engraving with v22 - cutter parameters

[brooklynmetal]

I've been testing out the engraving aspect of v22 and have come up against
poor quality cuts and poor resolution of the letters.
The final step in the engraving properties edit is the diameter of the cutter.
The mill drill endmill I'm using has a tip that is .03 wide at the minor diameter and tapers to .375 @ 60 degrees.
If I select a .01 depth of cut I get very poor quality cuts. (see attached photos)
In many cases there is material left that should be removed creating
islands inside the letters.
Is there a way to compensate for this? A true engraving cutter is also tapered and I assume would create the same issue.
Is it a font scale issue perhaps?

[Bobbyr70]

It appears to be tool related, poor cut quality, possible Dull Tool. Spacing between the outer cut and the inner cut is related to the settings you are using. It is doing exactly what you are asking it to do. It also appears your machine may not be holding tolerances very well try scaling down a thenth or so and see if that helps if your cutter is carbide try speeding it up. slow down feed speeds a bit, use new tool or sharp tool. Deflection of the tool or material could also be a factor.

[brooklynmetal]

Bobby,
The tool is very sharp and there is no noticeable deflection. The tip of the tapered tool is .030" wide, 2 flute. The D.O.C. I input was .01", The second part was aluminum and the speed parameter BCC set in the post was 10,000 rpm. My machine has a top speed of 4500 rpm so that is the speed the cutter ran. I have to check the cad file and see if the width of the top line of text is less than .03" wide.
I also need to check the width of the bottom text and see if it is less than .06The tool path runs twice for each of the larger letters. If there were more options within BobCad Cam cutter parameters for a tapered engraving tool, in this case minor diameter .03" and major diameter .375" with a L.O.C. of .187 then perhaps the simulator would run with a more accurate cut path.

What type of cutters do you use to engrave with BCC v22 and what is a typical DOC that you usually select?

[tobyaxis]

A mill/drill really isn't the greatest engraver. Try www.harveytool.com or http://www.endmill.com/ They provide better tools for engraving. If you want to engrave a Font Outline I would suggest creating the font then pocketing the inside with a small step over.

BTW: do not try to use the start point option in the pocketing, it isn't working properly yet.

Cheers

[brooklynmetal]

Toby,
Thanks for the tips, I just got the Harvey catalog and am going to order a few different engraving tips.
I am going to try an inside pocket tool path this time and I'm certain that it will turn out much better.
I'll post the results.
Best, Dave

[tobyaxis]

Cool!!! be sure to post those results. Though I have no real pictures (customer confidentiality) you can look at this one on my website. I have to break out the camera soon to update the site more, LOL, it's looking pretty lame.

http://www.axiscncprogramming.com/108.html

[brooklynmetal]

Toby,

The results for the true font engraving were improved by the 2D pocket suggestion however there are still tool path problems that must be a cutter diameter issue (see attached) The B's and R's have a part that does not mill or else it's an over cut into the negative space. I'm still not clear how the tapered cutter path is assigned since variations of DOC will result in wider or narrower cuts depending on depth. There is no major-minor diameter choice in the cutting tool parameters. The images attached were made with a .25" mill drill 60 deg. cutter.
(I am waiting on my order of Harvey cutters) Why would this occur?

[tobyaxis]

Toby,

The results for the true font engraving were improved by the 2D pocket suggestion however there are still tool path problems that must be a cutter diameter issue (see attached) The B's and R's have a part that does not mill or else it's an over cut into the negative space. I'm still not clear how the tapered cutter path is assigned since variations of DOC will result in wider or narrower cuts depending on depth. There is no major-minor diameter choice in the cutting tool parameters. The images attached were made with a .25" mill drill 60 deg. cutter.
(I am waiting on my order of Harvey cutters) Why would this occur?

Well, first off I do not think your doing anything wrong. It is probably a bug in BCC and the fact that there isn't a parameter setting for Tapered End Mills.

Have you tried limiting your step over using only the tool tip as the diameter?

[HMB3000]

try a ball mill like 1/32.

[Randy Stevenson]

I'll second HMB's ball mill idea. I've been using a .030 flat end mill on acrylic, with the Bobcad Helv font and it's working great. Tried the tapered cutter, but it was doing more melting than cutting. Same deal with speed; BC says 10K and best I can do is about 5K. I just keep it slow.

[brooklynmetal]

Randy and HMB,
I will try the ball end mill, thanks. The font within BCC is all well and good, however if
a client provides a 2D CAD file compatable with BCC then the CAM in this case BCC should follow it if the parameters are set up properly. Toby suggested there may be a bug with the program. I hope that this is not the case.

[HMB3000]

. Toby suggested there may be a bug with the program.

using an ingraving bit for a pocket routine is kind of buggie in itself. It not uncommon when people can't get the results they want to just say it a bug.
Even thou someone else sends you a font file you need to look close at it. as with some fonts the chained geomitry is sometime junk