CNC: Leveling an End Grain Cutting Board
George VondriskaPeople love end grain cutting boards. They’re exceptionally beautiful, and because they’re end grain not long grain, they’re very durable and last a long time. However, the same features that make an end grain cutting board durable also make them difficult to level after the final glue-up. A planer might seem like a good solution for this problem, but you shouldn’t run end grain cutting boards through a planer. A CNC router provides a great solution for this problem.
Set up the cut
Using CAD/CAM software like VCarve Pro, create a Pocket Toolpath. Use a light depth of cut, 1/16” works well. In the software, create a rectangle that’s slightly larger than your cutting board. Be sure to ramp the toolpath, 4” works great, so the bit eases into the work.
Secure the board
The entire cutting board surface will be milled, so you can’t use hold down clamps directly on the board. Instead use hold down clamps to secure scrap to your spoilboard, then slide wedges between the scrap and the cutting board to lock it in place. Make sure this arrangement is below the surface of the cutting board so it doesn’t interfere with leveling.
The bit
Any flat-bottomed router bit can be used for this but, like fly cutting your spoilboard, it’ll go faster with a large diameter bit like the cutter used in the video.
Multiple passes
Run the toolpath and see what you get. If, after running the toolpath once, the surface is still irregular, simply rezero the Z axis (don’t change the X and Y origin) and run the toolpath again. Rinse and repeat until the surface is cleaned up. Flip the board over, rezero the Z and do the same thing to the other side.
Is there a way to start the cycle with a perimeter climb cut so you don’t get the splintering?
Hello Mike,
Yep, in VCarve Pro you can choose to climb cut or conventional cut.
Sincerely,
George
What speeds and feeds are you using? I have tried slowing down my speed and feed. Rate with mixed results. I wonder if I shouldn’t increase the speed but keep a lower feed rate as well as shallower depth of cut?
Similar to using a router a large diameter bit in the CNC should be run at a lower rpm. I generally run a large bit around 12K rpm. Feed rate varies with material, but on an end grain board I’d do around 80 ipm and a 1/16” or less depth of cut.
The G Wizard is a great resource for dialing in feeds and speeds based on bit and material being cut https://www.cnccookbook.com/g-wizard-feeds-speeds-calculator-mill/
Paul
I tried this using a 3/4″ mortising bit in my router (with a router sled-I don’t have a CNC) with a bad result. I just got a 1-1/8″ surfacing bit, and tried it out, with a similar (but worse) result. In both cases, I’m left with an uneven surface with grooves and tearing that is a real pain to sand out (I don’t have a drum sander). I’m using curly maple, cherry, purple heard and walnut. On my initial pass, I’m going from left to right, and then I come back across from right to left. I’m cutting about 1/32″ deep, and taking off about 1/2″-3/4″ per pass. Do I need a different router bit?
Hello Craig,
Thank you for contacting us.
If you’re using a bit that’s specifically a surfacing bit the router bit shouldn’t be the issue. Unless, for some reason, it’s already dull. Tearing can be a symptom of a dull bit. You’d probably also get burning if the bit was dull, especially with maple and purple heart in the mix. If you end up questioning your router bit, this one is a great one http://amzn.to/2vrHtBU
Make sure the cutting board is secure before you rout it. If it has the opportunity to move, especially lift, that can cause an uneven surface.
Grooves could be caused by your router spindle not being perfectly perpendicular to the surface. This causes one side of the bit to cut deeper than the other. If you have this symptom you need to tweak your sled to make sure the cutting plane of the router bit is perfectly parallel to the plane of the board you’re cutting.
You can try lowering the rpm you’re running the bit at, and slowing down the rate you’re moving across the board. Tearout can come from moving too quickly across the work surface.
Sincerely,
Sarah
Woodworkers Guild of America Video Membership
Why not change your tool path to do a 1/4 inch perimeter pass in a climb cut (clockwise) path? This would eliminate any tear-out. Then switch to your back and forth field levelling passes.
Hello Robert,
Here’s what the experts had to say about your question:
Yep, that could help with the tear out.
Sincerely,
Sarah
Wood Workers Guild of America Video Membership
Why is this better than running through a planer? I don’t have a CNC machine. Would a router sled accomplish the same thing?
Hello Greg,
Here’s what the experts had to say about your question:
It’s dangerous to run end grain through a planer. It can destroy the piece, and cause dangerous kickback. Yes, a router sled would work as well.
Sincerely,
Paul
Wood Workers Guild of America Expert
Noticing the tear out at the end why wouldn’t there be a sacrificial strip placed against the sides?
Hello Gordon,
Here’s what the experts had to say about your question:
It’s easy enough to sand it out on this project, but if you want to use a sacrificial board that would help eliminate it as well.
Sincerely,
Paul
Wood Workers Guild of America Expert