don't know servo ratings required for diy mill

[mike_Kilroy]

actually mac, ur 14bit is only .00009" per pulse; most designers go for 10+ pulses or more resolution. someone should tell u that positioning as a servo system will dither +/- 1 count minimum. u describe a poor design that probably will not hold .0001 with perturbations as it will be bouncing .0002 all day long anyway.

as for ur comment that dmm is bestest, forget it; u do them a disservice spouting such nonsense.

[mactec54]

mike_Kilroy
(Quote) actually mac, ur 14bit is only .00009" per pulse; most designers go for 10+ pulses or more resolution. someone should tell u that positioning as a servo system will dither +/- 1 count minimum. u describe a poor design that probably will not hold .0001 with perturbations as it will be bouncing .0002 all day long anyway.

May be thats what happens to your poorly designed systems do, But mine do not

(Quote) bestest, forget it; u do them a disservice spouting such nonsense.

I see you are still blowing smoke, as usual

Thats why a major US optical company is using there system,on all there new equipment they manufacture, I guess they like the way they have perturbations as it will be bouncing all over there lenses

I use 20Bit encoders on some of my builds, But 14Bit/17Bit is what I use most of the time for a nice smooth ride

I did not say it was the best system there is, It is the best AC Servo system for the money

[jasminder]

chill guys, Christmas is coming.

I was just trying to say that a 16mm pitch screws is good enough for a router where you don't need a caliper to measure having a resolution of 0.0005.
I mean it is just not good for machines that need to cut serious steels (mostly high-chromium).
And my experience says that ballscrews have the tendency to back drive the motors driving it(in his case, the servos) The more the lead, the more the torque on his motors he would need while cutting under loads. But because he is having powerful enough servos on his build, and he is cutting wood or alu only. There will be less problems.
I cannot imagine to replace the 16mm lead balscrew with the existing 5mm lead balscrews on my lathe to get more rapids ( i will loose steps on the steppers and may need to decrease the rapids and will have almost the same rapids i had before, if i am not wrong)

As for DMM tech. Yes they are very supportive and prompt . At least in case of giving price quotations that i have tried. But I will try something being distributed locally because as i said earlier, i am always afraid that something will fry up.

One question still stands.--- What should i look for in a servo system if going with Mach3. I know i need step/dir inputs and not those +-10 or +-20.
What else should i look for?

However, those 16mm lead balscrews will be perfect if they have around 3 inch diameter (thanks to Al)
regards,

jasminder singh

[Al_The_Man]

One question still stands.--- What should i look for in a servo system if going with Mach3. I know i need step/dir inputs and not those +-10 or +-20.
What else should i look for?
jasminder singh

Once you have determined the torque required, and the maximum rapids or rpm required of the motor, it is a question of which technology you want to go with, when buying used, the less hassle of mix and matching different drives and motors is to go DC brushed, these can usually be had fairly reasonable off ebay, the main down side to brushed is lower max rpm and brush wear has to be checked periodically.
The next easily mix & matched is DC Brushless with 3 commutation pulses.
Again Ebay is a source.
When going AC sinusoidal, (the motor is practically identical to DCBL), it often pays to go with a matched motor & drive, as often the commutation method is alot more complicated, resolver or other technology.
For DC drives there is Larken, for DCBL there is Granite devices which will take motors such as Fanuc sinusoidal and obtain the commutation off the quadrature differential encoder, for just a couple.
Al.

[jasminder]

Once you have determined the torque required, and the maximum rapids or rpm required of the motor, it is a question of which technology you want to go with, when buying used, the less hassle of mix and matching different drives and motors is to go DC brushed, these can usually be had fairly reasonable off ebay, the main down side to brushed is lower max rpm and brush wear has to be checked periodically.
The next easily mix & matched is DC Brushless with 3 commutation pulses.
Again Ebay is a source.
When going AC sinusoidal, (the motor is practically identical to DCBL), it often pays to go with a matched motor & drive, as often the commutation method is alot more complicated, resolver or other technology.
For DC drives there is Larken, for DCBL there is Granite devices which will take motors such as Fanuc sinusoidal and obtain the commutation off the quadrature differential encoder, for just a couple.
Al.

Dear Al,
i am planning to buy new sets because automation hardware is not very common here in india to be found in surplus stores (it is like diamond if you see it in a such a store if the drive and the motors you got are not matching even) I will go for AC servos with matching drivers but can change my mind if there is a big difference in the DC/AC versions. Keeping the things for long life i will buy brushless only and i don't think that 3phase or 220 single phase versions makes any big sense to me. I will buy any of them. it is a matter of availability also and not only of choice. However, i am always thinking if a 220 servo giving 400watts or 2nm output is same to the 440 servo giving 400 watts or 2nm output in every sense of performance. Isn't it?

regards,
jasminder singh

[Al_The_Man]

The identical values of wattage and torque on different voltage levels remain equal.
A decrease in current is approximately directly proportional to the voltage increase.
3 phase for drives are usually required when using larger high current demand motors.
The drives I use, require 3ph supply for anything over 40amps if used at their optimum value.
Al.