Downsizing Screw Hole

[pushboater]

Anyone have any ideas on how to downsize a 10-32 screw hole to take an 8-32 screw without having to weld the hole up and re-drill?  I don't have access to a welding rig.  It's a Frizzen screw hole so there will be no force pulling against the threads.  I was thinking maybe J-B Weld and then re-drill with a #29 drill bit and re-tap 8-32.  Any other suggestions? 

[KLMoors]

Any welding shops nearby? A good welder can do amazing things, and around my area, a fix like that would be real cheap. Maybe $10 or so.

[pushboater]

Thanks KLMoors. I was trying to come up with a solution that didn't involve welding, but I may end up having to go that route. I've seen J-B Weld do some amazing things, that's why it was my first thought.  I appreciate your input.

[P.W.Berkuta]

Anyone have any ideas on how to downsize a 10-32 screw hole to take an 8-32 screw without having to weld the hole up and re-drill?  I don't have access to a welding rig.  It's a Frizzen screw hole so there will be no force pulling against the threads.  I was thinking maybe J-B Weld and then re-drill with a #29 drill bit and re-tap 8-32.  Any other suggestions? 

You could thread in a 10-32 plug and silver braze / silver solder it in then re-drill and tap for 8-32

[kutter]

If there is room,,take it out bigger yet and plug it. Then D&T the larger plug for the size you want.
Going bigger makes sure you won't rip the plug threads out with the new threads when you tap it.
Sweat solder (soft solder) the plug in or even locktite will hold it so it won't move when it's D&T'd for the new screw.
With out looking, maybe a 1/4-28 would work. Choose a fine thread to keep the trhread depth of the plug to a minimum.

[dogcreek]

I'd go along with P. W.'s suggestion, but acraglas, not solder, the 10X32 screw in place, then drill and tap it for the 8X32 screw. It's really pretty easy.

[pushboater]

Thanks gentlemen, your input is greatly appreciated.

Capt. David

[Stophel]

Definitely silver solder a plug in place.  That way it would be solid and your old threads won't peel off when cutting new ones.

By the way, exactly why would you need to do this?

[Bob Roller]

Make a 12x24 or 28 bushing with an 8x32 thread inside.

Bob Roller

[curly]

As Bob said, and one drop of permanent Locktite and your good to go.

Curly

[Hungry Horse]

 I replaced a frizzen, on a lock, that is no longer being made, some years ago, with a frizzen from another lock. The holes for the screw that the frizzen pivots on didn't line up. So, I threaded a screw into the hole, with a little Fel-Pro wicking thread lock on it, and after it dried, drilled and tapped it for the new screw. Its been working for quite some time without any sign of loosening up.

                   Hungry Horse

[okieboy]

 Is a helicoil out of the question? The drill for an 8-32 helicoil will take out the 10-32 threads and once done it would be invisible.

[oldiemkr]

I would go with Bobs repair.

If you know any machinist's they should be able to make one in short order. Lock tite and coutersink the hole, peen it over a little.

Denny

[pushboater]

Stophel,  I was working on fitting a Frizzen to the lock plate of a Chambers Early Ketland lock.  I didn't know exactly what size the frizzen screw was so I pulled out my trusty TOW catalog, looked up the lock, and in the section beside the photo of the lock where they have all the spare parts it said that the Frizzen screw was 10-32.  I should have double checked the screw but I didn't.  After I had drilled and tapped the hole I discovered that it is actually an 8-32 screw, NOT 10-32 as stated in the TOW Catalog.  Needless to say, I felt pretty stupid for not having double checked it.  What made me feel even more stupid was the fact that I had already fitted, drilled and tapped another frizzen to a Chambers Early Ketland lock plate about 2 months ago and didn't remember what thread size it was.  It Sucks getting Old!  Heck, I should have just been able to look at it and tell that it was smaller than 10-32!  Another learning experience!  Buy the way, I'm cutting the lock plates in two right behind the pans and using the front frizzen sections on the Fantasy Bucks County Swivel Breech that I'm currently building. 

I really like the Helicoil idea but I'm afraid that there's probably not going to be enough room.  The Frizzen screw goes right into the middle of the lock bolster on the back side of the lock.  The bolster is fairly narrow towards the front of the lock.  It's not much wider than a quarter inch or so.   there isn't a whole lot of room to drill a bigger hole.  I'm kinda leaning towards Silver Soldering a 10-32 screw into the hole and drilling and tapping it for 8-32.  That sounds like the easiest way to go.  Thanks again for everyones input. 

Capt. David

[Bob Roller]

Capt.David,
If you do go with the silver soldered 10.32,be sure to center drill it and use
the pan bridle side of the lock .
I think the 8x32/10x32 is a bit risky.The OD of the 10x32 is .187 and the
8x32 is about .158-.160. That leaves only about .015 between the 2 thread diameters.
I still think my 12x24 or 28 will give you the best chance at a fix.

Bob Roller

[Pete G.]

You could either buy a new lock plate or ream out the other homes to #10.

[keweenaw]

Take Bob's advice.  You need a larger size than 10-32 to safely put in a 8-32.  Leave the plug screw long and peen it in from both sides, dress it off and then d&t for the 8-32.  This is about a 10 or 15 minute to do fix so what's the big deal?

Tom

[pushboater]

Bob, There may be room for a #12 machine screw.  I definitely agree that it would be better to go a little bigger than 10-32 if at all possible. Thanks.

Tom, It's no big deal.  I just like to get as many different ideas as I can before attempting a fix because not everyone thinks alike.  Everyone looks at a problem differently and all possible solutions have their merits.  I'd be even more stupid than I already consider myself if I didn't take full advantage of the vast amount of knowledge this forum has to offer.  Thanks.

Capt. David

[Bob Roller]

Capt.David,
A #16 drill is the size for a 12x24 and the OD of that thread is .204-.206.
I made this size back when I was making set triggers for rolling blocks.

Bob Roller

[pushboater]

Thank you Bob.

Capt. David

[Luke MacGillie]

Is a helicoil out of the question? The drill for an 8-32 helicoil will take out the 10-32 threads and once done it would be invisible.

Helicoil'd screw holes hold the clutch assembly in the back of a M134 minigun throwing out 3000 rounds per min, so I would hazard a guess that it could handle a frizzen