On 14.02.13 09:37, dave wrote:
> Most machines I'm familiar with use either timing belts for relatively
> low power and gears for high power.
The thing is that even a hefty little NEMA23 stepper can come with a
radial thrust limit of 15 N, and an axial limit even lower. (I've just
bought one from a local CNC goodies supplier.) There's no way the
toothed belt pulley could be directly mounted on the motor shaft, and
the belt then tensioned to the "twang level" recommended on this list,
for acceptable backlash on the belt drive portion, is there?
I can see that I'll have to drive the toothed pulley, mounted on a shaft
with bearings either end, through a flexible coupling, to decouple the
radial thrust. The supplier has helical beam couplings with torque
ratings modestly exceeding the motor torque, but like Pete, I'm also
trying to find out what will actually reliably in the long term.
The bellows couplings seem impossibly expensive. The disk couplings
sound a bit like an X-shaped coupling I've seen - a bit like half a
universal joint. (CV coupling, in fancy language, IIUC.)
Maybe an Oldham coupling with a disc/X adaptor added will do the job at
an acceptable cost? (Or does a small angular misalignment merely cause
the Oldham coupling to wear faster, as the tenon slides in the mortise
of what is then a nearly zeroed swash-plate?)
Erik
--
> - Not all systems support hard links
>
Rolls eyes. Sure, but all _my_ systems do! UNIX dammit!
- Cameron Simpson, on mutt ML.
------------------------------------------------------------------------------
Free Next-Gen Firewall Hardware Offer
Buy your Sophos next-gen firewall before the end March 2013
and get the hardware for free! Learn more.
http://p.sf.net/sfu/sophos-d2d-feb
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
