I ALMOST GIVE UP

[Drcal]

I have progressed over the past 2-5 years in pen turning, but I have regressed in making bottle stoppers- the chrome type with a 3/8 in X 16 threaded stud. 4 out of 5 of my tries don't work. The problem is in mounting it on the lathe.

• I use a MT#2 mandrel with the proper 3/8X16 thread from Arizona Silhouette.
• I drill a 23/64 hole
• I tap it carefully using a ratcheting tap recommended to me by Ed Davidson
• I use the tailstock when I start turning

Sometimes when I go to mount the blank to the mandrel it spins from the onset, sometimes it starts to spin when I am half-finished.

I can get a stopper out of the session but I can never remove the tailstock so I can never do fun stuff n the top of the stopper.

I have tried smaller holes but, at the end, then I cannot get the blank off the mandrel.

I have tried putting thin CA on the threads, but it still spins.
I have tried putting thin CA on the threads, tapping it again, but it still spins.

I have thought about turning the blank on a 3/8 inch pin chuck and then gluing the threaded stud into the blank but I am not sure if that will hold.

I would appreciate any advice.

I have watched videos on YouTube.
I have read everything on the subject.
I have thrown things around my shop and I have prayed, but nothing works. Help!

Carmen
Tampa Bay

 

[David Keller]

I might try a smaller hole and wax on the threads to facilitate removal of the finished piece. I've never used the tap when I make them that way, but I'm not sure that would make a big difference.

 

[monophoto]

Sounds like the problem is that your threads are stripping.

You can always drill out the hole, glue in a dowel, and then redrill.

My experience (somewhatly limited) is that harder woods need a larger hole to avoid stripping, and aren't picky about the number of times you screw the blank onto the mandrel.

Also, it's helpful to have a sharp tap. I have two taps, one of which is well used and a bit dull. My experience with it is not as happy as with the sharper tap.

You may find that using a new 3/8" bolt (with sharp threads) works as well as using a tap.

Sometimes, it's helpful to drill the pilot hole, and then squirt some thin CA into the hole to strengthen the sides before threading.

Finally, I always use a small scrap of MDF as a waste block so that I can use the live center on the tailstock to lock in the workpiece while roughing it into a cylinder. I glued a bit of coarse sandpaper on the face of the MDF so that it 'grabs' the workpiece. Once the cylinder is round, I back off the tailstock.

 

[deweed]

Carmen,
Experiment with a 5/16 hole and then tapping. The 23/64 is too large IMO and then when you tap it then it's really large. I use the 5/16" hole on all of mine and had no problems with spinning.
Duane

 

[holmqer]

It may be overkill, but both before and after I tap, I put a couple drops of thin CA in the hole. I then run the tap in again to clean up the threads that have been filled in with CA. This make it like tapping plastic rather then wood.

Like Duane, I use a 5/16 drill for the 3/8-16 threads

 

[nava1uni]

I had the same problem, but then read on here about the 5/16" hole and it really works great. When they have been too big I just glue in a 3/8" dowel and turn it then drill out the dowel and glue in the stopper.

 

[fernhills]

I use a 11/32 seems to work. I have a PSI chuck and i use that with the tail stock snugged up in the beginning. Before that i used a regular Jacobs chuck with a draw bar. You have to make sure your hole is drilled straight and then tapped straight. I don`t make bottle stoppers but i do a lot of shaving brushes, same method. Good luck. Carl

 

[randyrls]

• I drill a 23/64 hole

I can get a stopper out of the session but I can never remove the tailstock so I can never do fun stuff n the top of the stopper.

I have tried smaller holes but, at the end, then I cannot get the blank off the mandrel.

Carmen; You are about to get a whole chorus of replies, but that 23/64" drill bit is much too big. Use a 5/16" drill bit (no larger than 21/64"). A strap wrench works well to remove the mandrel chuck from the stopper.

 

[rjwolfe3]

I use a bottle stopper mandrel to do my fridge magnet. I drill with a 21/64". I don't tap the hole if it is wood, just thread the blank on by hand. However I have a heck of a time getting the darn thing back off once I have it finished. I have tried a strap wrench but it leaves a black mark on the finish. I put blue painters tape on the piece and then tried it but then the tape gets smeared all over the finish. I haven't found a solution but I am going to keep trying.

 

[livertrans]

I use a 11/32 drill bit to drill the hole. I have made many bottle stoppers and other items and have never had a problem in either wood or acrylic. When you tap you need to keep on backing the tap out a couple of threads every now and then or the chips will make your threads over size.

 

[JeremyJ]

Some times locktite works well if you have some that are already drilled and you don't want to plug them.

 

[aggromere]

I think I have the same setup from AS. I was stripping the threads on my first few attempts. I mount the blank in my chuck and drill the hole, then put the tap in the drill chuck on the tailstock and bring it up to the hole. I think hand turn the headstock as I slowly (i mean slowly) advance the tap. Once I reach the desire depth, I back it out very, very slowly by turning the headstock wheel in the opposite direction. I then put the bottle mandrel from AS in my collet chuck screw on the blank and turn it. Hope that helps. I've only made about 10 stoppers though so I could just be getting lucky.

 

[nava1uni]

I use a bottle stopper mandrel to do my fridge magnet. I drill with a 21/64". I don't tap the hole if it is wood, just thread the blank on by hand. However I have a heck of a time getting the darn thing back off once I have it finished. I have tried a strap wrench but it leaves a black mark on the finish. I put blue painters tape on the piece and then tried it but then the tape gets smeared all over the finish. I haven't found a solution but I am going to keep trying.

Try putting a small plastic washer between the stopper and the back end of the mandrel. I have used one for this purpose with good results. I just turned it until it matched the mandrel and didn't cause any difficulty with the stopper diameter at the end.

 

[Daniel]

If the stopper is made from wood I would not tap it. Just thread the mandrel into the hole. The size of hole would be determined by how hard or soft the wood is. In short I want it to be really screwed in tight. like maybe the last half turn the blank has to be held in a vice tight. At least in my mind I imagine all this pressure is crushing the wood fibers and making them even more solid. as for plastics. I think I would at least tap them a size or so small and still make the mandrel a very tight fit. I don't think you will get the same effect though. Otherwise drill it out and add a wood plug and proceed as if it is wood. remember though the pressure on the wood is being transfered to the acrylic, don't crack it.

 

[rjwolfe3]

I use a bottle stopper mandrel to do my fridge magnet. I drill with a 21/64". I don't tap the hole if it is wood, just thread the blank on by hand. However I have a heck of a time getting the darn thing back off once I have it finished. I have tried a strap wrench but it leaves a black mark on the finish. I put blue painters tape on the piece and then tried it but then the tape gets smeared all over the finish. I haven't found a solution but I am going to keep trying.

Try putting a small plastic washer between the stopper and the back end of the mandrel. I have used one for this purpose with good results. I just turned it until it matched the mandrel and didn't cause any difficulty with the stopper diameter at the end.

These are for the fridge magnets. I don't thread this all the way done to the end of the mandrel. The problem me thinks is the wood is too tight on the threads and because it is such a small item there isn't enough grip available to get it off of the threads.