Building an AR as a display piece on the wall...

[Michele]

Hint- Tiny detailed weeding tools: pin, needle or a weeding set.

 

[Mooner]

Finally got a good finish out of the new Aluma-Hyde. Still sputters after a few sprays, but I have a shot glass of nozzles soaking in acetone. Just kept swapping can nozzles. Baked the finish this morning in the oven so I can reassemble it tonight.

Tip #1 DO shake Aluma-Hyde really, REALLY well before spraying.
Tip #2 Spray upside down until air comes out to clean.


View: https://www.youtube.com/watch?v=Pw9HjB5keGY&t=3s

 

[clm2112]

Etch of the first part of the roll stamp went well. Went pretty fast too, with that much bare aluminum being done at once, the current jumped up to six amps and it really sizzled away. Only did twenty seconds at a time and let everything cool back down, repeating the cycle until the pattern was deep enough into the metal to account for a finish coat over it.

 

[clm2112]

Tip #1 DO shake Aluma-Hyde really, REALLY well before spraying.
Tip #2 Spray upside down until air comes out to clean.

While generally good advice for any spray paint, doesn't help with this stuff. Again, this was a brand new can, with a brand new nozzle. It was rattled for about two minutes before, and repeatedly shaken between attempts to spray it. Temp was around 75 degrees.

The problem is the paint formula. It is curing as it leaves the nozzle, so instead of a mist of atomized liquid paint, you get globs of semi-cured paint hitting the part. Only solution is to wipe the nozzle, dunk it in acetone, and switch to a clean one. Over and over.

This can is about empty now, and it will join the others in the trash can. It is a shame, it used to be a good product, but now it sucks.

 

[clm2112]

And it is done... at least the etching part. It will still need machined.

 

[clm2112]

Morning screwing around. Started on the second NAPA Know-How 15 joke lower. But, wanted different safety selector markings. Needed some art work clean enough for Silhouette Studio to be able to trace into vector files. So, cobbled this pair of files as a left and right handed pair. Taking HK style safe and fire icons together with markers for the aluminum stops cast into the lower.

If anybody wants to use them, feel free to take them. The printed image needs to be scaled to 1.1875" top to bottom using the black border rectangle.

 

[Michele]

Here’s a nice vid on how to adjust downloaded art work to make it easier to print small stencils. Shows how to simplify the design by removing or modifying lines/points. This guy also has some interesting videos on adding textures, two tone and advanced etching techniques

View: https://m.youtube.com/watch?v=8fPySwspnIo

 

[Bobster]

And it is done... at least the etching part. It will still need machined.

Any significance to the serial number? Oil filter PN that screws onto a solvent adapter, perhaps?

 

[clm2112]

Any significance to the serial number? Oil filter PN that screws onto a solvent adapter, perhaps?

No, that would be a 4003 fuel filter (Wix 24003) which is, sadly, currently off the market. Probably a direct result of its unintended uses.

The serial number does mean something, though it has to do with the TAMS invoicing system and wouldn't work outside the store. The fellow, for whom this 80% was being decorated as a gift, would get the serial number reference. He's expressed an interest about building his own AR several times... so now he doesn't have an excuse. He's got a drill press, access to a machine shop, and access to a set of jigs, which a third employee currently has.

The second one, which I am finish up the etching on this afternoon, has a different serial number, but is also a number in the TAMS system that I am unlikely to ever forget. This one I'll finish into a functional rifle. (Just when I had swore I had done my last AR, along comes another...)

 

[clm2112]

And now the machining begins. Simple task last night and this morning. Drill the 3/8" hole for the safety selector, chamfer the hole, deburr the intersecting hole for the detent, and fit a safety selector. Did it twice before the first cup of coffee. Pair of ugly A2 grips, trigger guards and roll pins, and test fit the magazine releases.

