Pen Mandrel

[melogic]

I have been curious as to where I can purchase a screw on mandrel for my lathe? I assume these do exist? I have a 1"x8tpi. lathe. How much do they cost? I have been wanting to go this route as opposed to the regular MT mandrels. I think the screw on will give a truer turning. Thanks in advance for any and all information.

 

[vick]

a screw on mandrel is called a collet chuck[]

 

[Old Griz]

I use the Axminster Collet Chuck that CSU sells and love it...
The Beall is also great...

 

[melogic]

Thanks Vick and Griz.

 

[scubaman]

Originally posted by melogic
<br />I have been curious as to where I can purchase a screw on mandrel for my lathe? I assume these do exist? I have a 1"x8tpi. lathe. How much do they cost? I have been wanting to go this route as opposed to the regular MT mandrels. I think the screw on will give a truer turning. Thanks in advance for any and all information. [][]

Well, it's not more accurate, actually. The interior surface of the spindle is ground very accurately. In a thread, even if cut accurately, by necessity, there has to be some clearance. Lathe spindle noses ar enot laid out with a boss that forces alignment. So in theory, you will get better accuracy out of an internal taper. And I am rather sure that if you put an indicator at teh mandrel RIGHT at the head stock you'll find it's very true there - as long as you don't have any crud in the taper. That latter is VERY important of course. My lather, out of the bag, had some rough areas in there. A very light pass with a morse taper reamer took care of it.

I am lucky with my Beall collet chuck, it happens to be a very good fit and run very true on my lathe nose thread.

BTW I have never seen a simple screw-on adapter.

 

[Randy_]

You can buy a screw-on mandrel with a 1" x 8 thread from PSI.....catalog #PKM-BL. They run $26.50. As was mentioned earlier, I don't know that there is any reason to expect a screw-on type mandrel to be more accurate than one using a Morse taper arbor.

 

[ctEaglesc]

There are times when I use my Beall to hold a mandrel as in when doing casing pens,
That being said the money spent on a collet will buy a LOT of mandrels and adapters and with them you pop one out and put one in.
You will find a lot of uses for a collet cuck but as a dedicated mandrel holder alone it is a waste of money.
Forget the "pro" adjustasble mandrels that need two wrenches they are PITA.
As far as the threads having effect on alignment of the beall type collet,it would seem the milled head that hits the shoulder of the drive spindle would make up for any slop.

 

[scubaman]

Originally posted by cteaglesc
<br />You will find a lot of uses for a collet cuck but as a dedicated mandrel holder alone it is a waste of money.
Forget the "pro" adjustasble mandrels that need two wrenches they are PITA.

Agreed!!! And it wouldn't be all that hard to improve on. A knurled larger diameter collar would do the trick. There does not need to be a lot of holding force on the mandrel - as long as you don't tighten the mandrel nut before bringing up the tail stock.

As far as the threads having effect on alignment of the beall type collet,it would seem the milled head that hits the shoulder of the drive spindle would make up for any slop.

Yeah, there's a certain amount of 'centering' on the screw threads going on when the end of the chuck hits the bearing (that's typically where it bottoms rather than a spindle shoulder). But I can tell you that is not enough for good centering. A friend had a lathe with severely undersize spindle nose threads. I can tell you nothing on the spindle nose was usable! He didn't know face pltes needed to run true, thought this is the way they all are. Of course that was a gross case, but it simply exaggerates the effect that's there.

Originally posted by Randy_
<br />You can buy a screw-on mandrel with a 1" x 8 thread from PSI.....catalog #PKM-BL.

Ah, I was wondering but didn't check, since they make a Shopsmith mandrel with a 5/8" bore.

 

[melogic]

Thanks guys for all of this information. It has been a learning experience.

 

[ctEaglesc]

Scuba man said:
"Agreed!!! And it wouldn't be all that hard to improve on. A knurled larger diameter collar would do the trick. There does not need to be a lot of holding force on the mandrel - as long as you don't tighten the mandrel nut before bringing up the tail stock."

The problem is if they did do that they would charge more and yoiu still wind up with a dedicated 1/4 maandre.
The money would be better spent by saving to get a collet chuck that would allow you to use different mandrels, but I still would rather have an assortment of mandrel adapters and mandrels.
For the cost of one adjustable I could get 2+ mandrels and have 2 working at the same time.

 

[scubaman]

cteaglesc,
I'm by no means trying to convince you that an adjustable mandrel would be better for you ;-) There are other ways to turn odd length barrels - e.g. a split mandrel. I think single-barrel mandrels have pretty much disappeared. I bought one of the early adj. mandrels, when only WC had them, and it was extremely poor and non-reproducible. The machining was terrible, the morse taper didn't even fit. I hope they have improved since then!

I don't know if you ever came across the large diameter rubber collars that converted keyed drill chucks to key-less operation. With the large diameter you could apply a fair amount of torque. Something like that instead of the rear wrench flats would be a small improvement. I use a Beall collet chuck, and hardly ever use the wrench - the nut diameter is large and grappable enough I can simply hand tighten. An improved adjustable mandrel doesn't have to cost a lot! A collet for a single diameter needs only a slot - doesn't have to be the multi-slot arrangement that ER series collets have. These collets have to remain concentric over a grip range of 1 mm. If you have a collet that has to grip 1 fixed diameter this is not necessary.

Anyway, it doesn't HAVE to be expensive. Unfortunately, it looks like there is 1 source that all these suppliers buy from... no development on their own...

 

[Pipes]

I see there is 4 diffrent sets in 8 tpi but diffrent size of somthing ?? what is this size thing ! And does it have anthing to do with fitting the lathe I have a Nova Mercury ! ???????





http://affordablepipes.com/

 

[Pipes]

Originally posted by Pipes
<br />I see there is 4 diffrent sets of the Beall in 8 tpi but diffrent size of somthing 1" 1 1/4" and so on all 8 tpi ?? what is this size thing ! And does it have anthing to do with fitting the lathe I have a Nova Mercury ! ???????





http://affordablepipes.com/

 

[scubaman]

Originally posted by Pipes
<br />what is this size thing !

It's a simple way to make sure things fit together ;-) Here the spec is the thread size and pitch: 1" diameter, 9 Threads Per Inch

And does it have anthing to do with fitting the lathe I have a Nova Mercury ! ???????

You need a 1"x8TPI.