1520 plotter (was RE: Your VIC-20 is worth $300!!! W_at_W!)

From: Ian Koller <vze2mnvr_at_verizon.net>
Date: Wed Jan 30 21:21:06 2002

You'd really only make a mold like that if you intended
to produce many, due to the expense. And that would be if
your mold was at least a three part, with the mold cavity
having a through hole, to be capped off on each end by
other components of the mold. If you preferred a blind
( not through ) hole cavity, you would probably burn the
teeth into it ( after boring out most of the material
first ) with a conventional electrode type EDM machine,
which might also be a whole lot easier to home brew than
a wire type. But then you generally have to machine the
electrodes. Easier to do because you would be machining
the teeth on it's OD, but machining graphite is a messy,
nasty task, and you still need a cutter, though a hand
ground fly cutter might do ( milling saw type better ).

Other very realistic possibility is ...

For an alternate to thread wires, use the shank portion
of drill bits. Between all the fractional, wire gage, and
letter sizes, there are an awful lot to choose from. You
often are able to find something within a thou or so, if
not tenths.

For info on measuring gears etc, check Machinery's Handbook
put out by the Industrial Press. It is the machinist's and
mechanical designer's bible.

For Tony, having a lathe. If you had a plate, turned circular
to indicate it in when you set it up, with the same number of
holes as teeth on the gear, drilled in a evenly spaced circular
bolt pattern on the face of the plate, bolted to the lathe
chuck, and a fixed portion bolted to the bed ( or ways, or
headstock, etc. ) with a pin that would locate into the holes
in the plate, it could serve as a dividing head for use on the
lathe. Then hand grind a slotter type cutting tool to the shape
of the valley between the gear teeth, mount it in the tool post,
and by moving the carriage up and down the ways, cut that shape
into a blank a little shave at a time, dialing the next depth of
cut on the cross slide, just like on a slotter ( or shaper ).



Tony Duell wrote:
>
> >
> >
> >
> > > but the mould would be very hard to make (cutting
> > > internal teeth on a mould that size)
> >
> > Wire EDM
>
> Now that's an interesting idea.... I've seen books/articles on making an
> EDM setup. Looks like another thing I should investigate more seriously
> sometime...
>
> -tony
Received on Wed Jan 30 2002 - 21:21:06 GMT