Re: [CAD_CAM_EDM_DRO] Re: Bridgeport way wear

knives01us wrote:

>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 had .013" wear. but, a fantastically sharp carbide scraping blade would
not even make a MARK on the Sheldon ways. (I know I could have gotten
a mark, but it would have chipped the edge of the scraper badly to press
that
hard - maybe 100 - 150 Lbs downforce!)

>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 have a 25" straightedge, and a 24 x 36" surface plate. I know I can do it
by using the straightedge in two places. There are tricks you have to use
to avoid making warped surfaces or diverging from flat when you do this.
I have the Talyvel level, which is sensitive to 0.1 arc second, so i
could detect
a human hair over 20 feet or so. Using that to constantly check, I have no
doubt I could get it flat.

>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.
>
>

There are plenty of good ones out there. Chromed ways are fantastically
harder than cast iron, and probably resist wear by a factor of about 100!

There are some great mills out there other than Bridgeport. Tree, XLO
and Index
are a couple of good ones.

Jon