Cheap stepper motor couplings?

Plenty of the old wringer washing machines used a cloth reinforced rubber tube as a coupling, these had a 1/4 to 1/3hp motor, and the coupling, and motor well out lasted the life of the washing machine (usually junked for a flash new one, not because it had died, although the rollers on the wringer may need replacing).

For fitting to a machine tool, would it not be best a direct connection, maybe with a shear pin in case of jamb ups, any flexible joint would introduce inaccuracies------------- but what do I know.

Ian S C

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Ian,

We mortals are generally incapable of aligning [to the requisite standard for stepper motors] a hard-mounted motor shaft with a leadscrew in bearings.

The variety of flexible coupling that I linked yesterday is effectively rigid, in torsion.

MichaelG.

Ball and socket?

**LINK**

Accuracy depends on a dial gouge with a millionth graduations.

Regards Ian.

This amy be of interest?

For HUCO universal couplings in model boats, I have done the following in the past: Make the motor mounting plate a loose fit, and fit the coupling with a section of tube clamped over it to hold it rigid and straight. Pack and glue the motor mount in place. Once all is solid, remove the tubing from over the coupling, which will now be very accurately aligned.

Possibly a similar approach could be used for some types of stepper coupling.

Neil

Have a look at the Transmission Development web site, hardware section.

You could use a double UJ or a nylon sleeve coupling.

Better still would be a timing belt drive as you can have low backlash (Breco or Contiflex).

Prices from Trans Dev are very good. They sell a massive range of drive parts and bearings - mostly Chinese!

I agree with Adrianh. Timing belts make an easy set up. All that is needed to adjust the belt are slotted holes. You can have a 1:1 ratio on timing belt pulleys or increase or decrease the ratio. If top speed is not important because it is not a production environment then lower speed can give higher torque. If the stepper motors you are using are going to be open loop then higher torque is always better to avoid missed steps. Steppers with feedback, such as Leadshine hybrids, can give an error signal from missed steps but with open loop it is always a possibility. Timing belts also increase the options of the motor position relative to the leadscrew. This may not be a consideration for you but for people with restricted width setups it can be a bonus. The y axis motor can often be tucked under the table rather than having it stuck out in front.

Martin