Toolchanger hitting spindle tip causing bad tool change

jdholbrook33 · Aug 30, 2015

I was working on Saturday and we had a power outage.
It was right in the middle of a tool change on the VF-4
After power was restored I worked with automatic recover feature with no luck.
Finally went through the manual recover and was able to get the Z axis high enough to remove the stuck tool.

The tool changer arm went back to Zero position and I had the tool in my hand so we decided to call it a night.
I homed all axis and shut the machine down.

Now this morning I put the tool back in the spindle and did a tool change and BAM!!
The tool that was going into the carousel fell out and hit the chip tray.
Looking at the tool in the spindle I could see that it's not lined up with the dogs. I quickly pulled it out and tried a few dry runs.
Seems the spindle is too low during tool change, keeps the arm from going up to the proper height.
I reset everything, powered off and on a few times but.. still seems that the spindle is too low during tool change.

Any suggestions??

Pipes · Aug 30, 2015

Sounds like either your tool change position got confused during the power outage or something mechanical happened that affected the grid shift. The below excerpt from the parameter manual may be helpful, however, double check the current value against any backup you may have to verify that it has not changed before you try to adjust,

"64 Z TOOL CHANGE OFFSET
For turret, displacement from home switch to tool 0.
On Vertical mills: For Z-axis; displacement from home switch to tool change position and machine zero. About 4.6
inches, so for an 8192 line encoder this gives: 4.6 x 138718 = 638103
Alternately used for machines with type 4 servo axis pallet changer. It positions the pallet for a pallet change. For
example, Z-axis travel on the EC-400 is done by moving the pallet, not the column, and therefore will not affect a
tool change. Also, Parameter 64 is generally used during zero return, and that usage is consistent in the EC-400."

jdholbrook33 · Aug 30, 2015

Pipes said:
Sounds like either your tool change position got confused during the power outage or something mechanical happened that affected the grid shift. The below excerpt from the parameter manual may be helpful, however, double check the current value against any backup you may have to verify that it has not changed before you try to adjust,

"64 Z TOOL CHANGE OFFSET
For turret, displacement from home switch to tool 0.
On Vertical mills: For Z-axis; displacement from home switch to tool change position and machine zero. About 4.6
inches, so for an 8192 line encoder this gives: 4.6 x 138718 = 638103
Alternately used for machines with type 4 servo axis pallet changer. It positions the pallet for a pallet change. For
example, Z-axis travel on the EC-400 is done by moving the pallet, not the column, and therefore will not affect a
tool change. Also, Parameter 64 is generally used during zero return, and that usage is consistent in the EC-400."

Luckily I took a backup just after the machine was installed.
My Parameter 64 shows 350000

According to my backup it's 350000

N211 V0
N064 V350000
N212 V0

What kind of mechanical thing could happen?
Something slipped?
My understanding is that the encoders are not absolute but take the zero from the home switch position??

Looking at my Machine Coordinate page, when I home all axis, the Z reads 0.6308.
I can jog it down to 0.000.
I never noticed this before and thought it always read 0.000 when homed.
In fact I don't think it would even go past 0.000 when jogging up.
I tried the other axis and they will not go past 0.000.

Ideas?

Pipes · Aug 30, 2015

If the motor coupling to the ballscrew or the encoder coupling to the motor slips the mechanical position of the index seek from switch release will change. Check the value of parameter 127 to see if there is currently a grid shift. You may be able to correct the height offset with a gridshift.

"127 Z GRID OFFSET
Shifts the effective position of the encoder Z pulse. It can correct for a motor or home switch positioning error."

jdholbrook33 · Aug 30, 2015

Just out of curiosity I went through the alarm history.
I found one that stood out as it happened at exactly the time of the power outage.

236 Spindle Motor Overload

I will look at 127

jdholbrook33 · Aug 30, 2015

Pipes said:
If the motor coupling to the ballscrew or the encoder coupling to the motor slips the mechanical position of the index seek from switch release will change. Check the value of parameter 127 to see if there is currently a grid shift. You may be able to correct the height offset with a gridshift.

"127 Z GRID OFFSET
Shifts the effective position of the encoder Z pulse. It can correct for a motor or home switch positioning error."

