integrex alignment

[huntinguy]

So, I would think, if i turned a spud in lathe mode, then put my test bar in the milling spindle and rolled it to 90 degrees, put an indicator on the spud and sweep in the test bar, I should be able to put the indicator on the test bar and the spud should sweep in at zero as well. In short they should be in perfect alignment.
They are not... Y is .0035 tir and X is about .0085 tir. When the other is reading 0,0.
What am I missing?
(B is parallel within .0003 in X and Y over the length of the test bar. Runout on the test bar is .0002 and about the same on the spud).

 

[zak300sy]

Ok if you've got things mechanically aligned, now you've got to get parameters adjusted so that if you interpolate a hole at x0 y0 in the end of a part held in chuck, then check runout it's a couple of tenths. Check M parameters M16 perhaps? Once you get that correct you've got to adjust the two parameters to comp for center of rotation of spindle. Those control when you flip b to 90 degrees. You should be able to mill the end of a bar, then flip b to 90 and interpolate a hole and everything is within a couple tenths if you align it right.

 

[huntinguy]

Okay, will double check that.
So, will that fix the problem of the center of a hole, b at 90., with X,Y interpolation being off center with a hole milled, b at 90, using c ?

 

[DMF_TomB]

So, I would think, if i turned a spud in lathe mode, then put my test bar in the milling spindle and rolled it to 90 degrees, put an indicator on the spud and sweep in the test bar, I should be able to put the indicator on the test bar and the spud should sweep in at zero as well. In short they should be in perfect alignment.
They are not... Y is .0035 tir and X is about .0085 tir. When the other is reading 0,0.
What am I missing?
(B is parallel within .0003 in X and Y over the length of the test bar. Runout on the test bar is .0002 and about the same on the spud).

.
probably grid shift is off and needs adjustment. weekly i probe and or indicate a special ring gage set in a certain spot within .001" and measure how far it is off. then i adjust parameter and power down and reboot and zero return and measure again to confirm adjustment.
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each machine usually have a specific way to adjust grid shift and often is done in mdi mode and with write protection turned off and after adjusted turn write protection back on.
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many cnc machines need a grid shift adjustment on every power down and reboot. zero return is not enough for tighter tolerances under .0015"
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got to be careful with grid shift. too far off can effect tool change and other things. i always write down before and after adjustment numbers.

 

[Philabuster]

In short they should be in perfect alignment.
They are not... Y is .0035 tir and X is about .0085 tir. When the other is reading 0,0.
What am I missing?

What type of indicator are you using? How much is your indicator affected by gravitational droop? Some indicators are absolutely horrible for this phenomenon.

 

[DMF_TomB]

mazak has info on adjusting grid shift. some shops view it as only to be done by maintenance. other shops the operators are expected to measure and adjust often weekly.
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nothing worse than a mazak lathe with part in chuck but chuck not rotating and then a rotating drill bit thats suppose to drill a hole on center is over .005" off center. unfortunately i have seen that problem too often usually the operator may even be aware of it but has no ideal how to adjust the grid shift

 

[mkd]

or just go buy an Okuma Macturn.

they have absolute encoders and don't have this problem

 

[CarbideBob]

or just go buy an Okuma Macturn.

they have absolute encoders and don't have this problem

How does an absolute encoder fix alignment on a five+ axis machine that has been tapped?
Somehow you need do know the new axis rotation in space and it has moved.
If you don't smack one no problem regardless of encoder type , hit a 6 or 8 axis hard and ......Oh poop.

.

 

[mkd]

.

.
many cnc machines need a grid shift adjustment on every power down and reboot. zero return is not enough for tighter tolerances under .0015"
.

How does an absolute encoder fix alignment on a five+ axis machine that has been tapped?

.

who mentioned anything about a crash??

abs encoder machine doesn't need to rely on limit switches every day to know where the machine is at.
*should have quoted in first post, as to not confuse. sorry.

 

[CarbideBob]

who mentioned anything about a crash??

abs encoder machine doesn't need to rely on limit switches every day to know where the machine is at.
*should have quoted in first post, as to not confuse. sorry.

