TB6600 + general drive and driver matching question

[CNCStudent]

I'm well aware of the issues with some of the TB6600 boards, and I've read a load of stuff on various forums.

The leadshine drives look nice (£92 + VAT + del is a bit pricey), and I've noted the helpful comment above about 80V drives (which is essentially what the leadshine drive listed appears to be with a few added benefits (not a clue why you would need an RS232 interface directly on a drive but hey ho!).

But what's confusing me is the statement to run the steppers at 68V as they are 3nm steppers? Using the gecko guidance that seems to be a well tauted about rule of thumb (32 x SQRT (L) = Max Voltage), the drives are suppose to have a maximum voltage of 57V or the 25 x Motor Rated Voltage (68V), seems a little close if not slightly beyond the guidance on the gecko rules of thumb.

How critical is the stepper motor current rating? (given most of the drives have a range but no normally quite 4.2A as a current setting)

How does the RMS and MAX ampage ratings on the drives relate to the motor current rating (which setting should I use)?

Am I not just likley to end up with the same conundrum of actual current being lower than the motor rated current, given if the drives are 60W rated, and they are running at 60V..... it just means that they will be running at 1 Amp (still)....?

I'm not so much questioning the TB6600's [given yes I appreciate that everyone seems to feel that the issue is done to death], but curious why they appear to be only running at less than 1A current draw....

Thanks

[JAZZCNC]

The leadshine drives look nice (£92 + VAT + del is a bit pricey), and I've noted the helpful comment above about 80V drives (which is essentially what the leadshine drive listed appears to be with a few added benefits (not a clue why you would need an RS232 interface directly on a drive but hey ho!).

They can be got for much less than that but have no doubts they are worth every penny and I've used just about every drive worth bothering with. I don't even class the TB rubbish as drives, I've had Josh sticks that last longer and smoke less than these and they can't be compared in any way shape or form to these drives.

The RS232 is so you can connect directly to the drives thru software and configure it's parameters for things like resonance.

But what's confusing me is the statement to run the steppers at 68V as they are 3nm steppers? Using the gecko guidance that seems to be a well tauted about rule of thumb (32 x SQRT (L) = Max Voltage), the drives are suppose to have a maximum voltage of 57V or the 25 x Motor Rated Voltage (68V), seems a little close if not slightly beyond the guidance on the gecko rules of thumb.

How critical is the stepper motor current rating? (given most of the drives have a range but no normally quite 4.2A as a current setting)

How does the RMS and MAX ampage ratings on the drives relate to the motor current rating (which setting should I use)?

The Gecko thing is exactly that a guide and in practice you can run the motors quite safely with much higher voltage. It does lead to some iron losses etc which will eventually shorten there life span but it's nothing to worry about and at less than £30 a motor then the performance advantage is more than worth the price of a motor say every 5-6yrs, if that.!

Motor current rating is quite critical for best performance so just set the drives to motor PEAK rating or close to it. For best performance you want the motors wired parallel.

[Jonathan]

I'm not so much questioning the TB6600's [given yes I appreciate that everyone seems to feel that the issue is done to death], but curious why they appear to be only running at less than 1A current draw...

The input current doesn't have to be the same as the output current, but the power does, so given that, what can you say about the output current when the supply voltage is higher than the motor rated voltage?