@CoalWaterFarms I do not yet have a recipe dialed in, but I have learned lots that I am happy to pass along. After 20+ experiments, I finally learned I cannot outsmart CC with a tapered ball nose masquerading as a v-bit! After reading another thread on offsetting for the tip radius impacting CC’s z height calculation, I thought I could make it work. Unfortunately, the only way I got it to work was with a pretty big gap under the inlay, which won’t work for end grain cutting boards. I switched to a real v-bit (Whitesides SC50, 11degree.) I have only run few experiments with that bit playing with “glue” gap–more on that later. Only one was successful and another nearly so. Unfortunately, I have not had time to do more…storms took down a bunch of limbs so my free time has been cleaning the yard the last several weekends.
Here is what I 've learned so far (some duplicate above, lots of useful advice in the response, these are the ones that come to mind now sitting at the keyboard):
- Use a real v bit, tapered ball nose is not close enough.
- Use MDF until you get close to a recipe, it is cheaper and easier to work with
- Small tests are quicker and easier. I started doing the pocket and the inlays on the same 4"x4", bandsawed everything apart, and glued it up.
- wiggle the inlay to see if there is movement. If so, save some time and heart ache–its not going to work, no need to wait a glue up cycle.
- Always flatten pocket and inlay first.
- a 0.0"/0.11" pocket and 0.06"/0.14" inlay (start/max) worked, but I think will be too shallow for durability on cutting board. (that gives a 0.05" glue gap and 0.08" above the board so I can see clearly when it bottoms out/will be a bad fit)
- a 0.0"/.2" pocket and 0.15"/0.23" inlay almost works. (This gives the same 0.05" gap under the inlay and 0.08" gap between the pocket board and the inlay board above the top surface.) Since this is the amount of inlay I would like in the board, I need to figure out why there is still a noticeable (but close!) gap around the inlay.
- Ensure inlay does not go over 0.25" – I almost always had tear out so it won’t mater if it is gapless around most of the inlay when a chunk is missing.
- I either use a shallow inlay gcode (I duplicate the design leaving all the paths the same but adjust the start depth to 0 and the max depth to the start depth of the desired value above) or raise the z0 to +0.125", run the inlay, move z0 -0.125" (to be at material surface), and re-reun inlay. CC plunges to the start depth on the inlay and does not ramp in. The 1/8" upcut, while not optimal with a surprise 2xDOC, can handle it, but plugging the v bit almost a quarter inch into the wood is not good.
Problem areas:
- face grain hardwood and MDF are way to fragile for small inlays. The tear out is horrible
- face grain hardwood and MDF are can be marginal on smallish inlays
- face grain hardwood can be unpredictable on sharp corners of pockets with tear out
- I only did one end grain experiment early on (too much time invested in making the boards kept me from retrying until I have a better recipe) seemed to help with the tear out, but it was a fair bit of work to clean the fuzzies with an razor
I am not sure how the YouTubers make end grain cutting boards look so easy! This has been pretty frustrating. I’ve done many of epoxy inlays that look beautiful, but wood inlays continues to allude me.
OK, “glue” gap comment made in most of the how-tos bothers me. I would not tolerate a 50 thou much less 100 thou ‘gap’ at a glue seam. Glue gap seems like a misnomer. Glue, for any other joint, would squeeze into the wood fiber and out of the joint. It does not need a ‘gap.’ PVA wood glues are not gap filling glues. So what’s going on here? I would think it is about tolerances BUT I am holding +/- half a thou on depth for both pockets and inlays. A 2 thou gap for 3D alignment would be reasonable. a 50 thou or 100 thou “glue” gap? That seems unreasonable. There is something about the geometry and process I am not understanding nor able to replicate yet…other than one shallow inlay out of about 30 attempts. Subtracting the tapered ball nose runs, which apparently were never going to work, 1 of 8 worked.
In spite of the frustration, I will get back in the shop and figure out a recipe that is reliable and repeatable! I Hopefully that helps in your v carve inlay journey.