Hi all, I have a weird problem. I'm trying to match 3d printing and CNC. A plastic part is supposed to fit into a pocket I want to CNC in wood. Printer is well calibrated an the piece has the expected dimensions, however the pocket on the CNC is too small. Here's what I already checked: 1.) steps/mm. These are fine. If I move y 1m, it moves 1m. I validated this with all axes (smaller distances for X and Z of course) 2.) Bit dimensions. Dimensions are measured and correctly entered in the tool configuration. 3.) I'm using the same sketch to model both, the pocket as well as the piece I want to insert. I expect this to be very tight, but the outcome is not only tight, it's off 4.) I modelled a simple 20x50mm pocket and it came out too small as well (17,75x48,55) 5.) I don't seem to be losing any steps as all layers are exactly on top of each other if I do depth cuts in multiple steps. 6.) I doubt it's related to any slack in the lead screws as the results can be reproduced and are independent of speed and depth of cut. Also walls for multi step cuts are absolutely consistent. I doubt that this would be the case if I had mechanical issues. Now I'm a bit out of ideas what else I could try and where this might come from. I'm using Fusion 360 to model and cam, the openbuilds provided post processor to generate the gcode and openbuilds control to drive the machine. Any ideas? Thanks, Richard
Did you check that you didn't tick the "stock to leave" box in Fusion cam? I've made this mistake before because I have to scroll down to see it. Alex.
Hi Alex, this was it. Many thanks. Totally overlooked this option in CAM. After trying around with it I made use of it to make the two pieces fit and work around the tolerances. Actually needed some negative "stock to leave". Guess I learned something today See the attached images for the small success. Never mind the cracked plastic piece. Still work in progress. I guess I'm following an iterative approach Thanks again, Richard
