Stripped Threaded Socket, Can This Be Fixed?

Yes, better than new!

.... I missed what you said about the flat surface....which would be better,, FLAT or an INDENT?

Well, a flat would allow for some imperfection in accurate placement, a tapered hole would provide a more secure/positive engagement, but if the placement is off, some stress will be induced when you tighten the second screw.

That may be why there is only one flat.

AH, or others, may have an opinion about this.

hmmmm???? makes sense. My "aim" ain't so good with such a itty bitty thing like that. Flat would be easier.

As I recall, we used to build lots of our own pumps, housings and impellers. The sleeve/impeller shaft were machined to very close tolerances and we used only one flat on the shaft.

3-5 HP pumps turning at 3450 RPM.

Your sewing machine is lots less torque, I'm sure.

Yes. I would think so.

I'll measure that hole tomorrow and figure what size I'll need. I'll be back on tomorrow night if there are any questions.

Thank you and AH again.

Fried chicken smells about done....got to go before that woman gives it to that dang hound dog!

Thank you all again. Always a lesson to learned on CR4.

Putting flats on two side of the shaft for the set screws to make contact with to do any good takes a lot of perfection. In the alignment of the flats, the threaded hole, set screw threads and the flat of the end of the set screw. Then there is the reduction of the shaft in grinding the flat. What kind of stress is the shaft under?

What purpose is there to having a set screw hitting a flat surface and another hitting the rounded shaft? Just asking?

With a flat surface, there is less likely hood of twisting of the joint. The set screw will "dig in" to the flat surface since there will be more metal to move out of the way than if it were riding around the surface of the round shaft.

The second screw will do it's job of providing better alignment on the round surface of the shaft/sleeve, since the flat will resist any movement.

I hope that makes sense.

This part slips off the shaft when I loosen BOTH set screws.
Thank you for the tip. Into the busy season and I do the manual ( hand sewing) during the day and the smaller mesh ( machine sewing) at night. This just stopped production.. ha ha !

OK. I watched the video. That wire coil will hold that bolt in that big engine piece?

Will that kit come with something as small as I need? You can see it is really little.

The Set Screw just jams onto that round shaft.... I am NOT an engineer but it seems there should be some kind of indent? IF I wanted to put a 1mm indent on that shaft, what type of drill bit would be best? I think the shaft is stainless. how hard I do not know.

If its not too much to ask, could you elaborate on the thread locking version?

thank you.

Sure. Try this link at McMaster-Carr for 10-32 Helicoils with the locking feature.

I would still buy the regular 10-32 kit Inserts with Tool and just add the red locking Helicoils to your order and use them.

Don't forget to buy a new set screw.

www.mscdirect.com or www.Grainger.com have better pricing, more options and faster delivery.

Thank you for the additional lead....

Go with the heli-coil. They cover many sins and also assist in repairs when needed. I use them more frequently than I would like. One caution though, do not mix the taps for them with your machine screw or fractional taps. The coil taps end up being a weird pitch as compared to all others.

Heli-coils are used extensively in auto engines. When someone strips the threads on a spark plug hole these can be used to rebuild the threaded hole. With extreme caution and the right equipment this can be done without removing the head off the engine. These are especially convenient on aluminum where it is easy to over-torque and mess up the treads.

Good Luck, Old Salt

If the OUTSIDE dimensions of the hole are 2mm, do I order a 2mm repair kit or do i measure the inside of the hole.... or do i measure the set screw and use that as a gauge?

Once again, i am in un-known waters .

If the outside dimensions of the hole is 2mm, you want to purchase a kit which will accommodate the thickness of the heli-coil and the new hole diameter after the hole has been drilled and tapped for the heli-coil

Good Luck, Old Salt

If you have a hardware store nearby, take it to them and ask. These are fairly common any more.

