finding the center while in a vise

That's odd, I don't remember trying to win anything. LOL

"Billy G"
 
The old videos of assembly lines of machinests standing over their lathes and mills producing one part after the other shows a time in our country when we probably had over a million very talented fellows. They could reproduce the same part over and over again with amazing efficiency.
No safety glasses, no DRO's, using basic measuring devices, incredible.
 
Groundhog said:
I cheat. I stick the probe in and let the computer and the cnc do the work! :p
Click to expand...

Yep, and if your probe or spindle isn't perfect you can probe, zero, rotate 180, probe again, and divide by 2. I think I recall somebody said they had a Bridgeport that did exactly that automatically. If your feature is not the zero point of your work offset you then move to 0,0 and set the work offset value of the center of the feature.

You know, I need to put ports on all my machines for my probe, and put a connector on the cable... right now its hardwired into a machine that has a bad axis motor. LOL.
 
Tormach has a program in PathPilot that will probe pockets or bosses at the touch of a button and set the center point.

You are correct in that spindle and/or probe runout can affect the center point setting. The probes that I have seen have adjustments for centering the probe. There is still some possible spindle runout to contend with but if care is used to orient the probe in the spindle exactly the same, runout shooulden't be an issue.

Spindle runout is why I use an edge finder. Its design is such that runout doesn't enter into the determination. Prior the the jump, the edge finder is centered exactly on the spindle axis. Used with care I find that I am consistently repeatable to .0001". In fact, I usually repeat the process two or three times to verify that my trip point is the same to .0001".

My method is to come to an edge rather quickly to get a rough idea as to where the edge is, back off and approach the edge at about .0002"/sec. (my Tormach has a jog feature that moves .0001" with each jog). The reason for going so slow is that it allows the edge finder to find true center. If if is off center and hits the edge it can jump prematurely or if moving fast enough, overshoot the edge giving a false location for the edge. Moving slow gives the edge finder a chance to settle in.

I use a similar process for the mill drill but manually advance my feed while watching the DRO. I will advnce to increas/decrease the reading by .0002" (minimum resolution) and check the edge finder. The actual jump point will be between the last observed centered condition and the first observed jump condition. With some care and practice, rhis is repeatable to .0002".

To speed up the process, once I have hit the work edge, I back off and use my thumb nail or a pencil tip to nudge the edge finder to center again so the number of jogs to find the edge takes two or three seconds.
 
I use MachStdMill - an add-on program to Mach3 that has a bunch of probing and touch off routines. It seems to handle most any geometry, and find centers, corners, angles, velleys and islands, etc. After it probes it will set set zero for all (or selected) axis, set work offsets, etc.
I have my probe in a dedicated R8 holder and dialed in to a "home" mark on the the spindle. While not perfect it is acceptable for most things I do. I have it wired using miniature a RCA plug and socket (like a headphone jack). I don't have another machine to use it on but at least I can unplug it and get it out of the way!
 
For Mach Users the Blue Screen set has some probing functions coded in, and for more advanced probing Probe-It is a reasonably priced probing plug-in for finding centers, perimeters, etc.

If you don't care for the Blue Screen Set Klaus has a nice Mach Screen editor you can use to look at the features of a screen set and then create your own.

I am still learning the capabilities of my Tormach/PathPilot system.
 
I’ll throw this out there,
How about finding center of a hole in the vise clamped part ?.
 
If you are looking for a good screen set for Mach3 look at MachStdMill by Calypso Ventures. It hasn't changed in a few years but it really adds a lot to the functionality of my mill. There is a lot to it so it takes a while to learn.

http://calypsoventures.com/
 
dlane said:
I’ll throw this out there,
How about finding center of a hole in the vise clamped part ?.
Click to expand...

I saw this in some video so not my idea, but works well for my needs.

I use edge finder. Set this somewhere in the middle. Find e.g. farthest Y, set DRO to 0, find closest Y, hit "Center" on DRO. Move Y to 0, then set edge finder to left on X axis, set DRO to 0, then find right on X axis and hit "Center" on DRO, then move X to 0.
 
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