Question of the day:
Why??
I ran this fairly basic sign, just larger than I’ve done. I even slowed the feed rates down. See the pic below on my question. Just curious if anyone has any thoughts. I’m going to run the whole project a fraction of a mm deeper to see if that cleans it up. Else…sanding.
But I have the admit, the tall text looks pretty cool!
Usually this can be resolved by adjusting the Depth per Pass in terms of the Max Depth so that the ultimate pass removes only a very thin thickness, so if for example cutting 0.5" deep w/ a Depth per Pass of 0.125", making 4 full-depth passes, if one instead reduces the Depth per Pass to 0.124", then 5 passes will be made, w/ the last removing only 0.004" of thickness and functioning effectively as a finishing pass.
Essentially, what happens is that you run too large a DOC, and the end Mill pushes the wood. Then the wood springs back up, and now the bottom surface is at a different vertical location.
You can fix it by running a tool path like this.
Rough Pass. .25 EM 0.00" to .22" deep
Finish Pass .25 EM start at .22 finish at .25".
Essentially, you run a finish toolpath with a very shallow DOC, which will eliminate this problem. Unfortunately, the nature of wood is that it will move on you, versus steel or Aluminum.
Excellent. That’s great info, sir! Running that last final pass right now.
That makes perfect sense. This is a 2’ x 3’ HDU sign. And I can easily see this being the reason for the problem.
I wish there was a way to give multiple people the “Solution” nod. Both you and @SDGuy gave me great info that helped me solve the problem. 
I believe the explanation @SDGuy offered was better than my bare technical approach, so feel the assignment appropriate.
@SirGariff There is an additional reason I choose to do a “Roughing Pass” and a “Finishing Path”. When I am carving with a Bowl Bit, I will use a .375 step over for the Roughing pass.
IE.
Roughing Pass .75 diameter bowl bit, DOC. .125, Stepover. .375, Start at 00. finish at .48.
Finishing path, .75 Bowl Bit, DOC .125, Stepover .125" Start .48 finish .5"
I have found that reducing the stepover on the finishing path means less finish sanding is required.
I want the machine to do as much of the work as possible so I can focus on other tasks.
Great advice. I also learned that when going to fast (1 pass instead of having additional finishing pass) if there is thin material left in areas, it gets ripped out and leaves gouges in the HDU.
The more you know!
