Re: [CAD_CAM_EDM_DRO] Re: Tooth belts & gear suppliers

In a message dated 05-Nov-01 09:28:38 Central Standard Time,
mikep_95133@... writes:

> Belts and pulleys are a mistake?
>
> Why?

In MY opinion, the added "slop" would introduce error in EITHER direction
between the motor and the lead-screw position, equal to two or three steps.
Of course, this would be "non-cumulative", I guess, but "sloppy" for
machining!

If the belt were made tight enough that there was no "take-up", causing the
above, the added TENSION/friction would be rather severe, it seems to ME!
AND, the stretch of a fiber-core,neoprene "timing belt" would introduce an
"all-new" pitch between the teeth of the belt which might "fit" the
cog-wheels OK, but it would surely cause an "accumulative" error, wouldn't
it???

If the stepper is connected directly to the screw via one of the high-tech
"bellows couplings" or the "multi-helix" couplings (EDM aluminum stuff), with
CLAMP-hubs (not "set-screws"), you have no "lost motion" the chosen coupling
does not introduce.

I may be no wizened PhD machinist, but I KNOW what I have observed over the
years. I find it interesting that so many on this list talk about using
"timing belt" connection between stepper and lead-screw!

Oh, it may "work" for some — those who "just don't SEE that". Lotsa luck!

Jan Rowland


[Non-text portions of this message have been removed]