MCz changed

[1hander]

sorry to be such a PITA dave

i have a small dilemma i cant figure out...

so

after i crashed the last stylus.. i put on a spare which was shorter...
so i centered it
calibrated it
did a circle probe and it was within .0002 of measured size...awesome
then i ran the recalculate tlos maintenance...

i cut a complete part out with no issues..but was having a problem with depth of cut being correct which ended up being an incorrect stock setup in CAM(my fault)
but before i figured out it was my fault..i thought maybe the tlo for t4 is just off a bit...
so i decided to remeasure T4 and thats when the trouble started...

i touched off with T1... then mounted T4 and did g0z0 and T4 was above the workpiece about .100 or so...
afer a bunch of frustration..LOL...
i decided to check the height of the tool setter..it was correctly set in the box
i checked zero for all other tools and they were dead on
then i did a measure tool on T2 and it was sitting high like T4
decided to just redo the Set TCP TP MCz, i used 0 for the value and the nose of the spindle..
when i did that i noticed that value in the TCP TP MCz DRO had changed roughly .100 or so...
so thats when it hit me why T4 and T2 were sitting high when i tried g0z0 after touchoff

somehow the value in the TCP TP MCz changed.....

the only change i made before this started
was changing the PTL for T1 manually in the edit tool table then saved it...and running the recalc tlo script
T1 was mounted and it was in master tool mode, i never take it out of master tool mode.

any chance you might know why this happened...

the only thing i can reach for is the fact that the top of the stock... when i measured T4 is sitting LOWER than the top of the toolsetter top surface
or the way i entered the PTL for T1 somehow effected mCz


another question...instead of measuring manually and entering the ptl for t1.. since im using a moving TP....
could i make a dummy block that is exactly the height of the TP ...
and let the probe come down onto the top of the block during measuring...
theoretically would it work...
i know the dummy block would have to be the height of the TP when triggered.

[1hander]

im probly wrong but i may have figured it out... when i close mach... it always asks to save the tool table which i say yes... but when it promps for a save fixtures i always say no... is the tool setter a fixture///

[1hander]

i kept getting the same problem... then all of a sudden it stopped changing the offsets...
now every time measure a tool there is only a change of .0002 one way or the other...

i did a probe zero....
then checked T2 zero---- dead on

then remeasured T2---g0z0-dead on..

shut down mach3
referenced
did a probe zero
checked T2 zero---dead on

remeasured T2 and g0z0---dead on

changed the ptl of T1 ,,,
recalc TLO
recked T2 for Z0---dead on
remeasured T2---g0z0---again dead on.

its like it had a bug then after a few times it figured out what not to do...
ive had this problem with other functions in mach3 where it would act retarded then all of a sudden just stop making the same mistake... with no input from me...strange..

[1hander]

im not sure whats going on ... but its not fixed

the offsets keep changing when i do a tool measure .

and just a while ago...when i flipped the part... its like the mill thinks the part is shifted to the right and to the back... cuz its not spot drilling or chamfering on the correct y or x coordinates... i tried rerefering numerous times.. reprobing... on the toolpath window the corner of the part is in the right place in comparison to the spindle...

if you could shed any light on these i would appreciate it

rick

[DaveCVI]

somehow the value in the TCP TP MCz changed.....

That is rather unlikely. The MC of the TCP is simply a value that is stored by the TCP calibration steps. It is then read and used when a touch event happens from the TCP -but nothing I remember ever changes the value unless the user recalbrates the TCP location.

[DaveCVI]

im probly wrong but i may have figured it out... when i close mach... it always asks to save the tool table which i say yes... but when it promps for a save fixtures i always say no... is the tool setter a fixture///

"fixture" is mach dialog slang for "do you want mach to store the work coordinate offset values".

Lower right corner of the mach config general options dialog lets you control this.
I recommend checking the options for:
Tool Selections Persistent
Persistent Offsets
Persistent DROS (This one is important - if it is not checked, mach will not remember any DRO settings between runs - including USER DRO values - which is what MSM uses to store it's settings).

Dave

[DaveCVI]

the offsets keep changing when i do a tool measure .

Unfortunately, "offsets" is an overloaded word... by "offsets" did you intend to mean "work coordinate offsets" (XY) or Tool length Offsets" (Z)?

Dave

[1hander]

for some reason mach just does not like the two models im having trouble with...i made another model with circular pockets
half through on top side and just pas half way through on the bottom side.. both sides have chamfers on the holes..

i cut the first side and chamfered ..worked oerfect
then flipped..probed and cut and chamfered the flip side and the chamfers and the chamfers line up perfectly..the back side is projected geometry from the top side so i assume the holes line up correctly.. but the holes came out not deep enough ...dont know why..
so its the other models for some reason..

but heres the same problem i had before... i ended up making a new profile yeterday
i set the mcz ...put my tools back in the table... then measured all the tools..
its seems all was right except for the holes coming out not deep enough today..

i decided to remeasure T5 ... the offset only changed by .008
then i reprobed Z with the probe...
m6t5....then did G0Z0
and the tip of the tool at z0 is sitting .038 above the z surface...

it will stay that way until i reset MCz then the difference in old MCz and the new measured MCz is .008
which i can understand die to the moving tool setter differences...

but where is the .038 coming from when t5 is above the Z ...when it should be at the surface of the stock..

heres the funny part.. if go back and remeasure MCz it will change again by only .008.. cant remember if its + or - .. but if i remeasure MCz....
then reprobe Z....the mount T5 ... the tip of T5 will go back to the surface of the stock at Z0

[1hander]

i think i got it .. i got it bad (stupid) ..

when i cut the top sides of the parts...the damn vise was crooked...so now that the vise is straight...when i tried to cut the other two sides..they were offset ...thats why the chamfers were off.....
also in the tool table i had no diameter diameter set for the chamfer mill, im not sure of that caused a problem.
and i had the angle set wrong on the chamfer tip..its a 60deg ,,but in hsm you have to set 30 deg taper...not sure of that was causing a problem either..

the pockets didnt come out deep enough because
the touchplate height was off .004... i use it to set MCzero and i use it to set TLOs...
the PTL of my probe was too long by .023 ..
when i remeasured a tool, it would sit .031 above the stock a z zero when i set zs with the probe..
so .023plus .004 plus .004 is .031..
which is the .031 discrepancy i was getting when remeasuring a tool
please correct me if im wrong but i looks like the .004 from the mcz ...the .004 when measuring tools and the wrong length of the prob of by .023 was stacking up

all my fault...
again thanks for tolerating me in my learning process dave
i think i got at least this figured out..
theres just one more thing in one of the other threads i have a question on..the TC process

[DaveCVI]

...
all my fault...
again thanks for tolerating me in my learning process dave
i think i got at least this figured out..
theres just one more thing in one of the other threads i have a question on..the TC process

We all learn as we go...
Dave