I heard the chinese servos are difficult to tune without proper software (which probably doesn't exist for them in english, yet). This still means they can be tuned though, right?
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I heard the chinese servos are difficult to tune without proper software (which probably doesn't exist for them in english, yet). This still means they can be tuned though, right?
Yeah, and oddly enough they use 120/240 in Richmond BC, where I believe DMM is situated. That's in Canada!
N.A. in general has settled on 120/240 as a standard, you may still see appliances marked 110vac which is the old standard.
It is normal for a power grid service to fluctuate and generally the accepted industrial standard for fluctuation for industrial machinery is ±10%.
Al.
This would make a great HM47/RM45 mill spindle motor if it does what they say it does
https://www.ebay.com.au/itm/7-7NM-2K...MAAOSwxixZ5w~L
Free shipping to Australia, 649.90 AUD similar price range to a class F 2.2kw motor and VFD. This provides approximately the same torque (at max RPM) but weighs 10kgs compared to 21,
a big advantage when the z axis must deal with the mass of the motor. Might be a good way to test the quality of these servos where position control is not essential.
I sent them a message asking for the manual, will post on here if they send me one.
Ed
Perth
They got back to me in about 5 minutes.
https://1drv.ms/b/s!ArjCcDfiJFt0fm4tmJyHfblBVm0
They do indeed seem good. You can get them for 600 shipped.
Is 2500 ppr really a big deal on these servos?
Also servos outperform a leadshine in every respect, really? I am not after super fast rapids, I would like Tormach potential which boast under 150ipm for their ipm speeds on their mills and good ACCURACY. I am aware they use open loop with torque reserve and good engineering to not miss steps. With leadshine closed loop steppers I could achieve no missed steps and similar IPM / accuracy I think. Or with their clones. I have read steppers if they don't miss steps can actually be more accurate than servos (in my price range).
Prices for Aussie customers and pros/cons I've noted are as follows:
Leadshine CLONE CLOSED LOOP steppers for like $700 AUD delivered (clones so.... not as great drivers?)
Leadshine closed loop genuine (chinese models) are more like $900 (steppers, not servos, but is this really a disadvantage if you're not chasing massive IPM)
Chinese Servos come in at 1000 to 1200 (good but 2500ppr, and bad manuals),
Chinese servos with better encoders - around 1500-1600
DMM for just under $2000 delivered to Aus.
I am really really looking toward option 1 - leadshine clones. Save 1400 over DMM. I reckon they will equal whatever Tormach has and the money I'll save will be better spent on other things - better ballscrews later, hiwin rails for x and y, A nice surface table, or even money off a Skyfire / Tormach / VMC which I might upgrade too later.
You heard wrong they could never be as accurate as AC Servos, even the cheap ones, when you have to chase your dollars as I said before buy what you can afford, but don't get the servos that Edmunns just listed, if these where the ones you looked at
It looks like the genuine Leadshine is your best bet , with there encoders at,2500=10,000ppr if they are incremental, yes Encoders are a big deal, these servo's are not worth the extra money to buy them, the Dmm Encoder is 65,384ppr standard
Yeah, I wasn't suggesting to go down that path, you get what you pay for, especially with servos. That manual looks like a nightmare haha.
With encoder resolution, you can calculate your Least Input Increment, this is the smallest value the machine can position to.
For example, if the quadrature encoders are 2500 = 10,000 pulses/rev when x4, and you have a motor driving a 0.2" lead Ball screw direct, then the Least Input Increment = 0.2"/10k =0.00002", or 0.5 Micrometer.
To go much smaller L.I.I. with any accuracy would also require very precise machine mechanics.
Al.
There is really no comparison between closed loop steppers and servos. Look at a torque curve for a closed loop stepper. At 1000 rpm, it will have lost at least half of it's rated torque. A servo will have full torque up to 3000rpm, with 3x peak torque still in reserve.Quote:
With leadshine closed loop steppers I could achieve no missed steps and similar IPM / accuracy I think.
When used properly, an open loop stepper should give nearly identical performance to a closed loop stepper. They are both steppers, after all, with the same amount of power.