Advice on closed-end mandrels

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BHuij

BHuij

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Joined
Apr 23, 2025
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Location
Utah
I'm getting ready to try my first "semi kitless" pen. The plan is to steal the section and threads from an Atrax kit, and turn the cap and body with a closed end instead of using the finials. Then I'll drop a real Bock #5 nib in to replace the IPG that comes with the kit.

Is the CSUSA pin mandrel a good option? https://woodturnerscatalog.com/prod...closed-end-pen-mandrel?variant=40659746553879

I understand how the mechanism works, and I worry about the ability to mount it without significant runout, especially if I end up taking it off and putting it back on.

Anyone have experience with these mandrels, that can recommend them (or recommend something else)?
 
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I can't comment on their longevity/runout etc but I will say my next 'kits' I intend to buy ,excluding whatever comes in stock at McKenzie, is one of these two pen kits Artemis or Apollo, probably Artemis from Bullseye Turning Supplies and buying 4 kits gets you the proper closed end mandrel. Nice that with some spare parts you can switch from rollerball to fountain or vise versa. I should add I have the PSI collet chuck system for my lathe.
 
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I don't have experience with that specific mandrel.

What I did when I made a couple of closed-end Churchill fountain pens was this:

1. cut the blank for the barrel longer (about 1cm) than specified
2. drill to specified depth with the normal drill bit
3. drill 0.5cm further using a 7mm drill bit
4. glue a cut-off piece from a slimline kit into the 0.5 cm extension
5. glue the regular barrel tube in as normal
6. take a normal 0.247" mandrel (without a Morse taper) and grind the tip into a flat-blade shape
7. jam the mandrel into the wood at the bottom of the 7mm tube
8. slip the regular bushing into the open end of the barrel
9. add a couple of slimline bushings as spacers
10. slide the end of the mandrel into a collet chuck so it holds the barrel tight
11. turn ...
 
Thanks all for the advice. @duncsuss that sounds like a pretty smart way to do it actually - the 7mm tube to make sure things are still centered despite a larger pen diameter, and a fairly inexpensive sacrificial mandrel.

I think I will give these pin mandrels a try. They're pretty affordable and I would only need a pair of them to get started.

Artemis and Apollo area also pretty good options for a "proper" threaded mandrel. Might try those too at some point.
 
BHuij said:
I think I will give these pin mandrels a try. They're pretty affordable and I would only need a pair of them.
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Looks like Craft Supplies' sizes are limited. FYI Rick Harrell makes them and can do any size you need. Rick is a member here. None better and the price is competitive. No website but he has a catalog in the vendor forum with contact info.
 
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BHuij said:
I think I will give these pin mandrels a try. They're pretty affordable and I would only need a pair of them to get started.
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As Don said - you cannot do better than send @rherrell a message saying you'd like a pin chuck.

He's also your man for threaded mandrels, for die holders, and a whole bunch of other stuff that you'll wonder how you managed to make a pen without.
 
So CSUSA has in stock the 12.5mm size right now - the kit I'm using uses a 10.5mm tube for the body and a 12.5mm tube for the cap. I like buying from CSUSA because I'm actually about 10 minutes away from their warehouse, and they have a small storefront. So I can get stuff locally without paying or waiting for shipping.

Here's the thing - it's my understanding that if I'm going to use a 12.5mm tube, then I drill a 12.5mm hole in the blank and glue in the tube. That would indicate that the OD of the tube is 12.5mm, meaning the ID would have to be smaller. The listing for the CSUSA pin mandrel indicates that it "helps you create extraordinary pens using ordinary pen kits." Is that an indication that the 12.5mm designation, for example, is a nominal thing that would fit the ID of tube designed for a 12.5mm hole? Or am I going to find it's just a little too large to fit inside the tube?

If these ones are too large, then it probably makes perfect sense to order some from Rick Harrell. Good to know he's the guy for custom pieces like that!
 
Okay, CSUSA had the pin mandrel for a 12.5mm tube in stock and said it was designed to fit inside the tube.

They didn't have the 10.5mm version in stock, so I ordered one from Rick Harrell.

