# coupling types for stepper motors



## 8ntsane (Oct 18, 2012)

Im over on the SDP site, and looking at the couplers for mounting a stepper motor. They have all different types over there.

The question being, what type produces the least amount of back lash, and still provides the ability to handle some runout in the leadscrew shaft.

Im looking for a typical coupler that would be used on a CNC stepper install.


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## DMS (Oct 19, 2012)

There was a post about this in the "Basic CNC" Thread we had going. Basically, there are 3 common types, and they get better as the price goes up. They will all handle some mis-allignment in 5 dimensions (XYZAB). The cheapest is the "spider" type. It's a 3 piece design that has an elastomeric or plastic piece in the middle. Next comes the helical beam type. It looks like a spring. Then comes the bellows type. 

The spider type will run you about $15, the helical beam type around $25, and the bellows type around $50. There are of course, other types, but those are the basics.


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## Bill Gruby (Oct 19, 2012)

Emphasis on HAD.

 "Billy G" :whiteflag:


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## 8ntsane (Oct 19, 2012)

DMS

Thanks for your information.
I will have a look at the types you have mentioned. Maybe I should have mentioned that this coupler is to connect a stepper to my rotary table. Do you know if any certain type would be a better choice?

My concern here is, though mostly used for positioning. The coupler , if the wrong choice is made could add back lash to the mix. The worm gear allready has some, but not wanting to add to that. Also wondering about machining while the table is under power. I dont know if some couplers have any spring back or not.

Im probably over thinking this :nuts:


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## 7HC (Oct 19, 2012)

8ntsane said:


> DMS
> 
> Thanks for your information.
> I will have a look at the types you have mentioned. Maybe I should have mentioned that this coupler is to connect a stepper to my rotary table. Do you know if any certain type would be a better choice?
> ...



The helical beam type are almost universal now for CNC (and also the cheapest, generally under $5.00 if you order from eBay). 
 You'd have to load one really heavily to get any spring back when you reverse it.

Have a word with Jumps4 (Steve) who's running the exact setup you're describing.


M


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## 7HC (Oct 19, 2012)

Bill Gruby said:


> Emphasis on HAD.
> 
> "Billy G" :whiteflag:



C'mon Bill, most threads wander and stop and start from time to time.  
Lots of good information has been disseminated from it as this very thread demonstrates, and I'm sure there's more to come.


M


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## DMS (Oct 19, 2012)

Yeah Bill, we worked that thread to a pulp. We could start it going again with additional topics, but as it stands, its fat and juicy with info.

As far as couplers, any of these should work. They will all introduce some backlash, but it's very small, and backlash improves with price 

If it were me, I would go for the middle-of the road, helical beam type. I have used them before, and was pleased.


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## 8ntsane (Oct 19, 2012)

DMS

Again, thanks for your input.


Bill,
If you think this thread should be over with your thread, by all means just move over there. I dont care aslong as I get anwers Im looking for.
I just figured this maybe related, but not really a CNC deal, but for a R/T Im going to be using with a Division Master controler.

I allso have other things for my lathe in the planning stage. This will be adding steppers to the lead screws on the crosslide and carriage.
But again, not true CNC, as Im intending to use the ELS, or Putnam ELS controler.

I could post questions over on your thread, but I know you have a order you want to keep things in, and I dont want to interupt that order. But I can, If you want?:thinking:

I have found lots of good infro from your thread, keep it going guys. I wish I could get in on it more, but Im still learning the basics too.


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