Hi all, I have read several methods of setting toolpaths to flatten an epoxy inlay. I was wondering if the following would work.
This is based on a .75 inch stock thickness and leaving the inlay. 050 proud.
Set my zero to the top of the inlay. Set a pocket tool path to the top of the stock and my depth of cut to T+ .050.
Also, any suggestions on bit, feeds, speeds, rpm, and plunge rate?
Are you absolutely sure the epoxy is exactly 0.050" proud?
I usually work in metric, so that’s how I’ll write this example.
I would zero off the top-of-stock to begin with, then change that Z Zero to be a known amount higher, then pocket down that much. You then have a more accurate pocket depth so you end up right at the top-of-stock.
Now your Z Zero is exactly 1mm above the stock. Create a pocket with a depth of 1mm, and it should reach to exactly the top of stock.
I meant set the depth to T+ .80 to leave .050 of the inlay for final sanding
There are many ways to remove the overfill epoxy. I would never suggest a planner. It is quite violent and most planner knives do not like epoxy. I have several pieces pulled out by the planner. I have a Jet 16" drum sander. I start running the epoxy through the sander until it just touches the epoxy and re run it through one more time to get the whole top leveled out. Then I turn the hande about 1/16" of a turn and slowly take the epoxy off. Then I leave just a very thin layer and use a random orbit sander to finish. Good results. I realize not everyone has a drum sander.
If you are going to use a surfacing bit then draw a pocket about .5" larger than the material. Zero on top of the highest point and start surfacing. When you get down to the surface with a very small film stop. You can stop CM or just power off the machine. Then use a random orbit sander to finish. If you fo all the way to the surface you can cut away part of your project. You can sand to 320 or 400 and the epoxy will look dull as dish water. No problem. When you apply a finish it will shine up. Some people think they need to polish the epoxy and it just needs to be smooth. Use either water or oil based finishing. Oils like Watco Danish Oil work as well. If you use Danish oil do not it dry completely before applying subsequent layers. Once Danish Oil cures the new coats of finish do not stick as well because a hardening occurs. I like to use dewaxed shellac (Zinsser Universal Sanding Sealer because it gets absorbed in and takes less layers of finish. Shellac is compatible with both water and oil finishes. Plus the shellac gives a nice warm appearance. If you dont like the warm appearance use a water based sealer. However water based products tend to raise the grain and you must pre raise the grain or sand off the surface before finishing.
“T” is the material thickness from the setup page. So T + 0.050 would be 0.800, and T + 0.800 would be 1.550. I don’t think you want either of those. You want your depth to be about 0.050.
Touch off the top of the wood where there is no inlay. Type in a Z value of -0.050 (or -0.051).
Program your path to do 0.050" deep. This way, even if the inlay is not exactly 0.050 the path will stop 0.001 above the stock.
Thanks for taking the time to answer. I will try your suggestion.
Just for learning purposes, I can see I mixed up the T+ and T-. Given a material thickness of .750, would T- .760 leave a .010 margin at the top?
T - 0.760 = -0.010. I don’t think it will let you enter a negative number.
If you want a depth of 0.010, just enter 0.010. The “T” is not useful in this situation.
I do a lot of epoxy inlays. I just use my handheld belt sander using 60 grit and then 80, 120 and finish with 220. Epoxy polishes up nicely.
My vote goes to the guy who does this a lot.