pic: Cim with Encoder CUI Inc. AMT 102-V3524

[Twins Inc.]

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[Richard Wallace]

Nicely integrated!

Can you link a data sheet that includes the specific encoder shown in the picture? I did not see it in this AMT10 data sheet.

[Justin Montois]

Very elegant solution. Nice work.

[mman1506]

Nice! Have you tested compatibility with typical FRC gearboxes?

[jwfoss]

Using the CIM mounting configuration is a smart move as this can be applied to a large number of components from VEXpro and AndyMark. Is the plan to market this in the future or would you be willing to provide drawings/cad models?

[Chirag]

Any updates on testing this configuration? I'm really liking how slick this is but I'm very curious as to if the assembly can still be mounted to COTS gearboxes. We might want to pick up some of the FIRST Choice ones and try something similar

[Ether]

How much further out along the shaft will the CIM pinion be cantilevered?

[Richard Wallace]

Originally Posted by Ether

How much further out along the shaft will the CIM pinion be cantilevered?

The encoder is 9 mm thick. A CIM pinion (VP) is 19 mm long. The CIM shaft extension is ~31 mm past the pilot boss. So the encoder will fit between pilot and pinion, without pushing the pinion past the end of the shaft. However, it will be about 1/4 to 3/8 inch further from the front motor bearing than teams would typically put it, increasing the bending moment. In applications where bending a CIM shaft is foreseeable (I think a 254 mentor has posted about seeing that), this method of encoder mounting will increase the risk of bending the shaft.

[asid61]

Originally Posted by Richard Wallace

The encoder is 9 mm thick. A CIM pinion (VP) is 19 mm long. The CIM shaft extension is ~31 mm past the pilot boss. So the encoder will fit between pilot and pinion, without pushing the pinion past the end of the shaft. However, it will be about 1/4 to 3/8 inch further from the front motor bearing than teams would typically put it, increasing the bending moment. In applications where bending a CIM shaft is foreseeable (I think a 254 mentor has posted about seeing that), this method of encoder mounting will increase the risk of bending the shaft.

Would it be possible to press a bearing where the cim boss would normally go to negate the canteliever? Like put an 8mm bearing into the place where the cim 0.750" boss would normally go.

[Richard Wallace]

Originally Posted by asid61

Would it be possible to press a bearing where the cim boss would normally go to negate the canteliever? Like put an 8mm bearing into the place where the cim 0.750" boss would normally go.

The pilot boss might be considered part of the CIM's "integral mechanical and electrical system" per 2014 R30. I think the boss provides some of the mechanical support for the CIM's front bearing.

[asid61]

Originally Posted by Richard Wallace

The pilot boss might be considered part of the CIM's "integral mechanical and electrical system" per 2014 R30. I think the boss provides some of the mechanical support for the CIM's front bearing.

The boss plugs into the encoder plate though, which plugs into the gearbox. I'm not talking about changing that, just putting a bearing in the gearbox plate to make the cim not as cantaleivered.

[Richard Wallace]

Originally Posted by asid61

The boss plugs into the encoder plate though, which plugs into the gearbox. I'm not talking about changing that, just putting a bearing in the gearbox plate to make the cim not as cantaleivered.

Sorry I misunderstood your idea earlier.

So, if I am getting it correctly now, you would put a third bearing on the motor shaft, between the encoder and the pinion? Maybe a 608, with 8mm ID x 22mm OD x 7mm length. Then you'll have 31 - 9 - 7 = 15 mm left for the pinion and its retainer, so a standard 19 mm pinion would need to be cut down to about 12 mm. This will still be enough to engage a 3/8 inch (9.5 mm) gear tooth face. A little more demanding of axial gear alignment, with very tight axial clearances.

Edit: maybe leave about half of the 608's axial length protruding from the encoder adapter so it functions as a pilot for the gearbox? This would allow larger pinions (e.g., 14 tooth) to clear the pilot diameter, making gearbox assembly easier, while relieving some of the tight axial clearance problem.

[asid61]

Originally Posted by Richard Wallace

Sorry I misunderstood your idea earlier.

So, if I am getting it correctly now, you would put a third bearing on the motor shaft, between the encoder and the pinion? Maybe a 608, with 8mm ID x 22mm OD x 7mm length. Then you'll have 31 - 9 - 7 = 15 mm left for the pinion and its retainer, so a standard 19 mm pinion would need to be cut down to about 12 mm. This will still be enough to engage a 3/8 inch (9.5 mm) gear tooth face. A little more demanding of axial gear alignment, with very tight axial clearances.

Edit: maybe leave about half of the 608's axial length protruding from the encoder adapter so it functions as a pilot for the gearbox? This would allow larger pinions (e.g., 14 tooth) to clear the pilot diameter, making gearbox assembly easier, while relieving some of the tight axial clearance problem.

Am I wrong in saying that the axial tolerances can be a little looser, as the whole cim/encoder assmbly is mounted by two screws with no boss? I'm not sure if that would work, but wouldn't the cim shaft be aligning this anyway?

I would actually use an 8mm ID x 16mm OD 5mm long bearing. On a 3/16" thick plate, it only sticks out about a hundreth of an inch. It has a pretty high load rating too.

[Twins Inc.]

Originally Posted by Chirag

Any updates on testing this configuration? I'm really liking how slick this is but I'm very curious as to if the assembly can still be mounted to COTS gearboxes. We might want to pick up some of the FIRST Choice ones and try something similar

Be careful about doing this, because I believe the encoders on FIRST choice are a little different than the ones that we used here. While the pins here are parallel to the face that you are mounting to the CIM, the FIRST Choice ones are Perpendicular. So it wouldn't work for this application. However the CUI Encoders on FC are still very useful for the end of a shaft, like an idler, so we'll still be getting some.

The only testing we have done with these have been on a simple flywheel. We attached it to our Frisbee flywheel from 2013 with great results.

[asid61]

I'm sorry for necro-ing this, but:
Are there CAD files anywhere? I forgot to bookmark them if they're here.