Mandril?

[moppetsdad]

Hello folks new member here

I already have been turning for a few years so good some bad stuff turned out,, the thing is I've never dabbled in pens and have been given a small Axminster lathes which came with a mandrill and I was wondering if all mandrills are to same size diameter wise?

David

 

[21William]

No, they vary depending on the manufacturer. There are also at least two “main” sizes, one for slimline pens and another for larger pens. The small ones have a shaft a little under 1/4” diameter, I can’t remember the size of the larger one. On the subject of mandrels the best ones seem to use a collet to hold the shaft rather than just having a hole with a set screw.

 

[21William]

I just found this which lists the two sizes of this manufacturer.

Pen Mandrel Shaft B | Klingspor's Woodworking Shop


“A mandrel is a round steel rod that you slide the wood blank with the brass tube inserted onto. Unlike most other companies who offer only one size mandrel we sell two sizes. The A mandrel (sometimes called a "7mm" mandrel) which is 0.247 +0 -0.002 inches in diameter and and other mandrel which has a larger diameter, the B mandrel. This is 0.291 +0 -0.002 inches in diameter. We use the B mandrel on some kits because the thicker diameter helps prevent whip while turning and allows for a much better result”.

 

[moppetsdad]

Thank you,, the one I have has a morse taper one end and a countersink for a lice center the other end,, looks like I'll have to measure it to find out which size I've got Thanks again

David

 

[21William]

If it’s within your budget, these are better than using a standard live centre.

SCT Precision Machine Pen Centre | Chronos Engineering Supplies

 

[Curly]

You title took me back to a Faulty Towers episode. Fawlty Towers: Syb-ill - YouTube Mandril.....Sybill.

If you look around enough you will eventually come across Turning Between Centres (TBC). You con't use any mandrel just a 60º live conical centre and a 60º conical dead centre. You can us bushings or none at all and measure with callipers to get to your sizes. Reduces some of the out of round (one side thinner than the other when you look at an end) issues you can get with mandrels. I only turn between centres. Something you might as well look into and decide if you want to go that route.

Pete

 

[wm460]

Wasn't Berea pens the one that bought out the B mandrels?

 

[Penpal]

I personally have never used a B Mandrel I simply love a dedicated pen lathe always still these days use a Mandrel Saver from choice
The beauty of my system is the Mandrel remains locked in position by a collet that is held through the head stock locked in with a threaded stem. My 5 pence mate.

Peter.

 

[21William]

Wasn't Berea pens the one that bought out the B mandrels?

There are a couple of places in the USA that list “B” mandrels. PSI also sell what they call a “Maxi” mandrel. No idea who first came out with the larger size but many seem to prefer them as they don’t bend or whip as easily as the little ones.

I have no interest in slimline pens so I just bought a piece of 7mm silver steel rod and a 7mm collet for my ER32 collet chuck. I drilled out my mandrel saver to 7mm and also do the same with any bushes I want to use. This way it doesn’t matter how badly off size the bushes are to start with.

I’ve heard of people sanding down their mandrels to fit certain bushes but this isn’t ideal as obviously it will no longer fit some of the others properly.

 

[Phil Dart]

In this country, they're all nominally 1/4 inch. The Berea "B mandrel" has never taken off in the UK. In reality though, there is no recognised standard for mandrels, which vary in thickness from a pretty skinny 6.15 or thereabouts on the Axminster Evolution to a frankly too fat 6.27 or thereabouts on the Rotur. I know that 0.1mm doesn't seem a lot, but it's the difference between bushes rattling around, or in some instances, just not fitting at all.

A few years ago I got close to persuading the major manufacturers to adopt one standard, but when I made that news public, I met with such blinkered hostility in some quarters telling me I was wasting my time, mainly from pocket-change rattling old lags with myopia, that I decided the task was just too uphill, not with getting the manufacturers on board, but with getting the buying public to see it was a good idea. I wish I hadn't listened to them now - if I'd carried on, all UK mandrels would now be 6.2mm and holes through the middle of all UK bushes would now be 6.25mm

 

[21William]

The Berea A Mandrel is apparently 0.247” or 6.2738mm so probably one of the largest of the small mandrels if that makes sense. The B mandrel is listed as being 0.291” or 7.3914mm. The PSI Maxi is 9/32” or 7.14375mm.

I must admit I find it rather confusing as to how this all came about. Apparently the early slimlines used a 7mm OD tube with a 1/4” bore?! What a strange specification. Given that you can buy precision ground 1/4” steel rod virtually anywhere wouldn’t it have made things much easier to make the bore in the tubes slightly larger to accommodate existing stock?
As for the B size standard metric stock is available in 6.5mm and 7mm so why not pick one if those.

Metric Silver Steel

I guess it’s just about profit and forcing customers to buy “special” size tools?

As I mentioned earlier I had enough of this nonsense and went with 7mm as my “standard” as it’s simple enough to modify smaller bushes etc, especially if you have a collet chuck.

 

[Curly]

The first kits to come out were slimline sized tubes and likely fit what the kit makers had readily available. The B mandrel came along when they started making bigger pens like the Cigar, and while better because they were stiffer they didn't catch on. I think people wanted to stay with one size mandrel and the bushings for it out of convenience and costs. So while some still have B mandrels there aren't very many kits using them and nothing new has been made in that size for a long time. Now the manufacturing tolerances is another story.

Pete

 

[21William]

The PSI Maxi seems to get very good reviews from quite a lot of folks so someone’s buying them in the USA?

#2 Morse Taper Maxi-Mandrel at Penn State Industries

It looks to be a good product for the price.