Been a longish time since I posted here as a lot of "real life" things got in the way, anyhows, to my question.......:
At work, we've recently purchased a 6040 CNC off Ebay (Australia), converted to Gecko drivers, etc., and have started to get my head around Mach 3 which was already on a PC that powered a 6040 we had a few years ago. Yesterday I went through the testing of the steppers which was all OK, today I turned everything on for more "playing" but spent most of the time reading the Mach 3 manual and investigating where to mount limit switches.......I happened to put my hand on one of the motors and found it to be quite hot even though it hadn't been actually operating..........IS THIS NORMAL?
You are putting power into the stepper motor even when it is stationary. So yes, it will get warm.
If you are using a Gecko driver, you should be able to drop the max current a bit, at least for an experiment.
depending on which manufactures data sheet you look at
stepper motors run at 70 to 80 degrees Centigrade = 158 to 176 Fahrenheit , too hot to touch !!!
that's why many stepper drivers reduce the motor current when the axis has been idle for a short while
if you use a G540 to drive 3.5A motors don't leave the 3K5 resistors out
even though the G540 default current is 3.5A , the idle current reduction only works
with the resistor fitted !
I rechecked everything.......the motors are 3.0A and I remembered setting the current to 2.7A on the breakout board trim pots, the temp is sitting at 61 deg C.
Will the trim pots on the G540 have any bearing on this as I haven't touched them yet.
Ah - I don't know what BoBs you are using. The Homann BoBs I use (MB-02) do not have any pots. Regardless, I don't think they have anything to do with the current limit in the motor driver we are talking about. You need to put in the current limiting resistors on the G540 board. IF they are not there the motors will be driven at full power all the time, and that is why they will get hot. Put the right current limit resistors into the G540 board and they will cause the drive current to drop when the motor is static.
to me motors running at 61 deg C is not too hot for the motors but is too hot to hold your hand on it
I think every one is suprised by how hot they run
this is the Homann motor cable breakout boards with adjustable current setting resistors
not to be confused with the breakout boards used to connect to the printer ports 17 input / output signals
John
PS
I first become aware how hot stepper motors are , was when working on this sony betacart BVC-10 -
its robotic tape player that was designed the 1980's to play out TV commercials
it can play 10 second clips from 40 tapes in what ever order you program it
the first 4 tapes are loaded into the 4 VT machines
before the end of the 40 seconds the first tape has been ejected and replaced by 5th tape and is ready to play
There is a vertical column between the vt machines and the 40 tape bins
on the column runs an elevator that transports the tapes between the VT machines and the tape bins
the elevator is rapidly moved up and down by a size 42 stepper motor
(if I remember the motor size correctly)
Goes to show what I know.
I had forgotten about those DB9 things.
Ah well - perhaps turn down the current a bit more - keep going until the system starts to lose steps, then increase a bit?
Aaaahhhh tape.......here at home I have a "studio" and my favourite recording medium is our 1" 16 track R2R, the 16 track digital is good but just doesn't have the same mojo but back to cnc......your comments are appreciated, many thanks.
for the G540 , the current set resistor in ohms = current in Amps x 1000
If you have work with a limited range of resistors you can use resistors either in parallel or series to get inbetween values
for example the E12 range is limited to 10 , 12 , 15 , 18 , 22 , 27 , 33 , 39 , 47 , 56 , 68 , 82
Multiply or divide the values by 10 for other decades
Hello
I have a big laser machine 1600m x axis
and iam doing engraving so X axis can work continuously for 3+ hours..
Machine has in X axis 573s15 3 phase steppers.
Yesterday after 1.5hours of operation stepper in X axis stalled in the middle and not rotated.
Mechanically the machine is ok the ways are ok.
What can be the problem for loose steps ?
Very high temperature in X axis motor can be the cause for loose steps ?(the x axis motor gets pretty hot)
Iam asking that because the machine loose steps after 1.5 hours of operation not from start.
The load all the time is the the same because laser head moves in the air.
Got a way of measuring the temp of the steppers? That might give a clue.
Also, is the current limiting for your particular steppers set correctly? If it is set too high, that will probably cause the overheating.
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Stepper Motor Temperature
