Glitch during Plasma Cutting (Why?)

[DesertFabworks]

I have a custom built plasma table with steppers which for the past year has worked great.

recently I was doing cut and the gantry jerked a few times the machine lost its place and the project was ruined before I could hit stop.

I checked the gantry system and found the rails and tracks to be clear, the stepper drive track was clear and powered down the system and moved the gantry around and found non binding or obstructions.

I reset the system and completed a new cut no problems, I did this two more times with out a problem. This was a project with the same piece several times. The next cut it did the jerk motion and ruined the part. It was a different part of the table and at a different point in the cut. This happened three times before I quit for the weekend.

I use sheet cam and Mach 3 and did not find any errors in the code or the part. With it being different places on the table and different locations in the cut I'm at a loss to explain why this would happen.

Do steppers go out and what happens when they do? How long do they last with light use?

Thanks for any help.

[FiveORacing]

Check the gears on the stepper motors and make sure they are tight. If the allen screw got loose those little gears can slip under load.

[DesertFabworks]

Found the problem.

Not sure why but checking the gantry again I found that every once in a while it would bind. My gantry is gear drive and there was no one spot that was a problem. I put some grease in the gear rail and problem solved. I have never greased it before maybe I should have been but it fixed the problem. Ran the machine almost 8 hours straight doing cut after cut and no problems.

Thanks for the thought FiveORacing but the the set screws and gears were tight.

[I see spots]

I have noticed my y axis has gotten louder recently. It is a spring tensioned rack and pinion.

I thought about lubing it but was afraid the lube would attract more of the contaminate.


anyone else lube their racks?



bob

[elkriverfab]

I use a dry silicone spray after cleaning the tracks.
Not sure how well it lubricates but it is better than using a product that attracts the cutting dust.

I use it on my bearings too.
As a matter of fact today I was looking over everything and found the bearings to still be lubed after about 2 months since I used the dry lubricant.

I guess it is working.
I too was afraid of attracting debris and making it worse but it seems to be doing the job.