127 Z GRID OFFSET is the same in the machine and my backup.

N127 V-24172

magno_grail · Aug 31, 2015

Service manual 96-7045 says "if the ATC position changed Parameter 64 will have to be reset". By moving the ATC in and stopping it with the Emergency switch after the door opens you can measure the height of the tool in the carrosel. Remove the tool from the carrosel and put it in the spindle. Zero Return Z single axis. Jog Z-axis until the indicator reads zero (same as the ATC). Take the number in the Z-axis machine display and multiply it by Parameter 33 (Z Ratio STEPS/INCH). If the Z-axis work display is negative add the number you calculated to Parameter 64, if positive subtract it. Zero Return Z axis to initialize the new Paramaeter 64. When Parameter 64 is changed the tool offsets must be reset.
The encoder Z channel signal must occur between 1/8 and 7/8 revolution from the home switch released. If Distance to Go is less than 0.0295 or greater than 0.2065 it will alarm "Zero return margin too small". The ideal amount for Distance to go is 0.118. Set Grid Offsest to zero, zero return the axis the use the formula:
(Distance to Go - 0.118) X 33867 = Grid Offset {33867 = Ratio Steps/Inch}
Zero return the axis to use the new offset. Parameter 64 has to be checkes afterward. If any axis is reset the user's work offset has to be reset also.

jdholbrook33 · Sep 1, 2015

magno_grail said:
Service manual 96-7045 says "if the ATC position changed Parameter 64 will have to be reset". By moving the ATC in and stopping it with the Emergency switch after the door opens you can measure the height of the tool in the carrosel. Remove the tool from the carrosel and put it in the spindle. Zero Return Z single axis. Jog Z-axis until the indicator reads zero (same as the ATC). Take the number in the Z-axis machine display and multiply it by Parameter 33 (Z Ratio STEPS/INCH). If the Z-axis work display is negative add the number you calculated to Parameter 64, if positive subtract it. Zero Return Z axis to initialize the new Paramaeter 64. When Parameter 64 is changed the tool offsets must be reset.
The encoder Z channel signal must occur between 1/8 and 7/8 revolution from the home switch released. If Distance to Go is less than 0.0295 or greater than 0.2065 it will alarm "Zero return margin too small". The ideal amount for Distance to go is 0.118. Set Grid Offsest to zero, zero return the axis the use the formula:
(Distance to Go - 0.118) X 33867 = Grid Offset {33867 = Ratio Steps/Inch}
Zero return the axis to use the new offset. Parameter 64 has to be checkes afterward. If any axis is reset the user's work offset has to be reset also.

magno_grail,
I went through the instructions and I don't think they apply to my machine. I have the side mounted tool changer.

I think there is something mechanical going on.
Today when I came in the spindle was almost on the table. Also I noticed that the power level for the Z axis hovers around 50%. Is that normal?

A quick call to HAAS and the tech said it sounds like the coupler between the servo and ball screw has collapsed.
Doesn't make a whole lot of sense but I'm not an expert.

Where are ya'll getting these manuals from?
I would like to read them.

Here's what I see.
When I zero all axis the Z axis shows 0.6308 while the rest show 0.0000
When I do a tool change the Z axis drops to 0.0000 and the tool change starts.
The arm hits the dogs ever so slightly. Enough to spin the spindle when it moves away.

I found VF Series Service Manual 96-8100G and went through the GRID reset procedure.
It did not help. The Z axis returns to 0.6308 and the arm still drags.

Perhaps it's time to call the HAAS repair guy

Milland · Sep 1, 2015

jdholbrook33 said:
Perhaps it's time to call the HAAS repair guy

If you're not comfortable pulling the Z cover and doing a physical inspection, then yes, I'd call a repair tech.

magno_grail · Sep 1, 2015

Yes, 96-7045 is for the carrosel not the side changer, sorry. Since you have manual 96-8100G, look at page 176 for the ATC alignment.
On side mount changers the Parameter 64 setting is 0.625 x 138718 = 861699 (page 189). You might want to check that.

sagespecialized · Sep 1, 2015

You say "when you came in this morning your spindle was almost on the table."

If you have the gas style counter balance maybe it needs to be recharged? The lack of pressure will allow the Z to drop, therefor losing your position. If it gets real bad and if you hit e-stop the spindle will head for the table, which sounds like what is happening.

jdholbrook33 · Sep 1, 2015

Thank you gentlemen for the suggestions, guidance and challenges (Pulling the Z cover thing).

