Why am I getting these “dogbone” corners in this inlay attempt? Other practice runs did not have this. File attached, using the bits in the file. This for an inlay on a guitar neck.
Also: even though is it set up with the 1/8" end mill, the cut doesn’t use it, even though the degign is just over .125" wide.
The reason the 1/8" bit isn’t being used is because at the bottom of the cut, there are no areas that are wide enough for it.
The little dogbone corners are a bit of a mystery though.
There also appears to be a bug in either the toolpath generation or the simulation. Why are these corners round?
The design has square corners:
CC Pro 776, Windows 10.
The attached picture is the very first attempt at an inlay and it was perfect. Every other practice run has been different and not perfect. The bit is correct, unless the library has incorrect information. This is getting frustrating. The discrepancies in the software simulation is puzzling too.
The board is flat. It was milled on the jointer before I started the cut.
Was the successful run on a different version of CC than the others?
Typical reasons an attempt at cutting will be different from the 3D preview:
The great thing about CNC is that given a properly prepared file, a machine setup which matches the file, and nothing going wrong in the cutting, a part will be made correctly.
The awful thing about CNC is that a part will only be made correctly if the file is prepared properly, the machine set up to match the file, and nothing goes wrong in the cutting.
How did you secure your stock? Set zero relative to it? Manage all tool changes?
On my simulation of your file, the depth of cut is not 0.160 as defined (it seems to be cutting only ~0.06 inch deep). This goes away and the depth of cut reaches 0.160 inch ( and the inside corners become sharp) when I select my own 30 degree v bit. I suspect this is due to an oddly defined 30 degree bit in your library or this is a software artifact when I download a file with a custom bit not defined in my library. If the former is the issue, it may be corrected by redefining the bit, if the latter is the issue, I am of no help.
Edit: I have not reproduced dogbones in a v carve by too shallow of a cut. I can reproduce dogbones by using a bit of a smaller angle than what the toolpath was made for ( ie , use a 30 degree bit when the tool path was made for a 60).
Does your simulation look the same as the one Michael posted? If not, please post a pic of yours. Also post the 30 degree tool geometry (found in the Tool Database).
The most likely culprit is the Z-axis not being set to the correct height.
2nd option is the Tool Database error. Maybe the Tool is set up with a .25 diameter in the Database, but it’s bigger.
I am finding this very odd. When I download and open the file in CC757, the simulation does not match the tool path. The simulation is too shallow. If I replace the v tool with my own tool, the simulation matches the toolpath. I can fiddle with tool geometries, but I am still unable to force the simulation to not match the toolpath (the behavior of the file as downloaded). Is anyone else seeing this? I feel like I am missing something obvious. Here is my file where I have added a small rectangle, the toolpath generated for the small rectangle for my 30 degree bit.
0 ECM F Inlay TEM_bozod.c2d (56 KB)
Which versions have you tried?
Have you tried the current stable 774?
Here’s a link to the latest version 774
and just in case here’s carbide motions latest version 636
I’m downloading it right now. Thank you.
I just downloaded it a few hours ago.
On the simulation screen, it would seem to get hung up to the point that it didn’t show one of the vectors and I just closed the animation. It would also not load the simulation on the previous version that I was using, I thought it was the computer and not the file so I didn’t think to try another one. When I saved the male inlay in the new CC version I ran the simulation and it ran fine.
I wonder if it’s something with the actual vector file that’s causing this issue?
Is there a way to bypass the animation and just see the final result? I only had a few minutes to mess around with it so far.
Nope, but it defaults to the fastest setting, so it should be pretty close to the old simulation where you had to wait for it to generate. Just now you can see it.
Will, I can not tell for sure on this phone and the angle of the simulation on your version but it looks like the inside corners are round. That does not seem right.
Here’s a picture I went back and found from the first/“perfect” one. Even the corners are rounded on that one. Once glued and sanded, it appears to disappear. Maybe I’m being too picky or expecting too much, but I feel the machine and 30v bit should be crisper in a corner.
Will,
Here is a png of the simulation with my 30 degree v on CC757: Note the increase in width of the carve, the increase in depth, and the sharp inside corners compared to yours with CC774 . Other than selecting my bit, I did not modify the downloaded file.
My tool geometry :
Diameter: 0.125 in
Flute length: 0.500 in
Included angle: 30.0
Num flutes: 2
And here is an image of the original downloaded file’s toolpath only (no simulation). This tool path is identical to the path generated with my 30 degree v bit.
The original posted file with the original tool behaves as if the toolpath is just raised up by 0.100 inches above the surface of the stock. The depth of cut can be approximated by incrementally reducing the thickness of the stock /viewing the simulation until cut through occurs.
I have checked the two resulting Gcode files and they are identical except feedrate (when DOC for my bit is updated to 0.005). The difference seen in the simulations only exists in the simulations. The original post and the file with my 30 degree bit will cut exactly the same.
Dogbones and rounded inside corners will result when the true bit angle is less than the angle of the bit defined in CC. Rounded inside corners ( but no dogbones) will occur when zero is set above the stock. See the next pic. All toolpaths were for a 60 degree v bit defined in CC.
