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Author Topic: Encoder mounting bushing?  (Read 3615 times)

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Encoder mounting bushing?
« on: June 30, 2016, 06:10:32 PM »
I goofed and got my new encoders. They are 6mm and the old ones were .250". Before I order some new couplings, any way to sleeve them. A quick search came empty.
Don
« Last Edit: June 30, 2016, 06:24:42 PM by DonMarkey »
Re: Encoder mounting bushing?
« Reply #1 on: June 30, 2016, 06:44:54 PM »
?
« Last Edit: June 30, 2016, 06:52:54 PM by DonMarkey »
Re: Encoder mounting bushing?
« Reply #2 on: July 02, 2016, 12:06:00 AM »
This is a tiny difference, about .007/side. However, if you have a lathe with a collet that will fit the coupling body it can be done. Clean the bore with acetone or lacquer thinner. Then carefully coat the ID with JB Weld. Let it set for 24 hr. Chuck it up, and run a 6mm reamer through the hole, slowly. If I can find it, I will post the source of some couplings that will have the metric bore.
 
Re: Encoder mounting bushing?
« Reply #3 on: July 02, 2016, 07:05:06 AM »
Thanks. Never thought about epoxy. All the couplings I could find would require cutting one side or the other anyway. If you know of a source please let me know. If not I can pick up a reamer. How much luck do you think I would have using an 1/8" endmill and recutting in the mill, think the jb would pop? The encoders are 6mm and the motor shaft is .500"
Thanks
Don
Re: Encoder mounting bushing?
« Reply #4 on: July 03, 2016, 12:05:14 PM »
I first thought your shaft/bore difference was 6mm to 1/4". However the 1/2" bore is another problem. If it were just the small diff, the JB weld would work OK. With the larger bore to deal with, your only option is make a bushing to fit the 6mm encoder shaft. This is a lathe job, of course. If you have no facilities, I could make one for you.

The finished bushing can be put into the 1/2" coupling bore using Loctite #271, Red label. This stuff is super strong, and permanent. After it is set, you can drill on through the set screw hole, and run a tap all the way.

The website "stepperonline" has shaft couplings, and the type I prefer have a red non-metallic center piece, with the two hubs engaging the center with alternate teeth. The have many sized of different mating bores, but the 6mm largest opposing hub bore was 10 mm. Then the major OD of the hub jumped from 20mm to 30 mm. The 12.7mm bore is equal to 1/2", but the starting small side was bigger than 6mm. You can check them out. It has lots of steppers and amps also.

John


Re: Encoder mounting bushing?
« Reply #5 on: July 03, 2016, 04:02:36 PM »
No the old encoders were 1/4" and the new ones are 6mm. The motor shaft is 1/2"name the existing couplings are 1/2x1/4 and about 1-1/4" in diameter. So with the couplings I saw I would need to open up a 12mm to 1/2" or shim my existing couplings. I don't have a 6mm reamer but could use a boring bar in the lathe or and endmill in the mill. I don't have a collet large enough to hold the coupling but could dial it in the 4 jaw. Instead of jb, would I be better off opening it up then bush it?
Don
Re: Encoder mounting bushing?
« Reply #6 on: July 03, 2016, 06:04:03 PM »
I saw those love joy type, any issues using them for encoders? They are the only ones I could find with 6mm x 12.7mm.
Don
Re: Encoder mounting bushing?
« Reply #7 on: July 04, 2016, 04:11:01 PM »
I mentioned JB Weld for the very tiny difference between 1/4" and 6mm. However a large difference makes that impractical.
If you can sleeve a 12mm bore or a 1/2" bore to 6mm, that is the best way. It is a lathe job. If you can drill a bushed coupling to 15/64 (.2344), you are very close, but still under;  6mm = .236 . Turning slowly in the lathe, and scraping with a small round file can open it up enough. Of course, the best way is buy a 6mm reamer. They are about 15 or 20.00.

The lovejoy coupling is like a universal joint, and is not a very good alternative. You also want zero backlash.

It's always the little details that take up so much time.


Re: Encoder mounting bushing?
« Reply #8 on: July 04, 2016, 05:10:07 PM »
That is what I have just the tiny different between 6mm and 1/4". Right now the mill has encoders that are 1/4" the new encoders are 6mm. The existing couplings fit the 1/2" motor shaft and the old 1/4" encoders. My statement was if I replace the couplings I need 6mm x 1/2" if I use the existing one then just need to shim the difference. I can't find any couplings in that size, even on that site you recommended. I will just wait until Tuesday and stop at Msc and get a reamer. Sounds like the easy way to go.
Thanks
Don