Starting over

Ahh I assumed racks were mostly in integer pitches
(I have seen several that are specified in 12,24, 36 TPI etc)

PCW wrote: The distance per pinion turn should be the rack pitch * pinion teeth
It would be a bit odd to have Pi on the equation unless the rack pitch has a factor or Pi

Please correct me! My logic is the rack (20 pitch 20 degree pressure angle) has 20 teeth on a one inch pinion.

Were it 1 to 1 then 200 full steps would move it 3.1416 inches (63.66 steps per inch). Introducing a reduction gear makes the stepper require more steps to travel that same 3.1416 inches. What was 200 steps at the stepper is now 600 at the rack on a one to three reduction. So 600 steps equals 3.1416 inches or 190.985 steps per inch. If your drive has a 10X microstepping then you are at 1909.854 micro steps per inch.

On a side note, so it does not continue to miss inform the public, G540 has NO micro stepping, it Has a delay (most probably a CD4017 CMOS), so it does nothing for 9 pulses. NOTHING. Wasted 2 days a while ago to figure that out.
They do mention that on the web, so it's all good, and they are perfect for hobby machines.

tommylight wrote: On a side note, so it does not continue to miss inform the public, G540 has NO micro stepping, it Has a delay (most probably a CD4017 CMOS), so it does nothing for 9 pulses. NOTHING. Wasted 2 days a while ago to figure that out.
They do mention that on the web, so it's all good, and they are perfect for hobby machines.

Joy - smoke and mirrors.

I've noticed mine gets too hot too fast. Since I've not put this into production it's set idle under a strong fan most of the time.while I am tweaking Linuxcnc. I can't imagine what it would do if it were running hard. I thermal pasted the driver's chips to the back of the case - helped some but when it gets a little warm one port acts up.

If Gecko can't fix it under warranty I may go with another brand.

Did you wire the resistors on the motor connectors? You should, as without them it will run on full power even at a stand still. They need a 1kOhm per 1Amp of current, and even if you need full power, do add some 3.3Kohm to it.
I had 2 of them, still working without any issue, and never got to hot to act up, with no cooler or fan.
At what voltage are you powering it? I never used more than 32V for them on everyday use machines.

tommylight wrote: Did you wire the resistors on the motor connectors? You should, as without them it will run on full power even at a stand still. They need a 1kOhm per 1Amp of current, and even if you need full power, do add some 3.3Kohm to it.
I had 2 of them, still working without any issue, and never got to hot to act up, with no cooler or fan.
At what voltage are you powering it? I never used more than 32V for them on everyday use machines.

I did - I bought a 4 motor kit with cables featuring 3.5k resistor between pins 1 and 5 on the Gecko end and a 48V 12.5A switching power supply running 420 oz-in motors. I tested the cables when I got them.

Patrick Obrien wrote: Please correct me! My logic is the rack (20 pitch 20 degree pressure angle) has 20 teeth on a one inch pinion.

No, that is correct. a 20-tooth 20DP gear is pi inches per rev.

Update: I have been fighting the G540 for a while and realized it was a large part of my problem. It might have been just my own G540 but even in light duty build/test-mode that device is designed to get hot and heat makes it flaky, even with a serious fan blasting the high heat area.

The steppers were baking at idle, etc. Gecko suggests you use a heat-sink but all the MOSFETs don't touch the case and would not benefit from a heat-sink.

I installed four ST-M5045 and it is a huge improvement. The idle steppers are cool to the touch (utilizing the optional 1/2 hold power) and the drivers don't seem to be above room temperature probably because someone had a clue and designed heat-sinks into the design.

The G540 is $300 and if you lose an integral axis replacing that one G540 module is $80 but for $80 I can buy two standalone ST-M5045's.

No regrets.

andypugh wrote: Because the pin allocation is set in firmware, and not HAL, it turns out that the HAL code is almost (and sometimes exactly) the same even if the firmware and physical pins change. So you can use the settings for a probotix breakout as long as your actual firmware is G540.

So, in PNCConf choose the 5i25 internal data and prob_rfx2 option (which is a simple dumb breakout). and choose "accept component changes"
Then configure connector 3. (which is the DB25 connector on the 5i25) and you will see "unused stepgens" numbered 0, 1, 2 and 3. Choose axes for these to suit how you want to wire the G540, for example 0 = X, 1 = tandem X, 2 = Y, 3 = Z.

I think that GPIO 000 is charge pump on the G540? If so then choose GPIO 000 as control-> charge-pump

This setup should be really very close:

Attachment not found

I have had some success getting the axis working and the X2 set up correctly however PNCCONF doesn't seem to offer a limit/home for X2.

Did I miss something in PNCCONF?

It seems that Pncconf does not know how to add a limit switch for the tandem actuator.

You might want to consider switching to version 2.8 (not that Pncconf can do the tandem limit switch there either) but some elements of a gantry configuration are much simpler there.

(If you scan through the changes you might get some feel for how much better-suited for a gantry it now is)
linuxcnc.org/docs/devel/html/getting-sta..._configuration_files