Curious if any of you folks do your own engraving on receivers? I have a few 80s that don’t have the fire/safe marking for the selector. I have a 3018 CNC “engraver” but I’ve only ever used it to carve small wooden pieces. It’s big enough to hold a stripped lower so I’m going to give it a go most likely.
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Dremel it and post pics. 
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I’ll post pics but I think I’ll avoid the Dremel! 
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im very interested in seeing how your engraver turns out. I personally would lke to get a laser printer/engraver and give it a go that way. then agian i also wouldnt mind learning about 3d printing too, as i’ve never done it myself. both i think i would like a lot. it sure would beat having to take it to a trophy shop for them to engrave for me
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Ok, gave it a shot with the 3018. It runs on GRBL firmware. I just swapped out the motion control board which was ver 0.9, now it’s 1.1. The new version adds a port for an offline control so I don’t need to keep it tethered to my laptop any more. The offline control is a little touchscreen and so far it’s working out wonderfully. Since this was the first thing I tried to do since the swap, I thought I should take baby steps with it. I had previously printed a fixture to hold the lower in the machine. It wasn’t made for the t slot spacing on my table so I improvised clamps to secure it. I just squared it to the X axis and checked between the cutter and receiver in a couple spots with a feeler gauge to see if it was more or less level. Some paper shims got it close enough. To make sure I had the lettering located correctly, I 3D printed a test piece to insert into the safety selector hole with markers to indicate where the letters should be. Also has a circle to mark the hole and a dot in the center which marks the origin of the work plane so I can line up the spindle before I hit the start button. I zeroed off the face of the plastic test piece and it cut the markings pretty much spot on. Ok, so now I felt confident enough to try the actual cut. Here’s the plastic test piece-
I ran the machine super slow on the travel, max of 50mm/min and took several shallow cuts of .05 mm each. NFA markings need to be not less than .003” deep, I cut these to 0.2mm which is .008”.
How’s it look?
I need to mirror the fixture and print a second one to engrave the other side and if it keeps going good I might get adventurous and mark them for caliber also.
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That’s looks amazing!
With that jig, if you ever needed to drill a third hole it would be held well in place. Hypothetically, of course.
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If I ever needed to drill a third hole, hypothetically of course, I have way better ways of doing it but this big girl isn’t computer controlled.
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Looks good.
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Since this little router mill appeared to be working, I modified the fixture model I had found online to better fit the work table, printed a new one and mirrored the model in the printer’s slicer to print one for the other side. Now I need to model one for the AR9s and 45s.
I’ve had this 3018 for a few years now, I was looking on Amazon and I see there’s couple newer versions out. One has a 500watt spindle and is all metal with a much stronger frame and x axis. About $400 but that would probably be perfect for doing these or other small projects. I’ve got a pile of parts to build a bigger one with a 1500 watt spindle, I need to get on that project!
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Consider coming up with your own unique serial for your 80% lowers, now that you have a way to engrave them.
I actually LIKE the thought of having a readily-identifiable number, in case it should ever be Stolen/misplaced/etc. It’s just not any of the dang Government’s Business what it might be, or even that it exists at all.
Not a bad outcome for what it is. Can see a little offset skip on the ‘S’ when zoomed in. Looks 10x better than any of my work.
I’d be careful running that setup on anything anodized though. Anodizing tends to chip/flake.
I didn’t care what one SBR lower looked like so I dremeled it. Wow is it ugly. Took lower to local shop and asked them to laser same info below my doodles. They proceeded to ‘cosmetic’ (not even close to depth spec) laser over the top of my job. It looks even worse now. Oh well I tried, no longer care.
I’ve been pleased with Gray Laser (No affiliation or relation) for stuff I wanted to look nice and be in spec.
I think what you’re seeing is the font I chose, it added a little triangle at each end of a line.
The light blue line is the tool path, you can see the little v shapes at the ends of the lines.
And it shows in the engraving
Not sure how I get around that unless maybe if I model it very shallow and then set the cut depth deeper on the machine? Or maybe there’s some kind of stick font that would be just lines with no depth?
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I did NFA engraving for an SBR with an electric engraving pen. And I instantly regretted it.
“Oh… Oh no… yeah that DOES look like s*! 
”
YES! Exactly what I want to do! But the ones capable of cutting into metal are EXPENSIVE. I considered it as a part of the FFL gig, but it would take a year or two to recoup the cost.
Now, i’ve seen some small, CNC type units that are like 3D printers, but all are Chinese cheapness and I don’t want to risk spending too much and then respending for what i should have gotten the first time.
Lovely
as good as you are of a ffl, i dont think it would be a bad investment for your ffl gig. (im being bad arent i? ) but yeah i know what you mean there. i have a buddy who does that stuff and they are very very expensive. i’d still love to have one. i figure if i wait long enough the price should eventually come down. hopefully.