Thickness Gauge

[fleinbach]

I cut, mostly sheet goods, and as you know, they vary in thickness. 3/4" MDF tends to be dead on, exactly 3/4" so it's very easy to accurately cut to the depth needed. On the other hand, 3/4" plywood is not a true 3/4" thickness. So if I don't measure the exact thickness. I wind up cutting deeper into my school board then necessary. Of course I can use my micrometer, if I want an accurate measurement, but I was thinking it would be nice if it could be done with the Shopbot.

I believe the Z zero routine routine file could be modified to do this. The way it would work is to first zero to the surface of the table. Next you would put your material on the table and run the modified file. When this file is run instead of resetting the counter to zero, it would freeze the reading instead, indicating the thickness of the material.
TIA

[harryball]

Certainly possible... but the $35.00 I spent on my digital caliper was well worth it.

What I'd really like to see is software that would allow me to choose to zero on the table or the material top by toolpath and not the entire file.

I've shifted by 0,0 on the table to leave table surface exposed. When I create toolpaths I zero on top of the material for carving, pocketing and anything that does not cut through. For cuts I zero on the table top and let it cut.

Using this method suddenly meant the thickness of the material didn't matter. I can cut all my grooves and predrill marks with my 1/8" bit then cut out all my parts with my 1/4" bit.

I realize for somethings this doesn't work well such as pocketing and cutting in one toolpath. I'll generally zero to the table top for those.

In the end... it'd be nice to have the Zero to top or bottom as an option for each toolpath creation.

Robert

[Brady Watson]

The only method that I have found works is to put an extra pad of material off of the spoilboard (that also gets surfaced when the sboard does). Then if you are going to do dados & rabbets 1st, you zero off of the top of the sheet. When you want to do the XOut pass, your sheet is covering the spoilboard....so you use the extra pad (I use one that sits about -2" off of the X). This way you get the best of both worlds.

I suppose that you could automate the zzeroing off of the bed as long as you didn't do toolchanges between cutting the dados and the XOut passes. Something like a touch off switch would work, but may not be practical.

-B

[mikejohn]

Robert
This works,I think.
Z zero on the table.
Determine the thickness of the material and note it.
In your file place a variable with the material thickness.
At the point in the file you wish to change the Z-zero height, put the command
VA,,thickness_variable
This now Zeros Z at the top of the material.
However, it appears to me that, if you know that you are cutting with Zero either at the table or at the material height (different Z zeroes) you must be creating the filepaths seperately.

It would therefore be better to create these files seperately, then call them in turn as

J3,0,0,0
FP,D:\zero_on_table,,,,,2
J2,250,650,40
FP,D:\zero_on_material,,,,,2
J2,350,750,0
FP,D:\zero_back_on_table,,,,,2

The red values are the x,y co-ordinates of the last move, the green value the material height for new Z or the variable you have asigned for this

..........Mike

[paco]

Sometime ago, I wrote a "Check thickness" routine but I didn't use it very long before gotten bored of using it. It's actually using the Bot as a caliper. It's still interesting to use sometime for specific application though.

What I use the most is either a slight variation of the default Zzero to fit my need OR a more modified version that zero from the spoilboard BUT add the material thickness that I tell it to. I start the routine and it prompt me to enter the material thickness value and add it to the Zzero to spoilboard routine.


395

Another variation of this that I tend to use more and more, is to XYZ zero/reference to a fix block that is out of the working area. It act just like the Zplate but for all three axis. It's a little more time consuming but it's very accurate (within 0.002").

One can do about anything with the SB code. The my_variables system make it very organized and easy to write all repetive task under sub routines and call 'em whenever needed. With the latest new code update, even more can be done. Check it out and master your tool language.
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