My 3D model had wrong cut

I start rough then do finish

i was having this exact same issue some time ago and would have been pulling my hair out if I didn’t keep it cut so short. . I contacted support, I was suspecting a software issue and Vectric got involved. it turned out i was losing steps when the z was RETRACTING ( going up).
I had been using a shop made disk with a handle on the nut on the top of the acme rod to manually move the z axis (slowly!) and I had slightly looseend the nut. This, along with my z pulley grub screws having backed out a bit was allowing the step loss. ditched the manual operating disk tightened the gub screws, added blue loc-tite and retightened the top nut, and all was corrected. Then I went to a linear z axis upgrade, but that is another story.

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No only the finish did step lossing

Feed rate is 30 inch/sec
0.01step over
0.02 removing over

The acme rod did noises when go up, how to clean it and make it smoother

My acme rod started making noise when running up or down. even though it was very clean. I added some PTFE dry lube spray, available from home depot or most auto parts stores and it helped. My issue occured when in the finishing pass as well and looked identical to yours. Double check that the acme top nut is tight as well as the pulley grub screws. and try running it again.

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How to use this spray , I had WD-40

He also may have tight delrin nut problem. Could you please go over breaking delrin with hand drill. I’m outside.

Alan refers to using a cordless drill to run the delrin nut up and down the acme screw 25-30 times to wear in the threads of the nut to the shaft .

Also, Wd-40 will only last a short time and will attract dust like a magnet and cause more problems for you in the future with possible gumming up of the lead screw threads. PTFE dry lube “spray” goes on in liquid form but thi is just a carrier solvent for the real lubricant, a form of specialized powdered plastic that if caution is not taken can create a bit of a mess. Before using it, you may want to clean the acme rod of any dusty residue with an old tooth brush and an air nozzle. hopefully the dust will have absorbed any oily residue that oy uwill be cleaning off before the PTFE is applied


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30 inch/min
Sorry for that

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In artcam I use white and black photo in import relief then artcam express in toolpath I set finishing and rough and simulated the model in 3D and every thing is good
I use plywood and hardwood the same
I use end mill 1/8 inch for rough
1/8 pall noise for finishing

Gotta jump in here…given that the line (defect) is horizontal and it’s on all the carves I’m going to offer that there is something with the Y rails that’s causing the issue. From the pictures shown it looks like the finish passes are being done on the Y (front to back) and produces the height difference in horizontally. I’d look for what’s causing the X axis to jump up, like a hiccup on the Y rails as it’s going front to back. Just another persons perspective.

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I repeat the previous model and this is the rough was finished after I use spray for acme

I have new problem
at the start of the carve it suppose the z access go up then start carving
now the z access go down in the material , i check artcam and vcarve pro the same
i do not know what happened
i clean acme with spray
G0 Z0.1969
G0 X0.0000 Y0.0000 S10000 M3
G0 X0.5595 Y0.6024 Z0.0819
G1 Z-0.0050 F20.0
G1 X2.0398 F30.0
G1 Y0.6649
G1 X0.5595
G1 Y0.7274
G1 X2.0398
G1 Y0.7899
G1 X0.5595
G1 Y0.8524
G1 X2.0398
G1 Y0.9149
G1 X0.5595
G1 Y0.9774
G1 X2.0398
G1 Y1.0399
G1 X0.5595
G1 Y1.1024
G1 X2.0398

Check for a loose wire on the z-axis motor.

I check every thing is in good condition
After I finished rough and want to do finish the z access go down when I start sending g code

This is the last one I did 3 d model
The rough take 0.055
The finished take 0.02
When I change the bit from end milk to ball nose the zero not exact so the ball nose hit the edge of one side
I think this what caused the line on the top because I see strong hit after that the line appears
Thanks for your help
Can I set the finishing to 0.002
And I have to know exactly the zero

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Hi PhilJohnson
i understand now to calculate every thing in setting ,first of all i see how much the model high, then i sub 0.02 inch for finish then divide by 5 for rough.
my question is if i can reduce the finish setting to 0.002 inch because we do not need to take more from the service.
when I start roughing 5 times down in the surface ,it makes edge 0.25 inch ,when i start finishing, the bit hit the edge many times,I thinks with no adjust and calibrate the cnc will make this line.
I did maintenance to my cnc , I use spray W-40, at the beginning when i use it new problem happened.
the bit go down instead go up when i send my g code.
I wait two days and be fine now.
also I did calibrate to all belts ,and saw many videos .
now I will do many models to test my cnc
thanks for all my friends

now is good , i wait 2 days after use this spray w-40