THread repair question

You can make your own tool to drive the keys in if you have a lathe, just turn a step to slip fit in the minor diameter of the internal threads. The idea is to push the pins straight in without bending them sideways. An alternative would be a socket head cap screw the right size. You might be able to drive them in straight with a flat piece but if the keys get bent, the expensive insert gets tossed.

Be sure to use the correct tap drill size recommended by the manufacturer, it will be larger than the drill listed in a regular tap and drill chart.

According to Alex :

O.K. I've used similar inserts, though smaller than the smallest listed on that web page.

As above -- yes, except smaller.

The tool which came with mine was a piloted tool which fit into the threaded hole (without engaging the threads), and with a pair of milled grooves on the OD to engage the keys to thread it in. The inserts also had a very slight flared end so they would only go down flush with the surface (with a *very* shallow countersink).

Once you threaded it down to the surface, you lifted the tool partway to disengage the keys from the grooves, rotated 90 degrees (since there were only two keys, this gave the maximum separation between the grooves and the keys), and then hit the end of the tool with a hammer to drive the keys into the threads and lock it in position.

Note that you *don't* want to drive *between* the keys. You want to drive the keys into the engaged threads between the workpiece and the insert. They break free of the attachment to the insert, and make their own place in the threads, going into the grooves in the OD of the inserts.

The keys keep the insert from unscrewing, or screwing through the workpiece ahead of your screw.

Based on the information on your indicated web page, these get screwed in with your fingers (they are a bit larger, after all), and you stop just below flush with the surface (as these don't have the flare).

Then you insert the special tool, which you can make on a lathe (you *do* have a metal lathe, don't you?), with a pilot just small enough to slip into the inner thread, and with an OD large enough to overlap onto the surface into which you mounted the insert, and tap with a hammer. *Don't* try to drive the keys directly with a hammer -- you'll almost certainly bend them over instead of driving them in.

I would machine the tool in a lathe from a length of the proper diameter drill rod, then harden and temper. You don't want it so hard that it is brittle, and you also don't want it so soft that the keys will embed in the driving surface. Probably case hardened mild steel, with a good deep case might work just as well.

It looks as though the illustrated tools in their photo are double ended -- to work with two different sizes of inserts.

If you *don't* have a lathe, $14.00 for the tool strikes me as a deal, compared to the cost of any size of metal lathe.

Enjoy, DoN.

Hammer might work........try the hummer first, then a hammer Daveb

Without the pilot, the keys will force the insert inward away from the tapped hole in the item. The insert won't lock, and the insert will not accept the fasterner because it's been deformed.

Jim

"Don't use force, use a bigger hammer."

Happy 4th of July guys, we're gonna drive up and take in the Ruggles mine this afternoon, a place I've been wanting to see for years.

Should be a cool place, sprinkle breadcrumbs as you meander :-0

Mauro

Yes, the enormity of the hole they've dug through solid rock over the last 200 years took my breath away.

There were a dozen or so rock hounds among the visitors there today, busily hammering away all over the place trying to bust out some treasures to take away with them.

I was satisfied with collecting a few ounces of mica, mostly in silver dollar sized pieces, some of which were composed of many "layers" to a total thickness around 5/16", and some were just a single layer as clear as cellophane.

This photo of us and some folks behind us gives a pretty fair perspective on the size of just one part of the mine:

Jeff