So now I'm really confused.
How is a absolute encoder more accurate than an incremental one?
You don't actually "zero" off a limit switch on a cnc. The switch just tells you when to look for the encoder's index pulse.
I would think both would have the same error due to room temp and such.
Bob

 

[litlerob1]

Don't be confused Bob, MKD isn't sure what the **** he's talking about. Actually Okuma uses hard and soft stops (limit switches) for movement of any axe. But "home position" is against the soft stops to eliminate even the possibility of over travel. The point is the absolute encoder measures the distance from the soft stop (home on a fanuc) to the front of the part on Z for example.

What he was saying in post #7????? I have no idea. If there is a mechanical misalignment you should not/cannot compensate for that on an Integrex or on a Multus, that's just poor decision making, if the machine is mechanically out it needs to be fixed, Abs encoders don't have shit to do with it.

Robert my ±2

 

[DMF_TomB]

i measure grid shift every week. it changes when machine warms up. it changes for many reasons. my machines have abs encoders and they still require grid shift check and adjust for high precision work.
.
i know for a fact mazak has a sheet of codes to adjust grid shift. it is not for me to tell you what to do. grid shift adjustment is usually a advanced machinist adjustment. i would look for mazak info on it not hearsay from somebody other than from mazak.

 

[CarbideBob]

i measure grid shift every week. it changes when machine warms up. it changes for many reasons. my machines have abs encoders and they still require grid shift check and adjust for high precision work.
........

This actually makes sense to me.
My incremental encoder machines will home and repeat to within 5 millionths but the actual metal and bearings out there between the rotating points move around so you have to tweak zeros.
Grinders, so a bit fussy about matching cuts, but we find that we have to move them over the range of a day depending on running hours and coolant temps.
Over months, ways and tables move as they wear, rotary systems settle in, zeros move with them.
No encoder can hope to know if your abbe error is growing. It can't see it.
Even a granite base CMM in an inspection room "drifts" over time.
Generally worse of course in the first 1-5 years of life which is why old iron is nice.
Bob

 

[mkd]

Don't be confused Bob, MKD isn't sure what the **** he's talking about. Actually Okuma uses hard and soft stops (limit switches) for movement of any axe. But "home position" is against the soft stops to eliminate even the possibility of over travel. The point is the absolute encoder measures the distance from the soft stop (home on a fanuc) to the front of the part on Z for example.

What he was saying in post #7????? I have no idea. If there is a mechanical misalignment you should not/cannot compensate for that on an Integrex or on a Multus, that's just poor decision making, if the machine is mechanically out it needs to be fixed, Abs encoders don't have shit to do with it.

Robert my ±2

its called a joke, as in ford vs chevy joke thus the
lighten up Francis
btw contrary to what you are saying, grid shift/ parameters were put there to comp for physical differences.

 

[mkd]

So now I'm really confused.
How is a absolute encoder more accurate than an incremental one?
You don't actually "zero" off a limit switch on a cnc. The switch just tells you when to look for the encoder's index pulse.
I would think both would have the same error due to room temp and such.
Bob

edit: they are not more accurate, per se, but a sliver more reliable IMHO. when you take accuracy of switches sending a signal to your encoder, out of the equation, you are simplifying the system. the premium brands to it this way, in which i rest my case.
with incremental encoders, you do actually zero off the switch. from the zero, most non ancient cnc's have setting telling it how long the stroke is. end of stroke is xxxxx number of pulses from wherever the switch hit.
people will chime in and say, well in theory the switches are so much more accurate than the system, abs vs inc argument is moot.
in practice that is mostly true, but i have seen a few exceptions which wouldn't have happened to an abs encoder machine.
it' nice when you fire up the machine it already knows exactly where it is. no referencing switches every day.
just sayin

IIRC all the pre 2004 mazaks i touched all needed a zero return to switches on power up. okuma have been using abs encoders in the '90s on , i guess all their machines. could be wrong on some details here.

 

[litlerob1]

i measure grid shift every week. it changes when machine warms up. it changes for many reasons. my machines have abs encoders and they still require grid shift check and adjust for high precision work.
.
i know for a fact mazak has a sheet of codes to adjust grid shift. it is not for me to tell you what to do. grid shift adjustment is usually a advanced machinist adjustment. i would look for mazak info on it not hearsay from somebody other than from mazak.

