Engraving setup

[xfer42]

What's a good cutter, feed and speed for engraving small text (less than .01in height) on aluminum?

I bought one of those $155 brushless 15krpm engraving motors w/controller from ebay and mounted it on my mill (X3 CNC w/3ph motor).
20161226_145545.jpg

Heres the first test with the motor running full throttle. Im happy with the first test, but theres obviously room for improvement. Next test is to increase the feed rate, then reduce RPM. This is with a 60 degree V cutter:

12-26-2016 4-55-05 PM.jpg

12-26-2016 4-57-15 PM.jpg

[kcstott]

you buy single lip cutters and feed it pretty damn slow. like 5-10 IPM.
you can go faster with bigger cutters. Step your depth .005" or less per pass for the best finish.

[xfer42]

More info:

.125 cutter
7ipm
.005 step down on each pass.
15K rpm

The graphic was at 0.01, and the text was at .015
Text is probably at .01, since I didnt go to great lengths to true up the test material.

Im using these bits:
20161226_175310.jpg

[xfer42]

Changed cutter to a 30 degree.
Changed step down from .005 to .002
Changed engagement from plunge to ramp
RPM 15k (unchanged)
IPM: 4.8

Looks much better. The first test above (first post), the text was illegible after wiping away all of the debris and oil due to the burrs around each edge. I had to take a wire brush to it. This time I just hosed it off and wiped it down.

That small text is a little under .090in tall.
Depth is ~.005 +-.002

20161228_161158-1.jpg

[kevins750]

You need something to practice on?

[xfer42]

You need something to practice on?

Working on the jig now. Im thinking of a 3/4in aluminum plate with fixed steel pins for the takedown and pivot, and tapped holes to clamp the lower through the mag release (2 holes so it lines up regardless of which way you drop the lower on). The jig will be custom fit to the table so I can drop it in, tighten down the recessed bevel screws and it will be true on X and Y. Zero X and Y on the jig and Z on the lower.

You can QA test it. You will have to type in the text, and hit go.

[canid]

I'm currently building a fixture plate for a lower myself and I'll be very interested to see what you come up with and how it works out.

Mine is meant to be multi-use for mounting in the vertical as well as the horizontal and I've gotten as far as laying out and drilling the major holes so far but I haven't worked out how I'd like to proceed from there. I'm sure it could fixture a lower for engraving with a little shimming but I want to get the most versatility from the fixture as I can since 3/8" aluminum plate doesn't grow on trees.

[xfer42]

I'm currently building a fixture plate for a lower myself and I'll be very interested to see what you come up with and how it works out.

Mine is meant to be multi-use for mounting in the vertical as well as the horizontal and I've gotten as far as laying out and drilling the major holes so far but I haven't worked out how I'd like to proceed from there. I'm sure it could fixture a lower for engraving with a little shimming but I want to get the most versatility from the fixture as I can since 3/8" aluminum plate doesn't grow on trees.

It will be similar to what you have pictured. The top will have a lip on it so it hangs down in the table slot for alignment. Ill have 2,3 or 4 bolt holes that will clamp it to the table with T nuts on the other side. The idea is to clamp it the table first, then drill the holes in the jig. This will be so I can drop the jig onto the table, clamp it and have it true without having to bang it around.

The receiver will rest on blocks first. The pins for the takedown & pivot will be long so I can use an edge finder on it to get XY zero. Im curious to see how much I will have to shim it if the sides of the receiver are not parallel, and if not, how much it will affect the engraving.

[xfer42]

So heres the jig so far. The two little holes line up with the mag release depending on which side is facing up. Im hoping to have both AR and LR308 pins and holes.

20161230_134102-s.jpg

Please excuse the beater lower. It was one of my first raw forging builds.
20161230_134239-s.jpg

[kcstott]

Be advised AR308 pins are larger but i'm sure you could take a pin a spin one end down a bit to fit your .250 hole

Engraving looks good man.

My first paying job



Yes that's my daughter's bike in the background, Why? because the graver is set up on the kitchen table. Why? because I can. I bought and paid for my divorce many years ago.

[xfer42]

Be advised AR308 pins are larger but i'm sure you could take a pin a spin one end down a bit to fit your .250 hole

Engraving looks good man.

Thanks!

It will have different holes. Im planning on putting them above the AR holes. I started turning down some 3/8 rod and ended up with .268 somehow (wanted .277 or .278). I just gave up on it and decided to move on with the AR setup just to get something done.

[Beatone]

Nice work.

[xfer42]

Nice work.

Thank you

[CptDan]

What I have done for the engraver that I take my stuff to is provide 1/2 of a AR 80% jig

[rrwallace]

Excellent work!

Are you looking for work or setting up you own shop for ar15 lowers with serial numbers?