SEPA Milling Party?

[alpacaheat]

While you could offer the space, I am now convinced that a "milling party" won't be much of a party.

I milled out my first one today, and it took about 5.5 hours and I didn't have any issues. 6 with cleanup.


Some tips/lessons learned:

*Tape over parts you do not scratched, it's worth the effort, but have Goo Gone because the glue from the tape will get heated up and gummy.
*Don't bother with a drill press, unless it's a heavy duty one. I have a brand new, never before used 8" drill press...wouldn't cut through, I don't think you can get the leverage on a drill press handle that you can pressing down on a hand drill with your weight. I used an old CORDED Black & Decker drill, worked like a charm.
*Lots of lube. Oil the bits and end mill every time it's out of the hole.
*Don't drill too long without cleaning out the holes. I found a good tactic was drilling for 10 seconds, lift the bit out while still spinning to clear out the hole and go back in. Then after every 5 cycles, I'd stop and vacuum the entire receiver out, re-oil the bit and go for more. When I had holes fill with debris too much twice, the drill grabbed and nearly broke my wrist.
*Take small passes with the router and you'll have an easy time and clean product.
*Just take your time, vacuum after each pass to keep it clear and prevent a giant mess of shaving from piling up. Each hole I drilled covered the entire work bench so I can't imagine what your space would look like NOT vacuuming each pass.
*Drilling was the bulk of the time, very time consuming, and required some muscle. Routing was very quick and effortless.

I also watched each step from this video before moving onto the next step:



I bought a backup receiver in case I messed up, but it went pretty much perfectly and my jig is unscathed, so I'll probably mill a second one next week.

[alpacaheat]

[Gunsnwater]

Looking good. Nice pictures.

[alpacaheat]

Thanks!

Actually crappy pictures from the sun shining in the window but the inner wall i perfectly smooth, I'm surprised how well my first attempt turned out. The only flaw I see is that the trigger hole is slightly mis-shaped but it will work and no one will ever notice it but me.



NOW, I have to figure out if I need to coat the milled metal with a protective finish or leave raw. I am seeing conflicting opinions online. I'm thinking about getting some Duracoat spray and doing the inside and out, but then again, I'm easy to put the LPK in!

Anyone know if I really NEED to coat the inside?

[Hodgie]

It wont rust and if anything it will oxidize which actually makes it stronger from what I have read. I have seen raw 80%'s that were left that way once milled out and assembled into rifles without any issues after a few years. Once iI finished mine I was thinking about polishing one then giving it a clear coat so it shines.

[alpacaheat]

That's what I've heard as well. It's just the inside, unseen.

[jkl56]

Some tips/lessons learned:

*Tape over parts you do not scratched, it's worth the effort, but have Goo Gone because the glue from the tape will get heated up and gummy.
*Don't bother with a drill press, unless it's a heavy duty one. I have a brand new, never before used 8" drill press...wouldn't cut through, I don't think you can get the leverage on a drill press handle that you can pressing down on a hand drill with your weight. I used an old CORDED Black & Decker drill, worked like a charm.
*Lots of lube. Oil the bits and end mill every time it's out of the hole.
*Don't drill too long without cleaning out the holes. I found a good tactic was drilling for 10 seconds, lift the bit out while still spinning to clear out the hole and go back in. Then after every 5 cycles, I'd stop and vacuum the entire receiver out, re-oil the bit and go for more. When I had holes fill with debris too much twice, the drill grabbed and nearly broke my wrist.
*Take small passes with the router and you'll have an easy time and clean product.
*Just take your time, vacuum after each pass to keep it clear and prevent a giant mess of shaving from piling up. Each hole I drilled covered the entire work bench so I can't imagine what your space would look like NOT vacuuming each pass.
*Drilling was the bulk of the time, very time consuming, and required some muscle. Routing was very quick and effortless.

Are you sure your drill bit is sharp enough? I have not had to use very much downward pressure when drilling aluminum.

[t1066]

Are you sure your drill bit is sharp enough? I have not had to use very much downward pressure when drilling aluminum.

I meant to follow up on this. It sounds like either a dull bit, or edge geometry that isn't optimal for aluminum. Aluminum is a very easy material to drill, and shouldn't take much pressure.

[mrat]

And end mills aren't the best tool for plunge cutting. Run a drill of smaller diameter down first. If using a milling machine, the travel locks are your friends. Lock the axis not being used and keep the other snug and knee (z axis) locked. Also, have the spindle retracted when possible or at least shortened, on the stop, and locked. When drilling the holes, use a 1-size smaller bit, then cleanup with proper diameter. Having been a machinist and never did an 80% lower, I at least would like to observe in person, when all this shit dies down.

[Gunsnwater]

If your going to drill smaller, why not use an adjustable ream to size to pin?

A book on clock repair talked about swedging the holes to work harden the brass plate. Aluminum work hardens.