Re: [CAD_CAM_EDM_DRO] Extrusions for router rails

Sculptor:

Though a very ignorant and dubiously-experienced old troll, I HAVE "been
there"! Lemme see if I can be of use to you in answer to your questions:

Gawrsch, it's been 15 years ago when I built a 5 x 10' - "2½ axis" router/X-Y
Drill for a firm in England. Aluminum? For some small brackets and such.
but the "machine" was all welded steel! The router was a 3½ hp Perske, 400
Hz, 3-phase motor with a 1/2" collet. This hungry thing was fed from a
motor-generator "rotary converter" from same firm, which itself was powered
from the English 415 VAC/50 hz. "mains". I mean to TELL ya, when that
thing started, the Zip-Code changed! (Uh, pardon: POSTAL Code!) It would
punch a 2" dia. carbide-edged router-bit through solid oak, 1/2" deep, at 50
IPM without even loosing synchronous speed! SO? Word is: RIGIDITY!

I had "accuracy", too, as the "ways" were Thomson round case-hardened "Class
L" shaft-ways, with linear ball-bearings (the "SuperSmart" kind). FINE
stuff, but in a woodworking environment, one must do TWO things: Make dang
sure the dust can't accumulate in the ways inside the ball-bushings, and,
same are appropriately lubricated (i.e., "all the time!").

I used a Size-42 Superior Electric stepper for the 1½" dia. "Y" preloaded
ball-screw, and a Size-72 S.E. stepper on the [same] "X" preloaded
ball-screw. This machine was still being used when I next saw the machine
(in use!) during a visit in '96. I have recently heard it is still running!
The bearings and computer have been replaced more than once, not because of
OEM-part-failure, but because of 16-hr./day use! I do not know how the
Perske 24-KRPM motor has lasted. It's a famous firm for HF router-motors and
milling-machine quills.

The aluminum extrusions I see in catalogs and in magazine-ads may be fine for
the ol' boy with no machine-shop or welding-gear/ability, but such
construction makes me think of "plotters" or "light engraving machinery",
etc. NOT X-Y router-tables with more than a laminate-trimmer motor as quill.
Got me?

Lotsa luck. Remember: Rigidity is what you describe you need, not wobbly,
barely-holding-its-own-weight tinker-toy stuff!

Rack and pinion or timing-gear belting? MY opinion? Maybe OK for this
application, but LEAD-SCREWS, even ACME, seem a better choice to me! (See
top line again!) I'm serious!
What happens when this "cog belting" stretches? Before you say, "...spring
loaded idler", what has happened to your belt to REQUIRE that, and what
effect on the result does that produce?

What is an "epoxy motor"??? Filling tubular extrusions with goop might
"help", but masking-tape is good for some things, too!

The PTFE-lined linear bearings, a "substitute" for same-size linear
ball-bearings might be just fine for such an application. Would probably
defeat "dust problem"! But I have NO experience with same, so any opinion
from me on that would be invalid, were I to offer one. Were I to have to
"place a bet", I'd say "go for it" (and report back in the morning!)

Jan Rowland, Old Troll