I love Dar. He is great. I have found cutting MUCH easier than engraving, to be honest. Any suggestions on how to get a piece of sterling sheet perfectly flat, short of beating the heck out of it with a mallet?? For regular work using other methods, that seems to be fine, but when using a CNC machine it has to be perfect, and I can’t seem to ever be able to get it completley flat. This imperfection results in irregularities when it is engraving! This is very frustrating! I’ve tried very rolling it through the rolling mill at guage, that doesn’t help either. Put it between 2 steel plates and using the hydraulic press. That didn’t work either!
Have you tried milling a pocket in a fixture and placing the material in that?
Yes, that doesn’t help, though, if the metal itself is not perfectly flat!
The other option then, especially for metal would be to use a program which could probe the surface of the material and map the V carving to any irregularities.
That does sound like a tricky problem. I suppose two things could be going wrong:
(1) the sheet isn’t perfectly flat
(2) the sheet isn’t the same thickness all over
This might be incredibly difficult to solve depending on how thick the sheets you are working with but I would say in my experience there are a few things I would try (with caveat I haven’t attempting anything with sheets of sterling silver so YMMV)
(1) if you are using clamps to hold the sheet down change to something that has equal holding on all areas of the bottom surface like superglue or even a vacuum table if one wants to get fancy. Clamps tend to cause depressions or bows in surprisingly thick sheets of material. I started machining PCBs and even thick plastic blocks with clamps and was always surprised how they could deform under pressure.
(2) I know nothing about what sort of engraving you do so this might be completely off base but you might take a look at spring loaded engraving tools. These allow engraving on a wide range of surface heights and might allow you to get even more creative on some pieces. Should take care of your varying height problem. Will note I have not tried this tool so not sure how well it works but something to consider.
(3) No matter how you try it’s unlikely you will get a perfectly flat surface without taking a what is called a ‘facing pass’ across the surface of the sheet before engraving. If there is enough thickness in the sheet you do a pass with a square end mill over the entire surface of the sheet, removing a thin layer off the top and knocking down any high spots and leaving a perfectly(ish) flat surface with respect to the machine to engrave with.
Again will note I am not a jeweler and have no experience with sterling silver sheets - just throwing out some things to try.
Hope that helps!
I’m using a .5mm (.020") with .125" shank because it was the finest tip I could find at the time. The finer the tip, the better if you’re doing very tiny work like I am. I make tiny, edge lighted signs for model railroad layouts by etching a coating from polycarbonate sheet. The light shining from behind reveals very fine detailing. Carbide Create has an impressive list of fonts too. My favorites are Iowan Old Style-Italic, Santa Fe, Comic Sans, Brush Script, Marion Italic. Minimum depth is a trial and error process until all the lines are distinct. Probably start with no offset. From there, just try the offsets and depth adjustments to suit the project.
I didn’t address the problem of working with thin material before. The polycarbonate that I work with is as thin as .030. I couldn’t get any clamping to work without warping the sheet so I use carpet seam tape. The only drawback is that it sticks very well to a smooth sheet of anything. I use a benign solvent (LPS1) to remove the tape and adhesive from the sheets (after peeling them off of the table). I also use this method to etch circuit boards I make for my lighting projects. You can try these methods on a piece of hardware store brass sheet stock to see if you can get the results you want. If necessary, clamp a piece of 1/2" tempered masonite to your table to give you a smooth, flat surface under the metal stock.
I am using 14 gauge brass to start with (it was what I had that was thick enough) it measures about 2.7 mm thick. My problem is I am pretty ready to blow up my Nomad! haha, I am so frustrated. I had help getting my butterfly figure ready to use. I had to use Carbide Create for it, then I was like what do I do with it? I exported the gcode and now can’t figure out how to use this in Carbide Motion, it won’t let me load it. So frustrating. I can’t make Mesh Cam either load it up. I am so confused…So eventually I got it in Carbide Motion and started the job with the Vee Bit, and it just hovered above the material I put in it. I wish I had more direction as to what to do and be able to figure it out. Each time I learn more but I never really get anywhere. Yes me too like you I want to mill my pieces, making changes would be faster, easier (I hope) and be much more worth it, since a die can cost lots of $$. I don’t expect to do Pancake dies with the Nomad, I want to make items with pockets to fill in with enamels, possibly engrave them also with my engraver that I am also learning to use. What I want to do for my hydraulic press is silhouette dies and things like that to make puffy shapes out of metal. I don’t use much pancake dies (which I don’t really use) I have big 30 and 60 ton industrial presses that do cutting of shapes (my main business)…but hey, it is all good, anything that I can do with this new machine should be very helpful! I am sure all us jewelers can help each other out with this! It is so complicated…Thanks and Kind Regards, Laura