I have an ACE™ Hardware (Not an endorsement) store near my work and they have real people, who work real people shifts, and usually know what they're talking about. They also have a real "bolt room" and will sell you two 1/4-20 nuts, if that's all you need. I know the guy who owns the store and his two grown children who work there. (and they know me)

I have a big box HD store 1/2 mile from my house. I drive the 5 miles to the real store if I need something odd or need advice.

Here's a link to their website:

Insert Systems - Helicoil

Take your time, use a drill press, if you have one.

You'll do fine.

Thank you very much. I am on it.

If that is a 4-40 setscrew, you could always re-tap the hole to 5-40 ( slightly larger, and retain the threads in a new diameter. then using a 5-40 set screw it would be like new. The set screw on the flat is to stop the shaft from rotating in the collar, and the other set screw is for mechanical binding to the shaft. one could use a hardened poit set screw that would create its own dimple to rest in on the shaft. Setting the Flat screw first in the best position is the key.

Thank you. That explains the tow screws.

Put a threaded hole 180 degrees on the other side.

That's probably what I would end up doing, too.

The heli-coil is the best way if you feel it is necessary to continue to use a set-screw. I'm sure there are some drawbacks to horace40's solution, but for many applications, it sure seems like a simple, permanent fix.

For that matter you could use a spring pin.

Yes, why not. Or split pin, hair clip, bent wire.

It depends on what you have, the precision you want, and you skill in doing it.

Helicoil seems like a lot of work and fiddly if its a small thread. Why not just drill and tap another hole on the opposite side. Or get a taper reamer and ream it out with a taper pin knocked in. Leave the taper pin slightly long so that you can easily disassemble it if you need to.

Heli-Coil is a LOT less work than drilling and tapping a new hole in the coupling.

Reaming; with a "taper pin locked in" makes no sense at all. I assume you mean drilling and reaming the shaft, too? How's that less work?

Cheaper?

I think that this set screw arrangement, with no indenture on the shaft, is actually meant to give when the machine gets jammed. This happens twice a week sometimes. Sort of like an old shear pin in an outboard.

A bolt clean through would eliminate all of this but may cause something else up near the Roller mechanism to break off. Look to the right of the hole... see that ball joint? It rotates at an angle in that socket. Down in the machine there is a universal joint that rotates at another angle . I am still thinking 'shear pin' effect.

Thank you for the idea though. Later on it may become necessary .

If you drill through shaft and sleeve (which I do not recommend) be sure to use a shoulder bolt/screw and not just a threaded bolt/screw.

Using a spring pin there would give you the shear option.

Replace the set screws with 10-32 half-dog (McMaster part # 91381A338) with a brass tip.

This will prevent scoring the shaft if it slips and the brass should conform to the shaft when tightened.

Thank you all for the idea. I do not have a drill press and drilling through this small 1/4" shaft would be very awkward. The manufacturer also recommends a Heli-coil ( which is what they would do if I sent the piece back).

Thanks everyone for the ideas.

using the mounted collar as a drill guide would help a lot if you were going to use a pin, the threads would not matter anymore so the drill would be matched to the old screw. the bigger issue with drilling the shaft is that you risk weakening the shaft by cutting too much of the cross section.

Lock-tite form-a-thread may be easier to use than an insert on such a small size.

http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=1ydz5&op=search&Ntt=1ydz5&N=0&GlobalSearch=true&sst=subset

No offense to you, but I'd rather strap on a beak and peck $hIt with the chickens than use a plastic thread repair for this.

No way it will hold up.

I've worked with LockTite since the late 1970's, and some of their stuff is fine. Just not this.

Never used this particular product myself, just saw it as a possible option. I trust your opinion and will avoid this myself in the future. Thanks

Loctite, now Henkel never liked to divulge what went into their materials.

(This was particularly bothersome when trying to specify materials for spacecraft)

I assume this is filled with steel or aluminum, but still held together with a meth/acrylic resin.

tribefan1952, the expression came form an old grizzled machinist I worked with in the aerospace industry, many years ago.