Got an unpleasant reminder of chemistry class. While the salt-vinegar etching solution is a mild acid, it is still an acid and will continue to do its thing even without the application of an electrical current. The Olympic receiver got some corrosion in a few of the letters. I failed to neutralize all of the acid. Scrubbing with dish soap wasn't a strong enough base. Got to stop at the grocery store this morning and get some baking soda for a rinse that will cancel out the vinegar.

 

[clm2112]

I did etch the pattern from the Mega "Gator" receiver onto the front of the magwell of my copy of the NAPA receiver. Mixed feelings about how it turned out. Doesn't look machined enough in my opinion. I may go over the entire pattern with a ball end mill to give the grooves a rounded profile instead of the waffle look.
Still debating this... the aluminum that makes up the front of the magazine well on an AR is awfully thin. Cutting too deep might weaken it too much.

 

[USApat]

And now the machining begins. Simple task last night and this morning. Drill the 3/8" hole for the safety selector, chamfer the hole, deburr the intersecting hole for the detent, and fit a safety selector. Did it twice before the first cup of coffee. Pair of ugly A2 grips, trigger guards and roll pins, and test fit the magazine releases.

Got an unpleasant reminder of chemistry class. While the salt-vinegar etching solution is a mild acid, it is still an acid and will continue to do its thing even without the application of an electrical current. The Olympic receiver got some corrosion in a few of the letters. I failed to neutralize all of the acid. Scrubbing with dish soap wasn't a strong enough base. Got to stop at the grocery store this morning and get some baking soda for a rinse that will cancel out the vinegar.

View attachment 13442

Righteous etching there!
You're getting better at it.
Looks like a deeper etch and more defined.

Do you perhaps recall how long you were dabbing it with the gauze to end up with that depth?

 

[clm2112]

Righteous etching there!
You're getting better at it.
Looks like a deeper etch and more defined.

Do you perhaps recall how long you were dabbing it with the gauze to end up with that depth?

Thanks,

As to the time... umm... I really stopped timing the process and started just keeping tabs on how deep and black the etch gets. The thing is, the etch is variable based on the amount of current the battery charger is pumping out and the amount of bare aluminum being etched.

For example, the NAPA logo etched very quickly. The amount of bare aluminum in contact with the puddle of etching solution drove the amps way up. For a while it was shoving 6 amps into the part. It sounded like bacon in the frying pan. But doing the "SAFE" took longer and never went past 1 amp.

The other thing... the etch works best when you have a gap between the gauze and the surface of the part. I think it allows for the bubbles the move the aluminum oxide out of the way, letting to etching solution attack the bare aluminum under it. Sortta like brushing away the dust when you are sanding wood. So, when you see a lot of bubbles and this grey/black foam spooge flowing, it is etching more efficiently than just pressing the gauze against the metal.

And that kinda makes sense from an electrical standpoint. Bare aluminum is a great conductor of electricity. Rusty aluminum (aluminum oxide) is a poor conductor of electricity. And that is what the etching process is doing... converting aluminum into aluminum oxide as fast as possible.

 

[clm2112]

Milling in progress...

Nothing fancy, a 3/8" HSS 2-flute end mill and a lot of transmission fluid to keep it cool.

First cut is a slot along the length of the trigger pocket, roughly 0.455" deep, 0.500" wide and stopping well short of the bolt catch slot. (The black marker line & scribe mark is the "DO NOT CROSS" fence line... to keep from accidentally cutting into the magazine catch spring area. It is 0.110" from the edge of the slot.) When I get to the last cut, I'll sneak up to the line with width-wise polishing cuts to form the front of the pocket right at the scribe mark.

Second cut is to drop down approximately 0.630" and mill a slot the width of the 3/8" end mill. This connects the shelf under the rear take-down pin with the rest of the pocket. It also starts to open up the safety selector area. The actual depth here is just approximate, since I'm blending an existing milled surface to the rest of the pocket. It's not a critical dimension, it just has to look nice.

