I don 't think the cutting angle make any real difference, but thr graver must be very sharp. otherwise you get some flaking at the edges which is very annoying, but I think some alloys that have been anodized, are more prone to this than others
JJ - another thing to be careful of is that the bur thrown up can become long and curl around to drag as you are engraving. This will definitely scratch the anodized area outside of where you are cutting. When this happens you have to either make smaller section cuts where you eliminate the bur as you go (lift out) or take a pair of pliers and knock the bur/cut it off as you progress.
What are you going to cut ??
It makes a big difference..
Don't expect to do anything with any detail..
like any plating process,,,,,, you will have chipping along the cut...........
It may be small......but it's there
Different grades of aluminum and different anodizies cause a number of different results.....(did that make sense. ?)
I won't do any anodized aluminum anymore....
Some of the junk that's out there, cured me
The "only" thing I will do is the Flamed mini-mag lites I've been doing for 30 years........Because i know the quality, and what to expect..
everything else i send down the road..
PS... I use A-9 Cutting Fluid as a lubricant for all my aluminum work (which is extensive)
The same gravers I use for silver I'll use for aluminum.
A 45 flat with a 37.5 degree face and the heel and face polished with 4/0 paper. Some DAP cutting oil helps keep the aluminum from building up on the tip.
A 120 degree graver with 45 degree face and the heel sharpened on the porcelian wheel.
The angle of the face all depends on how much harder (or easier) you want the graver to cut. The steeper the angle the more of a fight you've got on your hands in the long run. Engraving large parts means you need to remove more material quickly ... after a while you'll notice yourself tiring out.
The quality of the aluminum makes all the difference. High tin, cast garbage will chip no matter what. Machined billet and high quality cast will give beautiful bright cuts with the sharpening configuration I use.
As for anodized parts ... don't take them in unless you know the part is made from machined billet.
Thanks everyone for your helpful replies. My reason for asking about anodized aluminum..I have a neighbor who wanted me to do some engraving on a paint ball gun. Has anyone ever engraved one?
JJ, there is a product called Alumicut it will slick up the cut nicely. Might need to go to a machine shop for the stuff. In a pinch Jergins tool aid will work also. You will be surprised how the graver/ chisel will slide with this stuff.
Kent
Tira's suggestion is a valid one, and it would include engraving on lacquered brass plates (common in the trophy engraving trade for plates similar to what Jim is doing). You can buy this plate material and it already comes lacquered.........That bur that rolls in front of your cut will also leave a trail in the lacquer, and you cannot get it out, so just another little additional bit of knowledge.
With the power tools, you can stub the point with a ninety degree face, and I make this with one little light stroke on a ruby stone after sharpening and acquiring my normal point. This will cause the bur to rise vertically rather than curl, allowing a longer cut. By hand, this wouldn't work nearly as well and the tool will be a little harder to control, but it is possible for you hand push engravers. It only takes an almost non-visible facet to produce this result unless you are cutting really deep which isn't wise with the palm tool without power. I got scars to prove it.
Ron S