I pulled the Z cover, looked at the ball screw, coupler and limit switch. All looked brand new with no sign of damage.
I ran a piece of metal across the prox switch and it triggered fine.
So I went to the manual and started reading again.
I did the measurement from "tool in the tool pocket" height to "tool in the spindle" height for the parameter 64 and it was only 0.004" difference and it was on the higher side.. not the lower side. (had to bring the spindle down 4 thou to get the same reading on the spindle as the pocket)
Digging deeper I found how to enter TRC mode (go to DEBUG mode, hit "Recover" and "F1" for tool changer recovery, hit "M" for manual and you have complete control of the tool changer. I slowly moved the arm into position but failed to orient the spindle first.
I did an "Orient Spindle" and saw the problem immediately. Spindle was no longer oriented to the tool changer.
Went through the procedure to orient the spindle in the manual and all is good.

Tried a few tool changes and it's smooth as butter.

Thank you again for all your help.

P.S. Don't know why I was intimidated with tearing into the machine.
I've been an Industrial Electrician and also Electronic Technician for more years that I want to remember, worked on much more complicated and expensive equipment.
Maybe the fact that if I screw it up.. I'm the one paying for it!

Now to go and re probe all the tools.

BGL · Sep 2, 2015

The only bad thing about Haas and most any machine tool, they are designed to be assembled quickly and cheaply not to be easily serviced and repaired. I plan to set up my spindle covers with 1/4 turn fasteners so like an airplane I can open it up quickly.

Mike1974 · Sep 2, 2015

Z axis load on newer Haas machine will always have some load (30-60%?) as the motor keeps the Z in position, there is no counterbalance. Mine runs about 50%, 2014 UMC-750.

haastec · Sep 2, 2015

jdholbrook33 said:
Thank you gentlemen for the suggestions, guidance and challenges (Pulling the Z cover thing).

I pulled the Z cover, looked at the ball screw, coupler and limit switch. All looked brand new with no sign of damage.
I ran a piece of metal across the prox switch and it triggered fine.
So I went to the manual and started reading again.
I did the measurement from "tool in the tool pocket" height to "tool in the spindle" height for the parameter 64 and it was only 0.004" difference and it was on the higher side.. not the lower side. (had to bring the spindle down 4 thou to get the same reading on the spindle as the pocket)
Digging deeper I found how to enter TRC mode (go to DEBUG mode, hit "Recover" and "F1" for tool changer recovery, hit "M" for manual and you have complete control of the tool changer. I slowly moved the arm into position but failed to orient the spindle first.
I did an "Orient Spindle" and saw the problem immediately. Spindle was no longer oriented to the tool changer.
Went through the procedure to orient the spindle in the manual and all is good.

Tried a few tool changes and it's smooth as butter.

Thank you again for all your help.

P.S. Don't know why I was intimidated with tearing into the machine.
I've been an Industrial Electrician and also Electronic Technician for more years that I want to remember, worked on much more complicated and expensive equipment.
Maybe the fact that if I screw it up.. I'm the one paying for it!

Now to go and re probe all the tools.

That's great that you were able to figure things out on your own and get up and running again. I hate to burst your bubble, but the fact that your spindle orientation suddenly changed without reason tells me that you are not done with your issue. You probably have made a temporary fix, but whatever caused the orientation to go out, will most likely happen again.

My suggestion is to remove the head covers so you can inspect the encoder belt and pulleys. Many times a bad belt or pulley will cause the orentation to slip and can also be the cause of your high spindle load because the machine is trying to compensate for fluctuations caused by both or either one. The pulleys can be difficult to inspect sometimes because of their locations, but also because the aluminum ones will reflect light in a way that makes the peaks and valleys of the pulley difficult to see clearly.

If these parts have some age to them, I would recommend replacing all three (belt and 2 pulleys) as good insurance regardless if it fixes the issue or not.

jdholbrook33 said:
Today when I came in the spindle was almost on the table.

Please elaborate on this statement as I find it very disturbing.

jdholbrook33 · Sep 3, 2015

haastec said:
That's great that you were able to figure things out on your own and get up and running again. I hate to burst your bubble, but the fact that your spindle orientation suddenly changed without reason tells me that you are not done with your issue. You probably have made a temporary fix, but whatever caused the orientation to go out, will most likely happen again.

