# Dry Shop Air - Step 2 (Compressed Air Manifolds)



## MtnBiker (Sep 10, 2021)

Too many compressed air connections are just barely enough. At least that's how it feels in our shop with a combination of fixed and mobile equipment.

Didn't see anything we liked from the commercial vendors so we decided to make some air distribution manifolds. Wanted 4 outlets per drop, minimal strain on the air lines and a drain to catch any condensate. A nice jam session in Fusion 360 and we had a plan.





We had some 6061 laying around the shop and, looking closely, I could definitely see some manifolds inside. Time to square up some stock.




Gave us a chance to use our new Haas face mill in anger (Haas had an amazing sale last year).

Time to do some big chamfering.




Setups presented some nice brain teasers - V-blocks with a little spacing was the ticket to get the right size chamfers for the 1/4 NPT fittings.




I might put this on our Christmas cards this year - love aluminum glitter. Outlines for three distribution manifolds and a pass-through that will feed our overhead hose reel.

We decided to use PEX as our primary air distribution solution. Because of the compressor after-cooler we'll never have hot air running through the lines. There will not be any degradation in the pressure rating related to heat. We also decided to use Shark-Bite fittings. Clean and easy. However, this solution requires NPT fittings. These manifolds will have a 3/4 NPT input and 1/4 NPT for the air connections.




We needed to make a central air channel. The 57/64 drill for 3/4 NPT threading would do double duty (this is the right size if you are reaming before tapping). 27/64 is the size for the 1/4 NPT.

The 3/4 NPT tapered reamer is BIG (.96" at the widest). Did not have a way to chuck this. But these NPT reamers/taps were all turned on centers and had index holes. A shop made 60 degree dead center chucked up on the spindle did the trick.





Without a chuck/spindle needed to use the manual down feed handle to apply the right pressure on the reamer while using the big-boy wrench to turn. The dead center keeps everything straight too. A little slow (and there were five 3/4 holes - not that fun). Worked great.




NPT threads are tapered and there is a depth you are trying to hit (rule of thumb is 3 1/2 turns hand tight for the male fitting). To do that you need to tap the hole to a specific depth (and it isn't all the way to the end). Same goes for the reamer. For both of my 3/4 and 1/4 taps, the right depth was 7 troughs still showing above the work piece. Pro tip: I used a little dental instrument to count the threads - easier on the eyes.

After tapping all 21 holes we did a finishing touch




Added another chamfer (first time using an angle block). A little tricky - centered a 3/4 end mill on the mounting tab so all the pressure was at a right angle to the vise jaws (the other way would likely have ripped the work piece out of the vise - geometry is better than friction).






Finished part and installation. Happy with the way this turned out. Fun and very educational project. Really got to practice re-using setups and "production line" techniques.


----------



## extropic (Sep 10, 2021)

Nice pieces. It's excellent that you're wise enough to put a condensate drain at every drop. Few seem to.

I hope you never regret putting the mounting screws behind top and bottom fittings. I would have put them where they were always accessible.

Your design will certainly slow down the manifold thieves if they ever attack your shop. 

You're not the GM guy responsible for having to lift the engine to change the oil filter, are you?


----------



## MtnBiker (Sep 10, 2021)

Yep. We thought through that - but wanted direct mount to a stud with the body as stable as possible. This seemed worth the little bit of extra hassle. Not planning on moving them.


----------



## extropic (Sep 10, 2021)

MtnBiker said:


> Yep. We thought through that - but wanted direct mount to a stud with the body as stable as possible. This seemed worth the little bit of extra hassle. *Not planning on moving them.*



I wish I had a nickel for every piece that I was not planning on moving.   

My $0.02, 1/4" mounting plate screwed to the wall/stud. #10 machine screws (accessible) to attach the manifold to the plate.

BYT way, kudos for using an NPT reamer. Another thing that I don't see very often.


----------



## aliva (Sep 10, 2021)

Nice work. All I use is retractable hose reel on the wall, but I did run a separate line for  my milling machine  power draw bar.


