bottle stopper help

[triw51]

I wanted to try turning some wine bottle stoppers so I purchased some kits that have 3/8-16 nc threads. I made a holder with a block of wood and a hardened 3/8 16 nc threads, to hold the stock while I turned. The wood turns true so that should not be a problem.
Then using the recommended drill (5/16th) drilled a pilot hole and cut threads in the wood. The wood is hard apple, mulberry and mesquite. When I started turning I used the tail stock and every thing went as expected but when I backed the tail stock off to turn to top the wood just spun in place (except of the mesquite). The threads I cut into the block of wood stripped out.
IF I am cutting threads in wood as apposed to steel should I use a smaller drill bit to drill the pilot hole? Any suggestions?
Thanks in advance for any help. William
PS If this post is in the wrong thread please move it. Thank you

 

[ctubbs]

I would coat the wood threads with thin CA, allow to set and chase them with the tap. This should give them some more strength. Light cuts will also help preserve the threads also. Just a guess, hope this works for you. As always, YMMV

Charles

 

[Jim Burr]

+1^. Also think about less pressure on the tailstock....tool selection and presentation. Happens now and then, but it can be overcome!

 

[Edgar]

I use a 9/32" bit to drill my hopes - that took care of the problem for me.

 

[BRobbins629]

For hard to thread materials, I use inserts made from an easy to thread material such as alumilite or ebonite. Usually drill a 1/2" hole, turn the insert to fit and glue it in. You can even save the pieces you've alreadsy tried to thread by drilling out a larger hole

 

[monophoto]

In the usual bottle stopper situation, the threads are in end-grain. Unfortunately, end-grain threads are notoriously weak. And obviously, different timbers thread differently - drier woods are more difficult than green woods.

But the good news here is that stopper threads are only used twice - once to mount the blank on the mandrel, and once to attach the metal base to the turning. And if necessary, you can use a little CA or expoxy the second time to make sure that everything stays in place.

So the real issue is making the threads strong enough to withstand the forces while turning. I use a 5/16 drill when I am going to need a 3/8x16 threaded hole. I try to be as gentle as possible when tapping the threads to minimize the axial forces on the tap that can strip out the threads as fast as they are cut. After cutting the threads, I saturate them with thin CA and let it cure thoroughly for several hours, and then run the tap back into the hole to clean up any 'fuzzies'. That usually results in threads that are clean and hard enough to withstand turning, and also avoids the need to glue the metal base to the turning when everything is done.

When turning, leave the tailstock in place to support the blank as long as possible, and then be gentle when finishing the end. I find that I have to keep telling myself that wood turning is not a contact sport, I'm not in a rush to get the piece completed, and a light hand produces better results.

 

[raar25]

I have started using metal inserts and they are capable of taking alot more abuse. I get them from amazon and thread them into a larger hole. It is another step but I am comfident I will not have any future damaged threads. If I needed to do soft wood, I would bond them into the wood with epoxy.

 

[Wildman]

I cannot help you other than direct you to Ruth Niles site for kits & mandrel supplies. She is very knowledgeable and can help if buy supplies from her. She likes to talk to everyone that buys from her and very nice person.

Stainless Steel Bottle Stoppers |Off-Center Jig } Design Gallery

Even if choose not to buy from her nice site to visit.

 

[mrrichieboy]

The problem with threading those holes is that you will never get the good grip you need to keep from spinning and stripping the threads. Those directions are for self threading and they will never grip completely, about 1/2 contact with the threads is what you get.

Buy a good 3/8" - 16 tap....drill an 8mm hole, then tap the hole and I guarantee you will have a grip that won't let loose. Solid contact all along the threads while turning. Never need to use CA or anything else in the hole to hold it.

Same thing if you are using a bottle stopper with a 1/4" - 20 thread....use a 5mm drill and buy the 1/4-20 tap.

I started using this method a few years ago, have never had one fail since.---Rich

 

[Edgar]

I agree with Rich about the tap. Taps are made to cut threads - bolts aren't. You will get much better threads & have fewer problems if you use a good tap.

I prefer to drill a 9/32" hole though. Even with a tap, I had a strip-out with a 5/16" hole in a soft spalted blank. No problems since going just that little bit smaller.

 

[bchawkins]

What kins and size insert??

I have started using metal inserts and they are capable of taking alot more abuse. I get them from amazon and thread them into a larger hole. It is another step but I am comfident I will not have any future damaged threads. If I needed to do soft wood, I would bond them into the wood with epoxy.

What kind and type of insert do you use? I am having the same trouble and am looking for some type of threaded metal insert to use.

PLEASE HELP!!

 

[Dan Masshardt]

What kind and type of insert do you use? I am having the same trouble and am looking for some type of threaded metal insert to use. PLEASE HELP!!

Pennstate now sells a threaded insert Adds to the cost though

 

[ChinaDad]

I would agree with Ed and Rich. A little bit smaller drill bit on softer woods and use a tap. I started turning stoppers and quickly found that the softer wood need a smaller hole to tap properly.