scraping

Some of you mention scraping curves into the way surfaces to allow for
material sag.
Others have mentioned building an angle into the vertcal column to allow for
weight of the vertical head.

Never saw any machine tools designed or made this way!

No matter what the size of the machine....if it has a curved surface built
into the ways (due to scraping or any other means), it will be physically
impossible to machine a true flat surface. Also, tilting the column to
allow for weight of the head will prevent the head from traveling
(vertically) perpendicular to the table. Ever try to drill a 5" deep hole
with a 3/8 drill on a Btidgeport when the head is not EXACTLY 90 degrees to
the table...in BOTH directions? Try drilling a deep hole using very small
drills under those circumstances and you will very likely break the dit.

I believe the real solution is building the frame strong enough to eliminate
the suggested "solutions". Another solution is to design the machine
properly in the begining to eliminate the problems...such as building the
"base for the table much longer so as to allow the table to be fully
supported thruout its travel (eliminating the possiblity of end sag.

Smoke

>How do you mean this? The counterarresting you do only on very long tables
>or heavy parts running on weak beams.
>Sven Peter
>
>Smoke wrote:
>
>> 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
>
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Smoke