PSI Bottle Stopper mandrel help

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bsshog40

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So I wanted to turn a couple bottle stoppers. I bought a kit from PSI that had blanks, stoppers, mandrel, tap and drill bit. Everything was going decent until I tried to take the blank off the mandrel. It just spin around and would not thread off. I eventually had to take the edge of a knife and put pressure underneath to get the thing to come off. Anyone ever use this kit and know what I can do for the next one to help get it off the mandrel? Thanks!
I know I could just TBC, but the blanks are just long enough to make the stopper. If I attempt to tenon it, I won't have enough wood to turn.
 

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epigolucky

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I glue in the inserts that thread onto the mandrel and stopper. Keeps things secure and allows the stopper to be removed for cleaning. You can also glue the stopper to the blank when complete.
 

monophoto

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Everything was going decent until I tried to take the blank off the mandrel. It just spin around and would not thread off.
Sounds like you stripped the threads. That's easy to do with some hardwoods, mainly because stoppers are usually spindle turnings, so the hole you are drilling and tapping is end-grain. As a result, the threads are very weak.

The best solution to this problem is to use a threaded insert. You can purchase metal inserts at the hardware store, and some stopper kits (but not PSI kits) come with inserts. I make my own from wood, but with the hole drilled and tapped in face grain so that the threads are much stronger. Here's an earlier thread on this subject.
 

Timber Ripper

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Everything was going decent until I tried to take the blank off the mandrel. It just spin around and would not thread off.
Sounds like you stripped the threads. That's easy to do with some hardwoods, mainly because stoppers are usually spindle turnings, so the hole you are drilling and tapping is end-grain. As a result, the threads are very weak.

The best solution to this problem is to use a threaded insert. You can purchase metal inserts at the hardware store, and some stopper kits (but not PSI kits) come with inserts. I make my own from wood, but with the hole drilled and tapped in face grain so that the threads are much stronger. Here's an earlier thread on this subject.
I too have had the treads strip as Louie described. I now use the inserts which i epoxy in.. The only draw back is, you have to wait to let the epoxy cure.
I got the inserts from "Wood Turningz" I have seen the same type for much cheaper at Home Depot but wasn't sure of the tread size. Next time i need some. I will bring the mandrel with me to size it..
-Anthony
 

TonyL

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The same thing happened to me with another manufacturer's threaded mandrel; I even used a silicone washer to prevent this. However, in my usual haste, I did not clear-out the "chips" as often as I should have when I cutting the threads. That is the only step that I could attribute my experience to.

To remove the bstopper, I tried freezing the mandrel, heating the mandrel, vibrating the mandrel, asked folks much strongrt than me to try. Eventually I just turned it off (basically destroyed it). Anyway, I now clear-out my threads more frequently. That is the only that I could think of for my situation.
 
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I don't use a mandrel at all on my bottle stoppers.. ran into similar problem and just looked for another solution... I use a pin chuck to turn bottle stoppers... a 3/8" rod in my collet chuck, then ground a flat on one end and use a small nail as the pin... tap the blank the flat with the nail in place and then twist to lock... when finished you can then wiggle the stopper a bit and pull it off the rod... I glue the insert of the stopper into the place.
 
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I have the same mandrel and have had the same exact problem. There are two things you can do that I've used. First, after you drill the hole in the blank, glue in a hardwood dowel then redrill the hole and do your threading or, use a live center on the tail stock that will give you the ability to put tension against the mandrel face. As for removing, you have to put tension on the mandrel while you try to unscrew the blank which usually strips the threads. That's where the dowel comes in. Good luck
 

bsshog40

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Sounds like it's just going to be a problem I guess. There are no inserts. I have to tap the blank and then just screw it onto the mandrel. I'm not really sure if I striped the threads though or at least all of them. After I turned it, the blank just spun around and around no matter how hard I tried to pull at the same time. When I finally got it off, the stopper threaded in just fine. I'm thinking that the mandrel made the threads loose their twist and wound up making the threads straight. The pressure from turning may have caused the mandrel to re-thread/tap so to say.
 

bsshog40

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I have the same mandrel and have had the same exact problem. There are two things you can do that I've used. First, after you drill the hole in the blank, glue in a hardwood dowel then redrill the hole and do your threading or, use a live center on the tail stock that will give you the ability to put tension against the mandrel face. As for removing, you have to put tension on the mandrel while you try to unscrew the blank which usually strips the threads. That's where the dowel comes in. Good luck
I may check into doing something different for the threads. Thanks for the tip. I do use my live center during the whole turn until I'm ready to work on the top.
 

dogcatcher

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I do it a little different. For hardwood blanks I drilled the hole and drizzled thin CA on the walls of the hole, I let it sit over night and then tap the threads, then again drizzle some CA glue on the threads, let it sit overnight, re tap the threads. This gives a better set of threads. Then I turn, before I start sanding I unscrew the blank, because the rough finish gives a better grip. Reattach the blank to the mandrel and finish with the sanding.

