How can I do this better?

Hey guys. Haven’t posted in a while (which is a good thing, things have been running well!)

Working on these 3d plaques which I will be making a lot more of. Basically I’m making these pockets around letters which are following the contour of the top of the project (the bottom of the pocket is not flat). I’m getting left with a lot of slop on the bottom of these pockets (see image). Using a .25 downcut EM with a 40% step over. This is resulting in a TON of hand sanding time to try to clean this up and the results after this still aren’t great.

Any ideas? Couple thoughts on my end:
Reduce stepover
Have the final pass reduce like .002" of material
Try a ballnose bit
Possibly in need of calibrating the machine better?
Blade is possibly dull? But even on a new blade I get this

Also this image is after a good amount of sanding.

Worst case I can try to cut just the pocket and add the letters later but it would not be preffered

Thank you!


Second image

An upcut endmill should give a much cleaner bottom (at the expense of fuzzier top edges) I think

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Cut to 1/16" from your desired depth with the downcut bit. For a roughing pass, I like to use a 67% stepover. Switch to an upcut bit at a 20% stepover for the last bit.

You’re getting a lot of deflection in the inside corners of your cut, and the bit is being pulled into the material (bottom corner of the inside of the P, inside corners of the T, top corner of the inside of the D). You could reduce that by doing a roughing path 1/16" offset from the final lines, then running a finishing pass for the last bit. I did a little example here that explains a little better. (I think)

If the bottom of your pocket is curved to follow the curve of the top surface, you’re going to need to use a ballnose to get that curved surface, otherwise the flat endmill will leave ridges no matter what you do. What are you doing the design in, Vectric? If so, feel free to send me the design and I’ll set up the toolpaths I would use to do it.


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