Re: [CAD_CAM_EDM_DRO] swiss turning in minature?

Hi Graham:
THE killer with Swiss turning is the requirements of the stock and the
lube.
Typically, the stock is fed through a carbide bushing under pressure
lubrication and is centerless ground before being used.
Every Swiss CNC and Swiss automatic house I have ever been to, has their own
centerless grinder to help them prepare the stock.
The stock typically has to be held to +/- 0.0002" for diameter and TIR to
work acceptably well.
These places tend to be pretty stinky too...it's the lube/cutting oil that
has that oh-so-unforgettable "nose" about it.
The poor man's way around all this is to use a gadget called a "follow rest"
or "travelling steady" on a normal engine lathe.
They can be made applicable to CNC machines without much
difficulty...typically it's done with hydraulic or pneumatic cylinders
driving the contact fingers through a linkage.
The fingers function similarly to the carbide bushing on a "real" Swissturn
machine, but are much more tolerant of geometric inconsistencies in the
stock.
Hope this helps
Cheers

Marcus

----- Original Message -----
From: "Graham Stabler" <eexgs@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, May 12, 2003 5:35 AM
Subject: [CAD_CAM_EDM_DRO] swiss turning in minature?


> I am working on some small metal working projects related to very
> small model aircraft. When I say small projects what I want to
> produce is actually the small thing, the project will no doubt end up
> being rather large.
>
> Some of the parts I need to produce are very small turned parts,
> rollers with accurate diameters and possibly some "crown".
>
> Although I do have a lathe is is neither suitable nor is it CNC.
>
> Anyway, after soom surfing I came accross the process of swiss
> turning. These special lathes feature a moving headstock that pushes
> the bar material through a special bearing. The cutting tool that
> moves in only one axis is located close to this bearing. This means
> that the overhang between the bar supporting bearing is constant and
> small. That's the basic idea although there is a lot more too it.
>
> My idea that I put forward for a roasting is to build a small desktop
> machine on the cheap.
>
> I have a pretty decent linear rail with two carriages, the rail is
> nice and wide as are the carriges, the idea is to stick the head
> stock on one and the tail stock on the other. The headstock does not
> need to be accurate as the accuracy will come from the
> bearing "chuck". I think a dremel might even do the trick. The
> headstock could then be moved back and forth under stepper control as
> could the tail stock. Between the two would be the bearing unit.
> Here I need ideas, what sort of bearings? Bushes?
>
> Then there would be a cross slide, another linear rail again under
> stepper control. Built solid with absolute minimum over hang.
>
> So, am I daft? Would it be better just to build a normal lathe?
>
> One other thing it has to be on the cheap. I have rails and
> leadscrews, steppers and drivers. I don't have decent spindles etc.
>
> Cheers,
>
> Graham
>
>
>
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