Losing steps while cutting

[Phil]

While cutting HDU on a 3D finishing cut I was losing steps. I was using a new Beckwith 1/4" carbide bit. Cut was 1/2" deep with a 10% stepover at 200"/minute. The cut would be fine for quite a while and loose steps causing the cut to be slightly off track.
Other than cleaning the rack and pinion and applying fresh grease what might remedy the loss of steps. The is a 10 year old 4g Shopbot benchtop. I have recently made cuts that are much more stress on a cut than cutting HDU. I also did a USB port test with the Shopbot utility, the rate was 76.5%.
The machine has not been used heavily over the 10 years.

Thanks, Phil

[martin54]

Other than the obvious have you tried slowing things down what is your dust extraction like?
Have you cut other materials at this speed without problems?

Reason I asked about dust extraction is it may be a static problem which might not be a problem when cutting wood

There isn't a lot of stress on the machine cutting sign foam but if your acceleration & deacceleration settings are set to steeply then that can cause lost steps, faster you set the feed rate the more chance there is of it happening

[Dan m]

Different controller but I know a guy who was having the same problem on a 3d tool path that had a lot going on. It turned out to be his PC causing the problem, he thought it was his driver's and upgraded to DMM servo's and like I said it was his computer not having the processing strength. I think the 3d tool paths tax your PC.

Hope this maybe helps,
Dan

[IslaWW]

One other item that affects these types of files is heat saturation. Running a stepper motor for a couple hours gets the motors hot. The drives get hot also, as each gets hotter it gets weaker, eventually causing a loss of steps. Those desktop motors are not power houses to begin with and Gecko chips always run hot, so if you cant find any other source of the problem, consider that.

[wmgeorge]

I'm thinking as Gary is and also as a electrician. If its been in service for ten years you might also have a binding issue either motor bearings or drive someplace.

[Phil]

Thanks to all. I learned a lot. Not sure exactly what the problem is but I have things to look for; hot stepper motors, feed rate too high, static.
I also contacted Shopbot support and performed a few maintenance items. These links are worth a look for anyone with a CNC.
Maintenance items http://www.shopbottools.com/ShopBotDocs ... 0%2024.pdf
Computer issues
Tips on setting up your PC https://mail.google.com/mail/u/0/#inbox?projector=1
I spent most of the morning checking out a number of maintenance issues. Now I hope all is good.

Thanks again,

Phil

[ezurick]

Thanks to all. I learned a lot. Not sure exactly what the problem is but I have things to look for; hot stepper motors, feed rate too high, static.
I also contacted Shopbot support and performed a few maintenance items. These links are worth a look for anyone with a CNC.
Maintenance items http://www.shopbottools.com/ShopBotDocs ... 0%2024.pdf
Computer issues
Tips on setting up your PC https://mail.google.com/mail/u/0/#inbox?projector=1
I spent most of the morning checking out a number of maintenance issues. Now I hope all is good.

Thanks again,

Phil

Phil, I was only interested in the "Tips on setting up your PC" to see if I could learn something new. I clicked your link and it just opened my gmail. So the link isn't any good... at least not for me.

[Phil]

One other item that affects these types of files is heat saturation. Running a stepper motor for a couple hours gets the motors hot. The drives get hot also, as each gets hotter it gets weaker, eventually causing a loss of steps. Those desktop motors are not power houses to begin with and Gecko chips always run hot, so if you cant find any other source of the problem, consider that.

I'm thinking that Gary has provided the answer. I set up the file to cut as a 3D raster finishing toolpath, running left to right. So the X axis stepper motor was doing most of the work. I was loosing steps in the X axis. I'm considering setting up the file either as a raster on a 45 degree angle or an offset toolpath. What are your thoughts.

Thanks,

Phil

[Phil]

Ezurick

see the attachment

[martin54]

Phil not sure what type of steppers your machine has but if Gary says it may be a problem with the steppers then this might be worth checking. When I got my machine (spares or repair) I had problems with one of the stepper motors, my machine was a lot older than yours though.
It ran on old style slo-syn stepper motors & apparently the magnets in these motors deteriorate over time & it was this that was causing problems with my motor. I just replaced all 3 motors as the machine was getting refitted & it seemed silly just changing the one & risking the machine only running a short while before I started to get problems again.

[Phil]

I'm in contact with Shopbot support. They are helping me troubleshoot. I'll be checking the motors next.

Thanks,

Phil