Bottle stoppers out of round?

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Marmotjr

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Picked up one of the PSI bottle stopper kits, including chuck, stoppers, blanks, tap, etc. I had been messing around using the silicone stoppers on the dowels, and just using raw cork (Hint, corks compress or expand depending on how they are mounted or at what RPM they are spun, makes for a real treat when trying to turn to a specific diameter).

My first BS went great. I love making these things now.

Next one is a beautiful Paduak, finished with a couple coats of Shellac, grooves inlaid with gold leaf, and then a few coats of Poly. I had to cut it off the chuck, as the poly had formed a film over the chuck. So I have to rework it a touch to get that sharp edge off. (Going to use a thin washer to offset future pieces from the chuck when finishing from now on).

I placed it on the stopper, and it's out of round. One side is >1/32" off from the edge, while the other side is flush. I try a second stopper, same thing. I mount it back on the now cleaned up chuck. While it does sit a bit prouod because of the finish, it's even all the way around.

My first turning was dead nuts co-centric with both the chuck and the stopper.

Could PSI have a run of stoppers (The chrome and silicone part with the bolt) that aren't turned properly? One of them that failed actually feels a little lumpy on one edge.
 
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Jolly Red

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One way to tell if the stopper is actually round is to measure several diameters with calipers. If all of the readings are the same, then it is perfectly round. This also needs to be done to check the centering of the stud on the stopper. The amount these are off will tell if it is too out of round to use. Personally, I don't think a thousandth or two is going to make much of a difference. The wood will swell and shrink this much during use. If you have several of these, contact PSI to see if they are aware of the problem, and if they will be willing to make it good to you.
 

Marmotjr

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The one stopper I did measure varied between .927 and .953, the chuck between .9615 and .960.

I could break out the dial indicator and see what the runout is if I reverse mount the stopper on the chuck, but that's a lot of work, and I don't know if my dial indicator will actually mount properly.

Looking closer at my first one, it too is not cocentric. But the design of the blank hides this as it immediately flares out. This latest one actually tapers in a bit (over aggressive sanding, whoops, but it makes for a nice profile).
 
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Marmotjr

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Can you post pics of your turning process? I used literally thousands of the silicone stoppers, and hundreds of the cork version and have never had a problem.

I used the starter Kit that PSI provides, which includes a screw chuck, tap, stoppers, and a few blanks.

I drill the blank with the bit provided in the kit, and then tap accordingly.

Mount it on the screw chuck, and turn it down like I would with pen bushings, so it's flush with the end of the chuck.

Finish to taste, and understanding that the finish will add a bit of diameter to the piece. I have now fashioned a HDPE ~1/4" threaded bushing to sit between the chuck and the piece to allow the finish to wrap around smoothly.

Then screw onto the stopper.

The bolt in the stopper does not appear to be cocentric with the outside diameter. The outside diameter is also varying in size and regularity, there are flat spots on it.

My first thought was there's no way my hand turned piece is more accurate than a machined part, but I'm thinking these stoppers are cast, not machined, and then chrome plated.

As for the cork, I have a large bucket of extra large corks. In order for them to fit in a standard bottle, I have to reduce their diameter some. I went through a lot of corks before getting it right, as they are fragile and expand when squeezed down between centers, or crush when put in a chuck. That makes the final dimension somewhat random when I remove the cork from the lathe.

I have no issues with the silicone on the wooden dowel stoppers, other than getting the blank to mate properly (resolved), and then holding the blank on the lathe (somewhat resolved).
 

monophoto

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The bolt in the stopper does not appear to be cocentric with the outside diameter. The outside diameter is also varying in size and regularity, there are flat spots on it.

My first thought was there's no way my hand turned piece is more accurate than a machined part, but I'm thinking these stoppers are cast, not machined, and then chrome plated.

