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A bit of everything!

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PTsideshow:
The reason I was told by an old time spinner years ago. Was they were cheaper to buy and it was easier to modify when they don't cost so much. Also since when doing the production spinning. The forms are made from wood the same lathe can make the forms and do the spinning. With only a slight change in the tooling and set ups.
But then again he could have been shinning me but it does make sense.

I have the tool rests and face plates for my Sherline lathe. And other than a mess with oil on the ways with sawdust,chips everywhere to clean up it works on small simple stuff.
 ;D

Divided he ad:
Fair enough P.T. I had never thought of that one... I was thinking that there could be other issues like loading  etc but then to cut metal is surely a harder task on bearings than cutting wood?

I will have a go at the tooling soon and see how I get on  ;D




Ralph.

Rog02:
Hi Ralph:

Sorry to take so long to answer but life has been interrupting my pleasures again.

Spinning a sphere will require doing it in two pieces and then either soldering or welding the halves together.  I do this frequently for a local spin shop and we have tried numerous different methods.  Hemispheres just seem to be the easiest way to go. 

The 9x20 lathe will work for such a small project without too much bother.  The practice of using a wood lathe is that they are considerably less expensive to purchase and normally have a much larger swing for a given floor space than a metal lathe.  The tail stock simply presses the center clamp into the disc so it does not require the same rigidity as a screw lathe.  The other advantage to using a wood lathe for conversion is that it will allow you turn your shape forms on the same machine you use to spin metal.

A professional spinning lathe (such as a Prybil) is more akin to a drop bed lathe as the throat in front of the chuck is very large to accommodate the large blanks required for the deeper parts.  A spinning lathe also has a massive thrust bearing as the force will be concentrated axially rather than the radial loading associated with a screw cutting lathe and a wood lathe.  For the average hobbyist the thrust bearings on a wood lathe should have a sufficient lifespan and I rather doubt if any of use will be spinning any 14 ga. stainless anytime soon.   

I have to mention the use of a center pin in the clamp fixture.  While it may be common practice for a professional spinner to clamp up a solid blank and spin a continuous hemisphere, the danger of throwing the blank out of the lathe is very real.  The addition of a center pin in the clamp may leave a hole to be filled later but the risk of decapitation is eliminated.  YES I have seen a 64" steel disc come unchucked and fly across the spin shop!  Never, NEVER, EVER stand in line with a spinning blank! 

As for the shapes in the lily, I use several combinations of shrinking and stretching.  All work on that piece was done with hammers and it was hand planished.  Since I have been doing sheet metal for the past 40 years my collection of forming stakes has grown large. 

Roger
AKA The Grumpy Old Man


--- Quote from: Divided he ad on July 19, 2008, 02:18:45 PM ---Hi.... I want to make a sphere!!!

There's the statement, here are the issues... I only have a small workshop and in it I omly have a 9x20 metal lathe... (I only want a sphere 2" dia)  Can you use this to spin successfully? I would obviously make a tool rest and appropriate tools (that's the easy bit!)
I just wondered why it always seems to be a wood lathe?


Oh, nice lilly too Roger, I like shiny  ;D  How do you get the shape/effect, do you just beat it?



Ralph.


--- End quote ---

Divided he ad:
Thanks for the reply Roger, I had already thought of making it in two parts and silver soldering it together.
Would you say that the form could be made from steel? (I assume alu' would expand too fast with the heat? )

I have all the tooling I need to make the required rest, pegs and curved forms, I just need to know a few minor details like where to find the grease/lube'  to use on the workpiece? The centre pin you talk about, would the live centre of a metal lathe be any good if the form has a small recess(centre drill hole) in it for the dent/tip of the centre to go through?


This lilly making sounds a lot harder than one might imagine!.... Shrinking, stretching and forming stakes!!! I have much to learn!!  ;D


Ralph.

Brass_Machine:
I am dying to learn metal spinning. I have thoughts about picking up a wood lathe and converting it to use. I do want to get over to one of the classes that Terry does at his shop.

Eric

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