[BayLit Signs]

Hello Everyone,
I've followed the forum in my spare time, just reading what goes on.
Now I am in need of some knowledge of you could kindly pass some ideas on to me...

I have a General i-carver 40-915x.
I have been using it for about a year and a half, half dozen hours a week or so goes on it.
Regular maintenance completed.
I have found at times (and happening more and more often now) that it tends to shift over randomly.
It jumps over in x and /or y-axis anywhere from .020" to 1".
I thought maybe a loose wire, shorting out possibly, or maybe too fast of feed in tight areas.
I slowed it down and yet it still did it.
I mainly cut the same profile repeatedly. 1/4" Endmill, in HDPE plastic. .050" depth of cut. Usually on carving mode low.
Sometimes it's great, other times it steps over scraps my job.

Any others that have seen this issue?

Thank you for reading!

Regards
Ross

 

[old55]

Welcome to the forum.

 

[marecat3]

welcome to the forum

 

[difalkner]

Welcome to the forum, Ross! Does your machine use belts, gears, direct drive, etc.? Is anything slipping? Does it do this in the same place each time? Can you run a toolpath where you know it slipped but do it in the air, not cutting anything, and see if it slips with no load?

David

 

[MEBCWD]

If everything is tight on your machine(no worn parts and properly adjusted), it might be that you are exceeding the cut limits of your machine. If the project blank is not placed on the bed where the cut area of the toolpath is inside those limits then it could be losing steps when it exceeds the limits.

 

[BayLit Signs]

Welcome to the forum, Ross! Does your machine use belts, gears, direct drive, etc.? Is anything slipping? Does it do this in the same place each time? Can you run a toolpath where you know it slipped but do it in the air, not cutting anything, and see if it slips with no load?

David

Very good points to try David! I have tried under no load and it still moves. That idea prompts me to try the same program dut in a different location to see what it does.
Adjusting drives I have not looked into. This machine has ball screws, I will have to look into their adjustment if that is possible to do.
I seem to think this happens when the machine has been on for a while and warm. Can it be just age....?
Thank you for those pointers. I will get into his deeper.

Regards
Ross

 

[BayLit Signs]

If everything is tight on your machine(no worn parts and properly adjusted), it might be that you are exceeding the cut limits of your machine. If the project blank is not placed on the bed where the cut area of the toolpath is inside those limits then it could be losing steps when it exceeds the limits.

Thank you for the reply. Usually, I have another program running out further towards limits and it cuts well. (example, my last jump I had was cutting the inside of a number "0", but I had just cut the outside with no issues.)
When I do hit the limits the machine alarms out and stops.
I am definitely checking for tightness and adjustments of each axis.
Regards
Ross

 

[difalkner]

Got any photos of the machine?

David

 

[BayLit Signs]

Got any photos of the machine?

David

yes......

 

[BayLit Signs]

So after a few tests. I can’t get it to repeat the problem! Go figure! Lol
After some talk with a couple millrights, they are feeling through experience that this may be happening just due to the fact that they are stepper motors and not servo motors. It is known (which I just learned after 25 years machining) that steppers tend to jump now and then. Not as reliable as servo motors.
I have recalled that my machine will jump the longer it runs.... maybe due to heat then in the motors itself. I’ve been cutting less at a time and haven’t had issues.
Cheers Ross