The first few stoppers I made used the PSI plated metal components. They are fine - the fact that they may not be perfectly concentric is not a major issue because they are just bottle stoppers. However, I very quickly learned that if you want quality metal bottle stoppers, you buy the components from Ruth Niles. Her's are turned, food-grade stainless steel. Yes, they are more expensive - that's exactly what you would expect.

Most of the stoppers I make are given away, so I don't want to sink a lot of money into them. So I tend to use the PSI dowel/silicone sleeve components for my 'everyday' stoppers. The only issue with them is that when you are making the turning, you need a hole in the blank (3/8x16) to fix it to the stopper mandrel, so you drill a 5/16" hole and then tap it. But when you finish the turning, the hole is too small to accept the wooden dowel. My solution to that is to use an 11/32" drill bit to bore out the tapped hole before gluing the dowel in place. I do it manually - hold the drill with vice grips and gently twist the finished stopper top to ream out the threads to leave a hole that the dowel will snugly fit into.

I take a different approach to the problem you encountered with finishing the seam between the bottom of the turning and the top of the metal component. I put a recess on the bottom to accept the top of the metal stopper component. One way is to use a forstner bit to cut a mortise about 1/16" deep. Alternatively, I use a spindle gouge to scoop out a recess. In either case, I do this with the blank mounted in a chuck with the bottom end facing the tailstock, and then reverse it onto the stopper mandrel for the rest of the project. But the result is the same - the bottom of the turning is always larger than the diameter of the mating component, and more importantly, when viewed from the side, the seam between the turning and the top of the metal component is hidden behind the edge of that recess. The result looks neater and avoids the finishing problem you encountered.
 

nava1uni

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If your drilled hole is not centered into the blank it will be off center when you assemble it. The drill bit can hit grain and be directed off center and it looks fine until it is put together.
 

Marmotjr

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I would like to "paraphrase" what Cindy says: Operator error! Practice may or may not make "perfect", but it will get better!:biggrin:

Not sure if the last couple posters didn't read the thread or not, but the turned piece is, surprisingly, round.
 

nava1uni

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I did read it and have found that if the drill wanders during the drilling. It will look good on the mandrel while turning, but will not be balanced when you assemble it.
 

dogcatcher

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I did read it and have found that if the drill wanders during the drilling. It will look good on the mandrel while turning, but will not be balanced when you assemble it.

Using the PSI bottle stopper chuck and the provided 5/16" drill bit. The hole will only be about 1" deep, it would have to be a flexible bit made out of hard rubber to deflect that much.
 

Marmotjr

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Yes, mandrel is true with no noticeable run out by feel (I have not setup the dial indicator).

Work piece runs true with no run out by feel.

When rolled on the table, all 5 stoppers are lumpy and bounce along. The hole is visibly out of center when rolled. By measurement, the hole is off center as bad as .01" in one case.

I'm just going to change the design of the rest of my stoppers to hide the poorly made metal parts.

I will be ordering from different supplies in the future.
 

monophoto

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If your drilled hole is not centered into the blank it will be off center when you assemble it. The drill bit can hit grain and be directed off center and it looks fine until it is put together.


Sorry, but this explanation isn't quite correct.

The normal sequence is to drill and thread the hole in the blank, and then screw it onto the threaded stud on the mandrel for turning. Unless the mandrel is flawed and the threaded stud isn't centered on the mandrel, the stud will be centered on axis of rotation of the lathe. So it doesn't matter whether the hole is centered in the raw blank because when it is turned on the lathe, the finished turning will be centered on the axis of rotation, and therefore on the hole.

What can happen, however, is that the hole in the blank is not exactly perpendicular to the face of the blank. Because the mandrel should be centered on the axis of the lathe, the turning will be concentric about the hole. As a result, when the finished turning is later screwed onto the metal stopper barrel, it won't seat properly around the top.

This problem commonly happens if the blank is drilled on a drill press or with a hand drill. If you are using a drill press, a solution is to first drill a shallow recess using a forstner bit, and then drill the hole without moving the blank. Effectively, drilling the recess squares the face of the blank with the axis of the drill.

