[DDMODS]

Hi guys uim building my second cnc machine at the moment.

The machine is 3 axis with 4 steppers (2 on the y) The steppers are nema 23s.

I didnt notice this issue on my last machine but with this one i am noticing it now.

THE ISSUE:
If i increase the rapid speed to anything greater than 1200mm/min the motors stall at certain points along the axis. I then decided to remove thethe rails and just see if it was a load related issue. at this speed i can simply squeeze the ballscrew as it turns with my fingertips hardly any pressure and make the motors stall.

Here are the details:
At the moment i am using a all in one controller with built in display. it can handle 16v - 36v for the input

Steppers:
200 steps per rev

Ballscrew
5mm/rev (1605)

Resolution 1/2

so 80 steps per mm ( i think)


The power supply is a 24v 10 Amp
I was reading the sheet for the steppers and it says power input is 24v - 48v

My question is mainly will there be much of a difference in any of torque at higher speeds running say even 32v at the same 1200mm/s versus leaving it at 24v @1200mm/s

If i have to upgrade the controller to a 48v capable or (50v) i will do so but dont want to do that if its not going to make much if any difference

Any input or link to other reading on the matter would be appreciated.

I have had a look around but couldnt find anything giving say a greater comparison on the specific steppers only general speed vs voltage vs torque graphs with little to no difference or great difference depending on the model and none on the same model as mine.

Cheers, Darcy

[eman5oh]

Short answer is yes more voltage will increase the torque at speed, the long answer may be found by reading this https://www.google.com/url?sa=t&rct=...Kcn1jsY0zSLLKg

[ger21]

Doubling voltage can give roughly double the speeds.

But it may not be worth it, depending on the motor specs. 1200mm/min is very slow, and even doubling that is not very good.

[awerby]

If you share the motor's spec sheet with us, it would be easier to say what sort of speed you could expect at what voltage, and how much torque you'd get at that speed. But yes, 24v is on the low side for most 23-frame motors.

[DDMODS]

Short answer is yes more voltage will increase the torque at speed, the long answer may be found by reading this https://www.google.com/url?sa=t&rct=...Kcn1jsY0zSLLKg

Thankyou! will have a read later today!

Doubling voltage can give roughly double the speeds.

But it may not be worth it, depending on the motor specs. 1200mm/min is very slow, and even doubling that is not very good.

i was happy enough with 1200mm for rapids so if i can get 1800 or so for rapids even 2000 id be extremely happy

If you share the motor's spec sheet with us, it would be easier to say what sort of speed you could expect at what voltage, and how much torque you'd get at that speed. But yes, 24v is on the low side for most 23-frame motors.

The motor model is: 23HS41-1804S

Some info:
Step Angle 1.8°
Holding Torque 2.4Nm(340oz.in)
Rated Torque 1.92Nm(272oz.in)
Rated Current/phase 1.8A
Phase Resistance 2.75ohms
Recommended Voltage 24-48V
Inductance 17mH±20%(1KHz)
Weight 1.5kg

this is the only sheet i could find
http://www.omc-stepperonline.com/dow...HS41-1804S.pdf

Cheers

[DDMODS]

oh and the board im using for control is this at the moment had from my last one so thought id try it before upgrading anything

4 Axis CNC TB6560 Stepper Driver Aluminium BOX SET Manual Controller Display | eBay

was thinking of getting this maybe as can handle the 50v
4 PCS Stepper Motor 5A Driver Controller 5 Axis Breakout Card CNC Router KIT | eBay

Would it be worth the upgrade?

Cheers

[109jb]

First off, the TB6560 is pretty sub-standard. You can get them to work but other options are soooooo much better.

The motor you have has 17 mH inductance. Using the commonly accepted formula for optimum voltage for that inductance yields SQRT(17) + 32 = 130 volts. High inductance hurts high speed torque and performance.

[DDMODS]

First off, the TB6560 is pretty sub-standard. You can get them to work but other options are soooooo much better.

The motor you have has 17 mH inductance. Using the commonly accepted formula for optimum voltage for that inductance yields SQRT(17) + 32 = 130 volts. High inductance hurts high speed torque and performance.

Hmm I knew the board is had was a cheapy. Would the other set it linked do better with a 48v supply based on the motors I have? Still on a budget so I don't want to replace all motors and controller. Would there be a noticeable difference in torque at speed running the new controllersite linked above at 48v instead of 24v do you think? Or would the gain be minimal?

[109jb]

Read "Step Motor Basics" at this link Applicaton Notes | Step Motor Controls

Basically - Yes, increasing voltage will increase high speed performance.

