Author Topic: Making a small metering valve for an angle head air impact -  (Read 176 times)

Offline goodfellow

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One of my favorite 3/8" impact wrenches bit the dust the other day. I hadn't used it in about two months and when I tried to turn the air flow valve, the dial knob broke completely off. It's cheap cast zinc alloy and not repairable.





Once I had it apart, I found that the metering valve had a crack in it. Which makes sense because the valve has been harder to turn of late than in previous years.



I tried to find a replacement, but the only importer of this wrench quit stocking parts years ago and besides, the market for angle head impacts dried up decades ago as well. Since it's one of my favorites I decided to make a new valve.

The dial was still intact and all I did was face off the broken end and drill and tap for a 5x1.5-mm machine screw. A few drops of red Loctite and the screw was permanently attaches to the dial.





The entire valve assembly looks Like this --







To make the metering valve I chucked up some round aluminum stock and slowly crept up on the diameter -- 0.473". Making such small parts in an imported HF Chinese 3in1 is a bit of a chore, but it does work.



a half hour later I had my roughed in part -- all drilled and tapped to receive the 5x1.5-mm machine screw I put in the dial.



A little more work with lathe and I had a new valve.



It was close enough to the original  -- a rough piece, but it can easily be hand finished.



A few zips with the a flat bastard and a round file and I had my cam profile back to match the original.



I used red Loctite to permanently fix the valve to the machine screw on the knob so that the entire assembly can turn as one unit. A new "O" ring completed the job and after reassembly is worked like new. Much easier to adjust and regulate than before.

Offline DeadNutz

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Re: Making a small metering valve for an angle head air impact -
« Reply #1 on: April 11, 2018, 09:30:45 PM »
Very nice job gf. That is the value of having machinery and knowing how to use it. Great saves like that makes it worthwhile. thumbsup2

Offline goodfellow

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Re: Making a small metering valve for an angle head air impact -
« Reply #2 on: April 12, 2018, 09:59:47 AM »
Thanks DN -- Sometimes even marginal imported Chinese lathes can do the trick on a delicate job like this.

Offline Uncle Buck

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Re: Making a small metering valve for an angle head air impact -
« Reply #3 on: April 12, 2018, 02:05:14 PM »
Thanks DN -- Sometimes even marginal imported Chinese lathes can do the trick on a delicate job like this.

More often than not, the decisive factor is the operator and not the quality of the machine, but I know that you know that too! That said, quality machines always help.  thumbsup2
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Offline Muddy

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Re: Making a small metering valve for an angle head air impact -
« Reply #4 on: April 12, 2018, 08:10:33 PM »
Great work Ray, saved another one!

Sent from the twisted mind of the Mudman.

"And on the 8th day, God looked down on his planned paradise and said, "I need a caretaker." So God made a farmer."

Offline tool hunter

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Re: Making a small metering valve for an angle head air impact -
« Reply #5 on: April 14, 2018, 12:02:27 AM »
Nice job GF. Your talents are unyielding.

The Garage Gazette

Re: Making a small metering valve for an angle head air impact -
« Reply #5 on: April 14, 2018, 12:02:27 AM »