View Full Version : unwanted finish lines

11-16-2008, 10:52 AM
What would cause unwanted lines during a finish pass.i,m doing a 3d model and in some parts all is smooth and in other areas i see lines .Useing a .125 inch ball endmill at 9% step over in one pass at .375 deep.Don,t have pics to show as of yet.

11-17-2008, 12:37 PM
here are some pics

11-17-2008, 09:50 PM
Looks like a tram problem. Have you checked the alignment of your spindle with each axis?

11-17-2008, 10:17 PM
some of it could be a little bit of cutter flex also 9% is too much step over thats over .010 on a 1/8 ball,that will leave a small ridge,or line standing material between each pass try a .004 step over,or roughly 3-4%

11-18-2008, 09:12 AM
Looks like your missing steps in the Z axis. You'll notice that on the eagle, there are no grooves on the flat areas where the Z doesn't move. But wherever the Z axis is moving, you're getting grooves. Try lowering the Z axis acceleration 20-50%.

11-18-2008, 09:42 AM
I will just say beautiful work...:)

11-18-2008, 12:40 PM
Thanks for the replies,to all. I,m rastering in the Y and slowed the max excell in the X the other day thinking that may of helped . Did not think about the Z ,but will play with that .One thing I,m also finding is that where I start and where program ends is not at the same start point ,it,s good in the Y but not in the X and Z returns to safe level about .20 which is fine , that is why i slowed the max excell in the X.About tramming ,not sure what that means. Thanks agian gentlemem for the replies, I,m finaly doing some nice cutting and trying to work out all the bugs,cheers Corrie.....P.S Mach3 Rocks.

11-22-2008, 09:36 PM
Well I thought I would post another pic. This is a les Paul top X-7 Y-5 Z-.25. I used a .25 inch ball endmill at full depth at 50 ipm,. with a 11% step over, still trying to find the best step-over value. I used a square to check the perimeter pocket and it is spot on. I,m starting to think that the wieght of my porter cable router and mounting plate are having some effect causing some of the unwanted lines?I,ve played with the max excells ,but not much has changed. Should I expect to get a mirror finish?I also installed a stand alone video card so not to share any cpu resource,cheers.

11-23-2008, 06:45 PM
Keep the stepover between 8-10% when doing a finishing pass. The 9% you were using should be just fine, that is if all is good with your machine. It should give you a nice smooth finish with minimal sanding. Anything smaller would be over kill. And frankly just take to long to cut. -WW

11-23-2008, 07:12 PM
Your Z axis lead screw is loose. Those lines are due to Z float. Sometimes up, sometimes down. Could be bad thrust bearings, loose bearings in their pocket, or loose lead screw in the bearings. It's doubtful the spindle is loose in your router as the lines are too uniform. If it were lost steps, its be progressive in one direction or the other. As the overall depth appears to remain the same but with variations, then your Z axis comes into suspect more than any other reason.

11-23-2008, 08:21 PM
Thanks for the replies,would be nice to have some kind of chart for best stepover rates according to which tool was being used.I will definately take a closer inspection to my Z and see whats up with it,thanks W.w and Mr.Wild,greatfull for the replies.

11-30-2008, 12:44 PM
Here are two more pics, one the L.P. and one of the Strat.Both were cut useing a .25 inch ball endmill at a .25 inch pass. Models size is 7.5x5.5x.25 deep. Run at 60 ipm with a 7% steppover just to see the difference from my last few runs. Although there are visible lines it is very smooth.Mr.Wild mentioned the up and down effects that I,m having and while running these last two models I may have found the culprite.I believe the way that my dust extraction hose is mounted to my dust boot and hung from the garage ceiling by bungee cords is not only part of the added weight factor but giving slight flex to the Z assembly across the bridge. I,ll take a pic of the setup as it is now and post later.I did check ball nut ,all was fine there and thrust bearings seem fine as well but new ones would not hurt.

11-30-2008, 04:05 PM
I,m cutting right now as i write and I have removed the dust hood and hose . I brought my step over down to 6% and what I noticed was that the Z stepper motor was actualy moving ,making one slight step while traveling on a flat plane,I,m thinking this has got to be software related.Rastering in the Y and stepping in the X. I,m figuring that after about .25 to .5 inches of stepping in the X the Z decides to do a little stepping on it,s own, explain this one to me.I,ll post pics when done.

11-30-2008, 08:06 PM
A few more pics