Looking for a Coupling for 1/2" motor shaft to KR33 6mm shaft

[DonW]

That pretty much says it. I have a KR33 actuator which I am using for my Z axis. I'm using a Rex RS34-600 motor with a 1/2" shaft, and I need a coupling that will work with the KR33. The problem of course is that the KR33 motor mount is very limited in size, and most couplings are too wide and too long to fit in the limited space. I ordered a NEMA 34 adapter for the KR33, so I'm assuming there must be something out there that will work, but as yet I can't find anything. I'm thinking that the adapter will help to align the motor and the actuator shafts perfectly, so I don't thing the coupling needs to allow for any concentricity issues so it doesn't have to be flexible. Anti-backlash would certainly be a plus, but I'm not holding out hope...

Any help would be appreciated!

Thanks much,

Don Williams
D.E.Williams Guitars
http://www.dewguitars.com

[BobF]

Don,
A picture might help.
Many people on here use lovejoy couplers. You can get them at most of th big industrial suppliers. Usually you can order shaft halves separately. Order 1/2" for the motor side and whatever size you need for the shaft of actuator.
Looks like the OD is just over 1". If that is too large, you will probably have to make something on a lathe.

[jeb]

Hi,
If you can bore one end on a lathe, you could use a 2464K3 from [URL="http://www.mcmaster.com"] It's 6mm to 1/4" and 25mm OD, so there is probably enough room to fit a 1/2" hole in. As far as the length goes, you either have to cut off the motor shaft or make it up in the mounting plate. I ran into this problem, and I found it was easier/cheaper to just order another motor. If you use a Nema 24 with a 1/4" shaft, you could use the above coupling without modification.
Cheers,
Jacob

[DonW]

Hi Bob,

Attached are a few pics of what I'm dealing with. The hole in the actuator motor mount adapter is only a tad over 1" in diameter, so I'm limited to that width for a coupling.

Jacob, where does one find a 2464K3 ?

[BobF]

Don,
The 2464k3 is a mcmaster part no. Go to mcmaster.com and type motor coupling in the search box on the left. They list a lot of types and sizes. Maybe you can find something you can bore to size. All the dimensions are there so you can measure to see if it will fit. If you start the bore with a step drill you should center it pretty well, of course a lathe would be the way to go if you have access.

[DonW]

Thanks for the info....I've looked on McMaster's site several times for something...perhaps I need to look more closely.

[DonW]

Looks like that part is a squeeky 1mm smaller than the opening. It just might work. Worse come to worst, I can have it turned down just a smidgeon.

Thanks again!

I hope to post pics soon of my project..which is my first home-built cnc.

[DonW]

Thanks for the suggestion of the part from MacMaster. I ordered it, and as usual received it the following day. Those folks are great!

The trick of course was modifying the coupling from 1/4" to 1/2". Not having a lathe to turn it on, I was forced to think a bit outside the box to get this done. Obviously, the spring-like nature of these things makes maching somewhat difficult.

Here's how I did it...

I wrapped the coupling in metal aluminum tape for a couple of turns, and burnished it down good and tight. I also slipped a little into the slots on the end to hold it open when clamped. This made it more rigid than if it wasn't taped. Next, I snugged it into a 1" hole in a piece of hardwood, and then clamped the hardwood onto my drill press table, after aligning the center hole with a 1/4" steel dowel in the spindle. I laid a pair of vice-grips down on the wood and clamped the top of the coupling with that to keep it from spinning, and then clamped that down to the drill press table on that end. Insert a 1/2" Dewalt drill with built-in pilot, which acts as a step/counterbore, and drilled it out.
After measuring the remaining rim, I was out of round by maybe .01" at most. Still, the shaft went in and stayed pretty close to center. It clamped down and holds like a rock, and fits perfectly in the limited space of the KR33.