Look up flexible couplings they are quite popular. Sure there will be a stockist near you.

Steve.

Hengstler or flexible beam couplings are pretty common so should be easy to find. RS components have then but they are a bit pricey. Zapp Automation might have them.

If you are converting something to CNC, they flex/bend and can sometimes bend/snap the leadscrew. They put a strain on the lead/ball screw, and sometimes also effect the fast movement of the X/Y axis. So for example if you are cutting/engraving a circle, at a certain point you may fail to get a perfect curve. If you are looking at a clock face, usually between 6pm and 9pm.

If you have alignment issues, better to look at oldam couplings, similar to this. These hold the position better. ARC will stop selling these after they are sold out becasue we stopped selling most things to do with CNC.

Ketan at ARC.

Then not a big deal. Most people use flexi coupling, but we stopped using them very early on. We still use the oldham type for the rotary table conversions we build, for quicker assembly, and still to get over alignment stress/strain issues.

Which ever way you decide is fine. Good Luck.

Ketan at ARC.

Thats a good write-up John.

Ketan at ARC.

Sorry Old Mart,

That is not the experience we have has with Oldham Couplings!

JS and I spent a long time developing the modifications to the KX CNC machines as well as the modulations from manual to stepper motor modifications of the rotary tables…. more than 12 years ago, well before most on here started to come up with the ideas.

Before we put the modified rotary tables with stepper motors onto the market, we ran Extensive tests, especially with Steve Blackmore – the demolition king, to break them. After additions of several D.C. Needle roller bearings and Thrust NRBs and Oldham couplings to the assembly, such rotary tables became a lot more robust. Because of the cost of the modified rotary tables, most of our customers for them were and still are industrial users who consider them to be cheap!

The SIEG factory made two versions of the KXs. We sent them the Oldham couplings for all the KX CNC machines we sold, after seeing the failure under certain ‘abuse’ conditions using the various flexi coupling versions they fit as standard. The KXs sold by others have flexi, including the clones. To the best of my knowledge, not a single one of the KXs we supplied over 10 years, including the one we use has had a ‘backlash’ / failure issue due to the U.K. made Oldham couplings fitted into the ARC supplied KXs, which are more expensive to buy than the flexi couplings… even from original Oldham couplings makers themselves, and even they recommend these over their own versions of flexi, for industrial applications.

Until around 2017, Oldham couplings were not made or available in China. Even when they started making such couplings in China, they had many failures initially, and only recently, they have made improvements. Even so, the Chinese equivalent is more expensive than their flexi, and sometimes their similar ‘looking’ types are still not Oldham types, but are marketed as such. It would be wrong to compare an Oldham coupling with flexi, in our opinion. But, as I said earlier, it is up to the user and their application.

Ketan at ARC

Edited By Ketan Swali on 09/05/2020 22:31:45

Also, forgot to say that Oldham couplings also have grub screws to fix/clamp them onto the shafts, and yes they are easier to couple up and are always better than flexi to maintain alignment without stress.

Ketan at ARC

Edited By Ketan Swali on 09/05/2020 22:35:37

The ones which ARC sells are made by HUCO.

Ketan at ARC

All good stuff, Nigel ^^^

… provided that you can be sure of axial alignment between motor and shaft.

MichaelG.

Yes Nigel, we had extensive arguements with SIEG over this type of flexi couplings too…, because, as MichaelG says, these too failed to dealwith axial alignment/mis-alignment, and still giving cut results under extream circumstances similar to what I said earlier: ' They put a strain on the lead/ball screw, and sometimes also effect the fast movement of the X/Y axis. So for example if you are cutting/engraving a circle, at a certain point you may fail to get a perfect curve. If you are looking at a clock face, usually between 6pm and 9pm.' Although I agreed with them that they were cheaper to obtain from within China and Taiwan, and the performance was/is much better than the OP type flexi coupling, and the curve was more near perfect.

This arguement became heated between SIEG and myself, we agreed to disagree, compromise and I couriered the Oldham couplings to them.

Regarding 'wear' for Oldham couplings, I agree with you and I wish there was, so that I could sell replacements to all the users of the products. But so far, in the 12 years we have been selling them, this has been rare.

Ketan at ARC.

.

Sorry if I was not clear, Nigel … I was comparing the properties of your illustrated coupling with the Oldham one, not the spiral cut aluminium type.

MichaelG.

.

Edit: ___ Incidentally, the spiral cut is [in my opinion] a poor substitute for the aluminium version that has a staggered series of ‘half cuts’.

Edited By Michael Gilligan on 10/05/2020 11:09:32