Looking for shaft coupling

[lilimike]

Hi,

I hope I am posting this in the right section.

After browsing this forum, Googleing, daydreaming, spending nights thinking instead of sleeping I have decided to build a small CNC. I have completed the X and Y axis and I am ready to get started on the Z axis. What I've built so far looks really ugly but both axis are straight and there is nothing loose. I am using this project as a learning process with the projection of building a bigger, better and prettier CNC at a later date.

The main material I am using is MDF and I have never realized before how much nuts and bolts can be so expensive but I managed to find everything else on eBay between China, USA and Canada and the complete project is now up to under $320, all electronics working well and I have 95% completed.

The only thing I am stuck with at the moment is the lead screw/motor shaft coupling. I bought some hose and clamps but I feel it doesn't make a rigid coupling, the hose had to be flexible enough because my lead screw is 1/4" x 20tpi and the motor shaft is 5mm (0.1968") so there is a big difference in size.

I tried to search on this forum using "coupling" as a search word but it returned 100s of threads and I admit not reading all of them but I could not find an answer.

I am hoping not to pay $20 each for such a small item. Can anyone make a suggestion?

Thank you

Mike

[diecutter]

Use the hose and screw clamp method, but use the thickest walled tubing you can find with an ID that is tight on the motor shaft. Then heat up the other end with a hair dryer or heat gun and it will slide easily onto the acme shaft.

[lilimike]

I was doing it the other way around and that might explain the backlash I was getting.
I will try your suggestion.

Thanks

Mike

[Rushwind]

I found some thick-walled (but small diameter) aluminum tubing at the local hardware store. A few minutes with a hacksaw, drill, and tap let me put setscrews in to hold the motor shaft and leadscrew.

It was probably somewhat more involved than rubber hose-and-clamps, but it held OK, and it was a perfect size for the ~1/4" shafts I was dealing with.

[gio666]

I have coupling like this for $15 each

[Kelinginc]

Originally Posted by lilimike Hi, I hope I am posting this in the right section. After browsing this forum, Googleing, daydreaming, spending nights thinking instead of sleeping I have decided to build a small CNC. I have completed the X and Y axis and I am ready to get started on the Z axis. What I've built so far looks really ugly but both axis are straight and there is nothing loose. I am using this project as a learning process with the projection of building a bigger, better and prettier CNC at a later date. The main material I am using is MDF and I have never realized before how much nuts and bolts can be so expensive but I managed to find everything else on eBay between China, USA and Canada and the complete project is now up to under $320, all electronics working well and I have 95% completed. The only thing I am stuck with at the moment is the lead screw/motor shaft coupling. I bought some hose and clamps but I feel it doesn't make a rigid coupling, the hose had to be flexible enough because my lead screw is 1/4" x 20tpi and the motor shaft is 5mm (0.1968") so there is a big difference in size. I tried to search on this forum using "coupling" as a search word but it returned 100s of threads and I admit not reading all of them but I could not find an answer. I am hoping not to pay $20 each for such a small item. Can anyone make a suggestion? Thank you Mike

Check here

http://www.kelinginc.net/CNCPackage.html

[tumutbound]

Try linearmotionbearings on eBay

[fabconv]

nothing is better than this (and cheaper)
http://www.usinages.com/files/thumbs...jpg_37_673.jpg
http://img81.imageshack.us/img81/7018/cncjpg44.jpg

[live help india]

What type of shaft coupling u exactly want : rigid coupling , flexible coupling or torque limiting coupling.

[lilimike]

When I said I didn't want to pay $20 it also meant I don't want to pay much for this as it is just a learning process and what ever I use will not fit my next CNC so even $15 is still too much.

Fabconv,
This looks like a good idea but I have no treads on my motor shaft.

But I found my solution from Diecutter's suggestion,

At first I was using a 1/4" internal diameter hose on the lead screw (which is 1/4") with a hose clamp and the other end on the motor shaft which is much smaller (5mm) and it was creating some backlash.

I found some smaller hose which fit perfectly the motor shaft and its outer diameter is slightly bigger than 1/4" so I put the 1/4" hose on top of it and everything looks tight and no more backlash.

Thank you all for your responses.

Mike

[lusocal]

i think that you are looking for 5x6.35 jaw shaft coupling.
here is the 5x6.35mm_20x25mm jaw coupling
may be it can help you to finish your job.

[wantacnc]

lilimike,
I have 3 of these couplers new in the bags Im not using. Have you bought them yet? Let me know if they will work for you.
Joe, St Louis Mo.

Edit. If you know someone with a lathe they can make a split collar to adapt to .250. to your shaft size.


Ruland Manufacturing FCR12-4-4-A Coupling, 6 Beam Clamp, Bore 1/4 x 1/4 In