Flexible shaft

Whoa! This is a fairly hefty amount of torque you need to transmit.  

You might try starting here. They have a handy comparison chart showing
the max torque for the different diameters of flexible shaft they offer.
Your application exceeds their highest maximums, even for 1/2" cable, by
a factor of more than 10! I don't think the low RPM will make up for the
difference. <g>

http://www.wmberg.com/T05002.html  

I wonder if pneumatics or even small hydraulics might not be called for
in an application such as this. Or, going from a flexible shaft to a
more traditional pull shaft. Even 1/8" steel aircraft cable can lift a
lot of pounds...it just can't twist that much torque.

-- Gordon

"Gordon McComb"

May I ask what a flexible shaft is and where/how it is applied?

Cheers

Padu

Basically its like a large wire attached to the motor shaft that
rotates as the shaft rotates, it is encashed in a sheath that doesn't
rotate. Its good if you need the power far from the motor, espically if
you may have to make a few bends to get where you need. Dentists drills
use this, some lathes, dremal tools can get one as an attathment option.

"Doctor Robotnik"

Got it! Thanks

How large would such a system be, I would need a comprressor, and tank.
Would that be really noisy as the compressor turned on, and how heavy
would a hydrolic system be. I would like this to be able to be on a
mobile platform.

Maybe consider using a universal joint rather than a flexible shaft?  
Something like this:   <http://www.peeron.com/inv/parts/9244>

Best,
- Joe

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It'll be a lot easier if you transmit, say, 8.6 LB-IN at 2500 RPM and gear
it down close to the load.  The 500:1 gear reduction can be implemented
compactly with 2 worm gear stages.

--
Matt

Can you help me find parts to make a 2 stage 500:1 worm gear box?

For that much torque, only expensive ones:
http://www.mcmaster.com/

How about taking whatever is giving you that 5 RPM off the end of the motor
and moving it to the other end of the flexible shaft?

--
Matt

Um Thats sort of what this whole thread was about.  Would this work I
wonder, cables attached to a sprocket on the motor going up to an arm
and attching to a corrasponding sprocket, I may not be able to get full
rotation, but if I limit each axis to 180 degrees, would this work, The
cables would be allowed to twist and bend. The arm itself would be made
from aliminum tubing with the joins between each segmant, kindo of like
an insect limb.

Matt Timmermans wrote:

    --Here's a photo of one device that *may* do what you want.
There's a pointer to where to get them in the MSC catalog, too.
    http://www.nmpproducts.com/artcar0508.htm

--
        "Steamboat Ed" Haas         :  Nihil curo de ista tua  
        Hacking the Trailing Edge!  :  stulta superstitione...
                   http://www.nmpproducts.com/intro.htm
                   ---Decks a-wash in a sea of words---

     You need to read  "Robot Evolution", by Mark Rosheim, and
see his web site, "http://www.anthrobot.com" .  He's an expert
in the engineering of tough, stiff robotic arms.  With the
numbers you've given, you need to get into some serious
mechanical engineering for this to work.

     Also, you need the catalogs from Berg and from Stock
Drive Products, so you can see what's available in parts.

     Flexible shafts are not usually used for such large loads.
For numbers like that, you usually have to use solid shafts
and universal joints, or gear drives at the output end, or
chains, or cables.

                John Nagle