Corner problem with pockets


(Tim Cable) #1

I’m seeing a problem in one of the corners of my pockets. In the picture, the top right corners are beyond the pocket size consistently. And, it’s only the top right corner.


(Tim Cable) #2

BTW, this pocket is 2x2 inches square 1.875 inches deep cut into pine. Any help would be appreciated.


(William Adams) #3

Usually this sort of difficulty comes down to some sort of mechanical issue or give:

Also feeds and speeds may be a consideration: https://docs.carbide3d.com/support/#tooling-support and see https://www.precisebits.com/tutorials/calibrating_feeds_n_speeds.htm for a testing technique

Beyond that it’s usually a matter of Calibration and Squaring the Machine c.f., http://docs.carbide3d.com/shapeoko-faq/how-to-calibrate-the-machine-for-belt-stretch/

Leaving a roughing clearance by insetting the pocket by a dimension which is larger than the offset which you’re seeing and then taking a finishing pass is one technique which works for some folks and some projects.


(Neil Ferreri) #4

In addition to what @WillAdams said, the more your bit is sticking out, the more deflection you’re going to have. That will magnify any other issue.


(Stephen Gullage) #5

As your bit moves into the corner and changes direction, the bit is getting pulled in to the material. For a moment, it’s digging in and the rotation of the bit causes a lot more torque on the bit. For cleaner pockets you need to ease your way into corners so the bit isn’t cutting more material in the corners than it is during straight line cuts. To do this, you can cut relief holes near your corners, cut your pockets smaller than you want it to be, then run a finishing pass. I did a little write up here in a previous reply