On 2008-12-20, Michael Koblic wrote:
DoN. Nichols wrote:
The question is -- do you want to be able to cut threads? If
not, then it could certainly do what you need for small things. (How
big a circle do you need to handle to make your solar powered
hourglasses. :-)
I am pretty much looking at it as two distinctly separate jobs:
In which case you probably will eventually want two different
machines -- one set up for each job.
1) The dial faces. Those will need something big if I want to expand in the
future. The biggest one now is 4.5" so a mini should be able to face it and
edge it.
Even the Taig should be able to do that with the riser blocks.
OTOH I have a nice 9" piece sitting in a drawer waiting for
attention. That one clearly is beyond the mini. OTOH (2) the faces do not
need a tailstock - headstock turning facility should be sufficient, which
brings us back to rotary tables etc.
That -- or the Taig with perhaps even *two* riser blocks? Not
very rigid, but probably sufficient for edging the face. I would have
to check whether two blocks stacked up would give you sufficient center
height to turn a 9" face.
2) The support structure and the gnomons. These are much smaller and a mini
or a Taig should be adequate. The maximum length is not an issue until the
dial diameter gets past 12" - pretty unlikely.
O.K. I presume that you would like to make the gnomons tapered?
For that, you do what work is needed on a cylindrical basis (probably
between centers) and then shift to between centers with an offset on the
tailstock so you can produce a nice smooth taper.
At this point I see no need to cut threads. However, as these things often
work out, I will want to cut one the moment I buy the Taig :-)
Hmm ... part of that cylindrical work on the gnomon might be to
turn a shoulder, and then thread up to the shoulder so the gnomon could
screw directly into whatever it mounts to -- as long as the gnomon
should be perpendicular to the mounting point. That saves you from
having to stock screws and work at hiding them in the assembled sundial.
O.K. It all depends on how much you plan to turn things which
are about four times longer than their diameter. For that (or longer)
you will need the tailstock.
For the gnomons pretty essential
Between centers for sure then.
You'll also find it very useful for drilling the initial central
hole before boring it to larger diameters. IIRC, the tailstock chuck
will hold 1/2" drill bits -- but the motor may have a bit of struggle
doing it all in a single pass in steel.
I thought the Taig only did 1/4".
I just went down and verified. *My* (rather old) Taig has a
Jacobs 1/2" capacity chuck which screws onto an external thread on the
tailstock ram. IIRC, it also screws onto an arbor to allow you to use
it powered in the headstock as well.
There is no *list* of what threads it cuts, so we don't know
whether any particularly useful ones are left out.
I would like to see a much more detailed list of what it has and
what it will do.
See, this is the sort of thing I would not know to look for...
This is the sort of reason why people suggest that you sign up
for a metalworking class at a nearby school (if one is available) so
you will learn what to expect from the tools. This will also give you
access to larger tools for some of your own projects.
It is a good suggestion in principle. There may be one in the New Year. Now,
to spend $465 on the course or a Mini-lathe :-)?
That can be a problem, too. The Mini-lathe or the Taig are low
enough power so you can afford to make mistakes without producing
serious catastrophes. A 12" or 13" lathe is a different matter, let
alone larger ones. For *those* the class first would be a *very* good
idea. And you *will* learn things from the class even with the smaller
machines. (Granted, I never took such a class -- but I learned (as an
Electronics Technician) from some good machinists at work, and as a
result was one of the few technicians allowed to use the machine tools
in the building.
Enjoy,
DoN.
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