The better approach is to drill on the lathe, first squaring the face of the blank (and preferably putting a shallow recess in the bottom so that the edge will hide the join between the metal stopper body and the bottom of the turning).
 

Marmotjr

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Did you ever get this issue resolved?

Yes and No.

No, I never heard from PSI, but as with a lot of the stuff we deal with, it seems there is only one manufacturer of a lot of this stuff and it gets resold by various vendors. So I'll have to search long and hard to find machined bottle stoppers.

Yes, as in the fact that I will no longer turn the blanks flush with the 'bushing' end of the mandrel. I will either have them immediately flare out from the metal part so any eccentricity will not be obvious, or I will drill a shallow 1" hole in the blank, concentric with the screw hole, so the end of the stopper is recessed into the blank a bit.

If I ever get a metal lathe, I might look into turning my own, and then using a mold to cast the silicone around it.
 
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Thad,
I've mentioned this in another thread, but I turn all my bottle stoppers on a pin chuck... I took a 3/8" steel rod, cut it to about 6", ground a flat on one end about an inch long, then mounted in a collet chuck. I use a finish nail cut to the length of the flat. Drill the blank with a 3/8" bit, push it over the flat with the nail in the middle, then twist it away from you... it's pretty secure, you can spin it pretty fast (I turn stoppers at 1900 - that's one of the stops on my Reeves unit).. you have room at the bottom to work on the bottom, just watch not to hit the nail.. it messes up the edge on your tools... if the blanks wants to wobble, use the tail stock until you're ready to do the very top, but if it's secure in the hole, it has to turn concentric to the hole.

As for the stopper inserts, I get all of mine from EZ-Pot.com....

Wholesale Stainless Steel Bottle Stoppers Blanks Kits Wholesale Teardrop Bottle Stopper Kits.

They are all 304 stainless food grade steel and are pretty nice. You can't tell them from anything PSI or Woodturners catalog sells... they are not made in USA, but really who makes that much fuss about where things are made.... we live in a global economy now and if you are in business to make a buck, you work with the best quality components you can get for the least cost. (None of our pen kits are made in USA)
 

Marmotjr

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Thad,
I've mentioned this in another thread, but I turn all my bottle stoppers on a pin chuck... I took a 3/8" steel rod, cut it to about 6", ground a flat on one end about an inch long, then mounted in a collet chuck. I use a finish nail cut to the length of the flat. Drill the blank with a 3/8" bit, push it over the flat with the nail in the middle, then twist it away from you... it's pretty secure, you can spin it pretty fast (I turn stoppers at 1900 - that's one of the stops on my Reeves unit).. you have room at the bottom to work on the bottom, just watch not to hit the nail.. it messes up the edge on your tools... if the blanks wants to wobble, use the tail stock until you're ready to do the very top, but if it's secure in the hole, it has to turn concentric to the hole.

I've tried similar setups with wood dowels, haven't had a steel rod to use yet, but I can see that working very well. My issue isn't with the chuck, it's dead nuts round. And for getting the edge, I've started using a threaded bushing/washer to offset the blank a bit from the chuck to get that part just right without mucking up the tools.

As for the stopper inserts, I get all of mine from EZ-Pot.com....

Wholesale Stainless Steel Bottle Stoppers Blanks Kits Wholesale Teardrop Bottle Stopper Kits.

They are all 304 stainless food grade steel and are pretty nice. You can't tell them from anything PSI or Woodturners catalog sells... they are not made in USA, but really who makes that much fuss about where things are made.... we live in a global economy now and if you are in business to make a buck, you work with the best quality components you can get for the least cost. (None of our pen kits are made in USA)

I'll definitely look into them. And I completely agree with the global economy bit. I've bought junk made in the USA, and quality pieces from China, and vice versa.
 
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