i3 M201 /w GTM32 Z-Home Procedure

[cw80]

Hi folks,

im currently having some trouble with my M201.
I changed the M8 threaded rods of the z-axis to TR8x8 and changed the steps per mm of the z-axis to 400.
The axis works super smooth now an the rods are completely staight.

But now there is a problem when homing the z-axis.
When i press z-home in repetier, the axis moves down until it reaches the endstop, moves up again for about 4 rotations of the rod and finally moves down again to reach home position. But as it goes down for the second time, it goes 3mm past the endstop. So why is it doing that? Shouldn't the Endstop represent the absolute 0?

I've checked this dozens of times, it always behaves like this. The first contact with the endstop is recognized correctly, but when it moves up and down for the second time, it's always traveling exactly 3mm too far beyond the endstop (would be 0.56mm with the original M8 rods).
So is it a bug or a feature, and how do i get rid of it?

Regards, Chris

[Newopint95]

Check your z offset in th firmware. The first contact of the switch is 0, the second time it moves it is adding any + or - Z offset.

[cw80]

Thanks for the advice, i forgot to mention that i have already checked the z-offset setting. It's set to 0.00.
The first time it stops is right at the click of the switch, the second time is at click-3mm but the display shows Z=0.00.

[William]

At the second time you can choose to adjust 3mm directly，Maybe there are some wrong autoing home in the second time.

[cw80]

Sorry, but i don't understand what you exactly mean, should i use +3.00mm z-offset?
I'll try that out, but as the problem wasn't here using the M8 rods i don't believe its some wrong offset values.

It seems like the Firmware drives it exactly 75 steps further beyond the endstop, this is why there ist such a big difference when using TR8x8 rods.

If it was some offset problem, the offset should always be 3mm but it's only about 0.5mm when using M8 rods.

[William]

Sorry, but i don't understand what you exactly mean, should i use +3.00mm z-offset?
I'll try that out, but as the problem wasn't here using the M8 rods i don't believe its some wrong offset values.

It seems like the Firmware drives it exactly 75 steps further beyond the endstop, this is why there ist such a big difference when using TR8x8 rods.

If it was some offset problem, the offset should always be 3mm but it's only about 0.5mm when using M8 rods.

Hi,
This is more of a firmware issue than a offset problem，If homing is done at high speed, the axis might overstep the switch actuation position with inertia so it retracts and tries a second time more slowly. The software assumes that the retraction is enough to de-activate the end-stop switch. If the switch is not de-activated by the retraction the software assumes that it has reached the activation point and stops any advance.
Here are the concrete solutions.
http://www.geeetech.com/forum/viewtopic ... 20&t=18420

[cw80]

Hi William,

so how can I change configuration.h without having access to it?
Now there the issue is known for more than 6 months, how about a little firmware update?

[William]

Hi cw80,
Can I know your firmware version you using now?

[cw80]

I'm currently using 1.0.5

[cw80]

So, any news about this issue?