Re: [CAD_CAM_EDM_DRO]doodling with ideas

Thanks Jon

While no expert by any means, I can appreciate fully the problems which you elude to in your post but to tell the truth if
the computer can do the math and control "the rotations" (screws spindle, etc.) and you use power tooling, (for the sake of the
conversation, [knowing that fixed point tooling could do some]) I don't see anything other then speed of production as being a major
problem and for the hobby or one-of guy I think that price would not be to high a price.

Bill

Jon Anderson wrote:

> Bill,
>
> There was an article on this subject in Modern Machine Shop several
> years ago. The limitations Joe mentions are the tip of the iceberg, and
> are more easily overcome that the issues of geometry.
> Think of turning a square. With the tool on spindle center, and one
> corner right at the cutter edge, as you begin to start the next side you
> will see that the tool must have a clearance angle exceeding 45 degrees!
> As the cutter passes the half way point on the side of the square, it
> will, just before reaching the far corner, have in effect a 45 degree
> negative top rake. This ultra extreme range of conditions is more than
> conventional tooling can take.
> I'd say this article appeared 4-5 years ago, ball park. Back then, they
> were having trouble just coordinating the cross slide to the spindle
> with an acceptable level of following error. Consensus was that squares
> were out of the question, but they did believe hexes could be done with
> more work. However, this is the realm of production and seconds count.
> There are other, faster ways to do these tasks.
>
> There are special lathes that produce hexes by orbiting a tool around
> the part in elliptical paths. These don't produce a true flat, but come
> close enough for real life. Volume production only.
>
> There is also an attachment available for vertical mills (manual type)
> that will cut internal and external hexes, ellipses, and other shapes.
> Used to have a brochure on it, but I do recall it's an expensive sucker.
>
> Jon
>
>
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