Starting position issues between projects


(Ryan) #1

Hello all,

I’ve been working on a couple of similarly structured projects which involve rather simple layouts. One of the projects has a designer layout of 160mm wide X 100mm tall and start position is lower left. Within those bounds, there is a rectangle with an outside toolpath, and some rectangles within using pocketed toolpaths.

Whenever milling this project, I’ve always noticed when setting my zero position and running that the entire job was about 4mm too high on the X axis. This was never an issue as I would cut off and sand the excess wood anyway.

My next project was a cribbage board which required me to flip the piece and mill on the other side. When setting zero for either side, my process was to insert an engraving bit and align the exact point to the 0,0,0 lower left position. When the job was completed however, there was the same 4mm difference and the finished piece was off centered.

In either of the projects, I have triple checked that the shapes are exactly centered. Also, the work pieces I’m cutting are the exact same dimensions as what’s specified in the project settings. Any of the simulations look good and centered.

Yesterday I created a very simple project 50mm square with a 30mm square inside. That inside square had no offset toolpath and I used the engraver bit. After running the job, all of the measurements were exact.

So, I’m wondering what may be wrong with my production projects causing the strange height difference. In the near future I’m planning on cutting without outside waste material so I need an exact zero starting point.

Does anyone know what could be causing this issue? To me it seems like a problem with my Carbide Create projects. FWIW I am running version 366 of Carbide Motion. This is on a Shapeoko 3.

Thanks for any help!

Ryan


(Daniel Loughmiller) #2

Post either a c2d file or screenshot of your CC layout (both would be great)


(Ryan) #3

After more experimentation it turns out the issue was with my piece not being clamped squarely in relation to the CNC.

In order to solve the issue, I created a project which carved out a 1mm deep line with a V-bit directly into my waste-board material at the lowest Y position possible. Now that the line is there, I can use it to square up clamping blocks which are secured with threaded inserts.


(Daniel Loughmiller) #4

Makes sense. I usually put a longer 1/4-20 bolt into my threaded inserts and use those as a stop to align the workpiece. Then I clamp it and remove the positioning bolts.