As for the drives you linked, I personally have not used those drives, but they are TB6600 based drives and there is a link on here somewhere that describes a design fault in them. They still work, but not as well as they should. I don't remember the specifics, but I would not recommend them based on what i have read. There are other TB6600 drives that reportedly are decent and would be better than the TB6560.

[DDMODS]

Read "Step Motor Basics" at this link Applicaton Notes | Step Motor Controls

Basically - Yes, increasing voltage will increase high speed performance.

As for the drives you linked, I personally have not used those drives, but they are TB6600 based drives and there is a link on here somewhere that describes a design fault in them. They still work, but not as well as they should. I don't remember the specifics, but I would not recommend them based on what i have read. There are other TB6600 drives that reportedly are decent and would be better than the TB6560.

Cheers thanks for the help I'll have a search around and see what tb6600 is the recommended one. Thanks again

[awerby]

The super-high inductance of those motors is what's causing your stalling. As was pointed out above, they really want 130v to perform optimally. At 24v, they're just limping along. While upping the voltage will help, you've got a very long way to go before you're in the sweet spot for those motors. And in the meantime, you'll blow up your crappy drives with the extra power. I'd say throw out all that junk, get a Gecko G-540 and some motors with 2.4 mH inductance, run the system at 48v, and you'll be amazed at the difference.

Either that, or send more money to China, get more garbage in return, and see how much you end up saving...

[109jb]

Actually, you can get decent drives from Xchina. I have kl-6050 drives from automation technologies and they work great on my G0704 mill running at 180 IPM on 0.2" pitch balls crews. I also have some other tb6600 drives that seem good, but I have yet to fully test them, so don't want to give a thumbs up yet.

Leadshine also reportedly makes nice drives, and are made in China. Lots of guys using the MX3660 love them.

The geckos are also good although higher priced.

I agree though that you I'll have to ditch the motors. The inductance is just too high. High inductance means a low speed motor. Would probably be ok for a belt drive machine, or a rack and pinion machine, but not a lead screw machine.

[Jon.N.CNC]

My advice would be to avoid tb chip drivers all together. They put more energy into making heat that they do the motors. Go for some mosfet drivers, Wantai do some budget ones that are pretty much the same price as tb6600's but miles better, They Run cool. Output the amps they say they do and are much more robust. There's no reason you shouldn't get 5m/min out of these drivers with that screw. Your motors are very poor though a nema23 in parallel should have an inductance of around |<3.2mH ±20% (parallel). Personally if i was going to buy new motors id be looking at 3.1nm or 4nm ones. This wantai driver will run all of those fine:Cnc 4.2A,50VDC,128Micro Bipolar CNC digital Wantai Nema23 Stepper driver DQ542MA | eBay

Or if you have a slightly higher budget go for the cw5045's @ £35 ea which have a basic level of dsp in them or cwd556's full dsp drivers @ £45 ea (i have two of these with 3.1nm 23's moving a 200kg gantry at 5m/min, probably go faster but i have gearing in not completely satisfied with). All these drivers come from the same company in Jiangsu, wantai just rebranded the cheaper ones but not the cw5045 which often get mistaken as the same, the cw5045 has twice as many components in (i took both apart and checked lol). I have one
machine running these and another with the cwd556 dspdrivers and the more powewrful cwd872 for over 3 years and they havent missed a beat.

[foreveryoung]

Inductance 17mH±20%(1KHz)

I think the motor's inductance is too high. Probably you salvaged it from a working machine?

I would suggest that you find another motor around 3mH to 6mH if you want to use 24v-48v. The recommended working voltage for 17mH motor is 130V if you want high speed & good torque.
Besides, high inductance motor can fry your 24v driver easily

[DDMODS]

I think the motor's inductance is too high. Probably you salvaged it from a working machine?

I would suggest that you find another motor around 3mH to 6mH if you want to use 24v-48v. The recommended working voltage for 17mH motor is 130V if you want high speed & good torque.
Besides, high inductance motor can fry your 24v driver easily

It was just the motors I had on my last machine.

I will get some new motors and maybe drivers after a few jobs and upgrade them and see how it goes. Cheers thanks for the help!!

[Jon.N.CNC]

Personally I wouldn't go for any over 3.5mh. Especially with the tb drivers. Over 4 and your back into the cheap and nastys.

[James Newton]

Tb6560... there's the problem right there.

[Propwrench1]

109jb,
Do you mind sharing what motors you have that run 180IPM? I am assuming they are nema 23?
Thx.