I have 4 frames that I cut out of 8mm poplar plywood with a Sculpfun S9 on Honeycomb with Air Assist. I want to glue 12 of those plywood frames of the same size on top of each other. The radiuses are the same on all four corners, both the inner and outer radius. I can duplicate and mirror each frame and the radiuses will align, yet when I cut them out, out of the 8 possible ways to align the frames (four corners on either the front or the back side) only one will fit. Either the radiuses do not fit or the outer edges do not align.
Is that related to the bending of the wood? I do not follow a straight rule of cutting concavely or convexly. Most of the boards have some slight bending, some are straight but I am still confused why one of the 8 alignments fits basically perfectly and the others do not.
Come to think of it, it cannot really be a bending issue becaus the “grooves” inside are not symmetrical on the y axis, so four ways of aligning are already ruled out by the grooves not fitting on top of each other. Also, sometimes the concave and the convex version are the one that fits.
I hope that was not too confusing. Anyone have any insight?
Unless the boards are absolutely flat during the actual burn, the dimensions of the burn will be off. Additionally, the angle at which the cut is happening is not perpendicular to the flat portion of the material.
The cut made by the laser itself is not going to be perfectly vertical. Depending on the material, the entry side will not be the same size as the exit side. For wood, the entry side is typically a wider cut than the exit side. You can test for this by putting a square up against the side of the cut. Or if you put two pieces next to each other on a flat surface you’ll see at gap at the top or bottom of the edge.
This is based on the assumption that your laser itself is setup correctly. It’s also possible that your laser is not burning dimensionally accurate parts. Run a square test to determine squareness and dimensional accuracy to the design.
It’s also possible that your laser head is not tram to the frame. This could cause your cuts to be made at an angle. This seems less likely without further investigation.
I’d suggest running a test burn on known flat materials that are easy to cut. Perhaps cardstock or cardboard. This will eliminate material flatness from the equation.
Thank you for your feedback. I will try to run some cardboard tests later. I am done with the cutting part already and need to do some sanding and waxing or such first. The result was good overall but I never understood this subtle symmetry issue.