Tom, I am certainly not saying that the grid shift does not need to be verified and adjusted I do it as often as I can or need to. What I am saying is the encoders don't have anything to do with it. Now that my dumb ass catches up with MKD's joke, life makes more sense again

Robert

 

[CarbideBob]

with incremental encoders, you do actually zero off the switch. from the zero, most non ancient cnc's have setting telling it how long the stroke is. end of stroke is xxxxx number of pulses from wherever the switch hit.

......

This is not my experience.
Not sure what an ancient cnc is but from my Milwaukee-Matic EB, which would be kind of old to many, up thru today's there are these things called index pules on the incremental encoder.
The physical switch tells you to decell and or reverse and begin looking for the encoder pulse which you then latch.
This position will always be within one encoder count unless something is broken.
Grid shift is use to offset this "Z channel" or marker encoder pulse to a known machine location since when building a machine the encoder disc or scale can be oriented anywhere.
I have seen DIY and steeper motor stuff use switches for zeros but those are not in the same class as even the most ancient Fanuc or paper tape NC.

Most of my machines don't get zero returned unless the incoming building power fails as they don't get turned off.
Since many of the PC based controls are on a UPS I have some that have not been reset for more than 7 years with power on cycle counts in the millions.
(gasp, running on windows no less, never rebooted)

I do remember the first time Buick powered down their machines.
It had been over 20 years and it was a mess since many machines did not have good batteries in them to hold the parameters.
They had the luxury of their own on-site power plant with the grid as a backup so they never had to deal with it before.
Someone thought it would be a good way to save money over the Christmas shutdown. Sometimes it cost less just to leave them on.
Bob

 

[zak300sy]

What type of indicator are you using? How much is your indicator affected by gravitational droop? Some indicators are absolutely horrible for this phenomenon.

Ok couple questions for original poster:

What model machine and what version of control? Do you have absolute encoders? True y axis machines like I/j/e tower series? Or slant(generated) style machines?

We've had b axis machines with the following controls:
640mt. Igx300sy
640mt pro igx200sy
640 m pro. E-420s
Matrix. J-200 & i300sy
Matrix nexus j200
Matrix 2 E-410s

Every one of those uses different parameters, etc to adjust things so knowing what you've got is very important. True y axis machines use m parameters for moving x&y and BA61/62 to adjust center of rotation values.

Older slant style uses bs13 to shift axes

Phil is absolutely spot on about the indicator droop being an issue.

I prefer to interpolate a hole at x0y0. Then put indicator on milling spindle. Find low spot by moving turret in x- while c axis is at c0. Now move the c axis around to 90/180/270 degrees. Measure the difference between c0 & c180, divide by 2, that's how far you need to move x, c90-c270 div by 2 is y axis shift amount. No indicator droop with this method cause it never moves. Once you've got this right you'll need to take a tool of a known length and diameter and start adjusting so things come out correctly at b90.

Mazak has a procedure for getting this stuff straightened out, it shows pictures of a Blake co-ax indicator being used. Good luck with that one!

Curiosity question: have any of you that replied actually worked on one of these before?

 

[litlerob1]

Mazak has a procedure for getting this stuff straightened out, it shows pictures of a Blake co-ax indicator being used. Good luck with that one!

Curiosity question: have any of you that replied actually worked on one of these before?

I shouldn't dignify an answer to that question, but yes, and I know Phil does and TomB, don't be a dick newb. If you can find me a better applicable indicator than a Blake send me a link I will buy it tonight.

Robert

 

[DMF_TomB]

read the manual

of course Mazak has a procedure to correct any alignment issues. as the saying goes when all else fails read the manual
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it usually is not in the basic operator manual as it is a advanced machinist or maintenance item. and of course sometimes the manuals are not very detailed on explaining things.
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adjusting grid shift which is basically a permanent offset on all coordinate systems i always repeat test to make sure i went the correct direction and amount.
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as i said before i have adjusted grid shift before too far and it affected tool change. i always write the before and after adjustment numbers of any parameter changes down.