Monday, April 14, 2014

The Welded Nut Mechanism

I have mentioned several times that I like this simple technique.  It isn’t elegant craftsmanship like drilling and tapping and wouldn’t be acceptable in finished products but it is quick and effective for making jigs and other shop tools.  I use it today mostly when making dies.  

It is important that the hole through which the bold will pass is oversize so that there is no chance of obstruction and no chance the welding current will pass through the treads and create a contact point gall.  I use both the drill press and the torch to make the holes and don’t see much advantage with either one.

I like to screw the bolt in all the way and lock it in place on the opposite side of the hole with another temporary nut.  This assures the perpendicular orientation and can lock the bolt in the centered position protecting the threads.

The outside nut is secured with MIG beads.  I may just tack the nut and remove the bolt before adding more weld.  Finally, I apply anti-seize and insert the bolt again.

As, I said before, these are usually 7/16” bolts.  I’ve twisted off some smaller thread stock but not 7/16” that I recall.

Forging press die saddle with locking bolt.

Drill over-size hole.

Lock in position to weld with temporary nut.

Remove positioning nut, apply anti-seize and chase threads

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