CNC Cutting in Steps on 2nd and 3rd Passes

[tatotatito]

Hello Everyone!

Hopefully I am posting this in the right place here. I have a home made woodworking CNC that uses the Desk CNC software. I did not build the machine myself, I bought it off an acquaintance for a very good price.

I am rather new at this, I have been tinkering away for the last month or so trying to figure things out, and have had pretty decent luck until now.

I am trying to cut out frames for artwork in various shapes, using 3/4 inch MDF board with a 1/2 straight drill bit.

The problem happens when I set the machine to cut in passes; it will do the first pass as directed, then for some reason I can't figure out, it will "step" the second and third passes so the edges of the finished frame look a little bit like stairs. Please see the attached photos, sorry for the quality!

Can anyone tell me what I am doing wrong? Is it software, the machine, or me?

[Khalid]

Might be interference, loose cables, loose connectors... This happens to many time to me, and i always found problems in electronic stuff.. see the cables and joints ..something is loose there..

[brtech]

If you cut two of them, would they look exactly alike (same error)?

If they don't, then Khalid may be right.

If they do, then there is something wrong with the software.

[Jason Marsha]

Did you say you are cutting with a drill bit?

You need to cut with a upcut spiral or a straight plunge bit. It looks to me from the pics that the bit is putting stress on the axis and thus giving a poor cut.

Jason

[tatotatito]

Thanks everyone for your responses.

Khalid: I hadn't thought about checking the cables and such, I'll do that.

Brtech: No, if I cut two they end up slightly different. I have been have having another small issue though that cuts exactly alike from frame to frame, so now I know to check the software for that one.

Jason Marsha: Sorry, I don't know why I wrote drill bit, I am using a straight plunge bit. Maybe I'll try a spiral cut and see what what happens.


I just noticed something else though: it looks like when the machine is moving in one certain direction, for the sake of description let's say it's cutting in the direction away from me - when it's cutting and moving away from me, it is having this problem. When it is cutting and moving toward me, there is less or no problem. ???

[Jason Marsha]

You need to check for flex. When I try to cut too fast I get this problem.

What speed are you cutting at?

Lets get close-up pics of the machine, we may spot a problem.

Jason

[Khalid]

one of the motor wire is loose in the controller box/...