I’ve been trying to make some wood pieces that interlock with each other (kind of like puzzle pieces, conceptually.) I designed the pieces using Fusion, then setup contour cuts for each piece. There are no corners or sharp changes in direction to cause any issues, but when I cut out the pieces, they do not fit properly. It’s as if the cuts didn’t follow the contour line accurately and didn’t take off enough material.
My first thought was that the bit I was using (1/8" end mill) might not have been truly 1/8". I check the diameter with a caliper and found that the diameter was, in fact, smaller by a few thousandths of an inch, so I compensated for that in the tool file settings for that bit. This did make the cuts somewhat closer to what they should have been, but not enough to allow the pieces to fit together.
I’ve been through all the parameters in Fusion’s toolpath settings, and I believe I have everything set properly.
It seems to me that what I’m trying to do should be a simple basic operation. I would appreciate any thoughts on what I might be doing wrong, or what I can do to make this work.
Whenever I interlock pieces, I need to build in a small gap in between. You can never rely on a 0.5" wide gap to accept a 0.5" panel.
I’m not certain, I think the primary reason is because of tool deflection, and the surface finish that is left after cutting.
The below shows the mating component 0.020" wider. This produces a pretty loose fit. If I wanted a tight “Hammer-it-in” fit, I would shoot for 0.005" wider.
FYI: Fusion has a “stock to leave” option, and if you enter a negative value, it will remove more than in the solid model. You can use this to cheat the toolpath a bit, and make slots a bit wider.
Thank you! That makes a lot of sense. I was unaware that Fusion allowed a negative value for the stock to leave option. This is great info. I’ll try some test cuts and vary the value until I get a good fit.
In another post today someone mentioned using conventional versus climb cutting as well.
If I recall correctly they stated that when you climb cut it tends to push the bit away from the cut line, which seems to be inline with what @MikeXYZ said about deflection in his post.
All that being said, if you’re climb cutting, perhaps try conventional as well as adding some tolerance per @MikeXYZ’suggestion.
I made the comment about a climb cut pushing away from the material. It’s something I learned pre-CNC when working with a router table. Here is a video that demonstrates this on the router table. Why you DON’T do this on Router Tables
