I setup a test cut for a memory box top with raised lettering in a different material from the main lid. Shown is scrap cedar i glued to scrap alder. The cut worked out for the most part but i see the same problem ive come across before. Different cut depths between the tools.
1st clearing tool was 1 1/4 end mill
2nd clearing tool was 1/8" end mill
Final 60 degree V
The 1 1/4" is clearly lower that the others or the others are higher.
Job is center datum, used probe on all tool changes and even made sure no burrs or anything affecting heights. Any ideas what may be causing this?
That is strange… You seem to have a bit of a tramming issue that might account for some of the error which you can see where the passes of the large bit overlap:
I don’t think this fully accounts for a .031" difference but could be contributory to it. Did you flatten your waste board and if you did do you have similar ridges in it?
Just curious, was this ever resolved? I’m having the same issue. I will run a pocket with clearance paths created in Vectric Pro 12.5 and the last bit will run a perimeter that is deeper than the rest of the paths, creating a mote in the inside edge of the pocket. I too use the probe the set the Z zero level in the same location on a section that didn’t get cut by any prior paths and I make sure that there are no burrs, splinters, dust, debris, or any other disturbances during the probing. I have yet to figure out what causes this.
The clearance tool leaves an allowance like an island so it doesn’t run into the raised letters. Try adding a second clearance toolpath with a 1/8" bit, it will cut closer the letters and may blend in the elevation difference. Years ago someone posted a video on this issue, but I can’t remember who but they described this effect.
I have not since resolved it. That being said i have focused on allot of laser work as that seems to be paying well right now. I do plan to carve a tonne of other projects that will force me to revisit. I also wish someone out there had the answer lol
This is just my opinion… and I’m sure others will disagree… in some cases strongly.
I have had similar issues, albeit not quite as severe as yours based on the pictures you provided. The guidance offered was similar to what you are receiving: tramming, bit / collet issues, tool setter issues, machine leveling etc. I have thoroughly checked / addressed all of those issues and still have not been able to completely eliminate it. I don’t know what you are using for a router, but I have an ATC spindle (heavy) and have come to the conclusion that the 1F is not rigid enough for it. Even with the 50mm rails and stiffy rail, I can grab the top and bottom of the spindle and with very light pressure see visible ‘twisting’ or ‘racking’ of the Z carriage / X axis assembly, especially when it’s out in the center of the span (48" machine). Up / down cut bits will exert the opposing force on the router / spindle, and I believe this is partially the cause of this issue. Also, I occasionally get toolmarks on the bottom of the pocket where the Z axis drops and has the sudden stop at its designated cut depth. The weight of that spindle suddenly stopping is slightly flexing the rails.
Again, you may have something else going on based on the severity seen in the pics… but I would look to a simple lack of rigidity in the machine.
As further evidence, I cannot flatten my spoil board without an approximately .005 dip in the center. Again, I have painstakingly leveled (and trammed) the machine, including diagonally across the Y axis in both directions… it is perfect. Yet I consistently get this .005 ‘dish’ in the center with the outer perimeter all the way around the ‘dish’ being perfect. The only possible explanation I can see for this after eliminating all other factors, is that the spindle sags slightly in the center of the spans due to the lack of rigidity of the machine. I realize that in woodworking .005 is not much, but it can affect cut depth based on the size and positioning of the workpiece on the spoil board. It gets me every time on profile cutouts. I have to cut that .005 deeper in the center of the spoil board or else I’m left with a hefty onion skin. If I set z-zero off the center to account for it, then I’m cutting .005 into my spoil board on the outer perimeters. Again, this is workpiece-size dependent, obviously not really an issue on smaller pieces.
I know this probably wasn’t very helpful, but just my way of saying maybe… at least some of the issue… is that the machine is not as rigid as we would like to think it is.
