During long cut projects, I sometimes have to stop and pick it back up the next day. I always take a picture of the machine position, so that I know where to go back to in case something doesn’t go right. When I re-initialize the machine, how can I be sure that it will go back to the same locations every time if this is changed and it’s off by a little bit one way or the other, then my machine position is no longer any good. Has anybody run into this or tested this out?
The repeatability is as good as the repeatability of the homing switches. Assuming otherwise good mechanical condition, this is really the only thing that would affect how repeatable your positioning from session to session.
Since it’s a function of the switches, I’m sure there is manufacturing tolerances that affect this - some switches are going to be better than others.
If you’d like to see how good your machine is, i think something like the followinbg would show it:
- Pick a small endmill or acute angle V Bit - something where small difference will look pretty obvious.
- Set an X-Y zero somewhere convienient, and load a piece of scrap.
- Use the bit to create a small hole.
You should be able to jog anywhere, then use Rapid Position to (0,0) to get back to the same spot. Jog down to see how well things line up. Before re-initializing, make sure that you have good repeatability within one session.
Zeros are kept between sessions, so you can power cycle (or just re-initialize), then Rapid Position to (0,0) to see how close things are.
On my machine I’m guessing about 0.5mm on X, a bit better on Y.
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That sounds like a good test. I am also going to make a point directly below the spindle with a V bit after the initialization runs, I’ll just lower the Z directly and see if it’s in the same spot. If it is off from there, then it’s going to be off everywhere. I’d really like to have a permanent 00XY coordinate and just adjust my stock to it as I build my basses.