Re: Hello

Dear Alfredo,
search for " drehstarre kupplung" and "kupplung cnc" on ebay Germany. They always cost around 10-15 euros per piece. I looked it up, sent to spain as a big letter (DINA4 size, up to 5cm thick and 500g weight) it will cost you 3 Euros shipping and handling.

In case this is too expensive and you have friends in the states, ask them to order 3 jaw couplings from use-enco.com for you and send them to you, price is in the 10 Dollar range. The maker is lovejoy, catalog page 1034. Be careful, you have to buy hubs and rubber spiders seperately. One coupling is three parts.

These use set screws to attach to the motors, you have to file or mill a little flat on the motor shafts to bolt down the set screws. Some of these couplings use grub screws with a pin that will make a small crater in the shaft so you can use them without the flat. however, the flat forms a crater with a donut shaped rim and when you want to take it apart, the rim will lock the hub and scratch it.

The cheapo approach would be to cut short length of 6mm id flexible plastic hose (guess your motor shafts are 6,35mm) and put it on both shafts, spindle and motor and use a hose clamp to fasten it into place. This allows for slight shaft misalignment and you can mill out a fancy coupler with your CNC to replace this makeshift coupling (that works exceptionally well, by the way).

Using glue, I would lean towards loctite 608. This can be bought at every car parts or bearing and motion parts dealer,they have an office in Barcelona or Madrid that can help you with technical informations and distributers. Look them up on the net. This is a high strength glue that can take torsion loads of 2 kilos per square millimeter. Be careful to clean and degrease the metal parts throughly. To take it apart, you can heat up the parts to 200°C and then break the bond while the glue ist still hot. A Stepper won´t survive this temperature so be careful you only heat the shaft.

Cheers,
Johann