Tailstock motion and turret motion in EMC -Lathe Mode-

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22 Jun 2019 03:05 - 22 Jun 2019 03:07 #137541 by Vitran
I want a way to ensure synchronization between Z and A offset so I don't break anything. I have a lathe with 8 tools on the turret and 8 on the tailstock. As is, turret is XZ and tailstock is A. I have tools 1-8 on the turret, 21-28 on tailstock.

https://i.imgur.com/WOJ7w8f.mp4

Things have been good so far. I got gmoccapy working and am finishing up a few other small issues with it. I have had a few jobs going through on the machine. I really need the tailstock to handle the c-drill / bore drill / end mill bore / tapping head / die head / live center / bar-pusher-stop / regular drill tools so I can put more tools on the turret.

When I setup tools I get my gauge block, measure tool 1, set it to 0, and go around setting each tool in the turret to the same Z0 point. Afterwards, using the same gauge block I set the tool offsets relative to A.

The challenge is if I machine something then want to drill it with the tailstock I need to have had both the Z local and A local off of the same reference point. I can copy-paste the Z offset and put it in the A offset for that local zero point, but I worry there will be a screw up sometime.

Is there a way to synchronize the Z offset and A offset so that when tools in the turret and tailstock are used together they are the same without manually setting them? Is there a better way to setup this type of operation?
Last edit: 22 Jun 2019 03:07 by Vitran.

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22 Jun 2019 04:54 #137553 by cmorley
Am I understanding right:

A is a linear axes of the tail stock yes?

The problem is when you set the user coordinate origin in Z axis, you want it to automatically set the A axis user coordinate origin too?

I assume you would need to know the offset difference in old Z to new Z and add that difference to the A axis (because the A axis position is independent of Z)

Chris M

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22 Jun 2019 05:02 - 22 Jun 2019 05:07 #137557 by Vitran
If Z0 is set -218mm from g53, then A0 is set to -218mm from g53. Everything is referenced to tool 1 on the turret. Both sets of tool offsets are referencing the same point as the zero point.

Is there a better way to do this? I can't be truly unque in having a tailstock axis. Someone must have done something like this before, no?
Last edit: 22 Jun 2019 05:07 by Vitran.

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22 Jun 2019 08:10 #137567 by pl7i92
first if you choose/ change A to W
you can work with a toolofset mode

and this is also the best advice as the interpreter regonices all ofsets within the codeline

then the safty comes from Postprocess as like fusion there is a turet warning

also you shoudt never interfear the G53
get the tool length to the G54-G59 offsets

you can always load a safty ngc via Mcode as you said
with IF commands
but this is not the way to go as it does not interfear the system direct

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22 Jun 2019 14:10 #137589 by Vitran
The original plan was to have the tailstock as the W axis, however halui would not launch. It would state that it did not have axis Y in control and would demand that Y was known in order to launch if someone had the W axis. I did not have a Y axis and thought this odd. I even tried adding a 'fake' Y axis that had no motion and was stuck at 0, but that didn't work. Something to do with halui seeing 3 axis and that it wanted XYZUVW in that order and was unhappy with XZW. That was back in October I believe. I forget who told me (ZincBoy or JT or PCW) said that I can change the name of the fourth axis to A to make halui to launch. I do not know if there has been an update of some type to fix that.

As for the offset, I was referring to the following:

When setting up the offsets:
G54, it would have a Z offset from G53 of -218mm so that when G54 is active, Z0 would be at a location of 218mm away from the home position. I would never change the G53 position, but all G54-G59 positions are relative to the G53.
However, I need to tell halui that my G54 A0 position is the same as my Z. I can manually copy -218mm from the Z offset to the A offset.

Maybe this will help. This is what I am thinking of:

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23 Jun 2019 00:42 #137623 by cmorley
If you want A ans Z to have the exact same offset in what ever G5x mode, then that is possible with a modified Gmoccapy.
Would need to tell Gmoccapy that anytime you change Z axis offset then change A to the same.

I must confess I don't understand how your machine works. If A and Z are not independent of each other why do you have two axes?

I would think that they are independent, and then that changes how offsets are set because the two are not necessarily in the same place when you change the origin of one.

That problem probably can be worked around too though.

Chris M

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23 Jun 2019 01:07 - 23 Jun 2019 01:08 #137627 by Vitran
A and Z are independent.

Here is someone else showing off a similar model. 8 tool tailstock on its own axis, 8 tool turret. Both A and Z are on their own axis.

Maybe this example will help:
The work piece is at a location (G54). I want to face the part at Z0 with my facing tool on my turret. I then want to drill a hole into that surface at Z0, but I am using a tool on my tailstock. I bring the tailstock forward. I want to drill 5mm into the surface at Z0. The tailstock is on the A axis, so I need the A axis offset to be the same as the Z offset and move the drill to -5mm in the A axis.

I would assume this would be the same for any tailstock, even one with only one tool. If I want to center drill the end of a shaft with the tailstock, it moves forward and drills but needs to have the same G54 Z offset on its axis. Also for dual turret lathes.

Last edit: 23 Jun 2019 01:08 by Vitran.

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23 Jun 2019 01:08 #137628 by andypugh

pl7i92 wrote: first if you choose/ change A to W
you can work with a toolofset mode


The tool table also allows ABC offsets for tools. I had always thought that was pointless until just now.

Does the tailstock also move linearly (W axis?) or is this a Swiss-style lathe where the work moves towards the tools?

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23 Jun 2019 01:26 #137632 by cmorley

Vitran wrote: A and Z are independent.


Ok that makes more sense.

Setting the origin in linuxcnc is always referenced from the current axis position.

So in my mind you must change gmoccapy's origin setting code to:
-calculate the at-the-moment difference between the A and Z axes.
-set the Z axis to the requested origin.
-adjust the A axis origin so that the same at-the-moment difference is maintained.

I think that would be reasonable easy to do.
It would be possible to screw it up by using the included offset editor (without modifying it too)

Chris M

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23 Jun 2019 01:48 #137633 by Vitran
Andypugh, the tailstock moves linearly.

Ha! Found a video of Rob H's tailstock moving. This is what I am looking for.

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