Z-zero plate

[john_hartman]

I've read Ken Rychlik's thread on this matter. I am convinced that zeroing from the bed is the correct way. I am wondering how everyone is doing this.

Have you created an "off-table" z-zero plate like Ken's or are you just zeroing directly off the spoil board? Zeroing off the spoil board seems like the easiest solution, but what if you have rezero while a sheet is on the table.? I guess you can't do that or does this even come up.

I believe having a off table z-zero makes the most sense however this file modification really worries me. I heard that you can set-up a file to surface the table and a seperate program will modify the z-zero plate by that difference. I have not done anything like this, programming that is..

Also, I have just added a couple of air drills to my alpha. Which means these have to be zeroed as well. What, if any, special considerations do I need to observe with these?

As usual many thanks for the help!

[pro70z28]

I zero off the surface of the workpiece with the "Z" plate. If I'm cutting something like aluminum or steel I put a separate sacrifice board down & plane it flat with a 1" end mill to make sure there are no high spots. This has worked well for me for better than 15 years. It's what I'm most comfortable with.

[dlcw]

Zero from table surface for all cabinet parts (plywood sheets) processing. I have a zero plate permanently attached to my table in an out of the way place. My cutting files have been modified to go to this location to rezero after a bit change.

When doing 3D carvings or smaller projects in solid wood, I clamp the material to a piece of MDO which is held by the vacuum table and zero to the top of the material with the plate.

[knight_toolworks]

I made a outboard z zero plate it has slots and it is held with screws. when I flatten the spoilboard I use a straightedge to set it level with them surface. No use wearing out blocks of aluminum.
I have a custom c# file that jogs to it zero's then asks me the thickness of material then zeros at that. very handy and works with sheets on the table. but it sucks when I forgot to level it after flattening.

[Gary Campbell]

John...
I am a firm believer in the fixed zero plate. Off table, that is. My own version has an aluminum plate (3 by 3 by 3/8) mounted near the ATC carousel. To make sure that I didnt have problems with my large surfacer, I mounted it with well countersunk screws. Also drilled and tappped one side to allow attaching a wire/crimp end. This wire goes to Input 1 on the SB interface board. The block must be insulated from ground.

The location is tricky on a 4 by 8 machine, especially if you have drills. Sometimes the only option is in the negative X area. I have used a 3 by 3 angle for this in the past. Once you have it mounted you can enter its location as "&my_ZzeroStartX= ?" and same for Y. SB setup can enter these, or you can put them in manually. Location is C:\SbParts\Custom\my_variables.sbc

If the zero block is mounted lower than the spoilboard, there is no need to move or surface it. The distance below the spoilboard is stored as a variable, just like the thickness of the zero plate. Simply a different number. I use a modified zero routine to write the offset as a variable to the my_variables file. (once)

Should you implement this, I have a surfacer routine that changes this offset amount by the amount that the table is surfaced.

Next step is to add the move to that location into the drill offset file. That will automate the drill offset routine.

Some other random thoughts:

Zero to bed isnt just the best way, it should be the only way.

Once you get into it, there are files included with the video that do, all this. Plus you have the ability to eliminate having to set the drill offset when you change bits. Its done automatically for you.

You can also add this variable to PWKs postP's that allow the same zero to bed and design from the surface as most of us are used to. The design material thickness is applied as an offset to the bed zero.

More info here: http://www.shopbotblog.com/index.php/2010/10/2201/

[gene]

John,
Can you post more info on the air drills ? I zero to the top of the materials, If you zero to the spoilboard what is the safe Z bit clearance set at? Where can i find more info on this? Thanks :rolleyes:

[Gary Campbell]

Gene...
Whether you zero to the table or material surface, the preset safeZ is applied as an offset by the MTC files. Whan a drill is active the amount of the drill offset is added to that offset.