Z-Plate

[davek]

I am having a problem with my z-plate. I run the file, the router does exactly what it suppose to. I have set safe clearance to raise to .500 and stop. Before I run a file I have to zero z then MZ -.500 then zero Z again . Now I can run the file. I thought I could start the file from the safe clearance of .500 and the software would compensate for the .500. Do I have a problem or is just a step I need to do? Hope explained this clearly.

[richards]

In the Shopbot Control Console, select the Tools menu and then select Shopbot Setup. On the second page of the setup routine, make sure you have checked the "I have a z-axis zeroing plate and want to setup the Z-zero routine". The next page has entries for the actual thickness of the z-zero plate (mine is 0.121 inches thick) and the safe Z-axis value (mine is the default 0.5 inches). Finish entering any other setup values and exit the program. Next, press C2 to run the Z-zero routine. If the z-zero plate is connected properly, the z-axis will go from some unknown height until it touches the z-zero plate. It will lift up and touch down the second time. At the end of the routine, it will lift and stop at the height that you set in the Setup Routine.

When you run a SBP file, the code in the file will probably jog to your start point and then jog the z-axis to a point just above the material, then it will normally use a move code to start the cut.

[btk]

Dave,

I am not sure if I am understanding your exact problem, however
Check that you are in Absolute Mode (as opposed to Relative).

Absolute makes moves to the coordinates listed in the file relative to 0,0,0. Relative mode will make moves relative to the current position.

In Absolute Mode, when you start the file from 0,0,0.5 (which is where the Z-Zero file leaves off), the machine will move to the first position in the file and cut. For instance if your first line of file was "M3 0,0,0", then the tip of bit would move down 0.5 from (0,0,0.5) to (0,0,0) and then go on to the next line in the .sbp file.

However if you are in Relative Mode and same first line of (M3 0,0,0), this would not move the tip of bit at all and would remain at(0,0,0.5), if the next line said (M3 0,1,1), then the tip of the bit would move 1 in Y direction and 1 in Z direction "relative" to current position of (0,0,0.5), so you would end up being at the Absolute postion of (0,1,1,5).

Now this was a very confusing explanation of Relative vs. Absolute and I know there is a doc on the Shopbot website that explains this more clearly.


Brian

[davek]

BTK,
I Think we are on the same page. I have had my ShopBot in Absolute since day one (jan'06). I changed it to relative mode to see what would happen. It works like it should. Starts at .500 moves to its starting point and drops to the setpoint (.125). Is it possible There is a wire crossed to cause this? What would happen if I left it set in relative mode and ran a file?
Dave

[btk]

Dave,

I would suggest perhaps re-installing latest version of shopbot software.

FYI, I can not see how it could cause a problem, however also check that the .sbp file does not change the mode (an "SA" command within the file will change the mode to Absolute).

Good Luck,
Brian

[billp]

I hope this doesn't confuse the issue, but I NEVER ran any of my machines in absolute mode for 8 years, and all accessories worked as they should have...

[bill.young]

Dave,

If I understand correctly you run the z-zero program and the bit ends up .5" above the surface and that's what the display says. Then you zero the Z-axis with a ZZ command..the display now says 0 but the bit is still .5 above the surface. You then give it an MZ, -.5 move and at this point the display reads -0.5" and the bit is at the surface of the material (or wherever you zeroed to). Then you re-zero the Z axis again with a ZZ.

Seems like you haven't really changed anything in the last couple of steps ..if you make an MZ,0.5 move you'll be back where you started after the Z-zero routine ran....at 0.5 above the surface.

What happens when you try to run a file directly after running the Zzero routine...without doing the extra ZZ steps?

Bill

[bill.young]

Hey guys,

Be VERY careful about running files that were created for absolute mode in relative mode...it can do some very strange things. For a good example, open the ShopBot logo file (C:\sbparts\s_sblogo.sbo) in the editor (FE) and change line 11 that says "SA" to "SR". Save the file with a new name and then run it in Preview. You'll be surprised at what happens.

