Losing steps/position, again

[JAZZCNC]

If I did it again I would get drivers that are rated upto 80Vac/110vdc and use a 70Vac toroidal transformer.
Something like a 2*35vac secondary outputs wired in series for 70vac.
Doesn't matter wether you have Nema 17/ 23/ 34size motors etc, the drivers regulate output voltage to the motors themselves.

That's WRONG information your giving out, the drives don't regulate the voltage they regulate the current. 70Vac which is 98Vdc would destroy those little motors in no time at all. It would also make them run like a bag of shite.

You cannot stick any voltage you like into a stepper, there is a limit where it starts to have very negative affects. Namely iron losses and motor heating which kills them.

Those Large voltage Ac drives are only really any good for larger steppers Like Nema 34 or very high inductance NEMA 23's. Your typical 3-4Nm 4.2a Nema 23 with 3-4mh inductance doesn't like to be run much more than 80vdc and at that, you are pushing them past there design threshold so are shortening there life.

For the NEMA 23 motors, which this machine will have fitted he'll only need drives with a max rating of 70Vdc and would run them around 55-60Vdc. Or 50Vac drives running at 40-45Vac.

[ngwagwa]

That's WRONG information .......

Thanks - obviously reducing the power I supply will also reduce the initial outlay (as well as havingto replace everything including burnt oout motors).

Could you be so kind as to point me in the right direction for what you would suggest and is there ay advantage with a toroidal transformer (a plug and play box suits me if possible).

Although I have asked elsewhere on this forum have you any reasons why I shouldn't use the AXBB-E motion controller?

[JAZZCNC]

Thanks - obviously reducing the power I supply will also reduce the initial outlay (as well as havingto replace everything including burnt oout motors).

Think I've just answered this one in last post but sorry you need larger not smaller for the reason stated below.

Could you be so kind as to point me in the right direction for what you would suggest and is there ay advantage with a toroidal transformer (a plug and play box suits me if possible).

Ok well the advantage with toroidal transformer, when used with capacitors and bridge rectifiers that make up a DC PSU, (yes you need these as well) is that it means you can get away with lower power rating than you would need with a switch-mode supply. You can also build to the exact power requirements you need.

It gets complicated but in a nutshell, let us say you have 4 motors all pulling 4a which means you'd need a 16a for a SWM supply to work reliably and keep up with drives/motors demands when working hard. In practice, the actual rating needed will be higher for reasons I won't get into now. But all this means a Large SWM PSU this size gets expensive quickly.

Whereas a Toroidal/capacitor-based PSU allows you to get away with PSU size only 60% of the motors total draw. It does this by drawing from its bank of capacitors and how the drives work. It also ensures a smoother flow of power because you always have a reserve in the capacitors.
So again, in a Nutshell, yes it's best for these reasons and the fact can size to exact needs and it's often much Cheaper when higher power is needed which is why it's used so much on routers and DIY builds.


Regards the AXBB-E Controller I have never used one personally so I'm not recommending you use it but I do know several people who have used them and are very happy with them. I've fitted several of its Big brother the Uc300ETH and they are also very good so I cannot see these being a bad card. The UCCNC software is also very good so I wouldn't hesitate if it was me.

[ngwagwa]

whoops post twice

[dazp1976]

That's WRONG information your giving out, the drives don't regulate the voltage they regulate the current. 70Vac which is 98Vdc would destroy those little motors in no time at all. It would also make them run like a bag of shite.

You cannot stick any voltage you like into a stepper, there is a limit where it starts to have very negative affects. Namely iron losses and motor heating which kills them.

Those Large voltage Ac drives are only really any good for larger steppers Like Nema 34 or very high inductance NEMA 23's. Your typical 3-4Nm 4.2a Nema 23 with 3-4mh inductance doesn't like to be run much more than 80vdc and at that, you are pushing them past there design threshold so are shortening there life.

For the NEMA 23 motors, which this machine will have fitted he'll only need drives with a max rating of 70Vdc and would run them around 55-60Vdc. Or 50Vac drives running at 40-45Vac.

Steppers are generally all rated 2-3Vdc yes?. So if said nema 17 / 23 or 34 (2-3Vdc) were put on the same driver why would I only blow the 17? (unless I didn't change the current output).

Also inductance. There are Nema 34's out there that are abysmal running on 60V supplies and ideally need at least 120Vdc to work reliably.

Also there are now drivers on the market with direct 240Vac input connections so no need for psu's anyway. These are aimed at nema17-23 size. Why would these not burn them up either?

I and many others use 60Vdc at least using larger 34 size drivers to run nema17 & 23 size motors. Even that goes against the grain and it's worked for years.

[AndyUK]

Steppers are generally all rated 2-3Vdc yes?.

My understanding is that if you give a coil on the stepper the rated voltage (2-3V) it will draw the rated current.

If you give a stepper a higher voltage, the current will also increase and the thing will burn up.

But we're not doing that - we're using stepper drivers. These give the motor the full voltage in "punches" to limit the average current to a set value. Therefore its entirely reasonable that the voltage supplied to the driver is important for the reasons Jazz sets out.

Blanket recommendations are dangerous either way - you need to consider all the factors like the steppers inductance and current limits to determine what will blow and what won't. NEMA 17 or 23 is just a mounting size, and has no real effect on this.

[JAZZCNC]

Steppers are generally all rated 2-3Vdc yes?. So if said nema 17 / 23 or 34 (2-3Vdc) were put on the same driver why would I only blow the 17? (unless I didn't change the current output).

I didn't say it would blow it up, I said it would destroy them and this is true. They couldn't handle the heat and that would kill them eventually depending on voltage.

Also inductance. There are Nema 34's out there that are abysmal running on 60V supplies and ideally need at least 120Vdc to work reliably.

Also there are now drivers on the market with direct 240Vac input connections so no need for psu's anyway. These are aimed at nema17-23 size. Why would these not burn them up either?

You'll find that many of the drives that use 240Vac won't run small motors for the same reason I mentioned before, most don't even limit current below 5a. The drives you speak of which use AC voltage and can run Nema 17/23 use Low AC voltage which you transform down from 230Vac and that gets rectified to DC in the drive.

I fit 230 Vac drives all the time and I can tell you that if I fitted those little motors or nema 17 motors to the drives they would be fried within hours. Even with small (4nm) Nema 34 motors you have to be very careful and make sure you limit current correctly because current it proportional to Voltage and you cannot limit the voltage so they get hot.
This is physics it's not me making shit up and just because you haven't experienced it doesn't mean your correct it what your saying. Unless you know it to be true then I suggest you STFU because it's hazardous to components life and even dangerous in some circumstances.

I and many others use 60Vdc at least using larger 34 size drivers to run nema17 & 23 size motors. Even that goes against the grain and it's worked for years.

No it's doesn't go against the grain and it's perfectly acceptable because the voltage is much lower and the motors can handle it. Again physics comes into play and there is an ideal voltage where motors run with-in safe tolerances, most people running more than 60vdc with NEMA 17/23 motors are running past the motor's ideal voltage but only just so it's not a problem. Think of it like overclocking a PC, it works but will shorten the PC's life unless it's cooled better, same shit here.! . . . Running higher than ideal voltages your actually shortening the motors life but who cares because it's going to take years if only 10-20v over but double the rated voltage or more and it won't take long. (unless cooled massively)