Tool Rest Angles

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Tool Rest Angles

Postby AlexanderTheLate » Wed Apr 10, 2013 1:00 am

I ran a quick search but did not come up with an answer. Is there a reason why the tool rest on bowl laths is set at an angle to the work? Aside from the necessity to do it that way due to the way they are constructed? The reason I ask is because I am in the process of building a new lathe, designed with all the bells and whistles, and I was wondering if the tool rest for turning bowls insides (face-plate turning, our electrical friends would call it) could be built running across the lathe bed. There would be two tool rests, both would be adjustable, both in their height and distance from the work (I still have to make a thread cutting tap and die set for this) and would meet at the right hand end at right angles, one running the length of the bed, for turning spindles and the backs of bowls, and the other one. Is this possible?
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Re: Tool Rest Angles

Postby gavin » Wed Apr 10, 2013 7:52 am

AlexanderTheLate wrote: Is there a reason why the tool rest on bowl laths is set at an angle to the work? Aside from the necessity to do it that way due to the way they are constructed?

Tool rest is at an angle because on a reciprocating lathe you turn between centres or poppets - you have no chuck to hold the work at one end only such as in a motor-driven headstock. It follows that ( viewed from the top) the reciprocating lathe tool rest will be at an angle & fixed on on one poppet ( usually right-hand one), and the other end on an outrigger or under-tool rest which itself is fixed to left-hand poppet.

AlexanderTheLate wrote:The reason I ask is because I am in the process of building a new lathe, designed with all the bells and whistles,

I commend your application, but suggest you first build a really simple, primitive lathe and turn say 10 bowls on that. There's a good reason old designs tend to survive for centuries.
AlexanderTheLate wrote: I was wondering if the tool rest for turning bowls insides (face-plate turning, our electrical friends would call it) could be built running across the lathe bed.

I think not possible if you are turning between centres on anything smaller than 8 inch diameter. The powered turners turn on one centre with a chuck, so they can access anywhere on the bowl's surface.

AlexanderTheLate wrote:There would be two tool rests, both would be adjustable, both in their height and distance from the work (I still have to make a thread cutting tap and die set for this) and would meet at the right hand end at right angles, one running the length of the bed, for turning spindles and the backs of bowls, and the other one. Is this possible?

No. Look, you may invent some two-tool rest lathe or Heath Robinson contraption with threads and so on and take satisfaction from that creativity - but if you want to make bowls, rely on the wisdom of centuries and do first what has been done before. Once you have done that yourself you'll be better informed about the merit ( or the fun) of then re-inventing the bowl lathe. I speak as the man who decided to make a bowl lathe from polythene pipe. It worked, but I'd have been better to just build what had been done before.
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hooks and bowls by Clare032 (Medium).jpg
An idea which seemed good at the time: the polythene pipe lathe - don't ever do it!!
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Re: Tool Rest Angles

Postby AlexanderTheLate » Wed Apr 10, 2013 10:06 pm

Well put, Gavin, I knew there was a sensible answer. :) I have a very small shop to work in, even worse, I have two very small shops to work in: each is only useable for part of the year, so everything has to be portable and compact. I have a very rough and primitive lathe, but wanted a more versatile rig, the face plate turning was more for the sake of 'having it to hand' then any big desire to turn bowls. :) I am going to have a built in mandrel for convenience, with two spikes to connect it to the work. Would this be able to hold the work without the second poppet/center to support the other end (which would allow the whole work to be open)? The adjustable tool rests are going to be included anyways, I spend too much time cursing at my tacked on tool rest and it's fixed height/ distance from the work, not to include this. I realize the traditional lathe is the most effective, but I cannot devote the space to a rig like that. Thank you for your time.
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