[Rocksalt]

Hi all, looks like you have a nice forum!

I have a Mazak Slant turn 50N with a Mazatrol T-Plus control. I was hoping by chance you could tell me how to display the following error. I have not played with this control much so I don't know the layout that well.

Thanks in advance,

Rocksalt

C.N.C. TEch, Galveston, Texas

EDIT:

I guess I will add the problem I am having and you might be able to give me some insight. I am having a vibration problem when threading the finish. The rough cut does not do it. I have measured the backlash in X and Z. X is .001 and Z is .003. I have not looked up the backlash parameter and checked how much is parameterized. This is what I have without zero'ing the parameter. I took an indicator and mounted it to the turret and put a 6ft. pry bar on the spindle, prying it outward. I can get .004 and it's springing back to 0 upon letting go. I did the same "pry" test on Z and X. I see about .003 and then springs back to 0. Take some ass on the bar to get the .003, so I am not concerned with X or Z.

I have been having a problem lately with coolant getting on the spindle belts. It's getting past the guard and hitting the belts. I have bought the necessary ingredients to remedy, but I cannot perform the work until the holiday season. The wet belts are causing them to slip. Oddly enough, the problem is not showing itself on rough cuts.. just the finish passes.

I have looked at the spindle speed while running and don't see a problem. I have also looked at the load meter and see no fluctuation. I am not sure if the feedback for the spindle speed is an encoder coupled to the spindle shaft. In most cases it's just that. In any event, the control is not displaying something abnormal.

My first guess would be the belts. Second is the spindle bearings.

Can anyone think of something else to look for?

[Al_The_Man]

Hi all, looks like you have a nice forum!

I have measured the backlash in X and Z. X is .001 and Z is .003. I have not looked up the backlash parameter and checked how much is parameterized. This is what I have without zero'ing the parameter. I took an indicator and mounted it to the turret and put a 6ft. pry bar on the spindle, prying it outward. I can get .004 and it's springing back to 0 upon letting go. I did the same "pry" test on Z and X. I see about .003 and then springs back to 0. Take some ass on the bar to get the .003, so I am not concerned with X or Z.

I have been having a problem lately with coolant getting on the spindle belts. It's getting past the guard and hitting the belts. I have bought the necessary ingredients to remedy, but I cannot perform the work until the holiday season. The wet belts are causing them to slip. Oddly enough, the problem is not showing itself on rough cuts.. just the finish passes.

I have looked at the spindle speed while running and don't see a problem. I have also looked at the load meter and see no fluctuation. I am not sure if the feedback for the spindle speed is an encoder coupled to the spindle shaft. In most cases it's just that. In any event, the control is not displaying something abnormal.

I would say that pry bar test is not showing you backlash, but the amount you are forcing the axis out of position as it 'springs back' if it was backlash I would expect it to stay out of position if backlash was present.
One way to test for entered backlash if any, and you dont have access to the parameter is to put a dial gauge on the axis final moving part and slowly handwheel in one direction, stop and when reversing .0001" you will see a fast movement of the ballscrew but zero movement of the dial guage (if the correct value is in the parameter). if no movement (or normal HW movement) is seen doing this in either direction then there is no value entered.
But if the ballscrew just turns slowly at the handwheel rate but the dial guage does not move, you have backlash with no correction.
The spindle encoder should be on the final shaft so some degree of belt slip should not affect the threading. But usually the best way is with heavy duty timing belt instead of vee's.
Al.

[HuFlungDung]

Vibration when finish threading can be a problem that will pop up for anyone, at various times. I think the typical solution is to dispense with the light finishing passes, and thread 'like a man'

If the light finish pass is mandatory, then play with the infeed angle parameter if you are using an automatic thread cycle. You would be striving to make the chipload differ on each side of the tool. Or, take the last finish pass as a G33, but vary the Z start point by a thou or two either side of the center, so that the tool is cutting on only one edge at a time.

[Rocksalt]

I would say that pry bar test is not showing you backlash, but the amount you are forcing the axis out of position as it 'springs back' if it was backlash I would expect it to stay out of position if backlash was present.
One way to test for entered backlash if any, and you dont have access to the parameter is to put a dial gauge on the axis final moving part and slowly handwheel in one direction, stop and when reversing .0001" you will see a fast movement of the ballscrew but zero movement of the dial guage (if the correct value is in the parameter). if no movement (or normal HW movement) is seen doing this in either direction then there is no value entered.
But if the ballscrew just turns slowly at the handwheel rate but the dial guage does not move, you have backlash with no correction.
The spindle encoder should be on the final shaft so some degree of belt slip should not affect the threading. But usually the best way is with heavy duty timing belt instead of vee's.
Al.

I checked the backlash the way you described initially. The reason for the pry bar test was to establish loose bearings in the spindle or loose clamping in the turret.

I guess I should have said "I have at least .003Z and .001X backlash + compensation in the control parameter"

[Rocksalt]

Vibration when finish threading can be a problem that will pop up for anyone, at various times. I think the typical solution is to dispense with the light finishing passes, and thread 'like a man'

If the light finish pass is mandatory, then play with the infeed angle parameter if you are using an automatic thread cycle. You would be striving to make the chipload differ on each side of the tool. Or, take the last finish pass as a G33, but vary the Z start point by a thou or two either side of the center, so that the tool is cutting on only one edge at a time.

This problem has come up before. The problem then was loose spindle bearings. I am not seeing a problem with the finish itself, it just rattles when making the finish cut. It progressively get's worse each pass. According to the operator this problem has been getting louder and louder with each week.

They are using a M54 then a G92 thread cycle(I don't know squat about programming). The insert is not a chip breaker, so the chips are stringers. The finish cycle is cutting both sides of the thread. I don't believe they have this problem on any other machine, including the 2nd Mazak they have. I believe they are all programmed the same. Maybe the "finish pass" is hacking off more than a usual finish pass would. The vibration does not occur when rough cutting the part.

[Rocksalt]

I just measured the chip break. It's .012 for the finish cut. The main cut is something like .060, which is nothing.

They also use air chucks. I don't know how good the springs are in them, but they are changed every year at x-mas time.

Something is wrong, I just can't pinpoint it.

[itmancnc]

If you have a parameter manual, you can change several servo parameters that affect the servo responses. High gains can cause this type of problem, the problem may not be in the spindle. If the problem is in the spindle it may just require a PLG adjustment.

[BAUMACH]

We currently have a SLT-50 that is less than a year old and we cut threads on about every part we do on it. When we first got it we had alot of chatter when threading. Mazak came in under warranty and checked out the machine. They were no help. We did our own investigating and found that the tool turret was off centerline about 0.015". We then put the machine back on centerline and it now threads like a champ. My suggestion is to check the centerline of your tools with a indicator. There are so many factors that can cause chatter during threading that it is almost impossible to narrow it down to a few things. One program might run good on one machine and terrible on the next. We always try and outrun chatter and this usually works for us.

[Rocksalt]

Sorry I didn't get back to this. It was the spindle bearings. I locked them down as tight as I could. JUST KIDDING. I can't remember the readings I got with the indicator, but I pryed on the chuck and had to much lateral movement. 1/2 turn on the spindle bearings did the trick. Reason I suspected this was due to previous work on the bearings. Had several things done at that time, all of which had to be gone back into for repairs. I was lucky in that I had some background information on the machine.