Re: Bridgeport way wear

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:

> >
> Having "scraped-in" a hardened Sheldon lathe bed that's SIX FEET

long, a

> cast iron
> Bridgeport ought to be a piece of cake by comparison. The Sheldon

bed

> is supposed
> to be flame sprayed, but it seemed to be as hard as tool steel all

the

> way through to me!
> I managed to get it straight to about .0005" over the full 6 feet,

but

> it was a bear to do with
> Cratex abrasives in a die grinder, lapping with bench stones,

checking

> with straightedges
> and spotting dye, and a Talyvel electronic level.
>
> So, now that I already have the tools and techniques, it wouldn't

cost

> me cash, just time.
> I could pull the table off and fix that up pretty quickly, but then

I'd

> have the table better
> than the rest of the machine. There's a loose spot in the knee

ways

> that needs attention,
> too.
>
> Jon

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

I scraped a 10" South Bend with 5 foot bed a few years ago, with 3 V
ways & 1 flat. Not a hardened bed but interesting due to .020" wear
at the worst spot.

I never did a Bridgeport, but I think the table would be a particular
challenge due to length. It seems as though it would require long
straightedges and a helper to do the spotting.

I think the commonly given advice to "get a Bridgeport" is not always
the best choice. But then most of the Bridgeports I see used are at
Boeing Surplus and they're very, very tired.

In my case, the parts I make for my business
fall within a 1 1/2" x 5" envelope, so the logical decision for me
was a
very stiff, heavy mill with 10" x 8" table travels. The wear of
production work is more proportional to table travel and I could
scrape a 20" long table if I have to.