My method for softer wood, I cut 1" long pieces of 3/4 maple dowels, and do the same as above. When I made these, I would make a BUNCH at one time. Then when I was ready to make bottle stoppers, I drilled a 1" deep hole in the end of my blanks and proceeded as described above.

Failure to let the CA dry, or get it to hot while turning, and you will glue it all together. you then get to turn the blank into chips and soak the mandrel threads in acetone. Same will happen with the tap if you try to tap it before the CA is cured.
 

monophoto

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Good point, Dogcatcher -

There are two problems - Bobby encountered the situation where the threads strip, and the turning just spins on the mandrel. In that case, there is always the option of taking the turning off the mandrel, finishing it, and then gluing the stopper hardware in place.

But the other problem is the really nasty one - where you inadvertently glue the blank onto the mandrel. That can happen if you use CA to reinforce the threading, but don't wait for it to cure fully before screwing the blank onto the mandrel. It can also happen if you get carried away when finishing the stopper, and allow finish to soak between the mandrel and the turning. Sometimes, using a glove on your hand when you remove the turning from the mandrel improves your grip enough to break the bond. Another crude option is to use a strap wrench, but usually that damages the turning. In most cases, the best solution is to declare that one a learning experience, use a gouge to turn away most of the turning, soak the mandrel in acetone, and perhaps use a die to clean out the mandrel threads.

Most of us have been in both situations. All part of the fun of turning.
 

sbwertz

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First, I use a 5/16 bit then tap it with a 3/8 tap. Then, if the wood is at all soft (like cedar, for example) I flood it with thin ca, spray it with accelerator, let it dry completely and tap it again. That hardens the threads. Haven't had one strip since I started using this technique, and we turn a LOT of stoppers at the blind center.

This makes much deeper threads than using the mandrel to tap the threads.
 

bsshog40

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Thanks for all the tips guys! I tried another one today making sure my drilled hole is nice and straight. I then put the blank in a vise so I could make sure that I tapped nice and straight. When I got done tapping, there was barely any threads tapped in the hole. Its like the 5/16th bit I have is a little larger than what the hole should be for the 3/8th tap. My calipers show the bit is 5/16 though. I'm thinking of drilling out with an 8mm bit and then tap. If I can tap that out fairly easy, then I may do the ca coat to reinforce the threads. I'm also thinking about just ordering some inserts also. I like doing the stoppers as it gets me back to using my spindle gouge more. I've been slacking on that tool lately. Lol
 
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Dieseldoc

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I would check your so call 5/16 bit and measure it make sure it;s not 11/32 or 23/64, reason I say this in check out the PSI bottle stopper kits specs they show use of two bits supplied one being 11/32 and other 23/64.

I know for sure if you use a 5/16 bit in a good hole your problem will be corrected.This is the same problem Woodcraft has with there Icecream scooper instruction saying with the 3/8-16 thread scoop use a 3/8 bit, Wrong.

Charlie
 

bsshog40

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I would check your so call 5/16 bit and measure it make sure it;s not 11/32 or 23/64, reason I say this in check out the PSI bottle stopper kits specs they show use of two bits supplied one being 11/32 and other 23/64.

I know for sure if you use a 5/16 bit in a good hole your problem will be corrected.This is the same problem Woodcraft has with there Icecream scooper instruction saying with the 3/8-16 thread scoop use a 3/8 bit, Wrong.

Charlie
The bit has 5/16th stamped into it and when I measured with the calipers, I set it to inch and it came up 5/16th.
 

bsshog40

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Not sure on how you are drilling. but apparently you have a drilling issue. Are you using your lathe or a drill press? Brands and method you are using?
I'm using a drill press with a jig. I wound up putting some blue tape on the mandrel threads and was at least able to turn it. The first one tapped better. The wood was zebrawood. The one below is the one that did not tap very well. Not sure what the wood is. It was a supplied blank from PSI.
 

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dogcatcher

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Get some scrap wood and try drilling with these sizes of drill bits. Letter N bit and a 19/64 bit. Try tapping them and see what happens. I think your drill press might have some runout and is making the hole a little larger than you need.

I also recommend using jobber bits.
 

bsshog40

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Get some scrap wood and try drilling with these sizes of drill bits. Letter N bit and a 19/64 bit. Try tapping them and see what happens. I think your drill press might have some runout and is making the hole a little larger than you need.

I also recommend using jobber bits.
Well the press is only about a month old and I don't have any problems with holes drilled for pen tubes. I don't have much for drill bits but I guess I could use a couple others and see if somethings going on with it. What are Jobber Bits?
 