My suggestion is to remove the head covers so you can inspect the encoder belt and pulleys. Many times a bad belt or pulley will cause the orentation to slip and can also be the cause of your high spindle load because the machine is trying to compensate for fluctuations caused by both or either one. The pulleys can be difficult to inspect sometimes because of their locations, but also because the aluminum ones will reflect light in a way that makes the peaks and valleys of the pulley difficult to see clearly.

If these parts have some age to them, I would recommend replacing all three (belt and 2 pulleys) as good insurance regardless if it fixes the issue or not.

Please elaborate on this statement as I find it very disturbing.

A good idea to remove the cover.
I almost had it off the other day and decided not to. A little reluctant to go climbing on top of the mill, would hate to bend the sheet metal.

The mill has very little time on it. Manufactured 5/2015 and delivered to me 6/2015.

When I leave the shop I always home all the axis and take the tool out of the spindle.
When I arrived the next day the spindle was about 10" from hitting the table.
It is possible I left the spindle in a lower position when I left that night. It was late and I was tired and there was a lot of excitement due to the power outage.
Since then it's been exactly where I left it... homed.
I'll keep an eye on it and if it is down again I'll start to worry.

haastec · Sep 4, 2015

jdholbrook33 said:
The mill has very little time on it. Manufactured 5/2015 and delivered to me 6/2015.

Why are you messing around with things if it is under warranty? I highly recommend that you not make repairs on your own for no other reason than to keep your dealer from claiming that you messed things up, caused further problems, or worst, damage.

If your orientation goes out again, call your dealer and make them figure out why and perform any repairs.

Good luck!

jdholbrook33 · Sep 4, 2015

haastec said:
Why are you messing around with things if it is under warranty? I highly recommend that you not make repairs on your own for no other reason than to keep your dealer from claiming that you messed things up, caused further problems, or worst, damage.

If your orientation goes out again, call your dealer and make them figure out why and perform any repairs.

Good luck!

Thanks for the good advice.
I actually called HAAS and they said it is probably a collapsed coupler between servo and ballscrew. Made no sense to me but I know how difficult it can be to troubleshoot something over the phone. I was going to call the HFO but to be honest, I have little confidence in the techs I've seen so far.
Why? When they delivered my ST-10 we were talking about the chuck and I watched them take a hammer to the allen key while tightening the bolts of the jaws. I asked if there was a torque spec for that and he said "get them as tight as you can then tighten them some more".
Later I pulled the manual for the chuck. 53 ft lbs is the torque for the M10 bolts of the chuck jaws. Definitely not as tight as I can get it then beat on the allen key with a hammer.
I am anal like that. The manufacturer gives a torque spec for a reason. Use it!

Mavika · Sep 24, 2021

Help

jdholbrook33 said:
Thank you gentlemen for the suggestions, guidance and challenges (Pulling the Z cover thing).

I pulled the Z cover, looked at the ball screw, coupler and limit switch. All looked brand new with no sign of damage.
I ran a piece of metal across the prox switch and it triggered fine.
So I went to the manual and started reading again.
I did the measurement from "tool in the tool pocket" height to "tool in the spindle" height for the parameter 64 and it was only 0.004" difference and it was on the higher side.. not the lower side. (had to bring the spindle down 4 thou to get the same reading on the spindle as the pocket)
Digging deeper I found how to enter TRC mode (go to DEBUG mode, hit "Recover" and "F1" for tool changer recovery, hit "M" for manual and you have complete control of the tool changer. I slowly moved the arm into position but failed to orient the spindle first.
I did an "Orient Spindle" and saw the problem immediately. Spindle was no longer oriented to the tool changer.
Went through the procedure to orient the spindle in the manual and all is good.

Tried a few tool changes and it's smooth as butter.

Thank you again for all your help.

P.S. Don't know why I was intimidated with tearing into the machine.
I've been an Industrial Electrician and also Electronic Technician for more years that I want to remember, worked on much more complicated and expensive equipment.
Maybe the fact that if I screw it up.. I'm the one paying for it!

Now to go and re probe all the tools.

I have the same problem for my kitamura mycenter 3xg. I had to reset my Z when I changed battery for the encoder. When I do tool change the ATC hits the spindle. Can you help?

Mavika · Sep 24, 2021

Mavika said:
I have the same problem for my kitamura mycenter 3xg. I had to reset my Z when I changed battery for the encoder. When I do tool change the ATC hits the spindle. Can you help?

Please feel free to email for any suggestions @ [email protected]

Toolchanger hitting spindle tip causing bad tool change

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