Making an air manifold from aluminum block

6061 is stringy. Spiral taps are much better for that. An alloy like 2024 is much easier to work, if you really want aluminum.
Brass or cast iron would be a better material for this application. So easy to drill and tap. Crispy little chips.

Hey Ig; 6061 machines real nice. Doesn't gum up the works like mystery alloy associated with extrusions etc. How do you plan to drill/bore the Al bar the 'long' way?
Ken.

That's very nice to know.
I was not going to actually.
My plan of the moment is as follows:
1) Drill 5" from one side, drill and tap a few holes in sides 2) Drill 5" from another side, drill and tap a few holes 3) Drill one through hole from the side in the middle 4) Drill one half hole from another side in the middle
That would let me distribute three kinds of air, or two kinds, I could be as flexible as I want. (kinds of air could be regular 90 psi regulated, 90 psi dried, and 90 psi lubricated)
i

Your brass idea is interesting. There are some bars like McMaster item 8951K511, kind of expensive at #35 though. Food for thought.
i

Consider why most commerical air fittings are brass. Not aluminum.
Of course, they're not paying boutique prices for raw materials.

Yes, I agree. I see some very interesting items on ebay, round stock though, but hard to beat the price.
i

I bought ebay item 200003744858. I hope that it will work for me. Thanks Richard!
i

Aluminum manifolds are not uncommon on machinery. Use tape or pipe dope and I doubt you'll ever tell the difference.
dennis in nca

This is very common in industry. 2024T6 as mentioned is nicer than the six thousand series to work with. When you go to tap it, be sure to check how far the fitting screws in. You need to have threads showing on the male part when it's fully made up, don't tap too deep.
Teflon tape or pipe dope will work fine, if you use tape do *not* tape the first thread of the male fitting, so you can keep the teflon out of the air flow.
If you tape the first thread the tape will extrude out in front of the fitting and the fine teflon particles can clog regulator seats. If you have any doubts on this, you might want to use dope rather than tape.
Jim

Jim, I bought some 1 1/8" hex brass bars on ebay, I will do as you say regarding threading.
i

As long as you are rooting through the catalog, look for ready built air manifolds. Usually they are about as cheap as buying barstock, without the work. Those are a couple types anyway.
I have used and made a couple out of black iron pipe. Cap both ends, drill and tap for the fittings. Way cheaper than barstock.
Cheers Trevor Jones

Thanks Trevor. These manifolds are nice, but do not do what I want, which is distribute several kinds of compressed air. I think that the easiest solution is to make one from barstock to my own spec. I got some brass hex stock, I hope that I could do it without screwing it up.
i

No argument, but I do tap 6061 quite often on one-off projects with no problem. Just use some tapping fluid or kerosene, and reverse the tap frequently. One can get away with a lot when doing one-offs where productivity is not an issue.
I'd probably make it of aluminum, save the brass for projects where I'd want to silver-braze or nickle-plate.

Production on high-speed CNC or other production machinery.

Dope is better for airlines than tape. Gunner sez bits of tape can get loose and screw things up. I find that dope seals better.

Iggy- If Ya wanna prevent broken taps then stay away from what is called a "spiral flute tap". These taps actually have helical flutes. What you want, especially for through holes, are "spiral POINT taps". These taps are ground such that the chips are forced down the hole in front of the tap. The spiral flute taps direct the chips up through the tap and out the hole entrance. When these chips pass the threads just cut by the tap they can hang up and damag e the threads. They can also jam in the flutes and cause the tap to break. So if you have room in the bottom of the hole, or a through hole, and a form tap won't work, then use a spiral point tap. Spiral flute taps are useful for the right job, and I use them. But as little as possible. And I use form taps as much as possible. ERS

Eric, I bought some brass hex bars on ebay:
For the tap, I got McMaster item 2525A113 this morning.
Are they going to work with one another?
In any case, if I encounter too much resistance, I would reverse, remove the pat and blow the chips out.
i

When I was writing about taps I was thinking about straight taps, not taper pipe taps. That tap you bought will work fine. Since it's tapered the full length (naturally-it's for taper pipe threads!), you will find that it it gets harder to turn the deeper you go. This is because it will be cutting the full length of the tap. I don't know what kind of brass the bars you bought are made of. But the most common form of brass in brass bars is called "half hard". It machines very nicely. However, drilling half hard brass can be touchy. Since you are only drilling a 7/16" hole you can drill this in one shot if you have at least an average drill press and the hole location doesn't need to be any closer that +/- .010". The problem with drilling arises when you already have a smaller hole in the part that you want to enlarge. When starting with the larger drill it will want to grab. This causes the drill bit to pull itself into the work. The next thing that happens might be a broken drill, or the part may come out of the vise, etc. To lessen this effect a small flat can be stoned on the leading edges of the drill bit. This flat should be parallel with the drill axis. However, like I said, you should be able to lay out the hole location, center punch, then drill with a 7/16" drill for a 1/4" taper pipe thread. The tap will get harder to turn and the chips will get packed in the flutes so you may need to back it out a couple times. If you do need to back it out then you might as well back it all the way out and blow out the chips. Since the tap is tapered you will find it spins out real easy after a turn or so. It takes so little time and effort to remove the tap completely you might as well do it so the chips can be completely removed from the tap and the hole. If the brass is half hard (as I assumed), the chips will be small and easy to blow out. You probably don't have a thread gauge for 1/4 pipe. It's been my experience that when tapping taper pipe holes up to 1 inch that when the last 7 threads on the tap are exposed the hole is tapped to the proper depth. This of course is one of those rules that's made to be broken. So when tapping your parts you should probably start checking for the proper depth when 10 threads on the tap are exposed. And your gauge will be the parts you will be screwing into the holes. Sorry for the long winded reply. It just seemed to me that I needed to be as clear as possible. ERS

Convert the drills over to brass drills before using them on that, othewise you will be quite suprised.
Jim