Re: [CAD_CAM_EDM_DRO] scraping beds for long tables

Hmmm...one of you experts should explain all this to the machine tool
builders in the auto industry. According to what I've been reading (here)
they've always been building machines incorrectly.

Smoke

>> 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.
>
>Sven;
>
>This is an accepted practice. Both Edward Connally (Machine Tool
>Rebuilding) and Wayne Moore (Foundations of Mechanical Accuracy) explain
>the process in their books. What is required is either lots of experience
>with what does or doesn't work, or extensive finite element analysis
>followed by lots of experience with what does or doesn't work.
>
>The ways of a gantry are arched to account for deflection from the weight

of

>the head. The column of a vertical machining center is tilted back to
>account for the weight of the head. The angle between the column and

saddle

>surfaces of a mill knee is slightly obtuse to account for sag due to the
>weight of the knee.
>
>Sometimes, however, it's just the result of sloppy workmanship. Even
>Bridgeport has had quality problems at times.
>
>Doug
>
>
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