.1g muscle wire actuator - RC Groups
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Nov 04, 2003, 11:57 PM

.1g muscle wire actuator

Pictured below is a .1g muscle wire dual actuator, which 30 degrees of throw each side of center. It is self-centering, with good centering accuracy and force. The reaction/return speed is good. Center/full throw/center less than .5 seconds. Current draw is approx. 50 ma necessitating an amplifier to drive it. Materials used in its construction include a .4 mm double-sided, copper-clad board, a .25 mm brass spring rod, .1 mm brass sheet and .001 muscle wire. The difficulty factor in building the first one is definitely a 10, but after you learn the tricks it is on par with building a .25 g magnetic actuator . I intend to post a step-by-step here for those interested.
Last edited by Bob Bailey; Nov 05, 2003 at 12:12 AM.
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Nov 05, 2003, 12:02 AM
Pictured below is a simplified drawing of the actuator function. The spring provides a force for centering and return. The off-center pivot, in relation to the muscle wire attachment points, provides a center equilibrium. When power is supplied to one side of the actuator, the muscle wire contracts, the control horn rotates, and the spring stretches. When power is removed, the muscle wire relaxes, the springs contracts, and the control horn returns to neutral.
Nov 05, 2003, 12:14 AM
Grand Poobah of Nothing
Trizza's Avatar
Very cool! After making a few 200 ohm coils using .05mm dia wire I swore I'd never make them again, and its what has been stopping me from trying micro stuff again. I'd be very interested in seeing some instructions on how to make these things - I'd probably build them larger though.
Nov 05, 2003, 12:22 AM
Registered User
billystiltner's Avatar
That is amazingly small.
I'm interested in the step by step process.

Nov 05, 2003, 01:05 AM
Master of the Wind
AIR MOVER's Avatar
How about step by step selling of them to us not so good at this new form of stepping.. =)~~~~~~~~~
Nov 05, 2003, 01:19 AM
Registered User
Thats the neatest, best designed muscle wire setup i have seen .
Great work , cant wait for more details .
Nov 05, 2003, 02:48 AM
Registered User
Koichi Tanaka's Avatar

Where can he buy a 10-micron muscle wire?
Nov 05, 2003, 07:49 AM
Only nerd in the village
Bob, thanks for sharing. By all means go ahead an post a build description. Did you program a PIC yourself for driving the actuators?

Koichi-san, I think Bob must be talking about 1/1000 of an inch which is 25 micron. This wire is available from Bob Selman and Graham Stabler.

Nov 05, 2003, 09:19 AM
Registered User
bselman's Avatar

Muscle Wire

I no longer carry the muscle wire.

Bob Selman Designs
Nov 05, 2003, 09:34 AM
Only nerd in the village
Sorry Bob, I had not noticed that. Is the batch that was custom made sold out?

Nov 05, 2003, 11:13 AM
Registered User
bselman's Avatar

Muscle wire

I have sold out of that batch I had, but I understand that the LT025 is going to be produced again so there is not a problem with availability.

Nov 05, 2003, 11:39 AM
in persuit of low wing loading
Gordon Johnson's Avatar
For those wanting to buy a ready made musle wire actuator, but a different type of design, you can buy them from uIR in Finland

Nov 05, 2003, 03:03 PM
Registered User


Well done Bob
Its good to see folks trying to make actuators with Flexinol - it has to be the way for micro planes. We just need to figure out the best way to use the material.

I have sent my aritcle on our APPA actuator to the publishers so hopefully it will be in the shops before Christmas

The article describes our actuator but then goes on to say how to install it into a suitable plane, in this case a 10" span Jigglet weighing about 7.5g. My point is if you have a super light actuator you shoudl put it in a super light plane to get the advantage from it.

Micro ducted fan jets woudl benefit from Flexinol actuators as jets are still a little underpowered at the moment, but hopefully that will be better now we can use two 90mA cells.

I think it woudl be better to use coil actuators for planes weighing more than 10 grams

Well done Bob ......... more! more!

Youruncle Mark

Maybe put the actuator in a micro Corsair like Joe's see our news letter

Nov 05, 2003, 03:11 PM
Registered User
Dave Wulff's Avatar
Uncle Mark,

What publication is the article going to be in?

Nov 05, 2003, 04:12 PM
Registered User
I checked the flexinol website and it appears they are selling the 25 micron flexinol again (still pretty expensive but it beats custom ordering it)

I too believe that flexinol is the future of micro RC. right now I plan on using flexinol to power a dragon-like ornithopter.

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