Sunday, January 6, 2013

CA Adhesive As A Machinist's Aid

Cured CA adhesive ('Krazy' glue or 'Super' glue) is not terribly heat resistant -- boiling water temperature will soften it. While that's a weakness of the material for some applications, it's a characteristic that can be put to good use in the machine shop at times.

I have a small gland nut from the valve stem of a propane torch with ruined threading on it. [Long story.] If I can turn down the mashed threads so that the nut's shank can at least re-enter the valve's stem-hole, I can get the valve back in working order. The difficulty is in mounting the tiny nut for turning on the lathe. That's where CA adhesive comes in. Here's a view of what I've done up so that I can chuck the gland nut.

A length of 1/4" steel rod and 9/32" brass tubing provide a foundation on which I can squarely place the damaged nut. I've applied CA adhesive and let it cure. Now I've got a 'mandrel' that I can chuck in the lathe.

When I'm done turning that, I'll dismount it, heat it up a bit with a propane torch and the nut will come free of the mandrel easily.

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That worked nicely.

Now I'll free the nut from the mandrel and I can reassemble the valve.

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Here's the valve back together less the knob.

After inserting the now threadless gland nut, I applied CA adhesive all around the perimeter of the nut's hex,[1] and set the thing aside for awhile for the adhesive to cure. That adhesive-secured gland nut should work fine. That nut really doesn't do much -- all it's there for is to provide a sleeve bearing for the valve stem. The gland nut has no sealing function, and it really has no load to bear of any consequence, so held-in-place-by-glue is just as good as held-in-place-by-threads.[2]

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Here's the torch fully assembled and operational.

CA adhesive is versatile stuff. I'm never without it on hand.

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[1] CA adhesive can be treacherous to work with in this sort of situation. The stuff is extremely runny, and it will wick in anyplace and everyplace it can. Never take the attitude 'if a little is good, more should be better'. You'll end up regretting it.

[2] This is a good example of the value of setting aside orthodoxy at times, and pondering what it is that a given component really does. As long as I remained fixated on having a proper screw-in gland nut, this torch just sat idle in a box under my workbench. Once I finally studied the problem more thoughtfully, it dawned on me that the repair method outlined above could work, and was worth pursuing.

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