[Delw]

How do you tell if your thrust bearings are out?

My Y axis when it goes towards the back it makes a thump noise. coming towards the front its fine.

the finish has 4 steps in it as well but only when the Y axis moves towards the back.

Thanks
Delw

[cadman]

How do you tell if your thrust bearings are out?

My Y axis when it goes towards the back it makes a thump noise. coming towards the front its fine.

the finish has 4 steps in it as well but only when the Y axis moves towards the back.

Thanks
Delw

Noise (especially in one direction), excessive backlash, bad finish on that axis, part feature locations keep drifting along the axis, vibration when cutting along that axis.

Our 8030 has all of the above issues on all axis and the thrust bearing on the Y axis literally fell apart while running late last year. Sounded like a car crash. The Z axis ballscrew needs replacement and the X axis isn't far behind. I'm hoping they fail soon so we can throw away this money pit.

Check the Y axis gibbs first. If the problem isn't there, inspect the thrust bearing. While you have the motor off you can also check that the rotor spins smoothly with no play. Also check the coupler. The older brass ones make lots of noise when they develop play.

[Delw]

cadman
thanks the backlash is fine(few tenths) the finish isnt bad its just like it stops and pause for a few turns on a straight Y cut.
size doesnt drift or anything either.

I am going to check brushs next. I havent checked them in 2 years on the y axis.

[cadman]

You mean the ballscrew pauses?

[Delw]

nothing shows anything pausing was just saying the finish looks like when you pause a tool during a cut, Slight indentation so to speak.
its had like 4-5 thumps when feeding 7" in the y axis away from the front of the machine.
at rapids you dont hear it only during feeds ranging from 100 ipm to 50 Ipm Havent tried it any slower.
parts still come out perfect and too size and I havent had any size changes.

its weird for sure thats why thinking comutator brushes or armature brushs in the motor.

[cadman]

If those dwell marks are always at the same place it could also be the ballscrew.

[Delw]

I took covers off today and checked a few things.
Everything seems to be normal. brushs look good, ways look good, ball screw looks good etc etc.

The Y axiss very little vibration going towards from the front of the machine, and lots of vibration going towards the back.

everything is tight motor and coupler wise.
I am leaning towards a ball screw cause the farther I move the machine in the Y the quieter it is. however Rapids and anything above 75-100 IPM you dont hear a thing and anything under 50IPM you dont hear a thing nor see any difference in the finish, Ill give it a while to see what happens, so far the blocks I am running are good even the finish is good, but not like a few weeks ago.

Delw

[carbidecraters]

What do you mean ballscrew looks ok? did you check to see if the ballscrew had backlash or bearing or table gibs? Their is a test for each and the backlash you test on the table top in the center of the table may not represent the total backlash. I would start with bearing then ballscrew then gibs or straps and then table top. This way you know where the backl;ash is coming from and you can actually tighten it up or notice it was more than you thought.

[Delw]

I check the ballscrew for smoothness by turning it by hand, both coupled with motor and uncoupled.The straps I am completely unfamiliar with on tightening/adjusting, I would need to talk to someone about that on the phone that has time

[carbidecraters]

I am trying hard here not to roll my eyes but you arent checking it right and your hand will not give you a good reading. You need an indicator or pay a couple hundred and have a service guy come over and do backlash and straps for you or just leave the way covers on and keep machining.

[GM81]

In the Fadal manual it gives simple instructions to check and adjust backlash. What do you mean by thump noise? We have a machine that makes noise becuase of the way covers. Have you tried just jogging back and forth in Y?

[Delw]

I am trying hard here not to roll my eyes but you arent checking it right and your hand will not give you a good reading. You need an indicator or pay a couple hundred and have a service guy come over and do backlash and straps for you or just leave the way covers on and keep machining.

Reread my first posted i checked it with an indicator first.

cadman
thanks the backlash is fine(few tenths) the finish isnt bad its just like it stops and pause for a few turns on a straight Y cut.
size doesnt drift or anything either.

I am going to check brushs next. I havent checked them in 2 years on the y axis.

I spun it by hand to see if anything felt rough,,
if you have a rough spot in a ball screw or on the slide or in the motor you won't know that by checking back lash.

this problem could also be noise or a bad connection maybe an amp or something going out.
I need to check the tuneing again anyhow. Might tear it down over the weekend,

[carbidecraters]

Ooops sorry Dell! Usually that thump comes from the coupler.

[Delw]

I will inspect the coupler a little better, that makes alot of sence. everything was tight fitting and I did take the motor off and put it back on, funny thing though I thought for awhile after playing the sound went away but then it came back, I was just thinking I had the feeds wrong when I ran it, cause it doesnt make a thump noise at rapids and or very slow feeds.
I never gave the coupler that much thought.
Thanks
Delw

[gaswiz69]

You mentioned the brushes look fine, can I assume your machine is a DC?
If so, did you remove all the brushes and blow out the carbon? If you run the axis in a program, and put your hand on the motor, can you feel the "thump" in the motor?
If not sure, try removing the motor from the ballscrew, and run a sample program to mimic the "thumps". If problem is confirmed in the motor, you may need to clean or replace the tach. Hope this helps.

[Delw]

Thanks.
No didnt blow out the carbon.
the finish came back to normal(ie perfect) last week, however the thump is still there. I didnt get a chance to take it apart over the weekend as I needed to use it.
I am betting it maybe be the coupler. I may call someone in , in the next few weeks to go through it, on some other issues I have had since the begining of time.

Delw