Tips for long cut times

I’m currently working on a project that will have about 10 hours of run time. About 7 hours of that will be with a 1/8” bit and 3 hours with a 1/16” bit. I will be cutting out of maple and cherry. I can’t go bigger because I will loose to much detail. My question is what are some good practices for long cut times. I’m still fairly new to this and don’t want to cause premature ware and tear if I can avoid it. Thank for you feed back.

one of the tricks, depending on the design, can be to build your own roughing pass with a 1/4" bit that takes big pieces away while leaving the fine detail to the smaller bits…

(also pay attention to things like retract height and the F&S )

1 Like

example_pocket_contour.c2d (29.3 KB)

is an example C2D file that shows the idea

1 Like

Thanks. Unfortunately add an additional roughing pass doesn’t change the run time. The amount out material removed with a 1/4” bit is very little. I’m am more worried about burning up the drive motors or damaging the router bearings because they get too hot.

I’ve not run a cut that long, 3 hours is my longest.
I would suggest making somewhat smaller segments, it makes the human side a bit easier
(you can take a break/etc/etc at defined points, or even restart a path)

How do you set up segments. I thought I knew but I have no clue. Thanks for your help.

Do you mean tiling? Please see:

sorry my question wasn’t asked very well. I didn’t mean tiling. What I was wondering is there a way to breakup a long cut into shorter cuts. Say taking my 7 hour cut and breaking them up into 3 equal segments.

Export multiple G-Code files as one would for a manual tool change?

Or, hand-edit the G-Code:

  • open up the G-Code file in a text editor
  • identify the preamble and copy it — see G-Code for the details of the codes
  • divide the file into multiple sections based on where you find a move down from safety height
  • paste in the preamble at the beginning of each section, do the same at the end for the post-amble
  • save each under a new sequential name

Thank you for taking the time to help. I will give it a try.

You may also want to invest in a BATTERY BACKUP !!

1 Like

It’s a long cut, but “burning up bearings and drive motors” isn’t likely to be a problem from what I’ve seen others do.

Some tips that might help;
Try running a roughing pass wtih a tapered round endmill or a ¼ round endmill. This may het more fo of the “overburden” out of the way for the smallers cuts.
I’d look closely at your speed/feed and stepover. If the stepover is too small, it have multiple your time by multiple x, but with little gain.
Be aware that a ball mill has some very specfic uses, I don’t know what you are doing here, but if you aren’t taking a very deep DOC with one, it won’t clear much material at all (and will wear out the tip rapidly).
I’d try roughing with a ¼" square endmill with a .125 stepover and see what that looks like, then do it with a .25" stepver and see if one or the other has more impact. - both shoul dbe able to run at much higher speed than the ⅛" endmill and clear out things rapidly.

Might help to have a picture here of roughly what this geometry looks like to get some better ideas of strategies that might be helpful. We’re pretty much poking at the dark here.

1 Like

These are both about 5"x5". They where both around 4-5 hours of cut time. I am doing a bigger one that will have that 10 hour cut time. Even adding a 1/4" roughing pass doesn’t seem to reduce the time. Seems to just spread it out over several tool changes. My current feeds and speeds are as follows:

Total depth from highest to lowest is 5/8"

1/8" end mill square
SO: .063
FR: 60RPM: 18000
PL: 15
STL: .01509

1/16" BN
SO: .0063
FR: 60RPM: 18000
PL: 15

I am happy with these settings. I find much deeper and faster I end up having to do a lot more sanding than I want to. The next piece will be my big cut at 10 hrs. That piece will be 6"x13". Even adding in a 1/4 pass it’s still at 10hrs. 2 roughing passes at 4 hrs.finishing pass at 5.8 hrs.

Thank you for taking the time to reply. I will play around with the setting more and see what I end up with.


I like the snow tops… cool idea!

I’ve done 5x5 inch landscape carving (Red Pin Terrain carve) and the cut time was maybe 2 hours…
(I used a 1/4" roughing pass, then a 1/8th" single pass and then a 1mm tapered endmill finishing pass)

“take a break” - You have a CNC. Take all the breaks you want lol. I’d set that and see it in the morning for sure.

Unfortunately, on a belt-drive system with no limit switches, and no sensors for detecting if an endmill has broken or come loose, leaving the machine running unattended is a recipe for a potential disaster, and is specifically disallowed:


One thing I have done to address the unattended issue is to install a small camera on the Shapeoko. Then if I do leave the shop to do something elsewhere in the house I keep the video and sound playing on my phone so I can be aware of what is happening.

I used a Nest cam because we have others around the house. But any cam you can connect to with a phone app would work, and I would say sound is important so you can be aware without constantly watching the video feed.

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.