scraping beds for long tables

Dear friends,
I am pleased that it turned out that there are quite a few persons here
who scrape bed ways.
I have a question I have for a long time and nobody was able to
respond satisfactory till now.
When my father initialized me in scraping and later in a practice
I was told that for a bed of a long travelling table (example x table of
a
Bridgeport that has a short bed) you should scrape into the bed
a curve so that the curve counter arrests the weight of the table
when it travels far out.
Because I never got an instruction about it how to make it well
and because I saw in quite a few mills that this curve was made too
deep.
(with the result that the flat parts of the dovetail way are very much
worn
at the tips and in the centre the table not even touches the bed
so that the oil oil pours out like nothing.)

Therefore I never made it in any of the machines I rebuilt.
Instead I preferred to leave the bed straight and with
as much as possible support area. Anyway in all cases the bedways were
so
worn that the improvement of a wrong scraped bedway was significant
against before the worn one.
I preferred to have a little error than a wobbly machine that wears out
fast.
Who can tell me how it is done right?
Thanks a lot
Sven Peter


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