I am creating a patio cover and thought it would look extra fancy if I made the rafter ends look like corbels. I created what I wanted and have 20 to cut. At random, I have had the CNC just cut in a line, not according to the design. I have been restarting the CNC and laptop and sometimes it works and sometimes not. Ideas of what I can do? 12 worked perfect. 4 could be fixed with a little surgery. Just need a few more to work.
Ideal if I could attach my file here for others to view?
The file would definitely help. Along with some pictures of what’s happening. Also what material, how it’s being secured/clamped, and which machine you’re using.
It could be that the machine is losing steps, which is usually from cutting too aggressively, or some kind of obstruction in the axis movement.
Construction lumber (especially from the big box stores) can be higher in moister content and have significant internal stress. The moister can make chip clearing more difficult and lead to binding. I would be conservative with depth of cut and not do any slotting as this could easily lead to the loss of steps if the stresses in the wood try to grab the bit. This is why table saws have riving knives or splitters to prevent the wood pinching the blade and causing kickback.
As stated seeing the file will help or maybe a picture of the random cuts. Aside from what everyone else said, it could be possible your retract height is set to low and the random cuts you’re seeing are from the rapid movements.
The wood is 2x6x10 pressure treated wood. Some were “dry” and some were wet.
Based on the recommendations, I lowered my cut (using a .25 end mills with 3 flutes) to .05 and slowed the speed to 70. The Shapeoko 4 XXL started cutting in about an inch lower than it should have, so I stopped it. I am just going to have a fake showcase of 4 rafter tails with a cut from an arm saw like I did it on purpose to be fancy. We will see if anyone calls me out on it.
Thank you for all the feedback.
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