Dieseldoc

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Just another thought.
What tap are you using , as there are three styles of taps. Starter, plug and bottom .
To get a good tap hole always first use the starter until it bottoms out and finish with a bottom tap.
Some time when tapping a bottom or plug tap to start a hole it will not go in straight and after travel down the hole will try to straighten out the threads which can cause 20 or 30 percent holes which are over sized.
 

nava1uni

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If you make the hole smaller then what the directions say by 1/64 to 1/16 it is less apt to strip. I also strengthen the threads with a little CA so that they don't strip out as easily
 

monophoto

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What tap are you using , as there are three styles of taps. Starter, plug and bottom .
To get a good tap hole always first use the starter until it bottoms out and finish with a bottom tap.

Good point. Only argument is that I think most people user the term 'taper tap' rather than 'starter tap'. And the taps that you most often encounter on the rack at a hardware store are taper taps - plug taps and bottoming taps tend to be special-order items.

But I think the problem that OP encountered is that it is difficult to tap a hole drilled into end grain. The grain is running parallel with the sides of the hole, and when you use a tap to cut threads in the sides, each thread is effectively a small ridge that is perpendicular to the direction of the grain. As a result, it is very easy for threads to shear off when they are subjected to stress.

Because a 'taper tap' is tapered, the cutting burrs are more shallow toward the tip of the tap. That means that as it works through a hole, it first cuts shallow threads that are subsequently made deeper as the tapping process proceeds. The tap actually rides on the threads it has already cut - that's how it maintains the pitch of the thread. But that also means that the initial threads have to withstand the stress caused by advancing the tap into the hole.

The problem when threading wood is that dry hardwoods are often also brittle. So now you have the situation where you are cutting shallow threads, and immediately stressing them as you advance the tap further into the wood. Depending on the species of the wood, and on how dry it is, it is not unusual for the process of tapping to actually just ream out the diameter of the hole, leaving only rough, shallow threads.

It's easier to tap holes in face grain because the grain is parallel to the direction of the threads. As a result, each thread is stronger and more able to resist of the stress of the tap as it advances into the hole.

Threading a blind hole with a taper tap alone leaves tapered threads - the threads are more shallow toward the bottom of the hole because the tap bottoms out before it can cut full-depth threads over the full depth of the hole. That can actually be an advantage in tapping stopper blanks because it means that the hole will have a tighter grip on the mandrel as the mandrel is screwed deeper into the hole. On the other hand, that can also mean that it's harder to remove the blank from the mandrel when you are done.
 

bsshog40

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I was just gonna drop down to a 7mm bit and ca the threads but I think I'm just gonna go with the inserts. I'd rather have stability and also be able to remove the top if I ever need to and replace or repair. Thanks for all the comments and ideas.
 

Q16

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Anyone have experience with stainlessbottlestoppers.com
They have mandrels that screws on to lathe.
I have not tried them, I am just looking into turning bottle stoppers myself and came across them at the woodshow.
 

Edgar

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I have the same PSI mandrel & tap. I use a 9/32” bit to drill the pilot hole. I find that that works well for most woods, but I don’t stabilize, so sometimes really sift woods will still strip out. In that case, I just redrill with a larger bit, glue in a dowel plug and start over with the 9/32” & tap after the glue cures.

FWIW I use mesh jar lid grips to remove the blank from the mandrel. Our local $ store has a pack of 3 or 4 fir a buck
 

sbwertz

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Get some scrap wood and try drilling with these sizes of drill bits. Letter N bit and a 19/64 bit. Try tapping them and see what happens. I think your drill press might have some runout and is making the hole a little larger than you need.

I also recommend using jobber bits.
Well the press is only about a month old and I don't have any problems with holes drilled for pen tubes. I don't have much for drill bits but I guess I could use a couple others and see if somethings going on with it. What are Jobber Bits?
The big Harbor Freight drill bit set is well worth the price. The 115 piece cobalt set is what I have here, but the HHS set is only 35 dollars and will get you out of a lot of problems. That is what we have been using at the blind center for four years and they are holding up really well.
 
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bsshog40

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Well I got the inserts in. Glued up about 3 blanks yesterday. Turned one this afternoon. Inserts work great. Didn't even have to use the tailstock. Think I'll stick to the inserts. Will be able to take them back off should I need to or even replace the top with another. Thanks for all the advice and comments yall!
 

monophoto

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The big Harbor Freight drill bit set is well worth the price. The 115 piece cobalt set is what I have here, but the HHS set is only 35 dollars and will get you out of a lot of problems. That is what we have been using at the blind center for four years and they are holding up really well.

I made a similar choice, but I also made a conscious decision that those bits would only be used on wood. I have a rag-tag collection of bits that I keep for drilling metal.

I have had two of the HF bits break - both small diameter bits, and both snapped when I tightened the jacobs chuck not realizing that the bit wasn't centered properly. I didn't know that could happen - - - but now I do.
 

MRDucks2

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I have the big 115pc HSS set from HF. Funny thing is that I bought their Brad Point set first and it was the first thing I ever returned to HF for my money back. There wasn’t a straight bit in the set.

Lady asked why I was returning the bits. Told they had a problem, they would not drill a round hole. When she realized I was serious she started laughing and said that was a pretty good reason.

The HSS set has been fine.


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