How many different mandrels are there? I have one for the slimline pens, the 7 mm. I know there is other sizes out there but not sure how many. Of the ones I think I know of is;
Thanks for reading
Berea, P.S.I., CSUSA, all have their own variation of the mandel. and some of them have a couple of them.
I woudl consider the P.S.I. version teh basic mandrel. maybe because it's the one I use most. and saw first.
it is CSUSA I think that has basically the same thing as P.S.I. aas well as the pro mandrel. which has an adjustable collar so that you don't have to add spacer bushings to fill in the empty space, I have read a variation on this idea that allows the mandrel to be pushed through the head stock while being held in a three jaw chuck. same idea just from the other end. and far more expansive to get the equipment to do.
Berea has a drill driver mandrel system. this is the other end of the spectrum in my mind. highest degree of engineering. as well as presision. their manderels come in two or three different sizes as well. in effect giving maximum beef to the mandrel for a given pen design.
Basically the drill driver works the same way the collet in your drill press works. it is a morse taper with a slit in it the mandrel is inserted in the morse taper and the whole thing is sandwiched betweenthe head and tail stock. the pressure from the tail stock causes the taper to grip the mandrel. according to berea it is the best way to get the mandrel accuratly centered in the head stock. to much Physics for me to be able to confirm but it sounds good. I've used a couple of their mandrels and they work really well. some turners prefer them for their heftier build. they flex less and you end up with a rounder pen.
their are also other mandrels for Wine bottle stoppers, Bookmarks, and other non pen items as well.
no dought I've left out something if not alot. so please fill in the blanks. this was just right off the top of my head.
To add on to what Daniel said, I think there are only two commercial diameters of mandrel shafts. Everybody has the 7mm shafts, but Berea with their "B" shaft is the only other size I know of. That does not mean that people can't make their own mandrel shafts, as well as the bushings to fit. This is one of the biggest reasons for a penturner to also have a metal lathe! If I had a metal lathe, I would make all my own bushings, and I would make them to fit the "B" shaft for all of the larger pens!
Amen to the makign your own,
In my opinion the suppliers of tools have left huge holes in what is available. Not critisizing, they have to be able to sell enough of what they develope to make it profitable. but a 1/4 " mandrel for a tube that is over 12"inside diameter. It is my hope that I can just put a 1/2 inch drill rod in the 3 jaw chuck and turn Gent's pens and the other large pens on that. this will require making bushings with the needed inside diameter. but hey I gotta get over $300.00 worth of something out of this lathe. I also want to make bushings that have the taper I want for the tip of my pen. bacically the same shape or taper of the pen nib if that makes any since. an example is the Polaris Pen. for me I ike the shape of the tip and the finial of the Polaris. In my minds eye the barrel needs to be a smooth continuation of this arc. Bushings that show that angle would take some of the guess work out of continuing this arc.
I make a sculptured slimline that I run into the same thing with. I want the pen barrel to be a continuation of the angle of the nib or tip. this one I have alot of trouble eye balling. even a small difference really shows.
At three bucks a set (I think that is ryans price) for standard bushings. it's not worht the trouble of making my own. but for the custom stuff. well it still took me two years to finally bite the bullet and buy the metal lathe. I wnt to make a stainless stell pen just to know if the little lathe can work the stuff. I am thinking stainless steel and Mother of pearl.
Yeah, if I could make my own mandrels and bushings, I'd use the largest size rod for my mandrel I could. Stiffer, and less chance of "whip".
If you're thinking of using a three-jaw drill chuck, as opposed to a three-jaw machinists chuck, for holding the mandrel for penturning, I have found that the drill chucks are not so accurate! But I picked up a neat idea (from Rich K.) who uses a Beall Collet Chuck to securely hold odd size items for turning. He uses it to hold his mandrels, which is nice since he can adjust the length of the mandrel depending on how far it is inserted into the collet chuck before tightening.
I just thought this was the neatest idea, so I bought myself a Beall Collet Chuck, but I was too cheap to buy the collets from them. It uses standard ER-32 spring collets, and I'm just waiting for the right combination of enough money and the best price to pick up an eighteen piece set from 1/8" to 3/4".
I had the three jaw Mechinist chuck chuck on my metal lathe in mind when I wrote that. it has the same capability that you mention, with beign able to pass the extra portion of mandrel through the chuck and the head stock.
I would need some kind of spacer between the chuck and the pen barrel though. these chucks are awfully big. and I don't think the knuckles would take many raps from it. I think my big lathe will take a 1/2 inch rod through the head stock. Your collet idea would be nice for that one. I've been looking at making a collet set for the metal lathe. I could just make a set for the other one while I'm at it.