----------



## benmychree (Sep 10, 2021)

The rule of thumb with pipe taps is to have 3 - 5 threads showing on the tap when at final depth.


----------



## MtnBiker (Sep 10, 2021)

I was getting 3.5 to 4 turns out of the fittings hand tight. Threads looked fully formed. That seems to be the consensus target - I don't think my Chinesium taps or fittings were reference spec. YMMV. There are plug gauges/go-no go gauges that would be calibrated references if you want to do this "right". I'd be happy enough if these were the last NPT fittings I need to tap.


----------



## benmychree (Sep 10, 2021)

MtnBiker said:


> I was getting 3.5 to 4 turns out of the fittings hand tight. Threads looked fully formed. That seems to be the consensus target - I don't think my Chinesium taps or fittings were reference spec. YMMV. There are plug gauges/go-no go gauges that would be calibrated references if you want to do this "right". I'd be happy enough if these were the last NPT fittings I need to tap.


Yeah, back in the day, I bought (used) ring and plug gages for a product that my shop made using 1/16" NPT (5/16-27 NPT) to insure interchangability with the product, gages with hollow needles to measure pressures in corked wine bottles to test how the vacuum systems on the corkers functioned.


----------



## MtnBiker (Sep 10, 2021)

extropic said:


> I wish I had a nickel for every piece that I was not planning on moving.
> 
> My $0.02, 1/4" mounting plate screwed to the wall/stud. #10 machine screws (accessible) to attach the manifold to the plate.
> 
> BYT way, kudos for using an NPT reamer. Another thing that I don't see very often.


Just shoot me if I decide to move these things. With the drops and hardware and having to patch and rework all the PEX lines...just no. We have plenty of options (3 drops like this one plus an overhead reel).

As for the reamers - I wanted to have the best fit possible given that this is aluminum. Seemed like a good idea. The 1/4 was no sweat since I could chuck it. The 3/4 was a PITA but using the mill to hold everything straight made it do-able.


----------



## Boswell (Sep 10, 2021)

aliva said:


> Nice work. All I use is retractable hose reel on the wall,



I added a bunch of drops scattered around my shop and other than the dedicated connections, and like aliva, all I seem to use is the retractable hose reel.


----------



## hman (Sep 10, 2021)

Am I the only one who noticed the FANTASTIC surface finish you got?  It's truly amazing.  Beautiful work!


----------



## MtnBiker (Sep 10, 2021)

Boswell said:


> I added a bunch of drops scattered around my shop and other than the dedicated connections, and like aliva, all I seem to use is the retractable hose reel.


Here is the short list of compressed air usual suspects we have, or will have, in our shop (just to give this post some perspective)

Mill:

air blow gun
power draw bar
misting/lube system
Lathe:

air blow gun
misting/lube system
Grinding Station

die grinder
accessory grinder
Weld Table

Fume extractor - filter clean (back-pressure)
CNC Plasma feed

Paint booth/paint sprayer

Tube Bender (future) air/hydraulic


----------



## MtnBiker (Sep 10, 2021)

hman said:


> Am I the only one who noticed the FANTASTIC surface finish you got?  It's truly amazing.  Beautiful work!


Thanks hman! I was pretty happy with the finish. Brand new end mills more than skill I think. I've also gotten into the habit of putting a very light coating of WD-40 on the part with an acid brush (less fumes).


----------



## MtnBiker (Dec 7, 2021)

Boswell said:


> I added a bunch of drops scattered around my shop and other than the dedicated connections, and like aliva, all I seem to use is the retractable hose reel.


We added a pneumatic die grinder at the grinding station, a mist-buster at the mill (will add another at the lathe) and another air gun at the mill. We're picking up the plasma tomorrow and there goes another one. Finally, going to port an air line outside through the garage vent to feed a paint booth on the back patio. We have 14 air fittings and have 10 connections in place or planned. Phew. This has been a lot of work to get the shop ready for our 2022 "go live"


----------

