RE: [CAD_CAM_EDM_DRO] Doesnt ANYONE have this drawn up??? was: John's CNC plans???

Interesting post Jon, It just goes to show that sometimes we can "make it
better" only to make things worse. I often find it extremely interesting
how things that are of older design, such as the BP yoke assembly, look
poorly designed, flimsy and cheaply made when in fact they may be the best
way to go for some parts. Those old guy's did not have CAD/CAM or computers
but they built machines that will last for a long long time and provide
great service and accuracy in the process.

John Guenther
'Ye Olde Pen Maker'
Sterling, Virginia

> -----Original Message-----
> From: Jon Elson [mailto:elson@...]
> Sent: Thursday, August 14, 2003 13:09 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Doesnt ANYONE have this drawn up??? was:
> John's CNC plans???
>
>
>
>
> Vince Negrete wrote:
>
> >Jon, you've very much enlightened me on using the existing screw
> dimensions.
> >Stupid me... I never thought of that! very cool!
> >
> >
> All this stuff is hard to make. Some things, like the shape of the end
> bracket, and
> the J head on a Bridgeport, are free-form, hand-made surfaces ground into
> mold patterns 50 years ago. I tried to measure many of these parts with
> granite surface plates, angle plates, vernier height gauges, etc. and
> still came
> out way off, so holes had to be drilled out, shims inserted, all
> that messy
> stuff. So, any way you can continue to use the parts that ALREADY fit
> fine has got to be OK. I made my own yoke (the block in the center of the
> saddle that holds the leadscrews) because I thought the Bridgport part was
> flimsy. Well, it was a big mistake, and I had a HELL of a time aligning
> things so the screws ran straight, etc. A number of ballscrew retrofits
> make cylindrical adaptors that either fit the nut right inside where the
> original bronze nuts went (that would require an undersized screw) or
> the nut sits just outside the yoke on the end of the cylinder. I now
> realize why they do that - to preserve the factory alignment of the screws
> and nuts.
>
> Just a rambling comment on some of the pitfalls I ran into when doing my
> own retrofit.
>
> Jon
>
>
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