Increasing swing on older cast iron lathes. How much is too much?

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Of course, that there were some cheaply made older lathes in the past
before the woodturning revolution with it's multiple facets and wide
popularity. However when labor & materials were cheaper, the major
manufacturers at the time seemed to over build their better quality
smaller swing lathes. These lathes were essentially for turning spindles
(not much large face work being done then), but they were made of fine
grained quality cast iron with rugged bearings, castings and decent
machining, yet often limited to a 6" throw and less than that at the
tool rest.  

There are a lot of these fine old timers around and reasonably priced at
that. I suppose they could be easily and safely converted to a much
larger swing and many have been, either outboard or inboard with raising
blocks. I realize that how much larger the swing allowed depends on the
lathe and its supports, the timber, the balance of the blank, the
turner's ablility, the grimness of his facial expression and the
decibels of his grunting and swearing.

What can you do to improve on the old machine's specs. for larger face
Are there any rules of thumb or warning signs and symptoms that you use
to predict a particular face turning you can safely swing or for that
matter that you've gone too far?  (ie. before the catastrophe)  :)

Turn to Safety,  Arch                          

Re: Increasing swing on older cast iron lathes. How much is too much?
On Mar 27, 8:42 am, (Arch) wrote:
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Hello Arch,

Welcome back to the group. I don't have any actual specifications on
riser blocks, but I think that most of the time they are limited to 2"
to 4", which increased the swing by 4 or 8 inches. It is not very
practical to place a riser block under the tool rest banjo, so part of
the limiting factor would be the strength of the tool post; i.e., I
think on the smaller swing lathes, they generally had smaller tool
rest posts, like 5/8" or maybe 3/4" at the most. Boosting an 8" swing
lathe to 16" with the 5/8" tool post might bring on disaster is
turning a 16" bowl blank at the furtherest edge of the tool rest. It
will be interesting to see what other say.

Fred Holder

Re: Increasing swing on older cast iron lathes. How much is too much?
Most of the old ones allowed outboard turning of bowls.  That would be 36"
or 1 Meter more or less.

Some older ones were only heads - they were bowl machines.
Some older ones were only spindle machines.
So it depends.
Some old ones weigh in the range of 1000 pounds.
Most can use weight in the bases.

I can do 16" plates or 10" spindles / bowls.  Plates can be 5" deep.

Martin (Owns a 1947 (birth date ) wood lathe my Dad bought.)

Arch wrote:
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Re: Increasing swing on older cast iron lathes. How much is too much?
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Here is a Powermatic 90 that has factory original riser blocks front
and rear and a kit to extend the reeves drive system the additional 4"
including the belt cover.

I have discussed the performance of this lathe prior to trying to
modify my own PM 90 and the owner reports there is no problem in any
way with running this model modified to 20" swing (it is close to 600
lbs as is). I did locate a kit of all the factory parts required but
it was almost 5 times what I paid for my lathe or a bit over $1,000 so
I will have fabricate the modification myself.

Here is a DYI example to increade swing and length:



Re: Increasing swing on older cast iron lathes. How much is too much?
In message  
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In my own case , I went for a simple design in  oak, with extenders for  
the headstock and tailstock bolts.

Just cut a block to make a channel for head/tailstocks, do the reverse  
on opposite side, so you fit the lathe bed. Drill a decent size hole in  

Use an extender to increase bolt length, inside thread one end to match  
existing bolt, outside thread other end to match existing. Ideally drill  
a hole through the bolt and extender to allow for a split pin to ensure  
no unforeseen unscrewing.

Works quite well, all I need to do is find time to get to the lathe and  
play again, its been a year now, and withdrawal symptoms are setting in.  
I have enough wood for an item a day for the next ten year and I want to  
get started :)

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