whats the matter!

[John S]

Robin,
We really need Gary to reply on this, I have only ever had one test unit of these to look at and the one we had was just an 80 volt driver with an in built power module.

Gary's may be different, after all there are many driver manufacturers out there although a lot share the same technology.
The one I had was rated at 240 volts but turned out to be designed for a 220 volt power supply, as our mains here can easily get to 265 volts at peak it didn't last long :nope:

[Robin Hewitt]

The one I had was rated at 240 volts but turned out to be designed for a 220 volt power supply, as our mains here can easily get to 265 volts at peak it didn't last long :nope:

This one protects itself, if it goes over-volts it switches off and needs a reboot. You have to watch the fault output. The manual clearly states, "can be connected directly with single-phase 220V AC power to save the cost of a transformer".

[John S]

Yes I read that but we are not on 220 volts like a lot of countries, so it it defaults on one axis whilst cutting and trips you wreck the job ?

.

[Robin Hewitt]

so it it defaults on one axis whilst cutting and trips you wreck the job ?

No, surprisingly enough, so long as it doesn't expire on a G0, they've thought of that :naughty:

It tells you before it fails so you can stop everyone, then powers up to the same phase settings it was on when it failed.

[John S]

No, surprisingly enough, so long as it doesn't expire on a G0, they've thought of that :naughty:

It tells you before it fails so you can stop everyone, then powers up to the same phase settings it was on when it failed.

So that relies on you being there ?
Not a lot of use to me then, My big CNC is running all day today, last half hour I've been down Asda buying a new kettle but it's still churning out parts.

.

[Robin Hewitt]

So that relies on you being there ?

No more than you have to be there to turn the handles, computers can handle fault conditions.

I can see you aren't impressed :rofl:

[Tom]

I've wondered about this too. We buy motors based on charts and curves, but the manufacturers don't declare anything of the test method.
How tricky would it be to build a simple test rig? Budget ~£100?

Stepper -> direct coupling -> load
The load could be something like a motor with variable resistance across it.

I'm thinking: set a stepper, drive, and power supply combo running at a known RPM from mach or EMC2. Measure the voltage and current through the load, gradually increasing the load (by removing resistors in small steps), until the stepper stalls. Plot the data point, then increase the RPM and repeat.

Obviously the results would only be valid for the stepper/driver/power supply combination tested. And the results between different test rigs (if more than one were built) would not necessarily be directly comparable because of efficiency differences of the load motors. It would allow you to check the effect of a power supply voltage increase, or a new motor type, or a new driver, or moving to microstepping, or etc etc etc...

How much work is there to get to the point where the results might be comparable between rigs? Would defining a "standard" dc motor type be good enough (eg choose an appropriate RC motor P/N from a popular manufacturer)?

Just thinking out loud...

[John S]

Tom,
Good idea but still relies on "Is the motor in the box the same one the spec sheet is for ? "

And to be honest working with the Chinese I'm very sceptical.
Out of a box of 40 rotary tables that all had the exact same run out error according to the spec sheet? every one ?