[turmite]

There seems to be two homing functions going on here, and I'm getting confused about which we are talking about.

Yes there is dual homing in the set up I use. Machine cords and each of my programs contain a G92X0.000Y0.000Z.000, which in reality sets the home , or better yet, the Zero position of those 3 axis to 0,0,0. I can run the same program anywhere on my table should the need or desire strike!

1) You want the piece to be located on the table exactly the same time after time (and to flip the piece over).

2) You need to home the tip of the router in Mach 3 relative to the table in three axis (x,y,z).

I get that using a jig drilled or clamped to the table will make certain that your piece is the same relative to the table, but how are you proposing to "home" the spindle relative to the jig/table/workpiece?

Will you jog the spindle to a mark on the jig/table/workpiece and eyeball it?
When I drill or place a fixture on the table I record the Machine cords to the particular index pin I have drilled either for the part or for the fixture. Once that cordinate is recorded I can use MDI to position the machine to that recorded postition.

Can you, or will you, rely on limit switches in the corner of the table? Yes and no!(nuts) (nuts) If so, will you change the coordinate system in your CAD/CAM program to reflect the table's limit switches? No, all my programs are drawn from x0y0z??? depending on how I normally machine a particular part. What if your bit is not exactly the same height time after time, will home switches give you an accurate "z" home?Again, yes and no. I have a tool set fixture that is located permantly under my x0y0z0 position and I set the tip of the cutter from that fixture via a script and button I have on my Mach screen. Do I trust it for everything? No. My tolerences are not even close to what guys need in the metal working field so sometimes the switch is close enough. If not, I position over the part and set a new z zero manually.

I hope this helps to explain it a little. I promise it is not complicated but may seem that way to someone who has never seen it in action.

Mike

[hindocarina]

Alnico,

Your fixture location problems are solved easily by using the offsets in Mach 3. There is a good video on the Mach 3 website at:

http://www.artsoftcontrols.com/artsoft/videos.htm

Watch the video called "Coordinates / Homing"

All my work is double sided. When I flip the piece over I use a different "Y" set of pins on the same fixture so that I always reference the same side of the piece. I re-zero the Z axis to the workpiece manually with every tool change.

Charlie