Im using a custom design machine that uses openbuilds parts. I am using the blackbox 32 controller and fusion 360. I tried to cut a pocket in plywood with a 1/4" bit with the dimensions of 4.04" by 4.04". when i cut it, it measures less than what is desired. I have calibrated the axis using the wizards. Not sure else to do.
Hi Scott, how far off is it? sometimes the actual measurement of the bit is different than the listed diameter. Make sure you don't have any excessive play in the lead screw bearings, the motor couplers or wheels.
did you leave the default stock to leave setting in fusion? it defaults to some non-zero number for all the roughing type operations like pocketing radial stock to leave will leave stock on the sides of the cutter (essentially increasing the width of the cutter) axial stock to leave will leave stock on the end of the cutter (increasing the length of the cutter) you can fine tune a critical cut dimension by adjusting these parameters and recutting since the Blackbox does not do internal cutter compensation.
I was calibrating the x and y with 100mm. as soon as i did it with 500mm, the error was greatly noticeable. i also switched to a vbit instead of an endmill for my testing. I have the numbers dialed in and it is repeatable. I have not recut since changing them, but hopefully soon.
So I revisited this again. I moved Y to 50 inches and it was off a little less than a 1/4". I decided to run the calibration for the complete length and width of the machine. Actually I did a little bit more. I did Y at 2500mm and X at 1250mm. I recommend this tape measure as it helped me do this as my biggest metric ruler only went to 500mm. Komelon Self Lock Evolution 26-ft Auto Lock Tape Measure in the Tape Measures department at Lowes.com So now I am running some dry test cuts and may be doing some real cuts tonight!
