Can anyone explain how this happens?

[Jayman72]

Hey all,

I have noticed that recently I have been having an issue with my pens.

When I turn a pen my "cap" barrel is on the left of my mandrel with the clip side farthest left and the "base" barrel is on the right side of my mandrel with the nib side farthest right.

I use a mandrel saver and not a live center as well.

I have noticed that the section that the Nib gets pushed into is continuously off center.


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While at the same time the other side of the same barrel is spot on


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Now this seems to be happening on every pen, no matter the kit type, so I do not believe its an issue with the bushing being off center.

To be sure I put a caliper on the bushing I was using that produced this blank and it was pretty close to round (off by */- .03mm which I assume is well within tolerances.)

I am going to make my next pen with only using one barrel at a time and push the the mandrel saver all the way up to see if the issue is my mandrel getting out of round on the far end.

Being able to cut both barrels at once is a time saver but not having to remake a barrel is an even bigger one.

Any ideas will be welcomed.

Thanks
Jay
Tampa, FL

 

[TBCbushings]

I would make sure the headstock taper is running true. After that I would see if the mandrel is running true at the headstock. If not the problem might be the mandrel. If you have 60 deg centers put a blank tube between and see if it is still running out.

 

[TurtleTom]

You probably have a bent mandrel.
Take everything off the mandrel, put it in the lathe with the live center and turn it on. Mark the out of round with sharpie and bend it straight between two metal objects or just on the flat metal surface.
Make sure your Morse Taper Socket is clean too each time you insert the MT2.

 

[magpens]

One factor which may contribute is improper alignment of the headstock axis and the tailstock axis.

I believe I have this problem. But I do not believe I have the measuring instruments or the skill to check for and correct the possible misalignment.

Doing what you are planning to do (turn one barrel at a time rather than both barrels at once) did, I believe, reduce the magnitude of the problem.

Another factor could be inaccurate sizing of the center cylindrical portion of the bushing (the part that goes into the tube). If that is just a shade too small, you can get the effect you notice. The axis of your blank end will not coincide with the bushing/mandrel axis.

Turning between centers (TBC) without using bushings can help to eliminate this problem. Use a dead center in the headstock and a live center in the tailstock. Both centers should have conical tapers (usually 60*). The brass tube makes contact with the conical tapers. Use calipers to measure for correctly-sized turning.

 

[TonyL]

I don't know how it happens, but it happened enough to me, to TBC and ditch the mandrel . I would make 6 or 7 of 10 fine, and 3 or 4 out of round using a mandrel (mandrel saver too).

 

[Jayman72]

Turning between centers (TBC) without using bushings can help to eliminate this problem. Use a dead center in the headstock and a live center in the tailstock. Both centers should have conical tapers (usually 60*). The brass tube makes contact with the conical tapers. Use calipers to measure for correctly-sized turning.

You'll have to excuse my ignorance but can you point me to what a "dead center" is? I checked woodcraft and don't see anything called a "dead center"

I totally get what you are suggesting and it sounds like a great idea.

Thanks
Jay
Tampa, FL

 

[KenV]

Turning between centers (TBC) without using bushings can help to eliminate this problem. Use a dead center in the headstock and a live center in the tailstock. Both centers should have conical tapers (usually 60*). The brass tube makes contact with the conical tapers. Use calipers to measure for correctly-sized turning.

You'll have to excuse my ignorance but can you point me to what a "dead center" is? I checked woodcraft and don't see anything called a "dead center"

I totally get what you are suggesting and it sounds like a great idea.

Thanks
Jay
Tampa, FL

They look like this

http://www.amazon.com/Grizzly-H7967...=1442448644&sr=1-1&keywords=lathe+dead+center

and are available from about $5 and up depending on the source and the precision


60 degree cone is standard

 

[Jayman72]

They look like this

http://www.amazon.com/Grizzly-H7967...=1442448644&sr=1-1&keywords=lathe+dead+center

and are available from about $5 and up depending on the source and the precision


60 degree cone is standard

Awesome. I'll look into getting myself one and giving it a try.

Thanks
Jay
Tampa, FL

 

[edstreet]

Interesting enough in posting your progress you answered your own question in the process.

 

[Jayman72]

Interesting enough in posting your progress you answered your own question in the process.

Well following the thought process of "the simplest solution is normally the best one" I figured doing one at a time would be the best way to figure out if my mandrel was the issue.

But being new to this I wanted to see what ideas the professionals had about why it was happening.

And I think I got some pretty good ideas.

Thanks again.
Jay
Tampa, FL

 

[MikeinSC]

I had that same problem and fought it to the point of utter frustration. Here's what I've learned.

Keep the head and tail stock in line with each other best you can. Especially if using a Harbor Freight lathe like I do.

I no longer turn both parts of the pen at once. I shorten the mandrel down to just the part I'm working on. That was likely the biggest thing to get me back to running true. Think of it like a batter choking up on a bat.

I ditched the mandrel saver. I was not happy with that thing at all. I found it to be a complete waste of money.

When I ditched the mandrel saver, I replaced it with a 60° live center for the tail stock.

Don't clamp down with a lot of pressure when putting the live center to the end of the mandrel. It just needs enough pressure to stabilize it.

So...60° live center and choking up on the mandrel helped me with that same issue.

 

[randyrls]

Jay; I had the same problem and it turned out that the ends of the barrels were not exactly true (90 degrees) to the tube. When tightening the mandrel nut or saver, the angle would pull/push a bow into the mandrel. When released to check the mandrel it was straight of course.

One way to test your set up is to mount bushings and bare brass tubes. Turn the speed of your lathe to slow. Carefully lay a wood turning tool at 90° to the rotation of the lathe. Any vibration indicates an out of round condition. Now that you have a way to test, you can work to eliminate the vibration.

Hope this helps.

 

[sschering]

I had that issue with my Jr pens.. It turned out the bore on the bushing was off center slightly.. Thanks for reminding me I need order a good set of Jr TBC bushings..

 

[Mortalis]

One factor which may contribute is improper alignment of the headstock axis and the tailstock axis.

I believe I have this problem. But I do not believe I have the measuring instruments or the skill to check for and correct the possible misalignment.

Doing what you are planning to do (turn one barrel at a time rather than both barrels at once) did, I believe, reduce the magnitude of the problem.

Another factor could be inaccurate sizing of the center cylindrical portion of the bushing (the part that goes into the tube). If that is just a shade too small, you can get the effect you notice. The axis of your blank end will not coincide with the bushing/mandrel axis.

Turning between centers (TBC) without using bushings can help to eliminate this problem. Use a dead center in the headstock and a live center in the tailstock. Both centers should have conical tapers (usually 60*). The brass tube makes contact with the conical tapers. Use calipers to measure for correctly-sized turning.

Misalignment of the head stock to the tailstock will result I. a taper not off center. This is more than likely a bent mandrel or foreign material in the morse taper.

 

[Jayman72]

Hey all,

Well with a little work I was able to salvage it.


View in Gallery

And since this one I have made a few others and am doing each half one at a time. Seems to be working out just fine.

Thanks for all the info and support.

It's very much appreciated.
Jay
Tampa, FL

 

[pianomanpj]

Nice! That pen came out great!