Newbie- Probably a crazy idea!! Linking steppers??

[nick-a-million]

Hi All,

This is my first post on this site which i have to say seems a fountain of all knowledge.

I am totally new to this and have got a 1940's Sheldon Lathe that to me looks like it could do with cnc as an experiment. Since my budget is almost zero i can't be choosy.

I have also been donated a large number of unknown 1.8deg stepper motors. All the same as each other designed for seriously top end moving lights. They aren't huge and are normally driven i believe by 3771 ic's. They are bipolar. Approx 5mm shaft front and back and the bodies are approx 30mm cubed. 4 wire.

My question is that since it is a beast of a machine i was wondering if it is possible to physically link the drive shafts of two motors to give more torque?? These motors were built for precision and are exactly the same spec.

Probably a stupid question but since they kinda landed in my lap and will save me a great deal of money on this project i was wondering what people think???

Many thanks to all who read and reply.

Best regards,

Nick

[dilbert0815]

Originally Posted by nick-a-million Approx 5mm shaft front and back and the bodies are approx 30mm cubed. 4 wire.

30mm ?
Sound a little small. Even Nema 17 has 42mm cubed.

I would have some serious doubts that these motors can move something more severe like a lathe. May need some rather large gearing, which is a little counter productive for precission.

Even two of these might not even come close to a single Nema 17.
Any data availabe to judge the motor torgue ?

[nick-a-million]

Hi dilbert0815,

Thank you for your reply. I have contacted the lighting manufacturer that has the motors made to see if they can supply any torque info.

It seems i have no concept of size because i measured this time with a ruler and they are 42mm sq and 35mm deep. I just wondered if i did connect the spindals together whether this would throw up problems. I only ask because i have so many of these motors! Shame not to use them up, in fact i have about 15!!!

Thinking about it, if i can join forces of two then it might reduce the chance of missed steps because both would need to miss at the same point. I think they are probably fairly high torque, especially if i use them in full step.

What minimum torque would you think i need for this mahince? It moves really quite smoothly.

Many many thanks again.

Best regards,

Nick

[dilbert0815]

Originally Posted by nick-a-million It seems i have no concept of size because i measured this time with a ruler and they are 42mm sq and 35mm deep. I just wondered if i did connect the spindals together whether this would throw up problems. I only ask because i have so many of these motors! Shame not to use them up, in fact i have about 15!!!

I don't belive it would be a problem having a rigid coupling of two motor.
That's provided that the motors are connected identically to the same driver and they are aligned .

Wether they can realy drive the lathe support realy depends on a lot of facts.
I would search here for similar projects and compare the motor sizes being used.
I would still expect some gearing might be needed, but I'm not the one with the calculation know how to derive the numbers.