Machine Zero Offset

[ThreeDJ16]

Either I don't understand how this works (likely the case) or there is a bug. I'm using version 1.2101 but have been seeing this issue since 1.2039. I'm running ScreenSet 2017. I thought that putting in a value would set the machine zero the number of units placed in this field back away from the limit switch. It only allows me to input a negative value, which my machine moves negative from 0 so doesn't seem odd. But with any value other than 0, the machine will hit the limit switch rather than the soft limit.

As I stated, most likely I just don't understand this value. But could someone explain it or tell me if there is a problem?

Now I am wondering if this value is a ScreenSet 2017 value or a UCCNC value (as I see it was just implemented in the latest UCCNC beta, but I've had in Screenset 2017 since installing). Wish i could post the screen shot to clarify.

Thanks,
Jasen

Tried to upload a screenshot, but getting an error that the board attachment quota has been reached.

[cncdrive]

Understanding offsets is relatively easy.
The Current coordinate equals the machine coordinate minus the offsets. Current coordinates = machine coordinates - offsets.
When you change the Current coordinates then the Offset changes to keep the equation correct and when you change the Offset then the Current coordinates changes to keep the equation correct.
The only stationary is the Machine coordinates, the value of that you set with homing the machine.

I don't clearly understand your description, I mean what the issue is, but my above description of the offsets may make you understand how the offsets work and hopefully then the issue will be resolved, or if not then please give us some further description of the issue to let us see it clearly.

[ThreeDJ16]

Understanding offsets is relatively easy.
The Current coordinate equals the machine coordinate minus the offsets. Current coordinates = machine coordinates - offsets.
When you change the Current coordinates then the Offset changes to keep the equation correct and when you change the Offset then the Current coordinates changes to keep the equation correct.
The only stationary is the Machine coordinates, the value of that you set with homing the machine.

I don't clearly understand your description, I mean what the issue is, but my above description of the offsets may make you understand how the offsets work and hopefully then the issue will be resolved, or if not then please give us some further description of the issue to let us see it clearly.

I'm not really sure how to explain it any better. I posted an image to imgur so maybe that would help. Again, not sure this is a function or UCCNC or just Screenset2017, so I emailed Gerry too. The feature is called Machine Zero Offset (machine sw. position). What I am saying is that if I set it to a -2 (mm), then it placed my soft limit behind the limit switch set zero by -2mm. It only allows me to set a negative number (maybe because I home positive). By the description, I would think the intention is simply to move the machine zero out in front of the switch by stated value of this field. But it doesn't, it moves it in reverse. This causes the switch to always actuate before the soft limit is reached. So my point is this field value doesn't seem to work.

I will look at the base UCCNC screens and see if there is a similar value in it, as again, this maybe a ScreenSet deal and I just posted here by mistake.

Here is a pic, it's under the homing speeds and homing speed backoff setting.

[cncdrive]

OK, I understand it better now.
That function (machine zero offset) is a UCCNC function, not screenset function only.
The value you type there sets the machine coordinates on homing. In other words the machine coordinates will get this value when you home the machine and the axis triggers the home switch.

When you set your softlimits + and softlimits -, it basicly defines your workspace, it will be the range of between the softlimits- and softlimit+ values.
So, you can the machine zero offset in between the softlimits- and softlimits+ range.

The software allows you to set a negative number only for the machine zero offset if your positive softlimit is 0, because then your softlimit range will be from the softlimit- to 0, where the softlimit- has to be a smaller number than 0 in this case if the softlimit+ is 0, because it is the negative side softlimit, so then the possible range you set only includes negative numbers and so you can't set a positive machine zero offset, because it would be out of the softlimits range.

[ThreeDJ16]

OK, I understand it better now.
That function (machine zero offset) is a UCCNC function, not screenset function only.
The value you type there sets the machine coordinates on homing. In other words the machine coordinates will get this value when you home the machine and the axis triggers the home switch.

When you set your softlimits + and softlimits -, it basicly defines your workspace, it will be the range of between the softlimits- and softlimit+ values.
So, you can the machine zero offset in between the softlimits- and softlimits+ range.

The software allows you to set a negative number only for the machine zero offset if your positive softlimit is 0, because then your softlimit range will be from the softlimit- to 0, where the softlimit- has to be a smaller number than 0 in this case if the softlimit+ is 0, because it is the negative side softlimit, so then the possible range you set only includes negative numbers and so you can't set a positive machine zero offset, because it would be out of the softlimits range.

So basically when I set it to -2, it makes the home switch trigger point -2 instead of zero? Which makes sense due to the fact I was trying a Z0 and actuating the switch before getting there. Guess what I don't understand is when would this function be used? Personally I would rather see it function as setting the 0 position -2mm in front of the switch (which is what I thought it was doing originally). Sorry so many questions, but I haven't found much reference to it anywhere. Always try to get the most out of my software by learning as much as I can about all the settings, but this one is still puzzling me as I don't see the application for it?

Thanks for your responses and have a Happy New Year!

