Insert for stripped thread in Shaft

[bruppert]

I have to repair a shaft with a stripped thread.
3/8-10
ID of Ringwork .625
Depth minimum 1"

Questions. Do you think making the OD on a phenolic insert .425 is big enough? That leaves at least .025 per side at the major thread diameter. I really don't want to make any bigger than needed.

Thanks

 

[JoeyInCali]

I have to repair a shaft with a stripped thread.
3/8-10
ID of Ringwork .625
Depth minimum 1"

Questions. Do you think making the OD on a phenolic insert .425 is big enough? That leaves at least .025 per side at the major thread diameter. I really don't want to make any bigger than needed.

Thanks

I like 1/2 20 TPI with an unthreaded portion up top so you don't see nasty lines on the face.
Bore the hole at .480 ( .010 a side of threads is really enough if you use good epoxy ) then bore the top 1/8 to dead .500. Run the tap.

 

[bruppert]

I like 1/2 20 TPI with an unthreaded portion up top so you don't see nasty lines on the face.
Bore the hole at .480 ( .010 a side of threads is really enough if you use good epoxy ) then bore the top 1/8 to dead .500. Run the tap.

Thanks Joey. I think I have a 1/2-20 tap but no way to chase the threads on the insert (I have a solid 5/8 phenolic bar). I only have a HT Deluxe and don't own a chasing head.

The way I was planning to make it was drill, bore, tap the 3/8-10. Use a true running pin to put that onto. Faceoff and turn OD. Then I know the thread is dead true. Bore shaft for a snug fit, add some glue grooves to insert and shaft and epoxy the insert in. Then face only the insert portion below the ring face. But I see your point, I'll be relying totally on the epoxy to hold it.

I guess I could do it with a 1/2-20 Die but if I get the internal threads a little off he'll notice when he screws it together. He's a good guy but always running his mouth and I don't want him running it about subpar work I did for him.

My friend George from G's cues just called and had some threaded inserts made up so if I can't find something before then I'll take him up on his kind offer.

Thanks for the help!

 

[conetip]

Thanks Joey. I think I have a 1/2-20 tap but no way to chase the threads on the insert (I have a solid 5/8 phenolic bar). I only have a HT Deluxe and don't own a chasing head.

The way I was planning to make it was drill, bore, tap the 3/8-10. Use a true running pin to put that onto. Faceoff and turn OD. Then I know the thread is dead true. Bore shaft for a snug fit, add some glue grooves to insert and shaft and epoxy the insert in. Then face only the insert portion below the ring face. But I see your point, I'll be relying totally on the epoxy to hold it.

I guess I could do it with a 1/2-20 Die but if I get the internal threads a little off he'll notice when he screws it together. He's a good guy but always running his mouth and I don't want him running it about subpar work I did for him.

My friend George from G's cues just called and had some threaded inserts made up so if I can't find something before then I'll take him up on his kind offer.

Thanks for the help!

The thread only needs to be enough to pull the assembly into line at the bottom of the insert. If the pin is less than 1 inch long, make the insert 1.3 inches long and thread only 1st .250 or so,leaving 1.05 for the pin internal thread. The rest of the insert can have a spiral vent/glue groove at .01 deep.
Neil

 

[olsonsview]

Die may work

For threading the OD of the insert. But glue it into the shaft before boring the internal hole. Just bore and thread the shaft with the phenolic insert. SO even if the insert threads are not perfect and the insert is slightly off center in the shaft, you bring it all into the proper center line by cutting the bore with threads last. Assuming you are dialed in with your cue lathe, and you should also consider using a 3/8 X 10 tap with a machined nose button to the same size as your bored hole, to hold better tolerance.

 

[aphelps1]

I like to give my inserts more meat than .425 for a 3/8 pin. I would use .500 plug. Just make sure the plug is only long enough to fill the existing cavity in the shaft.

Hope that helps,
Alan

 

[Cue Crazy]

I use phenolic joint rings and inserts tapped 3/8-10 on PH break shafts. No outside threads on the insert, just blood grooves, and press fit. OD of the inserts run between .480-.500

I have never had a breakdown, not even had one move at all, and they have been put through the test plenty of times. Obviously I would not disagree that a mechanical bond is a nice added insurance, but it is not imperative that you do them that way as long as the fit is good, and good adhesive is used. Most phenolics I have used take glue very well. Something like delrin or teflon is another thing entirely, but you should be alright with phenolic if you don't have any way to do the mechanical bond on the OD. I've used phenolic this way to make inserts for smaller pins as well. Quite simply put, It works for me.

 

[bruppert]

Thanks for all the input guys, its greatly appreciated!

I pretty much did it as I was planning. Trying to make a threaded insert was too much trouble since I don't have a metal lathe. I tapped the phenolic, put that on a pin and turned and faced. Put a couple glue grooves around it and about 8 down the length staying an 1/8" or so from the end. Even cut in several X's. Made a slip fit in the shaft, put epoxy in the shaft and gave it a few minutes to soak in then pushed the insert in which also had epoxy all over it. Wiped it all down and let it sit. The only thing I forgot was grooves in shaft. If he manages to wrench it out of there I'll try to remember to let you guys know.

Thanks again

 

[bruppert]

Oh, one thing I forgot to mention. I was actually glad I did it this way. The phenolic spun several times when I was trying to tap it plus stopped the chuck a few times since I ran it at such a low RPM. If I had stuck the insert in first then drilled & tapped the 3/8-10 and it spun I may have messed up his shaft. Not hard to fix a little groove but he didn't ask me to sand his shaft or clean it up.

So for me this worked well, I didn't hurt anything and I know that insert is dead center. Hmmmm, I hope the original was dead center!

 

[whammo57]

insert

I tap phenolic inserts by hand and slowly. They are very sticky. It is not really necessary to thread the od of the insert. Put some glue rings on it with the corner of a file.

On a repair job on a shaft, It is a good idea to drill and tap the insert first and then chuck on the pin and turn the od of the insert to slip fit the bored hole in the shaft. I think Dieckman did that on his cues. Use a good epoxy.



Kim

 

[Cue Crazy]

I found that My dremel mounted on My slide with a small endmill works well for cutting the glue grooves. I index at several positions to make the parallel cuts, then dial in, and turn the headstock spindle to make grooves in the other direction. Just have to make sure that you don't dial in too deep, especially if using a thin walled insert. You can do this while making a solid core plug that will later be drilled and tapped once in the cue, or simply do the same thing after truing the OD on a mandrel or joint pin when you drill and tap first. I use both methods. When I'm building a cue or matching to a cue that is fairly true then I may elect to drill and tap after the shaft is plugged, but a lot of times on the repair end I will tap first then turn the OD. I've worked on a lot of basket cases, sometimes It's the easiest way to deal with those, still have the cue roll straight on the table. It can also help to keep the handle and shaft flush with each other when you don't have any meat to trim and match them up.