Flexible shaft

I am looking for a flixible shaft able to transmit forces of 4240
in/lbs at 5 rpm. Its for a robot arm, I want it to be strong but not
bulky so that pretty much leaves me with the option of having the
motors not in the arm itself. Gordon McComb this may be up your alley.
Reply to
Doctor Robotnik
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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.
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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
Reply to
Gordon McComb
May I ask what a flexible shaft is and where/how it is applied?
Cheers
Padu
Reply to
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.
Reply to
Doctor Robotnik
"Doctor Robotnik"
Got it! Thanks
Reply to
Padu
Maybe consider using a universal joint rather than a flexible shaft? Something like this:
Best, - Joe
,------------------------------------------------------------------. | Joseph J. Strout Check out the Mac Web Directory: | | snipped-for-privacy@strout.net
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Reply to
Joe Strout
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
Reply to
Matt Timmermans
Can you help me find parts to make a 2 stage 500:1 worm gear box?
Reply to
andrew Gamlen
--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.
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Reply to
steamer
For that much torque, only expensive ones:
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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
Reply to
Matt Timmermans
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:
Reply to
Doctor Robotnik
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.
Reply to
Doctor Robotnik
You need to read "Robot Evolution", by Mark Rosheim, and see his web site, "
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". 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
Reply to
John Nagle

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