an entry level way to get into custom gearbox design. I think you could stack two 6" pieces of VersaFrame and make a standalone gearbox if you want.

I haven't priced it (depends on your gear choices and if you go as crazy as I did with extra supporting gussets). My quick calc says as shown it is $50 plus the cost of the 5 gears (~$50), plus the mounting hardware, collars and shaft pieces. Not as cheap as the Vex Double Reduction at $60, but not bad for a custom gearbox with no CNC required IMO.

-matto-

[aldaeron]

Originally Posted by AdamHeard

1.125" OD x .75" ID bushings are available on mcmaster. I'm assuming the goal is to pilot the CIM in a 1.125" bore?

This is what happens when late night designing with "holiday cheer"

Should have thought of that!

[s_forbes]

Originally Posted by aldaeron

Basically you get two gear reduction pairs of any two hex bore 20 DP gears that add to 84 teeth. The largest reduction is 66:18 (3.67).

If you are going from a CIM, you can have a 12/72 reduction, or even an 11/72 reduction using vexpro's 11 tooth pinion gear (link).

[Oblarg]

I really like the easy chain access with this design. Clever.

[asid61]

Originally Posted by aldaeron

I knew one of the many gearbox designers would know how to help. Added link to the STEP above.



It is the .090 sheet metal Vex Face Bearing Gusset. It is sized for 84 Tooth 20 DP gears (C-C is 2.103). Vex Drawing is here.

Basically you get two gear reduction pairs of any two hex bore 20 DP gears that add to 84 teeth. The largest reduction is 66:18 (3.67).

It may not be as reuseable as other gearboxes and does take some assembly work, but is an entry level way to get into custom gearbox design. I think you could stack two 6" pieces of VersaFrame and make a standalone gearbox if you want.

I haven't priced it (depends on your gear choices and if you go as crazy as I did with extra supporting gussets). My quick calc says as shown it is $50 plus the cost of the 5 gears (~$50), plus the mounting hardware, collars and shaft pieces. Not as cheap as the Vex Double Reduction at $60, but not bad for a custom gearbox with no CNC required IMO.

-matto-

The largest reduction could even be 70:14 if you use 3/8" hex bore gears.
If there was a way to easily align these across a tube, like some kind of C-channel acting as a square, you could just make a gearbox with oversized holes made with a step drill and a piece of versaframe.

[aldaeron]

Originally Posted by asid61

The largest reduction could even be 70:14 if you use 3/8" hex bore gears.
If there was a way to easily align these across a tube, like some kind of C-channel acting as a square, you could just make a gearbox with oversized holes made with a step drill and a piece of versaframe.

Originally Posted by s_forbes

If you are going from a CIM, you can have a 12/72 reduction, or even an 11/72 reduction using vexpro's 11 tooth pinion gear (link).

The original design used 8mm to 1/2 adapters and was supported by a hex bearing and therefore required a hex bore gear. As Adam pointed out, using a bushing is a better idea and allows you to use CIM gears.

If you want a less aggressive first stage, you can still use the adapter and a hex bore gear.

[Ari423]

It looks like the two pieces VersaFrame still need to be precision machined for the gears to mesh well. Am I wrong? If not, how is this any different from any other custom gearbox?

EDIT: How are the CIMs attached to the top piece of VersaFrame? There are holes through the gusset plates, but I don't see anything through the VF itself. Is the plan just to mount the CIMs to the gussets?

EDIT 2: Is there any reason why the first reduction has to also sum to 84 teeth, or can that be any gear ratio provided you use the right C2C distance?

[Lil' Lavery]

Interesting idea. Have you done any price comparisons between using your method and using clamping gearboxes*?

*See the "gearing options" portion at the bottom of the page.

Originally Posted by Ari423

It looks like the two pieces VersaFrame still need to be precision machined for the gears to mesh well. Am I wrong? If not, how is this any different from any other custom gearbox?

All the machining required on the versa frame for this can be done with a drill press or hand drill and a dremel. You can match drill all the gusset holes. Any slotting required for clearance for the first reduction gear can be done with a dremel, cutting wheel, and some patience. All the piloting is handled by the gussets and bearings, so no precision machining is required.

Originally Posted by Ari423

EDIT 2: Is there any reason why the first reduction has to also sum to 84 teeth, or can that be any gear ratio provided you use the right C2C distance?

A total of 84 teeth (20DP) is the "right" C2C distance for the 2.103" spacing used by Vex for the gussets.

[Ari423]

Originally Posted by Lil' Lavery

All the machining required on the versa frame for this can be done with a drill press or hand drill and a dremel. You can match drill all the gusset holes. Any slotting required for clearance for the first reduction gear can be done with a dremel, cutting wheel, and some patience. All the piloting is handled by the gussets and bearings, so no precision machining is required.

I didn't realize you could use the gussets as a guide to drill the other holes. That's a smart idea!

Originally Posted by Lil' Lavery

A total of 84 teeth (20DP) is the "right" C2C distance for the 2.103" spacing used by Vex for the gussets.

I didn't see the double plates in there; I thought they were all single plates. Never mind then.

Overall, I really like this design! I might just suggest it to my team.