-Jasen

[ger21]

Personally I would rather see it function as setting the 0 position -2mm in front of the switch

To do this, you would set the home offset values to 2, and home in the positive direction, or -2, when homing in the negative direction.

I'm not going to reply to your email, as CNC Drive has already answered the question. If you have any other questions, feel free to email again.

Guess what I don't understand is when would this function be used?

Here's how I use it. My X axis has roughly 45" of travel. My X axis home switch is at the positive end of travel. When I home the X axis, it gets set to 45, so that Z=0 is at the other end of the table.

A little note about using the 2017 Screenset with 1.2101, and possibly even 1.2047.

There are a lot of new settings in UCCNC, which are not in the 2017 screenset, and this can potentially cause problems.
Here's one example that I know of: There's a checkbox to turn the toolpath boundary display on and off, that is not in the 2017 screenset. If you happen to change the boundary color, it will automatically uncheck the boundary on/off checkbox, and you can't turn it back on, because there's no check box.

I'm beginning the process of updating the 2017 screen, but it's going to result in a nearly complete redo, which will likely take a few months.

[ThreeDJ16]

Personally I would rather see it function as setting the 0 position -2mm in front of the switch

To do this, you would set the home offset values to 2, and home in the positive direction, or -2, when homing in the negative direction.

Actually if you look at my screenshot, I am homing positive and you can't use a positive number as my limits are 0 to -162 (on the Z, which is where my problems started). That is why it seems backwards to me. But at least your example gives me a better understanding of when you would use it. I was looking for a bit of a safety buffer for my switches and don't really want to change up all of my axis numbers now that I am used to them. So I just set this number back to 0 and everything works fine.

Thanks for the heads up on some of the other new menu items being missing from Screenset 2017. Problem is that the newer version finally solved my openGL issues, so really don't want to downgrade. I never change the colors on the boundary settings. But guess it would be a good idea to really look thoroughly at the original screens of the new versions.

[ger21]

Actually if you look at my screenshot, I am homing positive and you can't use a positive number as my limits are 0 to -162 (on the Z, which is where my problems started).

Unfortunately, you can't have your cake and eat it too.

There are two things you can do here.

1) Set your Softlimits to -3 to 159, and set the offset to -2. I don't know how much travel your switch needs, but I would think that 1mm wouldn't hurt anything?
2) Have your Home All button call a macro that does the following:
a) Turn off Softlimits.
b) Home the machine.
c) Turn on Softlimits.

If you are trying to avoid hitting the switch, then option 2 is probably the best option.
This code should do it, but I'm in a hotel right now, and can't test it.

Code: Select all

exec.Callbutton(519); // Turn Off Softlimits
while(exec.IsMoving()){}

exec.Callbutton(168); // Apply Settings

exec.Callbutton(113);  // Home All
while(exec.IsMoving()){}

exec.Callbutton(518);  // Turn on Softlimits
while(exec.IsMoving()){}

exec.Callbutton(168); // Apply Settings

Just save it as M20777.txt, and change the number of the Home All button to 20777 with the screen editor.

[ger21]

Thanks for the heads up on some of the other new menu items being missing from Screenset 2017. Problem is that the newer version finally solved my openGL issues, so really don't want to downgrade. I never change the colors on the boundary settings. But guess it would be a good idea to really look thoroughly at the original screens of the new versions.

The issue with the boundary color is the only one I'm currently aware of, and there are a few ways to work around it.
There may not actually be any other issues. Just wanted to let you know that the possibility is there.

[ThreeDJ16]

Actually if you look at my screenshot, I am homing positive and you can't use a positive number as my limits are 0 to -162 (on the Z, which is where my problems started.

Unfortunately, you can't have your cake and eat it too.

There are two things you can do here.

1) Set your Softlimits to -3 to 159, and set the offset to -2. I don't know how much travel your switch needs, but I would think that 1mm wouldn't hurt anything?
2) Have your Home All button call a macro that does the following:
a) Turn off Softlimits.
b) Home the machine.
c) Turn on Softlimits.

If you are trying to avoid hitting the switch, then option 2 is probably the best option.
This code should do it, but I'm in a hotel right now, and can't test it.

Code: Select all

exec.Callbutton(519); // Turn Off Softlimits
while(exec.IsMoving()){}

exec.Callbutton(168); // Apply Settings

exec.Callbutton(113);  // Home All
while(exec.IsMoving()){}

exec.Callbutton(518);  // Turn on Softlimits
while(exec.IsMoving()){}

exec.Callbutton(168); // Apply Settings

Just save it as M20777.txt, and change the number of the Home All button to 20777 with the screen editor.

No worries, as i mentioned, everything is fine. Was just looking for a buffer when my program does a rapid G53 Z0 move. I slowed the mill down a tad and haven't had any issues since.

Seems to me that homing ignores soft limits now. As it has to go past zero to hit the switch. Zero isn't set until the switch is actuated then backs off till release.


I really do appreciate your help. Your examples helped me understand where it can be used and that I really don't need it in my situation.

Thanks and Happy New Year to you!

Jasen