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Setting Tool Length Offsets....
« on: July 24, 2009, 07:09:44 PM »
What is the normal procedure, if there is such a thing, for setting tool length offsets in the tool table for a mill?  Here's what I envision, which may be completely wrong:

Gather up the set of tools to be used for a given job, and one-by-one, probe each tools length, and set its offset into the tool table using G10L1.  When done, probe, using any tool, to set the fixture offset to the top of the workpiece.

Also, when I tried modifying the M6 macros, I found M6End never gets called on a toolchange unless "Stop Spindle, Wait For Cycle Start" is checked.  What's up with that??  How do I write a toolchanger macro if M6End never gets called??

Regards,
Ray L.
Regards,
Ray L.

vmax549

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Re: Setting Tool Length Offsets....
« Reply #1 on: July 24, 2009, 09:03:00 PM »
Ray mach gives you 2 options for tool changing.

(1) Stop spindle wait for cycle start where it calls M6 start then waits for that to end then calls M6end on cycle start.  (manual mode)

(2)  Auto where mach calls the m6start and then it cycles throught a tool changer routine and restarts itself. ( auto mode)


For setting tool lengths you set against a master. so mach understands the offset.

(1) Master plug, where you have a master plug to use as the master. It sets the reference for ALL tools. ( usually known as tool1 but it can be any tool#)

(2) Master tool, set the working group of tools against a master tool. That will either be the shortest or longest tool of the group. Using a knee mill I would lean to the longest seeing you only have about 5" of z travel.

(3) Set first tool, then reset against the last tool used. ( used when a collet system is used)

Hope that helps, (;-) TP
Re: Setting Tool Length Offsets....
« Reply #2 on: July 24, 2009, 10:57:54 PM »
OK, I think I've got it figured out.  I got stuck on trying to figure out how to make it move back to the same Z height it was at prior to the toolchange, but I've now got that working.

I don't understand why the "master tool" needs to be either the shortest or longest tool.  Seems to me, it really doesn' matter, since tool offsets are always based on the difference between the master tool and the other tools.  I can see if you have limited Z motion, and a wide range of tool lengths, some care would be needed in setting up.  Is that the only concern?  In my case, tool length compensaion will be done with the knee, so I have 20" to work with.

Regards,
Ray L.
Regards,
Ray L.
Re: Setting Tool Length Offsets....
« Reply #3 on: July 24, 2009, 11:03:08 PM »
Probably because it will accept negative value for a tool lenght unless you include in your VB that lenght will always be Positive.

If you get negative value, Try using the command ABS(variable)

This will return the absolute value of the variable.

Jeff

Re: Setting Tool Length Offsets....
« Reply #4 on: July 24, 2009, 11:37:23 PM »
Probably because it will accept negative value for a tool lenght unless you include in your VB that lenght will always be Positive.

If you get negative value, Try using the command ABS(variable)

This will return the absolute value of the variable.

Jeff



Is there a requirement that offsets be only positive?  Seems to work fine with positive or negative offsets....

Regards,
Ray L.
Regards,
Ray L.

vmax549

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Re: Setting Tool Length Offsets....
« Reply #5 on: July 26, 2009, 08:06:18 PM »
HIYA RAY, working with a Knee mill I only have 5" of quill(;-)   The only real concern is that you set up the machine with what every you consider the master.  It can be any tool or a separate guage tool.

Offsets can be either way in mach

(;-) TP

vmax549

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Re: Setting Tool Length Offsets....
« Reply #6 on: July 27, 2009, 03:25:15 PM »
RAY how are you doing TLO with the knee???  In the normal Gcode convention the G43 adjust the Z to compensate for the tool length. Unless your knee IS the Z?

Another point with a knee mill I use the longest tool as the master as this makes ALL tool oofsetts in the neg direction and it will NEVER cycle up to the Z upper lilimts. If there were a drill bit in the mix and the shorter tool was the master then without very carefull planning as to quill travel and where the top of the part is(zero) it would retract the z up into the limits and stop the program.

AND the same is true with a long tool as master, you have to make sure there is enough Z travel so the short tool does not TRIP the lower limits as well(;-)

(;-) TP

« Last Edit: July 27, 2009, 03:27:51 PM by vmax549 »
Re: Setting Tool Length Offsets....
« Reply #7 on: July 27, 2009, 03:41:51 PM »
RAY how are you doing TLO with the knee???  In the normal Gcode convention the G43 adjust the Z to compensate for the tool length. Unless your knee IS the Z?

Another point with a knee mill I use the longest tool as the master as this makes ALL tool oofsetts in the neg direction and it will NEVER cycle up to the Z upper lilimts. If there were a drill bit in the mix and the shorter tool was the master then without very carefull planning as to quill travel and where the top of the part is(zero) it would retract the z up into the limits and stop the program.

AND the same is true with a long tool as master, you have to make sure there is enough Z travel so the short tool does not TRIP the lower limits as well(;-)

(;-) TP



Terry,

You have to fudge the DROs in the M6Start macro, to reset the Z DRO by the amount of the tool offset, then apply the offset in the knee instead.  Would be nice if Mach had an option to do nothing on a tool change other than call M6Start, as it's kinda fighting what I want to do in several places....

Regards,
Ray L.
Regards,
Ray L.

vmax549

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Re: Setting Tool Length Offsets....
« Reply #8 on: July 27, 2009, 09:50:51 PM »
RAy I believe the auto function is what you want it only calls the M6start, which would contain the code for the actual toolchanger function. WHen that code ends Mach restarts automatically

SO you do not do a conventional G43H#  tool length comp??

(;-) TP
Re: Setting Tool Length Offsets....
« Reply #9 on: July 27, 2009, 09:59:14 PM »
RAy I believe the auto function is what you want it only calls the M6start, which would contain the code for the actual toolchanger function. WHen that code ends Mach restarts automatically

SO you do not do a conventional G43H#  tool length comp??

(;-) TP

Terry,

That's how I have it set now, but Mach still sets the new tool offset before M6Start is even called.  It would be nice if, when Auto toolchange is selected, if Mach did *nothing* other than call M6Start, then M6Start could do whatever it wanted/needed to with no interference.

Regards,
Ray L.
Regards,
Ray L.