Re: best type of hub for pulleyts (DONT USE A KEY)

Something interesting I recently learned from motorized wheelchair
users regarding the use of keyways to fix a wheel (pulley) to a shaft
is : DON'T

Keyways are excellent for use where there is no reversing cyclic
load. In that instance, the load is always on one face of the key.

For a reversing cyclic load, guess what happens. If the pulley isn't
tight enough on the shaft without the key so as to keep the load from
changing from one key face to the other, in short order you have a
lot of wear, a very sloppy connection, and noise.

It turns out this design flaw is incorporated into almost every
motorized wheel chair and causes no end of complaints when the wheels
get a little loose and the key starts to wear. CLUNK CLUNK with every
direction change

In a CNC machine where backlash is undesired, the slop is equally
unwanted.

Recommendation from the mobility impaired? A friction clamping
pulley no key.

Chris




--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "lathehand_2"
> <lathehand_2@y...> wrote:
> >
> >
> > Dave, I been that route and have made my own XL pulleys, for

sake

> > of arguement, I usaed plastic, and hubs come loose and there goes
> > your project, or someone elses work, that you have scrapped.
>
> I used plastic for my first machine and made my own steel hubs.
> McMaster sold solid plastic pulleys cheap as they used to have all
> alum, plastic with alum hub and all plastic.
>
> But, with the plasma cutter, it will be seeing much higher forces.
>
> I'll probably use the plastic in the high speed, low torqe section
> and metal in the low speed, high torque section. Luckily, my

needs

> are for sheetmetal for my own parts so scrap will be mine and not a
> customers.
>
> I would like to put in keyways, but don't have a way to do the

keyway

> in the shafts.
>
> Next month is the Homier road show, so if they have the 200 pound
> drill/mill I'll bring one of those home and may do keyways after

all.

>
> Dave