Lines in 3D Carve

[Juder]

This is the second 3D Carve that I have done with Vcarve Desktop using UGS 2.0.12 that has left lines in the carve. This carve has two lines and the previous carve had one down the middle. The previous 3D carves I have done using Easel to send the gcode, I have had no issues with. The board is clamped tight in the corners. Just wondering if someone might know what this problem could be? I am using a 2mm Tapered Ball Nose at a 10% stepover and Raster angle of 40 degrees. No roughing pass as this is a dish shape and it's not necessary. I'm using just the standard GRBL Gcode post processor as I didn't see one just for UGS. For Easel I am using the Easel post processor. My machine is a Fox Alien 4040XE so I run slow at 30 IPM as this machine isn't as sturdy as a lot of you have. I'm just a retired home hobbyist. Any help would be appreciated! Thanks!

[sharkcutup]

Strategy Setting for the 3D Finish Toolpath - Which Raster or Offset???

Do the lines show in the Simulation Preview???

Sharkcutup

[dealguy11]

This sort of thing is nearly always a problem at the machine. You are losing steps in Z for some reason. All the normal mitigations apply, including making sure everything is properly tightened and lubed.

[SteveNelson46]

Try using a brand new sharp bit and slow the feed and plunge rate down. I don't know what type of wood you are using but you may also need to adjust the spindle speed.

[ZipperHead55]

The only time I gets lines like that are when I pause the machine for an extended period of time (leaving the shop) or if I have cut through all the way on a 3D carve and the wood lifts up as tension is released in the wood. I suspect that the wood is lifting (or lowering) somehow, whether it is as I mentioned (tension being released or the wood lifts due to having no support on the edges). Or, as mentioned, you are losing steps in the z-axis, which could be mechanical (coupler loosening) or electrical (do you have any dust collection running that isn't grounded?).

If the lines shift from project to project, it isn't a software issue, as mentioned (you would see them in the preview).

Allan

[Juder]

The lines do not show in the preview and I had the corners all clamped down really tight. The wood is pine 3/4" 11 3\4 X 10 so I do understand that the wood can still warp during carving so maybe that's it then. No dust collection but I do vacuum occasionally to keep the dust down. Would that create the static they warned about with dust collection? I keep the machine clean and well lubed otherwise. Thank you all so much for all the replies and I will try a new bit and slower speed next time! I will also avoid touching any metal with the vacuum nozzle! Learning every day but having so much fun!!

[ZipperHead55]

I will also avoid touching any metal with the vacuum nozzle! Learning every day but having so much fun!!

I have stopped using my dust collector (small 1HP) for anything except really dusty cuts (MDF especially, and surfacing my spoil board specifically). I use a ShopVac to pick up the dust every once in a while, and I usually put my other hand on the metal frame of my machine (which is grounded) to reduce static discharge. Not sure if it does anything, but I haven't had any really weird issues (that could be explained by static effecting stepper motors, etc), so I continue to do it. The thing you need to watch out for is accidentally getting the nozzle too close to the moving parts (spindle, gantry, etc) which might cause the machine to be bumped/stopped throwing off the toolpath.

I suspect your pine has a high moisture content (maybe not kiln dried?) and the tensions being released are more extreme than with kiln dried wood, or hard woods. I don't do any carving of pine. At all. Where I live, pine was actually more expensive than hardwoods, during the COVID era especially, since there was a HUGE building boom, and construction lumber (pine) prices exploded. I haven't looked lately TBH, but I have avoided pine since my first few projects, since it gums up everything (saw blades, router/CNC bits, etc) and is horrible to finish. If I need to do a test cut, I use scrap wood, or cabinet doors I bought at HabitatForHumanity Restore for $3 or $5 each.

I would recommend doing a half- or quarter-scale cut using a different wood (half the size takes a quarter of the time, and used less material) to see if your machine reacts differently. It's possible your z-axis is missing steps, and this might be amplified by using a harder wood (more resistance).

Allan