I want to repair a thread with a Key-Locking Screw Thread Inserts like
on this page -
question - do I really need to buy a tool (costs $14)? Looks like I
can just hummer this insert with a hummer and a piece of metal that'll
go between keys.
Does anyone has expirience with this inserts?
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 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
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.
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
This photo of us and some folks behind us gives a pretty fair
perspective on the size of just one part of the mine:
That big column behind my left shoulder has a sign on it reading,
"PLEASE DO NOT HAMMER ON THE PILLAR". Good idea I think.