Threaded madrel for close end pens.

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alexkuzn

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How should a mandrel for a close end fountain pen for Lou's nib holders plastic should look like?
I assume it's a plastic rod threaded at the end that goes into beall chuck.
Right?
Now, since this is not an expanding mandrel it will not fit tightly into all drilled holes. A hole made with the same drill bit has slightly different diameters in different materials. If unthreaded part of the mandrel does not fit tightly into drilled pen body hole then mandrel does not provide much support along the whole length.


Am I missing something here?
 
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leehljp

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Here is a link to a previous post on the subject:

http://www.penturners.org/forum/showthread.php?t=46877

Within this post are 2 other links, one to SkipRats closed end mandrel and one to RedRiverPens. In the link to RRPens, scroll down to the "closed end pens" and click on those. Both of the above links work well but are somewhat different.

You are right that the farther out you go the less support there is. But this is a technique problem and most of that is patience and a sharp tool.

One other thing: Make ALL cuts starting from the closed-in end and cut towards the chuck. If you don't the blank will have a strong tendency to go flying.
 

alexkuzn

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Do we really need a pin chuck?
The advantage of pin chuck over regular friction fit mandrel is to prevent rotation.
In our case a pen body has internal thread and mandrel has internal thread on which we screw on pen body. A pen body will not rotate and also will be centered if you have a "shoulder" on your mandrel and pen whole opening was squared.

My problem with pin chuck is that if it is not a perfect fit it'll hold hold a pen off center.

Please feel free to correct me if I am wrong.
You guys have real experience. My opinoin on other hand is mostly "theoretical" :)
 

alexkuzn

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What do you think about using expandable brass cylinder from "Expandable Brass Cylinder Lap" that we can screw on our mandrel?
It'll make it easy to insure good tight fit. With this barrels you do minute adjustments to make sure it's not too loose or too tight.

It'll require us to thread the end of our mandrel to accept the brass barrel.
In other words our mandrel has about 3/4" long threads for nib holder and then instead of long unthreaded part will have a short threaded end(just like on the shank on the picture below) to accept brass cylinder.

These brass cylinders are very accurate and stay concentric when expanded.
Cost of a barrel is $4 and they come in small size increments.
You can find them on www.mcmaster.com
Expanding barrel:

barrelthru.jpg


Adjusting screw:
(you rotate this screw to expand barrel)
screw.jpg

Whole lap assembly:
thrushank.jpg


4548ac1l.gif
BarrelBlindHoleLaps.JPG
 
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Texatdurango

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How should a mandrel for a close end fountain pen for Lou's nib holders plastic should look like?
I assume it's a plastic rod threaded at the end that goes into beall chuck.
Right?
Now, since this is not an expanding mandrel it will not fit tightly into all drilled holes. A hole made with the same drill bit has slightly different diameters in different materials. If unthreaded part of the mandrel does not fit tightly into drilled pen body hole then mandrel does not provide much support along the whole length.

Am I missing something here?[/quote]

Maybe it's me who is missing something, but perhaps we're not talking the same thing.

You don't NEED a mandrel to make a fountain pen or any other closed end pen as long as you have a Beall chuck and a decent assortment of er-32 collets.

In preparation for an upcoming pen show I made these pens yesterday and there wasn't a mandrel in sight and they were made on a Jet mini lathe. I'm working on the caps today and don't plan on using a mandrel on them either, just my trusty Beall collet chuck. These front sections are not made by me but even the ones I make do not need a mandrel.

If interested in an alternative to using mandrels PM me and I'll share some thoughts.
 

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rstought

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The nib holders sold by Lou are "stepped" (e.g. the diameter changes several times across the length of the piece), so I think what Alex is looking for is some guidance as to whether or not any mandrel he might make to support a custom front section he is making might also have to be stepped in order to properly support the piece, or could he get by with some sort of expanding gizmo, etc...

I am interested in this topic as well, since I will soon be doing the same thing. George, in reading, it would be great if you could share some of your thoughts around front section construction here rather than in a PM...
 

nava1uni

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I would also be interested in hearing some of these thoughts. I am working on learning how to make fountain pens. I keep getting questions and requests to make. There is something about them that is scarey to me. Don't know what, oh well. Must conquer this fear.
thanks
 

PTJeff

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like this? for holding the body.
or this?
I have made something similar, substitute tap for brass mandrel, that holds the section.
 

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PTJeff

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Let me start by clarifying your question
How should a mandrel for a close end fountain pen for Lou's nib holders plastic should look like?
To me this is 2 questions.
1. "How should a mandrel for a close end fountain pen"
this represented by pic's #1 and #3
and
2. "Lou's nib holders plastic"
This is what we call the section. The section holds the housing, which is what Lou sells and that is what pictures #2 and #4 represent.
 
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