The next cut, after some coffee, will be 1.249" deep to open up the safety selector and an area for the tail of the trigger to pass under it. This will be the floor of the entire trigger pocket.

 

[clm2112]

Also, I've had a little change in plans. I've been trying to figure out how to make the dummy trigger work, and my original idea of coming in from the bottom isn't going to work. There just isn't enough motion to work a micro-switch.

So, I'm going to machine the lower like any other functional AR. I think I can use the hammer pin to retain a circuit board and speaker. Then use the top of the disconnector to operate the micro-switch. That really simplifies things, and it includes the safety selector as part of the mechanism. To get it to make farting noises, you put the safety into the fire position and that allows the trigger to move far enough to close the switch and turn on the electronics.

Who ever said making a joke was easy.

 

[clm2112]

What a day. No sooner than I had posted that photo this morning, I went to start the next cut on the milling machine... and POP!!!... Nothing. The damn chink contactor broke and shorted out. Spent a few hours going over the wiring diagram and around 9:00am made a trip to work for a simple DPST switch. The mill got simplified. At some point I'll put a second switch to be able to change spindle direction, but for the moment it is running again. (Heck, might never do it.. I can't remember the last time I needed the spindle to run in reverse.... and besides, I'm still planning to put variable speed motor on it anyways.)

With the mill back in operations, cutting commenced again. Got a little chatter in one spot... didn't see that coming. But, it isn't in an area that will cause problems. Finished the rest of the cuts and now it is in the oven having the epoxy finish cured.

 

[clm2112]

Happy Labor Day!

And.... the NAPA Know-How 15 is done! Ok, still need to make up an upper for it...haven't even though much about it. Perhaps a A5 variant, with a Vltor stock, 20" 1-7 barrel, and the M5 rail. Really just have to think through how much I'd want to sink into another AR. I still have an A2 upper to cobble together for the Olympic Arms wall hanger.

For the moment, I'll just borrow one of the clone M4 uppers to test the rifle out. I expect it will go well, the internals are mostly CMMG fire-control with an Expo Arms ambi safety. Decent pull weight on the trigger.. about 5lbs. but reasonably smooth. The spare parts drawer is slowly emptying out.

 

[NavyVet83]

Damn she's pretty... That castle nut... Is yours backwards or have I been installing them backwards for a very long time now?

 

[clm2112]

Damn she's pretty... That castle nut... Is yours backwards or have I been installing them backwards for a very long time now?

No, you aren't seeing things, I put them on backwards. I do that to most of my rifles, since I don't stake the castle nut for a while. Keeps my little hooked hand wrench from slipping. I've got maybe 20 to 30 ft. lbs. on them most of the time. (the tool I use is an old Colt stamped metal combo wrench... castle nut hook on one end, 1911 bushing on the other. It's just handy for stuff than gets constantly disassembled and reassembled.)

When I settle on a setup I like, I'll put it on the correct orientation, torque it, then stake it in place.

I guess it sortta shows my view of staking and the amount of torque to use. For my own stuff, hand tight is plenty. I've never had one try to disassemble itself in use. Same goes for AR barrel nuts. If it is somebody else's AR, I'll torque the barrel, buffer tube, and do the staking. If nothing more than to dissuade the owner from trying to take it apart.

 

[clm2112]

Back to milling the faux Olympic lower. Took a break for a little while working on the NAPA lower, but loaded it back into the jig to make some more cuts on it.

Here is milling the cheeks of the trigger pocket. I didn't measure it, just transferred the dimensions directly from the commercial CLE lower with calipers. The exterior widths of the Tactical Machining 80 lowers matched up with the CLE, so I don't even have to adjust the measurements, just duplicate the thickness of the pocket walls. When the right hand cheek is done, I'll move to the left side, cutting till the width of a hammer and trigger just fits. That will minimize the clearance, so the parts can't walk side to side.

Got plenty of coffee, stereo playing albums (currently the Car's Heartbeat City) over the hum of the milling machine. Good times for a Sunday afternoon.