Shapeoko 5 Pro Spoilboard surfacing time with McFly

I have a brand new Shapeoko 5 Pro (4x4) and I am very new to the world of CNC. I ran a bad job and put a pretty sizable cut into my spoil board. I figured now is a good time to surface the spoilboard for the first time. I purchased the McFly bit from Carbide3D and was planning on doing the job today but after seeing the estimated cut time of over 8 hours decided to double check with the forums.

My Carbide Create setup:

  • Set the stock material to 48x49,
  • Drew a slightly bigger rectangle then the stock (49.5x49.75) and centered it.
  • Created a pocket tool path and chose the McFly bit with the default speeds and feeds (.5 stepover, 0.020 depth per pass, 12.0 plunge rate, 75 feed rate, 18000 RPM)
  • Set the depth of the cut for the pocket to .1015 (the depth of my mistake).

Am I doing something wrong or should I expect to have to endure a 323 minute cut job every time I need to surface the spoil board? Curious if anyone else has surfaced their spoil boards on a 4x4?

I am planning on upgrading to a 2.2Kw spindle soon, so if the McFly is really going to take this long, I might look at getting a bigger bit from Amana.

If you have never surfaced then it would be good. However after the initial surfacing you will cut the spoilboard/slats away quickly if you surface every time you get a cut on the slats. It is called spoilboard for a reason because it gets spoiled.

To avoid cutting up my spoilboard prematurely I use the bottom of material about 90% of the time. There are cases to use the top but the bottom saves my spoilboard. I replaced my SO3 XXL in October 2022 and it barely has a scratch on it. It is a pain to cut a new one and move over a hundred tee nuts so I just avoid cutting it up if at all possible.

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Unless the area cut into the spoilboard is large, there’s no need to surface all the way to the bottom of it. If for some reason the stock you are using is so small that the cut into the spoilboard affects how it sits, then it’s small enough to just move to another area of the spoilboard.

The real reason to resurface is to ensure the spoilboard is co-planar with the movement of the tooling. I would start with something small (like .02"), and scribble (pencil mark) all over the spoilboard. Run the flattening pass, and if there are still scribbles, drop .02" a time until they are gone.

Also, the speeds from CC are quite conservative. You can increase the speed in CM up to 200%, that would get you to 150 IPM. When I’m resurfacing, I usually start at 100IPM and increase in CM, sometime all the way to 200IPM.

Simulating .02 I get a cut time of 64 minutes. I will give it a try and see if going to 200% in CM works out. Thanks for the suggestion.

I don’t have the Mcfly specifically, but a similar 1.25" endmill for surfacing wood. I run it at 275 ipm, 18krpm, 1" stepover. It takes about 9 minutes to surface. Surfacing the mdf you can run it at max speed and it won’t even blink.

I should probably say, I have the 1.2kw spindle, but I imagine the makita/dewalt router could handle that as well.

To estimate this, round up to 50 x 50. At 0.5 stepover your tool would have to make 101 passes to lace/zigzag cut that area. 100 x 50 is 5000" to travel.5000" / 75 IPM = ~66 minutes.
So at 150 ipm it would be 33 minutes.

0.1" seems like a lot to remove. I usually do 0.005 - 0.010 at a time. I set my depth of cut to 0.0001, and it outputs Z0.000. Then I just set my Z zero to wherever I want it to cut. i.e. If I want to remove 0.010" I move the tool down to touch the material and type in 0.010 in the Z box on the Set Zero page.
THen if I need to take 0.010 more, after it cuts it move up & to the back. I open the set zero page, and whatever the Z value is, I add 0.010 to it & enter that. i.e If it’s at 4.284, I change the 8 to 9 & enter.
Then run the path again.

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Through cuts are often necessary. But if you can, leave half the thickness (give or take) then remove the piece and use a flush trim bit on a handheld router or router table to finish the edge. This saves a lot of cnc time, keeps your spoil board intact, and provides terrific results.

NEVER use a bearing bit on your cnc.


That’s quite a bit of thickness to remove — my inclination would be to source some MDF and make a replacement filler strip using the pulled one as a template — that will remove the need to convert so much good material into sawdust.

Thanks all, I ended up doing 3 passes at .005 at 200% feed. Each pass took about 35 minutes.

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