Finish passes in a pocket


(Kris Van) #1

Trying an idea for a christmas gift, using Fusion 360. Cutting pockets in pine, 1/4 endmill, 17k, 50ipm, .15" stepover, .08" doc, finishing pass .008" with same stepover. Still getting lines like below. Cutting almost 200 of these, like a scrabble board. Is it the pine? Not sure if I can change the stepover on the pocket finishing pass, maybe could rough out the pockets then finish? Tried a half dozen iterations so far, getting better but not sure where to go from here. Thanks!

Kris


(William Adams) #2

Pine tends to compress when cut, then spring back, leaving such marks.

One way to get a finish pass effect for a pocket is to calculate the depth per pass so that the initial passes are at some reasonable depth, then the last is a thin cut.

Another possibility is your spindle isn’t square — ways to address that:


(Kris Van) #3

Hoping it’s just the pine. Pockets in harder wood have been turning out pretty well. I may have to run an really small stepover finish, not a big deal. Thanks for the input Will!


(Phil Thien) #4

The three samples are too consistent for this to be attributed to the wood, imho.

My guess is you’re taking enough off in each pass to cause the bit to pull into the stock.

Reduce th DOC for each or the final pass, is my suggestion.


(Kris Van) #5

That’s a good point Phil. I ended up running a finish pass to clean up the .01" stock I left. Minimal sanding at the end, still one line in the same spot in each pocket. I realized though that I really don’t like pine. It was cheaper for this project and I haven’t made larger panels out individual boards before, but I need to figure it out soon. Have to do some touchups and sanding, but overall happy with the outcome. By far the largest and longest run I’ve done, 24x24", almost 4 hrs run time.


(Phil Thien) #6

You might want to also check your Z-axis pulleys to make sure they’re night and snug, that could absolutely contribute to the type of consistent unevenness you’re seeing.

Check all your pulleys while you’re at it.

Your final panel looks terrific.


(Tito) #7

Scrabble?

Looking good!


(Kris Van) #8

Thanks! Yep, scrabble board. Christmas gift for my parents, will make tiles with their names and all 10 of the grandkids then find some way to fit them all in (hopefully). Planning on walnut for the tiles with the letters engraved then painted.


(Daniel Loughmiller) #9

Make your name worth the 10 points :slight_smile:


(Steve) #10

You should try to keep your stepover to 50% of the tool diameter or under, it will increase your tool life quite a bit. Are you using an upcut endmill.


(Kris Van) #11

Steve, even for roughing passes? I just ran a project last night with almost 100% stepover for roughing but 25% for final pass, looked great. Maybe I just got lucky…


(Steve) #12

Depending on the material. If your cutting wax or foam then 100% is fine. When you get into wood it is better to keep radial engagement 50% or under. The forces of the endmill pulling into or out of the material, depending on upcut or downcut, will be drastically reduced. Its also much better for chip evacuation. If 100% works good for you then go for it. Just dont be surprised if you dull endmills faster or have a lot of deflection.