Hi, so I was noticing some of my flip machining was off by a little and upon stumbling across some of the older posts I did measure and notice my bed was shifted 3/16 from each other across the diagonal measurements. So I readjusted and got them dead nuts to each other.
Upon tightening and re verifying every step I tightened it remained the same measurements to each other. Then I go to set the gantry to the rear to check that both ends hit at the same time, but when I send the gantry to the back the left Y hits first and the right has about the same gap as the front. I have about a 3/32” gap on my left side compared to the right side hitting the front first and just about the same on the rear with the right side.
Am I missing something? I had a theory I could try to loosen the rear belt on that side and and tighten it a little more to create more pressure to counter the motor wheel to offset it forward and hopefully should counter it enough to even it out. What do y’all think?
I figured it was such a minuscule difference because the limit switches usually keep it further from those points as it is anyway but Winston made that part of the setup video seem a little important, but again this is after I had tightened my eccentric nuts I should have put that in the post too. Maybe my loose eccentric nuts caused it to skip. I will look at the post to add to my knowledge. Thank you for the reply Will.
So basically what I think I am reading from the post is to cut a rectangle the full length of the bed on the X axis then leave the start in the corner and flip it to the Y axis and run a same tool path within my limits and it should be exact by verifying with my caliper/other precision tools?
If the machine is in good electro-mechanical condition and you have a sufficiently long caliper which is sufficiently precise/accurate, yes.
Note that this sort of thing can get quite maddeningly tail-chasing — at some point you have to just call it good enough (or figure out how to maintain a spreadsheet which has all the actual movement positions and calculate on that or work up a workflow where one cuts to a rough dimension, then cuts an initial pass which touches all surfaces where dimensions are a concern and measures them, then adjusts a copy of the file based on those measurements and then cut the actual finishing pass).
@LiamN thank you. Wait so do you have to press the gantry to the back during every start up or just the initial one when squaring to the cuts you made for the dowels?
Also at what point should one remove their finger press from the rear once it’s started? After the initial power up clunks are heard or…?
You only need to hold the machine against the reference stops until the stepper motors go clunk, after that the machine is in control, you also should only need one finger in the middle of the X axis, there’s little force required as you’re only asking for a mm or so at whichever end sits forward.
I tend to push mine back against the stops each time I start up, but that’s because I have quite an early machine from before C3D had their big CNC to cut the X gantry ends really clean & square and I never quite got mine shimmed to sit straight on it’s own.
You might be able to get yours to sit square with a little shim stock between the gantry and end plates, you may be surprised how thin that stock can be, aluminium cooking foil folded over a couple of times is frequently enough.
If your machine will sit square resting it should start up square, if not then you’ll need to check if your frame is square enough to push the gantry back into the frame, mine is still not quite good enough, which is why I put those 3D printed stops on the ends of the Y rail.
Thank you for all that. I came across your video of your methods too and it makes it all more comprehensible in my mind. I am going to give this a go and try to verify the different ways you did with the test pieces and dowels and the measurements with the machine on and off.