Quote:
|
Originally Posted by jdveritas
Hey... I was hoping somebody'd say it was gonna be ok...  will mind the advice Steve. I didnt think I had incorrect tool geometry... per say, and this is why you all had to practically beat the numbers out of me... maybe I experiment further with heel angle, but imagine the depth of cut is the problem. Dose it sound correct to you that a greater angle on the heel, and increased negative relief would be desirable for relieving tight squirrly back ground area? Jim |
I guess you are going to have to define what a tight squirrly background is! Then it becomes an issue of what tool to use.
Generally the easiest way to remove a background is to crosshatch it with a 90 and then go in with a flat to remove the metal. That way you can control the depth eavenly across the field. Problem with flats is that if you do not heel them ( and it doesnt take much) they tend to dive right in and do more damagethan they do good. So there are two options. 1st just take the flat and cut a tiny heel at whatever angle fits your fancy. This gives the graver the ability to slice and dice without digging in. Another option is to radius the heel by rocking it up and down while moving forward and backward over your shapening material. Again, keep it relatively short. It's not that critical, you could have a 1/4 of an inch heel and it would still work but not well in a confined area. If you are working in tiny areas you just grind narrower flats and make multiple passes. With the crosshatching in place you can keep pretty consistant, it's fast but it has it's limitations due to the size of the intersections. The angle of the heel on a flat just changes the position of the the angle you hold the airgraver at to make the cut. Nothing more nothing less. It's simply flat on the bottom with a sharp leading edge. Glorified wood chisel. Nothing magic going on. Polish it and you get a shiny cut. Thats all there is. Negative this and that doesnt apply. In fact, go down load a picture of a wood chisel, flip it upside down and there is your flat.
Another trick i employ is to work over the area with a sharp stipple tool at a set air pressure and idle speed, after the area is covered evenly I then go after it with the flat. By using the same impact rate and pressure (joys ofthe airgraver!), the indents are at the same depth. The removal of the material is easy and flat as you just cut down to the point where the dots disappear. You can repeat this as many times as necessary. I find it works better than crosshatching for small stuff and softer metals.
Also keep in mind that there is no rule that says a flat must have a square shaped face. You can taper, round or otherwise roll off the corners and sides to control the way it cuts. There are places standard gravers just dont fit. Thats why you have to make tiny ones from other materials, like remounted 1/16 rod. When i cut and inlay the eyes of a person on a coin the channels i cut or drill or whatever are way smaller than one could accomplish with off the shelf tools. It's always a case of make them smaller. It all depends where you draw the line on your product time vs money. At some point it's gets futile to go so small that it takes a scope to see the refinement. People really don't care that much. Now the coin crowd, they are a bit differnt. They all have scopes and picky picky picky. For the rings and other jewelery stuff. You have a lot of lattitude. I see platinum rings sell for thousands with engraving that wouldn't fly on a nickel.
Hope this makes sense.
sle