View Full Version : coupling motor to lead screw ideas?

09-15-2003, 10:52 AM
Hi all, have a problem coupling 0.25 motor shaft to 3/8 allthread and 1/2 acme leadscrews. 'Real' couplers are too expensive. Bought some cheaper couplers of the fork and rubber spider type in the appropriate sizes but there's runout on the thread section and the shaft moves around. Tried drilling and tapping smaller sizes to larger and still have the problem. Tool or my technique too inaccurate and the part is too soft to use the existing hole as a guide for the larger drill/tool.

Does anyone have any smart coupler methods that I can produce? Tool challenged here, no access to a lathe so its a drill press and table saw only.


09-15-2003, 11:09 AM
You could try a short length of rubber hose. Wrap the smaller shaft with tape or something to bring up the size a bit if necessary. Cinch the hose up tight with some hose clamps.

You might also try a coil spring for a coupling, if you can find something the right size. Or, maybe a light coil spring over top of the rubber hose.

09-15-2003, 11:10 AM
check out this page.


1/4 Coupling 990-4044
3/8 Couplng 990-4045
1/2 Coupling 990-4046
Spider 990-4042

You've got to order each piece separately but they are super cheap, I ordered some and they are going to work out just great.


09-15-2003, 12:18 PM
I used a flexible coupling made from high pressure hose. My shaft diameter was 1/4" and my leadscrews 5/16". What I did was I bought some hose with 1/4" ID, and TAPPED it for the 5/16", and then screwed it on. This actually held it just fine, but I went one step further and used a hose clamp too. Then I slipped it over the motor shaft, and used another hose clamp.

Seems to hold just fine.

If you have *too much* difference in size, I'm sure you could build up the smaller shaft diameter a bit, perhaps with tape or another hose? Do it in steps?

Or, there's always the commercial option -- just throw money at the problem by ordering the "right" couplers. Most of the major suppliers, like McMaster, ENCO, etc carry them.

-- Chuck Knight

-- Chuck Knight

09-15-2003, 12:18 PM

Thanks. Order placed. Would you believe I went through that catalog about 6 times last night and missed that stuff. Too much time watching F1 at Monza and too little attention to the book I guess.


I went to try that Saturday. Had springs but needed the pipe. Couldn't find anything local that looked as if it would work or at a reasonable price.

Thanks for the fast responses, Helps a lot!\