Advice on buying servos.

[Agathon]

Is it important that the servo driver and motor are from the same manufacturer? Or is just that the driver and motor must match electrically speaking?

[Ger21]

The most important is that the encoder connections on motor match what the drive requires.
Some encoders/drives use 12 or more wires, some use as few as 5 or 6.
Imo, unless you really know what you're doing, it's best to but a matched set from the same manufacturer.

Not sure if they are available over there, but here inthe US, and Canada, DMM are the best bang for the buck.

[Agathon]

The most important is that the encoder connections on motor match what the drive requires.
Some encoders/drives use 12 or more wires, some use as few as 5 or 6.
Imo, unless you really know what you're doing, it's best to but a matched set from the same manufacturer.

Not sure if they are available over there, but here inthe US, and Canada, DMM are the best bang for the buck.

Many thanks Gerry. Those DMM servos are very good VFM.

[Boyan Silyavski]

The Samsung servos need a Samsung drive. Or better said, you could not hook other servo motor to a brand drive. As it auto detects motors and will give " Faulty" all of the time. Samsung motors have 9 wires to encoder, some 11. The one on link is with 9 wires.

The only way you could make a similar motor work is Universal servo drive like Granite Devices.

And yes, that motors are good price and good ones, but you can check the Samsung PDF manual link i send you earlier and see that for yourself. But remember what i told you about the servo cables. Dont make decisions without knowing what will cost you when you include them. The good thing is these motors are in Europe. You could buy the drives for around 130 each, used.

DMM are out of question in Europe. Going that way is better to buy Chinese drives or the second hand Samsung. I have pondered over that many times last years and every time money and price prevails.

[Agathon]

Thanks for the reply.

I've taken a punt on these: http://www.ebay.co.uk/itm/322584699618

I spoke to the young lad whose selling them and it seems his grandfather worked in the motion control field. They may not work of course, but not much lost if they are US.

Will keep an eye out for motors to match.

[Boyan Silyavski]

I think you misunderstood what i said. Drive and motor combo from different manufacturers will NOT work!!!

You need a drive that lets you program the motor parameters, not a drive that lets you choose from certain motors!!! Check that in manual.

[Agathon]

I think you misunderstood what i said. Drive and motor combo from different manufacturers will NOT work!!!

You need a drive that lets you program the motor parameters, not a drive that lets you choose from certain motors!!! Check that in manual.

Thanks for the clarification. I'll be looking for used Omron or Yaskawa motors for the drives I've just bought (it appears that they had a joint venture).

It does seem that the issue of whether different manufacturers motors can be driven from different drives is not straightforward: http://www.cnczone.com/forums/servo-...vo-driver.html

However, I take your point. At £90 for two drives I'm willing to have a play and see what happens.

You mentioned cables in a previous post. Is it impossible to make up cables given the correct plugs and sockets?

[Agathon]

According to the specs this is the correct motor for the drivers I just bought - http://www.ebay.co.uk/itm/OMRON-R88M...-/182634177958

[Agathon]

Just out of interest, via a socket screw axial to the ballscrew, I used a precision torque screw-driver (usually used for very carefully setting the torque on small screws) to see how much torque was required to move the table. As might be expected the initial torque required to overcome the stiction was higher that what was required to keep it moving. However the maximum torque required was surprisingly low - 0.5 Nm. I might just pop a 16mm slot-drill in a collet and see how much torque is required to make it cut steel...

[Agathon]

Having thought about this for a few mins, I am now a little unsure that a 200W servo will be powerful enough for my table. The Omron R88M 200w motors produce 0.637 Nm continuous torque with a peak of 2.2 Nm.

I think I noted in one of my first posts on this forum about stepper replacement that Fehlmann now fit Omron 400W servos to the P21 which is a similar machine to mine (but with a slightly larger table) - I'd forgotten about this until doing some searches earlier on.

I suppose that if I do as you suggest Boyan and fit the servos with a 2:1 reduction a 200W Omron servo might be adequate. Being more optimistic, a reduction of 3:1 would produce the best part of 2Nm continuous torque - which will probably do the job.