Bit issues

[John Jaquet]

I am new to the ShopBot. I have been using a CarveWright for a couple of years.

I am really excited about the ShopBot, but I'mBit Drawing.JPGBit Drawing.JPGTool data base.JPGlines in carve.jpg having some issue's getting a good carve.

I made my own form tool and I think that might be the issue. I have had good luck with the 1/16 taper that the CarveWright uses and wanted to use that.

I am going to try and attach pics of my drawing and of the tool data base. I even set the stepover to be 1% and ended up with the lines.

I have tried a preview using offset and it's no better.

If I preview an 1/8 taper ball nose it looks acceptable. I don't have one and with the 1/16 thought I would get better quality.

Any help/ideas would be greatly appreciated. Thanks, JJ

[coryatjohn]

I'm guessing you have a problem with your tool definition. I suggest copying the 1/8" taper definition and change it to fit your own tool. That would probably fix it. There's really no difference between a 1/16" ballnose and a taper except the strength of the bit and the diameter of the shank. The way you have the tool defined looks like it would be wacko. Which is probably why you see lines. It's a 1/4" diameter tool to the database. At least that's the way I see it.

[scottp55]

Enter it as a Ballnose or Tapered Ballnose depending on which it is, and enter the correct values.
I know when I use a Tapered Ballnose the stepover is a percentage of the Radius(?), BUT when I use my engraving bits for my really Tiny stuff...
It's a percentage of the tool diameter, and I have to look at the actual decimal stepover rather than percentages.
scott

[John Jaquet]

Bit.JPG

I thought this was attached. How would I define this? The 1/8" Tapered Ball Nose looks nothing like this. JJ

[scottp55]

John,
Hard to tell with the small pic, but looks like a .25" shank Tapered BallNose with whatever Radius it is.
Can you check the manufacturer's specs online?
Usually it gives the side angle, and just plug the rest of the measurements in.
In the note section it helps to add the tool #/total bit length/and the CEL(bit me in the as* recently that I didn't have the tool length in there)
scott

[John Jaquet]

Thanks Scott. What do you mean "bit length"? Pass Depth?

[scottp55]

John,
Total length of the bit is good to know if you're at your design computer, and your BRAIN says the bit is 2.5"...When the actual length is 3".
If it had been in my notes the other day, I would have skimmed a little more off a burl. I had to put the bit all the way into the collet to the cutting edge, and STILL had to change my SB3 VC(Value Cutter) Safe Z to .02" so it didn't top out...also had to change Z1/Z2/and homeZ in the Vectric file to .02" as well..
And barely squeaked by with my Desktop Z.

CEL is Cutter Edge Length, and that's the deepest pass you can make in 3D when all you're usually cutting is the stepover.

Pass Depth is the depth of cut each pass will make and is set in your tool database, and will vary with the design/machine/and materials.
Pass depth is IGNORED in a 3D "Finish" toolpath, as it assumes you've done a "Roughing" pass.
Hope it helped.
Maybe add which machine you have in your profile...may save a lot of questions later if people know
scott

[coryatjohn]

I recommend getting a few 2x6's to play with. They are soft wood, cheap and are less prone to breaking bits than plywood, plastic, hardwood or other materials. Ruin a lot of cheap, soft wood with cheap bits before you start any real projects. Plus, being 1.5" thick, if you screw up your depths, you're less likely to punch a hole in your spoil board.

[jerry_stanek]

I use the carve wright 1/16 bits and treat them as a ball nose and use the default settings other than speed and get very good results.

[John Jaquet]

Compare Popeye.JPG

The top carve is from the CarveWright.

I did the same carve on my CarveWright and ShopBot and the results are unsatisfactory. If I increased the stepover would that help with the "saw tooth " text?

These are the settings I used. My bit Tool data base.JPG

I am also curious on feed rates. Talking to ShopBot they say run at 6 in/min. Looking at the above post and the stock settings is 2-3 in/min correct?