Having issues with consistency on concentricity of parts. All were drawn from One then copied and pasted and created tool path…
Top trim edge is not concentric on any of the parts
Top trim edge is not concentric on any of the parts
A bit hard to tell exactly from the pictures bit it could be the bit slipping and therefore getting different depths.
All the depths are correct. It’s the concentricity. If you look at the top edge, it’s thick on one side thin on the other. I ran another test piece on a plain piece of wood. Same thing concentricity issue.
How was the board attached to the table?
My guess…assuming the entire workpiece isn’t moving, maybe they are warping a bit after milling out the pocket, leaving the walls just a little out-of-round. You might try milling the chamfer before milling the pocket to prove or disprove this. Or make the pocket more shallow and see if you get the same result. From the photo, it doesn’t appear that the top surface was milled so there could possibly be some variation in the height/thickness of your stock.
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If problems are repeatable this indicates where you should start looking.
So if you cut several pieces and they are all wrong the same way and then you cut another and it is wrong too the same way - then that points to the g-code not being right.
I know you are probably saying “how can that be” - well to start with - are the circles in your CAM software actually concentric? They may look so but maybe not.
Did you select the right circles in the software… etc?
I have done it myself, selected the wrong thing, and it was not enough to notice until I made the part.
Just saying it’s a thing to check.
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I would rule out gcode since it was copy/paste and the error is not in the same place on each part. My money goes on the top surface being slightly above or below Z0 across the entire nest. In that case, a face cut would eliminate the problem. If not, the wood is moving as you go along from part to part, and tape is not going to prevent that.
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Tomorrow I’m going to run a concentricity test to see what’s going on. Ran the g code in 2 different softwares and everything looks good visually. Been in the CNC industry programming and running machines and then a precision machine tool mechanic for the last 27yrs. Machines are big enough to put a car in and we hold ±.0005 tolerances. This little machine is not gonna win!! I’ll post up what I find after some tests. Going to test run the program at work tomorrow on some aluminum on a mill to verify the gcode not being the issue. Even double checked in Fusion 360 and all looks good. Material was good and flat, trammed it before I ran my second test yesterday, flat within .010. The concentricity was off by .050 on the worst piece.
After 27 years in the industry, you’ll be able to look at the gcode and see right away if that’s the problem.
So are the trim edges off on all the parts in the same direction?
Your original post does not say - so I zoomed in on the picture you provided and it seemed to me that all the outer chamfers were shifted the same way.
If they are not then it is not the gcode of course. If they are all the same way it would still point to gcode being most likely.
I would just open up the gcode and look to see where the outer and inner circle centers are.
Code looks good, it’s pretty obvious in the photos what is going on. Just had an issue with loose Y coupling on the slave motor so I reset both today. Will test tomorrow on a true milling machine to verify. Let’s hope it’s something simple which is pretty standard on these machines. Just funny how I run a batch and the 2nd batch has the issue.
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@760woodworking Alex: Sounds like you could be teaching us how to run these machines.
I would be looking at Y axis steppers, lead screws and ball nuts to make sure they are synchronous, and snug. While doing that check the X, seems like the Z is working fine. I recently had a problem that crept up on me, the screws holding the machine in place had been forced out of whack, took me weeks to find that a couple of the Y axis anchors were allowing slop. Another problem was that because my fingers are no longer steady, I inadvertently changed one of the stepper settings and it took days for support to figure it out.
@ynot after the test on the machine tomorrow at work that will verify the program. Curious to see if I have the same issue then. That means it’s the programming. Just upgraded to vector 12 pro series. I looked at the g code. Seems to be pretty good. Ran it in two different programs so we will find out. I’ll post up what I what I find
Well----- the program ran good on a Prototrak controlled Bridgeport mill. Guess I’ll take the other side apart (Y) and then the X.
Check the nut on the opposite end of the ball screw, this controls backlash.
Pat
Alex, Did you have any success figuring out what the issue was? I have been having the same problem.
I would check the cables. I had one coming out the end that got loose somehow and was causing me problems in x and Z. Hopefully you get it figured out. If not send the code to me and will try it on my machine.
Turns out it’s when I updated the drivers software version. Infinity had me take the controller apart. Pull the mini USB out and reload it and the problem went away
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MicroSD not USB. Darn voice to type. Not sure how that was the issue, but it went away after that, ran a few items since then and no issues.
That was the cause of your circles not be on center? I did just update my software.