Re: Engraving...

Mark,
Thanks for the valuable info.
But the hermes.com seems to be a fasion site ?!!

Are you sure of the name?

Thanks

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Mark <mfraser@h...> wrote:
> hermes.com has lots of good reading on the subject.
> Quick overview of what I think I've learned...
>
> Real engraving spindles turn at 20,000 rpm or much higher,
> because a very small diameter tool can't be pushed very fast
> thru any material or it will break. Figure on 3 inches/min
> for a 1/32 inch dia toolbit. maybe even lower, for a 5,000
> rpm typical mill spindle.
>
> The V-shaped cutter is typical for rotary cutting. It will have
> an included angle and a tip width spec - read the hermes stuff.
> A "D" cutter is most often found on real machines for rotary
> cutting.
>
> There is also diamond-drag engraving, which is non-rotating.
> Just a point that gouges or scratches the surface.
>
> For rotary, use lubricant - rapid-tap, e.g., for non-ferrous
> metals, alumitap is another.
>
> I rigged up a holder for a dremel on my spindle head, which
> increases table travel by 6-7 times the speed. If you're
> doing small stuff where a thou is an important parameter,
> the dremel likely won't be stable enough.
>
> since the surface of the workpiece may not be perfectly flat,
> you'll get variable width (due to variable depth of the v-cutter)
> as you pass over the high and low spots. Many "real" spindles
> are spring loaded so that they apply constant force of the cutter
> on the workpiece, yielding better uniformithy.
>
> Use engraver's double sided tape. Carpet tape and other double
> sided stuff takes way longer to remove than the engraving takes.
> Heat gun or hairdryer helps. I HATE that DUCK brand has taken
> over most outlets, their double sided stuff isn't well suited to
> workpiece holding. Strong, yes...
>
> I've done quite a lot of experimenting with carbide and HSS
> cutters, have had fairly good luck making D-cutters from
> broken carbide PB-board drills. Use a diamond wheel to shape
> them. I've found that I can make a fairly "polite" drag tip
> by grinding to a point, then working it over with a diamond
> bearing rubber polishing wheel on the dremel. Smooth, not
> surgery-sharp, no burrs on teh workpiece.
>
> Fonts are another challenge - truetypes are outlines only, which
> doesn't necessarily look all that great. So, I often will pick a
> font with 'fat' vertical portions, then use my cam program to
> pocket each letter, which usually produces 'not bad' results.
> Set it up so that the lines (drag, usually) are spaced wider than
> the dia of the scratch, for best results.
>
> And I'm still learning... At 10 cents a letter, I don't see any
> way of getting real rich real fast, at the speed my mill works, a
> nd the time it takes for setup and tape-removal...
>
> Vac table experiments will happen soon, I guess.... / mark