Re: [CAD_CAM_EDM_DRO] Shafting

In a message dated 11/8/2002 1:13:48 AM Central Standard Time,
capper@... writes:

> Im thinking of using 1.250 shafts to span 6' and 1.00 to span 48" on a cnc
> router. I am wondering if that's big enough or if I should go bigger? any
> thoughts would be appreciated. thank you.
>

Capper: I built X-Y routers with 1" dia. "class L" 60-case shafting over a
48" wide table, and it was BARELY adequate to support the router if moved
manually VERY gingerly. I also built three "linear drills" with a much
LIGHTER "quill carriage" on 1" dia. [same], and it "was kinda OK", but when I
got an order for a FOURTH such machine, I used 1.125" dia. [same], and, as I
had guessed and hoped, it was MUCH better! More solid; gave a better "feel"!

Then, in '85, I built a huge X-Y for an English firm, and I used 2" dia.
60-case shafting, and that WAS expensive, but this one had a 3/5 hp 400 Hz.
3-Ø router, 1.5" dia. ball-screws with preloaded ("double") ball-nuts, and it
was clear, once done, I had "just lucked out" selecting such "huge" shafting,
as it WAS capable of supporting the carriage under operating-load
conditions.(say, moving a 2" dia. cutter into oak, cutting 1/2" off per
pass).

So, no, for six foot spans, I think the 2" would be MINIMUM, if you want this
to be a "serious" professional machine! And I'd go a MINIMUM of 1.25", if
not 1.5" for the 48" span! Remember: I have BEEN there; DONE that! And
when I did, even Thomson coldn't give me tips, so I just hadda GUESS. That
first one was "chincy", and looks like whatever caused you to state the sizes
you did with your question was SAME stuff I musta read! But the HEAVIER
diameters I stated here are definitely better, particularly if you expect
this machine to do fine work for more than a few months before needing
"$help"!!!

Lotsa luck! Jan Rowland


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