The Best Steppers/Servos Setup Thread

[andy_con]

but the machine doesn't need the worlds biggest servos, its not like it will take massive heavy billets. are there no small decent servos?

the table doesn't need to move at 1000mph.

Your budget is the limit!
However, the problem with a Triac, is you're limited on space to mount servos, unless you start doing some major rejigging of motor mounts. As part of my retrofit, I measured things to see how much room is available for upgrading at some point. X would need the motor flipped and mounted in front/behind the table other wise it'll hit the enclosure. Y would either need the motor flipped and sticking out the rear, or the ballscrew extended to give enough room. I think Z is the only one with plenty room to keep the existing mounting position.

However, ignoring fitting issues. Drive upgrade will give a noticeable speed improvement. I've got Leadshine EMs fitted, and I'm no where near pushing them to the limit. I still need to see just how fast I can push the original motors, but not got that far yet, as I'm still fixing/finishing other things.
Modern motors would also give a boost, but I'd rather spend money on servos.


I've got Kinco servos (400 and 700W) on my lathe, and they work well. I'm running them using +/-10V using a KFlop+kanalog, and they tuned up well.
I know DaveK fitted some cheaper Chinese servos to his Bridgeport, but the lack of separate logic power supply (means if you kill power to the drive, you lose position - better drives use a separate 24V power for logic, so the encoder works even when drive power is lost), and I know he had some issues tuning them. I am tempted to get one to try, but I've yet to find a suitable use for one.

[m_c]

but the machine doesn't need the worlds biggest servos, its not like it will take massive heavy billets. are there no small decent servos?

the table doesn't need to move at 1000mph.

There are, but gearing is the problem.
Stock steppers are 1.1Nm stall, with a gearing ratio of 12:30, giving roughly 2.75Nm at the screw.

A 50W 3000rpm servo, which from Kinco is 83mm long (should fit in a similar place to the steppers), gives 0.16Nm. So to get similar torque you need in the region of 17:1 gearing, and you limit screw speed to 176RPM (roughly 880mm/min).
Move to a 100W version, which from Kinco is 110mm long (I think this was very borderline for fitting to the X, and wouldn't fit on the Y), gives 0.32Nm. Ratio needed is about 8.5:1, and you'd get 1.6m/min speed. If you could manage the gearing ratio, this size would probably be a good match specification wise, but 8.5:1 involves a very big pulley. A gearbox would be a good option, but you add cost, and length.
A 200W 3000RPM servo, again from Kinco is about 120mm long, and gives 0.7Nm continuous torque. You need a ratio of about 4:1, which is very achievable., and you'd be up over 3m/min if you ran it at full speed.

Off course all those figures are based around the continuous/rated torque of the motor. Instantaneous/peak torque is typically 2-3x the continuous figure, but you normally rely on that for acceleration, which is where you should get the real benefit over steppers. If you were to run the figures above using the peak torque, then you would have to limit acceleration, and performance gains would be far more limited.

IIRC, the servo Triacs used about 200W DC servos. I'm sure I read the Y servo stuck out the back of the machine, but I've got no idea how the X was fitted.

[andy_con]

I'm guessing all the leadshine and other Chinese AC servos on ebay are naff?

[m_c]

I'm guessing all the leadshine and other Chinese AC servos on ebay are naff?

Some of them are perfectly good. Kinco is Chinese. Leadshine is good.
The big thing is making sure whatever you buy will do what you expect it to, and comes with reasonable documentation.

[Skiprat]

I bought a full set up of hybrid closed loop stepper motors and associated drivers etc (Purelogic and leadshine) from Zappautomation a few years back and have had nothing but praise for the setup and zappautomation.
Closed loop does exactly what i wanted and i think i oversized the hybrid steppers but at least i can sit on the machine and take a ride...obviously only done under the influence of alcohol ..

Tommy

[andy_con]

there are lots of things like this over ebay

http://www.ebay.co.uk/itm/CNC-AC-Ser...gAAOSwMgdXyS7x

and even cheaper stuff??

http://www.ebay.co.uk/itm/EU-Stock-N...4AAOSwoBtW58KV

I don't mind spending a few quid to get good results

[m_c]

there are lots of things like this over ebay

http://www.ebay.co.uk/itm/CNC-AC-Ser...gAAOSwMgdXyS7x

and even cheaper stuff??

http://www.ebay.co.uk/itm/EU-Stock-N...4AAOSwoBtW58KV

I don't mind spending a few quid to get good results

750W would be overkill for a Triac. I'd aim for 200W, or maybe 400W.

The second link is actually a closed loop stepper system. Technically it is servo system, however it won't have the same performance as what's more commonly referred to as a servo system.

I had been hoping DaveK would of chimed in with his views on the generic Chinese servo systems, but I guess he's too busy playing with his new toy...

[Zeeflyboy]

I bought a full set up of hybrid closed loop stepper motors and associated drivers etc (Purelogic and leadshine) from Zappautomation a few years back and have had nothing but praise for the setup and zappautomation.
Closed loop does exactly what i wanted and i think i oversized the hybrid steppers but at least i can sit on the machine and take a ride...obviously only done under the influence of alcohol ..

Tommy

I'm also running closed loop leadshine steppers and drivers, very happy with them.

[andy_con]

so these?

http://www.ebay.co.uk/itm/CNC-Leadsh...EAAOSwsN9XA89p

[zorro]

Hi,
does anyone have experience with HSS86 and/or 2HSS86H drivers?
http://www.jss-motor.com/product/nem...nd-driver.html
http://www.jmc-motor.com/products.php?cid=225&id=157
Is there a tuning software available for these drivers?
How is the overall quality of these drivers and motors?
Thanks.