Screw on mandrel vs Morse taper

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jbg230

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Would a mandrel that screws onto the head stock necessarily stay more in round throughout a turning session, versus a Morse taper mandrel? It just seems intuitive that something screwed onto a shaft will be more inherently stable than something that is just press fit. Just questioning it since I was oblivious until now that PSI sells a screw on mandrel for my lathe's thread pitch.
 
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Kenny Durrant

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As far as pen turning goes I’ve always used a tapered mandrel and have never had any issues. I tried a collet chuck and had issues because as soon as you put pressure on the material without a tail stock it would come loose. That’s when I went to a screw on collet.
 

bmachin

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It depends.

The concentricity of just about anything inserted into the morse taper should be better than something screwed onto the shaft. However, something needs to be keeping the taper well seated: either a drawbar or pressure from the tailstock.

Just my opinion for what it's worth.

Bill
 

monophoto

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Morse taper fixings have been in use for more than a century, and work exceedingly well. So a morse taper fixing should be just as good as one that attaches by means of the spindle thread.

But stuff happens, and either fixing could be confounded by circumstances. If there is trash inside the spindle, a morse taper fixing could end up misaligned. If a threaded fixing doesn't seat tightly against the shoulder on the headstock spindle, it could be misaligned. And in either case, the mandrel could get bent.
 

magpens

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The Morse taper fitting is extremely accurate, provided the cavity part of it is kept clean (crud can get in under the best of circumstances)

So keep the tapers clean on both sides and it is preferrable to a screw mount, in my opinion .

Crud can get into a screw mount also on both sides and the 1" x 8 TPI threads (or whatever) are not a particularly precise fit all the time. .
I know that they should be if you screw up tight to the shoulder .... but more chance of problems in the case we are talking about.

Just my opinion, of course.
 

leehljp

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For screw on, collet chucks come to mind and some people use them for specialized turnings. They still can cause problems and sometimes require re-fitting, re-setting and adjustments.

Morse tapers, when kept clean has worked for more than a century. On Metal lathes where finer accuracy is needed, they use screw on items but they cost 2 to 10 times as much.
 

jbg230

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Ok- thanks for all that. I'm sticking with what I have. I guess there's no need for me to reinvent the wheel. Thanks again for "setting me straight".
 

Curly

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There are some older or inexpensive lathes that did not come with a Morse taper in the headstock, just the threads. So one of those lathes would have to have a threaded setup of some type to work. If you are contemplating purchasing a lathe like that, don't even if it is cheap. Similarly you'll be happier getting a lathe with a #2 Morse taper over a lathe with the smaller #1 Morse taper. There is more tooling available in the larger size.
 
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