An Air Fitting...

Joined: January 1st, 1970, 12:00 am

August 10th, 2018, 3:24 am #1

In the Airlines Project thread, I spoke of putting a compressed air outlet on my workbench, close enough for easy access to my main work area. This particular area was a short section left over from when I rearranged and rebuilt my bench several years ago, to mount the wide map drawers.

It was too narrow for shelves or drawers, I didn't have anything tall and thin I needed to store in there, it was too small to stuff a trash can into, and so on, so it just sat. yesterday I made the plywood cover to enclose it, and the plan is to connect the new compressed air system to that cover, via a bulkhead fitting of some sort.

Now, the trick is, I wanted to keep the quick-disconnect kind of out of the way, as the vise directly above is a busy spot on the bench. I didn't want a QD sticking out that might interfere with something long and thin clamped vertically in the vise, I didn't want it oriented so that swarf from any sawing or filing activities might foul it, and just generally keep it out of the way so I didn't bash a knee on it, or snap it off with an errant hammer swing or something.

So after pondering it for some time, I came up with something i though would work, and then painstakingly modeled it in wireframe CAD:

I wanted to make it so the threaded junction was basically as close to the plywood face as I could get it, and angle it downward at 60 degrees, rather than the normal 45 degrees, for that little bit of extra clearance.

So, I went and bought 3-1/2" of 2" OD aluminum roundbar...

Milled approximately 2-1/2" of it down to 1" thick and centered...

And flatted the short sides in case I need to clamp there.

Using a 30-60-90 triangle, I set the thing up in the vise and milled a centered flat 'bout thar.

That got a blind hole drilled and tapped to 1/4" NPT...

Which was checked for depth...

And then milled flat and true to the axis of the fitting.

Rotating the part back to vertical, I then flattened off the sides of the boss, also to 1" thick.

(Continued next post)

Joined: January 1st, 1970, 12:00 am

August 10th, 2018, 3:37 am #2

Now for the fun part. I could have left that boss squared off like that, maybe smoothing the corners up a bit with a file, but that's just not how I roll. 😁 So I got out the 1/2" corner-rounding cutter, and very gingerly cut as much of the high end of the boss as I could reach without contacting the flange.

Then, a bit of masking tape on the already-milled portion as a sort of contact indicator, and some careful etch-a-sketch milling of the rest of the boss to follow the contour.

Like so... complete with one touchdown flub which of course will be too deep to sand out. 😫

Then it was time to get out the files. A few minutes out in the late afternoon sun and I had the milling marks smoothed down.

However, I didn't like that line left from milling off the mounting face....

So I threw it back into the mill and shaved the flange down a bit more.

After that, it was back to the post vise for a bit more careful filing and shaping. Easy peasy, just takes a bit of patience.

And then, a quick trip through the deburr wheel smooths up the file marks and softens the edges somewhat.

Unfortunately, that was all I had time for today, I'll finish it up Friday. 😁


Joined: January 1st, 1970, 12:00 am

August 11th, 2018, 5:51 am #3

Continuing this little project that clearly has all of you riveted to the edges of your seats... or something... I was never too good with metaphors. 😋

Anyway, back into the mill to get a drilled passage connecting to the angled passage at the front, then tapped to 3/8" NPT:

Then, the blocky back half is hit with the same corner-rounding bit to shave off a little bulk. As this part is hidden inside the cabinet, this isn't for aesthetics, it's for clearance.

And, same game as before, the corner where the bit couldn't reach due to the flange, is milled out etch-a-sketch style to get rid of the bulk of the metal.

That, too, is then smoothed down with files:

The underside of that boss is then milled down, this time leaving it flat and with a bit of extra thickness- the original plan was to tap a drain valve off of it, but as the design evolved, that had to change.

Finally, it was time to do a little touch-up with the files, and take a little more care blending the peak a bit better.

And some wet-sanding to get rid of the file marks and smooth things up nicely. I may try polishing it. 😁

And finally, a pair of countersunk screw holes to take a pair of the ubiquitous stainless allen-drive screws:

Et Voila`! (Which I'm still pretty sure is French for "check this s**t out!" 😋 )

It drops the QD down at 60 degrees rather than 45 for extra clearance, gets it right up close to the bulkhead, and has enough length inside that I could add a drain right at the assembly if I need to.

All that's needed now is a funky hole in the plywood insert...

And a couple blocks screwed to the bench legs for the insert to attach to. And that's it! Nice and low profile, out of the way, and is actually about an inch further in than the edge of the workbench itself. I'll call that ideal.


Joined: June 2nd, 2015, 3:34 am

August 11th, 2018, 8:24 am #4

It is possible to commit no mistakes and still lose. That is not a weakness. That is life.

Joined: September 12th, 2014, 3:32 am

August 12th, 2018, 4:47 am #5

Verra nice!