Hopefully these will work okay in my Jacobs chuck! A collet chuck is on the wishlist, but I've spend a frightening amount of money on this hobby in the past few weeks, so I'll give the Jacobs chuck a shot before spending more.
 
Good call on the draw bar. I'll have to check and see if my Jacob's chuck is threaded on the back end of the morse taper.
 
BHuij said:
Good call on the draw bar. I'll have to check and see if my Jacob's chuck is threaded on the back end of the morse taper.
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Andrew; If it is not threaded, you can likely remove the taper from the chuck base. Jacobs Chucks almost always have a taper in the base of the chuck that is either a JT6 or JT33. Some chucks are made in one piece and cannot be switched. Little Machine Shop is a good place for tooling.
 
@rherrell I actually found and watched that video yesterday. Runout is my #1 concern. I have a dial gauge arriving today, so hopefully I'll be able to get my pin mandrels running true before committing expensive materials to them.

@randyris - My jacobs chuck definitely came in two pieces. The "jaws" part and the MT2 arbor were separate. Are you saying I could probably find a different MT2 arbor (that is drilled and tapped in the back for use with a draw bar) that would fit the chuck?
 
BHuij-Is that a baby Sinar? I have been making closed end for a long time and have unique holder....it screws and expands in the blank....sorry don't know where I got it..PennState maybe?.... it works great and have 10.5 and 12.5 sizes....
 
BHuij said:
@rherrell I actually found and watched that video yesterday. Runout is my #1 concern. I have a dial gauge arriving today, so hopefully I'll be able to get my pin mandrels running true before committing expensive materials to them.

@randyris - My jacobs chuck definitely came in two pieces. The "jaws" part and the MT2 arbor were separate. Are you saying I could probably find a different MT2 arbor (that is drilled and tapped in the back for use with a draw bar) that would fit the chuck?
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Yes; If you find the specs for your chuck it will likely tell you the taper. JT6 and JT33 are most common. This is a JT33 with a drawbar attachment
from Little Machine Shop (Calif) https://www.littlemachineshop.com/products/product_view.php?ProductID=1883&category=

Much more accurate is a collet chuck. ER32 can thread onto your lathe and get a set of metric collets. An ER32 chuck and collets are universal but only within the ER32 family.
 
@moke It's an Intrepid 4x5. Similar in many ways to a Sinar, though not as high-end. But it keeps the film dark and holds the lens at the right distance and angle, so it gets the job done :D Is the mandrel you're using the one that has various diameters of soft tubing that get compressed to grip the brass from the inside?

@randyrls I tried yesterday to put the Jacob's chuck in the headstock so I could throw my 12.5mm pin mandrel in and check runout with my brand new dial indicator. The morse taper has a non-round part at the end of it that renders the whole thing too long. It bangs into a headstock bearing before it seats properly. Was never an issue with the tailstock, which is the only place I've ever mounted it. I've always just used it for drilling blanks, and I guess that's what I'll keep using it for.

That ended up being the push I needed to just buy an ER32 collet chuck set. It will be here today. Hopeful that the arbor it comes with can be fitted with a draw bar, but I guess it's good to know that I can probably swap it out with a different arbor if I need to.
 
Collet chuck arrived yesterday - it screws directly onto my 1x8 headstock spindle screw, so no draw bar required, looks like. I tested it yesterday with the 1/4" collet and the 12.5mm pin mandrel I got from CSUSA, and found it had less than 20 microns of runout. God enough for me!
 
BHuij said:
Collet chuck arrived yesterday - it screws directly onto my 1x8 headstock spindle screw, so no draw bar required
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This is by far the better type of collet chuck. The first one I bought was from Woodcraft, it has a morse taper - which means that I can't push long rods through it. The screw-on type lets me push rods through to shorten the amount sticking out. (I still use the WoodRiver chuck from time to time, for example if I have drill bits that are too large for my Jacobs chuck to hold.)
 
I have Rick's (and Bulls Eye's). Regardless of the one used and the length of the tube, try to support the closed end with tailstock as long as possible.
 
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