Bottle stopper question

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JRK

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Feb 25, 2019
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I am thinking of trying a bottle stopper. In the video that I saw, a hole was drilled and tapped in the wood blank. This seems like a weak connection that would strip out easily.

I am concerned about this during turning (safety). When it is in use, this connection will be pushed and pulled. Seems like it could loosen or fail with time.

Should I be concerned with stripping the threads?

I was wondering about putting some CA on the wood threads before final assembly?

Thanks

Jerry
 
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Hi Jerry. The mandrel you're probably looking at does need support on the tail end, at least I use one. You can drill and tap the hole and thread it on the mandrel but I would suggest you use a live center on the tail to help support the piece. On all the bottle stoppers I've made I've only screwed the stopper in place and it works fine. There are some threaded inserts you can buy but I've never used them so I can't really say anything about them. I'm sure someone else will see this and post to it about the inserts. If you look further on line I'm sure you can find instructions on how to use the mandrel and live center technique. Hope this helps.

Edit: Like Bob said above on the threaded inserts. ( I'm sure someone else will see this and post to it about the inserts)-

The one thing I forgot to mention was that on my stoppers I drill my first hole slightly larger then glue a hardwood dowel piece in the hole and then re-drill the hole with the correct drill bit and then use the tap.
 
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monophoto

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Jerry -

Your observation about the relative weakness of the threads in a wooden bottle stopper is 'bang on'. This can result in a failure when the blank is mounted on a threaded mandrel for turning. Also, when you cut threads with a tap, the tap rides on the threads that have already been cut as it advances into the hole. So depending on the timber you are using, it is even possible for the stress imposed by the tap as it advances to strip out the threads it has already cut. The basic cause for this problem is that stoppers are usually spindle turnings, so the hole is parallel to the grain in the timber, and threads cut into end grain are weak.

Some people use metal threaded inserts to avoid this problem (and some stopper kit suppliers include an insert as part of each kit they sell). You can also buy threaded inserts at a hardware store in either steel or brass (hint - steel is better - brass inserts are more expensive, and the soft brass can be damaged in the course of screwing them into a blank).

Another approach is to use wooden inserts with holes that are perpendicular to the direction of grain (ie, in 'face grain'). The result is that when the hole is threaded, the threads are much stronger. I normally make them from ash which produces very strong, clean threads in face grain, and as Bob suggests, I also saturate the threaded hole with thin CA to reinforce the threads. I make my inserts by drilling and tapping a series of holes in a scrap of face-grain ash, cut them apart, and then mount them individually on a stopper mandrel to turn them down to a final diameter (usually 5/8"). Then, when I make a stopper, I drill a 5/8 hole in the blank, and glue in a pre-made insert.
 
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JimB

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During Turning I usually knock off the corners and do a bit of initial shaping before I mount it on the mandrel because this is when you would be stressing the threads the most. If needed I re-enforce the threads using CA and re-tapping as already mentioned. Use the tail stock when turning. Using sharp tools will minimize the problem.

As for when people are using the stopper, pulling and pushing, most stoppers go in and out of a bottle fairly easily. If the threads are REE forced with CA it should be a problem. You can also glue the stopper into the wood with CA or epoxy.
 

WriteON

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I drill and tap. When finished the stopper gets glued.... but not necessary. Please do not use the Niles mandrel for a tap. Buy a tap kit.
Just my thoughts ... the stopper can be glued as it’ll most likely never get separated by the owner. Take your time. Threading is fun when you get the hang of it. And you’ll learn fast. I started with Niles inserts. Quit using them as fast as I started.

The concern about threads coming loose while turning. They will not if you get a good threading. The blank stays tight. Let the chisel do the work. Use sharp tools. Do not not apply excessive pressure when turning. The threads will not strip once your technique is fine tuned. Cut and check. As always if you feel or get a strange report turn off the lathe and check. Definitely wear the proper face shield when turn a stopper. Protect lungs.... turning a wood stopper blank is a mess. Protect face, ears,lungs,skin(arms)
 
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dogcatcher

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This is how I handled the threaded bottle stopper process. First I drill with a smaller bit, a 3/8-16 tap calls for a 5/16" drill bit, I drill with 9/32". I then drizzle the inside of the drill hole with thin CA glue and tap the next day. I then again drizzle the inside of the threaded hole with thin CA, and wait until the next day and run the tap in and out and then it is ready to turn. It is time consuming, but the customer pays for it. I never had one come back to me for failed threads.

At one time I also made my own threaded inserts, I use a 4" grinder with a stand that works like chop saw to cut 1/2" diameter aluminum rod and 1/2" long. I both drilled them with a 5/16" bit and tapped them on my wood lathe. I also faced the front of he insert to clean up the saw marks with a round nose scraper. These took longer to make than the CA drill and tap process, so I eventually quit making them.
 

greenacres2

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Jerry - Thin or medium CA on the threads, then retap - I do this twice - or use Ruth Niles threaded brass inserts fitted into a 7/16" bit-drilled hole - here are the inserts:
https://nilesbottlestoppers.com/product/threaded-inserts/

Warm regards - Bob
Thanks for that Bob. I've not been able to successfully thread the wood, and haven't been enamored with traditional threaded inserts. Don't know how i never saw those on Ruth Niles' site before.
earl
 
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I may be the exception here, but I don't use a mandrel at all for bottle stoppers, nor do I tap the blank.... I dirll a 3/8" hole that I have a 3/8" rod with a flat on one side and a small nail to from a pen chuck... I tap the blank onto the pin chuck, twist it slightly to lock it in place and then turn...I usually turn a stopper at about 2000 rpm and can have one shaped and sanded in about 10-15 minutes... the threaded end of the SS stopper will thread itself into the 3/8" hole and with a drop or two of CA will not come out.
 

bsshog40

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I use the threaded inserts. Don't even have to use the tailstock for these. Haven't had one problem turning them.
 

TonyL

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Alpharetta, GA 30004
Someone may had mentioned this above; please forgive me if is the case. Assuming the material is wood, a stronger thread is achieved if the threads are perpendicular to the grain. If I want to orient the BS with the grain, I will use a brass insert. I also use epoxy when securing the stopper and/or insert. If I sure the insert, I apply the epoxy to the outside of the insert - not the inside (I don't know if that was clear from my statements above). Without the insert, my BS is permanently attached.

As far as stability. I ride it up to the tailstock as long as I can, and I use a simple drawbar of the headstock side. I agree though, even though I haven't had any fly-off, I can see where one will one day.
 
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