I’m doing diamond drag engraving in stainless steel with a spring loaded tool. The objective is to match the character of manual engraving done 56 years ago. Testing with a Shaper Origin demonstrates that it can be done but it takes three passes at full pressure to get the right line thickness (ditch width).
Testing with my Nomad 3 is very promising but I’m looking for a way to quickly get the three passes at full pressure (maximum spring compression). The file made in CC wants to do one or more initial passes at less than full depth (less pressure) which is really wasted time in terms of displacing steel.
Is there a way in CC to get a single full depth pass to immediately repeat? Without going home and rechecking tool depth and all that?
Or does this have to be done by cutting and pasting g-code?
What happens if you increase the spring pressure by increasing the initial depth of cut rather than doing multiple passes? For example, my non-Carbide Create diamond drag tool (yes, I’m properly ashamed but got it before the MCEtcher was available) has 10mm of total spring compression and half the total depth, 5mm, seems to work best on aluminum.
Do you have any photos of your work, it sounds interesting.
Working with stainless steel. What looked great in my test on 6061 looks anemic in stainless, forgot the alloy but it’s the most common and medium hardness.
I’m using a tool made by CNC-Aid in Canada. it’s unique in a couple of ways. First it comes with five different stiffness springs. I’m using the heaviest. The thicker wire means less compression travel. I’m working right at the maximum already. Any more Z- and it might as well be a rigid tool. Maybe that’s what I need to do. I’ll still have the ability to engrave any slight depressions in this nominally flat bar.
Here is detail pic of the test bar.
Top row engraving was made by a commercial engraver using settings recommended by the manufacturer of the machine. The font is exactly right because this company (Gravotech) is what remains of the company that made the pantograph engraver used back in 1966 (New Hermes). The defects are artifacts of the rotating spindle, which was suggested to use when the machine could only make faint lines otherwise.
The second engraved line is made with a Shaper Origin. I was pushing it to or a little beyond it’s limits here. You can see some lines are wavy but the line thickness is good. There are too many chances to screw up (36 characters in all) with this handheld machine.
The middle line is made with the Nomad 3. Good straight lines with consistent thickness but a little light. Well worth refining.
Fourth row I made with an old pantograph engraver. More than enough line thickness but it is inconsistent because of my lack of skill. No reason to develop the skill other than for this project so it’s really impractical. You can also see where the tracing stylus skipped out of the groove in the Master Copy and scratched outside of the line.
Bottom row was made by another commercial engraver. They couldn’t get heavy enough lines either so turned to and outline font and fill.
My original task was just to find a commercial engraver to fulfill the contract. Ended up being my problem but I’m getting close thanks to the help I’m getting here.
I think I found the recipe. Maybe need another thou of Z.
Took the tool out and compressed the thing completely with a small Quick Grip. Found out there were a few more thousands of contraction than I thought so added a couple to the beginning and end with three .0001” passes between.
Top row upper image is the new result.
Lower image is the original engraving we need to match.
Don’t have to match original handmade idiosyncrasies like the tapered number 1.
Your top row looks nice, not that I’m remotely close to an expert. I did some 2mm high test lettering back when I was playing around with straight line guilloche.
I have one of those 60s +/- engravers, minus all the stencils. It had been used for nameplates in our local hospital, one of the ER docs ended up with it and stored it in his pool house where the bromine fumes did some damage. He sold off the stencils on eBay and gave me the rest, which is still sitting on the shelf in the get-to-it pile. It all seems to work, other than the long cutting bits have a fair amount of corrosion on them. Don’t remember the brand, and it’s inaccessible until the snow melts. Seriously high RPM spindle speeds iirc.
Back in the day, just prior to computerized engravers coming onto the market, New Hermes ruled. The NH motorized engravers all used 10k motors for engraving both brass and plastic. The cutters were split point, more or less equivalent to single flute.
The rotary spindle on NH engravers had an adjustable nose (nicely polished with rounded edges) that literally rode the surface of the stock being engraved. I suspect the guy who engraved the object I’m duplicating used that spindle with the motor turned off (maybe with Scotch tape on the bar to protect it) and the nose piece prevented the diamond from reaching the surface near the edge of the bar were polishing made it less thick. Hence the tapered vertical elements, thinner closer to the over-polished edge.
The NH engravers could also be fitted with the “feather touch diamond stylus” which didn’t have the training wheel nose piece. It would have followed the the surface undulations like the spring loaded cutter does. More skill required, one of the reasons I wanted to use the Nomad.