In the Windows software files ALWAYS run in Absolute mode, unless you set them to Relative mode by putting an SR command at the beginning of the file. If you just set the toggle in the control panel to Relative then commands that are entered from the keyboard will be in Relative mode but files will still run in Absolute mode (unless they have an SR command in them).

I can't remember if the DOS software works the same way....it probably does.

Bill

[paco]

Dave,

could your file be 3D offset? 5th parameter of the FP command or second of the Fill-in sheet (Offset in 2D or 3D)... maybe you're running the file in 3D offset from the start.

BUT, I'm not sure I understand your zeroing method AND your actual problem if any there is...

[davek]

Bill,
If I use the zero plate in absolute mode and let it go to .5 and run a file from there it will move to its starting point and only lower whatever I set it to when I created the tool paths with the v-carve program. If I tell it to cut .125 deep it will drop .125 and show .375 on the display. The tool will actually at .375 above the work. If I run it in relative mode it will drop .5 plus the .125 and show -.125 on the display. When would I want to use absolute mode? I have ran a small file in relative mode and seems to be ok.
Dave

[btk]

Bill Y,
In his original example, Dave is Zeroing his bit and then he is running command MZ -0.5
If the bit is just moving down 0.5 back to the table/part surface, then it must be in relative mode.
Otherwise, it would have moved down one inch to -0.5 (absolute) and would have gone into the part/table.

I think for some strange reason, Dave is in Relative mode, even though his Screen shows Absolute.

Brian

[bill.young]

Dave,

I'd suggest a call to tech support...they'll help you get sorted out.

When you say you ran the file in Relative mode, did you manually add an "SR" command to the text of the File? If not then it still ran in Absolute even if the toggle in the control panel was set to Relative mode.

Bill

[davek]

Bill,
I didn't add the "SR" command. (didn't know I could) Does this mean the Z-zeroing routine is being run in Relative mode and my cut file is being run in Absolute mode even though the display is toggled to Relative mode? Something else to ponder on huh.
Dave

[bill.young]

Dave,

The z-zero routine runs in Absolute mode and that's what you want it to run in. As far as I can remember I've never written a file that runs in Relative mode...all the ShopBot files that you can download from the ShopBot web site, including things like the sawhorses and zeroing routines, are all in Absolute mode. A file written in Relative mode is pretty confusing to read...you can't tell from reading the file where the bit really is.

How about emailing me your part file and I'll see if I can duplicate your problem.

Bill

[davek]

Bill,
Its on the way.
Dave

[john_r]

I got the exact same problem. I tried everything suggested here. (Was there a resolution to this problem?) I'm trying to cut a simple 2D cabinet out of .75" baltic birch in 2 passes -.375 in each pass. My bit Zero's out at .5 after running my ZZero routine. I start my file and it moves to the start point, it plunges to about -.2 if that...the Screen says it's at -.375, then it makes the second pass, again same amount...screen says -.75
I also tried running it in preview and it looks to cut all the way through. Just like it's supposed too.
I've looked at the file in the editor, nothing looks odd or out of place the Z plunges never change from -.375, -.650 and -.750

[bill.young]

Hey John,

If the file looks OK in preview and the display reads correctly but the cut is not the correct depth, here are a couple of things I would look at...


*) After the file is finished, what happens if you make an MZ,.5 move? Is it still 1/2" above the material surface or has it lost position?

*) Could the bit be slipping in the collet? This can especially be a problem if you're not using an end-cutting bit or are using an up-spiral bit with an older collet

*) What are your Z-axis speeds? If it's a Part Wizard file are they being set too high so that it's losing steps?

Bill

[evan]

I had a similar problem with inconsistent depth/ not going to full depth. It ended up being the arbor on the router had vertical play of about 0.125” to 0.1875”; a couple of screws that hold the arbor up had worked loose. After checking the brushes and bearings I tightened it all up again, using a little Lok-Tite on those two screws and all is running smoothly again

[john_r]

I just wanted to update this one. Bill Young helped me figure out that my problem was with my CV number on the controller on the Z axis for my set up. This thing is cutting Dead nuts now. Thanks Bill for your help.