Cutting above surface with V-groove cutter

[pyrodenis]

Anyone,
I'm cutting some small text with an amana v-groove bit (.01 flat surface)
Some of the sections of some of the letters are thin, and therefore result in a single line toolpath, that I would expect to be shallow. However, the bit is not actually cutting there at all. In fact, it looks like the tool is passing above the surface in the 3D view (but I can't figure how to zoom in more in that view).
I don't think it's inaccuracy in my Zzero setting(I use the zzero tool.)
When I created the bit in the database (on a separate computer), I called it an engraving tool, so that I could enter the flat measurement where the point should be. Is that the mistake? Does it have to be called a v-groove?
Anyone?

[bleeth]

If you are creating a v-bit tool path then where there is a single line in your text it won't cut there. The program must see two lines to create a centerline for the tool to run in.

[pyrodenis]

Oh, I misstated the condition. I meant to say that there is a single toolpath line. There are two lines that are close together.

[jim_vv]

Greetings, Denis

I have a couple of ideas. . . .

Are you V Carving your text? For V Carving small text I usually use a 1/4" 30 or 60 degree engraving bit with a .005" flat tip because that is what I have a bunch of. I just select a 1/4" 30 or 60 degree V Bit from my tool database and don't worry about the flat tip.

If the two lines in the text are closer than .01", and you have included the flat tip in your tool setup, the software is pulling the tool up and out of that area.

Or, if your cutter isn't cutting everywhere then perhaps your table isn't flat?

If your table is flat then start adding an offset to lower your Z below Z Zero .005" at a time until you are satisfied with the result.

Kind regards,

JIM

[garyc]

Denis...
Have you verified your Z height?

Move over material where problem area is.
If zeroed to top of material, then MZ,0.
If zeroed to bed then MZ,{material design thickness}.

Bit tip should be touching material. If bit is at material surface, then problem is in the design or file. If not, then problem is with material thickness or an innacuracy in zeroing.

[bleeth]

You are probably overdoing the parameters of the bit and just not quite deep enough on your zeroing. It is common for the z zero position as determined by the plate to be not exactly at true zero. Many who use finer bits and need to have more precise determination will go to the "sheet of paper" method after zeroing with the plate. The entire nature of the Shopbot (other than the desktops) is that although with careful set up it can approximate engraving it is not an actual
engraving tool.

It is easy to tell in your design software whether your generated toolpath is actually cutting the part or in the air. The color of the line when previewed in SB control software will be different.

The true thickness of your zero plate, how flat it really is, the flatness of your spoilboard as well as the consistancy of your material being cut are all factors.

As you gain more knowledge through experience of your machine you will learn the fine tuning adjustments to get the results you need from various bit types, cutting strategies, and materials.

My advice on this one? Drop your bit a few thou, set it at z zero manually, and run it again.

[Bob Eustace]

Hi Denis

We too use the Amana bits but on engraving acrylic. We always use Quick Engrave set to 0.02 and get consistently good results on the Buddy. We do jig and ALWAYS surface the pad it sits on.

[pyrodenis]

thnx to all.