Small (1 inch x 2 inch) soft maple inlays into walnut. Both woods are fairly soft as hardwoods go and are similar in density. I pocket the walnut and contour the maple. They fit snugly, but there are gaps at the top of the clouds, clearly visible in pics, ranging from .08" to .012". I can see light through the gaps. All of the inside curves have a radius greater than my 1/4" bit.
The only thing I can think of is calibrating for belt stretch (which I have not done lately), though I’m not convinced that could be the issue. I’m using the same file - just pocketing on one side of the line and contouring on the other. No offsets.
I feel like I’m missing something obvious. Why the gaps? Ideas?
It’s not a direct answer to your question, but rather a method to patch/correct what you already have.
If you have some sawdust from one of those materials, put CA glue in the gaps and then rub in the saw dust. It will look messy at first, but then sand it back. There are several videos on YouTube showing this.
On the pic it looks like the gaps are mostly along the Y axis? Not sure what to conclude from this though.
Calibrating may help but I suspect it won’t, as you are not after accuracy on absolute dimensions but rather consistency between two cuts of things the same size (i.e. even if calibration was way off, it would be off the same way for the two cuts)
I tend to think it’s tool deflection like Will mentioned, and just being super conservative on depth per pass may fix this.
Will’s suggestion will minimize effects from deflection, but if that doesn’t completely fix the gaps you may need to lie about the size of your end mill; if the remaining problem is a mis-sized mill (or runout) this can correct things.
I was thinking this, too. The gaps are on the Y axis. I would rotate the models 90 degrees and cut with the same sort of strategy as the first time. Then look to see if you’re still having gaps on the Y axis or if the gaps turn along with the model.
Thanks for all of the ideas. I solved the problem so I thought I’d share…
I stated earlier that the inside curves had a radius greater than the 1/4" bit, but this was not accurate. Zooming wayyyy in, I discovered the inside curves had a radius slightly smaller than 1/4". Because of this, the bit didn’t get completely inside the curve, and the radii of the inlays and pockets were therefore different.
I fixed the radii, and then had a perfectly shaped insert, although .003 undersized. I made the inserts bigger with a .003 offset and now they are tight fitting as shown below. Still working on the bowl - I’ll post to the gallery when it’s done.