Re: [CAD_CAM_EDM_DRO] Belt vs. Direct Drive

Doug wrote ?:

>(snip).. I use steel/rubber spider/steel couplers which work great.
>Very rigid in torsion (snip)
>
>

I have seen some that go a little beyond the normal used on NewHermes
machines. It is not just a typical spider setup, but one that has its
"fingers" curved around the rubber/urethane portion for an even tighter
grip. They pull apart very hard. I even have some takeouts laying
around. There may have been a "wind-up" on them but we ran those
machines on fine diamond drag work that if it was off position, you'd
see it when the machine changed direction. Even the finest of images
were perfect.

>What scared me off (early aluminum) helical couplers was that they
>tended to break, (snip)
>

I've seen them break too as they are actually fragile. I think even
though they are made to give you some deviation in alignment, your still
best of getting it as aligned as possible to avoid breakage.

>(snip) I think they must have a little 'wind up' and hence a resonant
>frequency,
>

Boy, If one actually did a twist measurement test, it couldn't be much.
Even the smallest of ones I've seen seen rotationally tighter than tight.

One thing I DID conclude is that noise transfer sure can be excessive
with the helicals especially on Stepper drives. So, if it's noise you
dislike. Stick with Rubber on those direct drives.

C