RC India

can anyone help me out on how to make actuators for micro rc planes?

hmm..seems like no one is interested?

More likely, it seems this is not something people generally tend to do.  Of course, there are discussions on international sites, which you may be able to adapt.

can u give some links i dont find them easily in that information-yard[seems more to be a junkyard]

may be you need something like this:

http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=10416&Product_Name=Spektrum_Ultra_Micro_Servo_0.079kg_/_1.5g_/_0.14

A young lad like you, should be investing time on more interesting areas like aerodynamics, interesting plane designs etc. in R/C, improvisation in electronics/Tx/Rx is mostly done due to scarcity unless one has more inclination towards electro-mechanics itself.

The biggest challenge faced during improvisation are while miniaturization. I am telling from my experience in electronics, coz like in your age, I had already made my full fledge HF HAM Radio transceiver (modified NR60) and my later attempt to make hand held VHF TRx was a big soup.

I am not discouraging you but the scarcity of mass commodity electronics in the country. Things have definitely improved in the recent 10 years, from days of EFY/Vega/Visa/Kits 'n' Spare, but the scene is still meager.

Just for a possible hint, my all time electronic pal and I made a small servo using 2 coils from wall clocks movement. They were terribly weak and used in vibrating mirror for Laser strobe light.
For making a servo DIY for a micro plane (assume 1-2gm), you would need a very light pico motor (400-800mg), set of gear (another difficult part), preset for feed back and ultra small driver circuit (again challenge to build). All in all, the BOM (bill of material) are hard things to find unless you are really lucky and watchful (Hint: Chinese toys/stuff)

If googling is not helping you enough, it tells is itself that how many people might have tried this. All the best any way!!

actually i plan to build one
will be using unwounded coil of a transformer as the wire used for winding,magnet from a speaker for the central magnet and a small magnet from earphone to auto center it
ujjwanna,the link u have given is of a 1.5gm servo which is stocked by sai uncle also at a much cheaper rate

Ankur,
I guess Sai has the servo you have been looking for. The HC item is indeed exorbitantly costly

for your DIY servo, don't do too much RE (reverse engineering). The 36 SWG enameled wire is a good one to start with for a 'Galvanometer', you can make the actuator with. You can find this wire with most of the Fan/Transformer repair guy and are relatively cheap. You can use small pocket AM radio's Antenna's Ferrite core to make the magnet which are more appropriate than using iron core, which have large retentivity (remain magnet even when electricity has been removed)

Something interesting :
http://www.dealextreme.com/details.dx/sku.30658

ok will try what u say
can u tell me from where to source very small magnets to auto center my actuator as used in micro flight actuators[see their assembly video]

btw the the link u  have given along with some other product seem to be interesting
will definitely order if possible to ship without problem[it falls under toy category if i m right so can't be shipped]

Hi Ankur,

What is the reciver which you are planing to use for driving the actuators. actuators are used where you have to reduce the weight of each channel mechanical component to less than 1 - 1.5 gm. you cannot use bigger magnets nor bigger core.

I have fabricated acctuators using magnets which are there inside defective CD rom drive Lens these magnets are very small strontium Magnets. Centering magnets are not very essential if you are not using linkages to move the moving surface. Only coils wound using plastic tubes like plastic straw as former with around 36 SWG enamel insulated wire with no core. the coils is fixed using CA glue. coils wound to an impedence of 50 to 150 Ohms. the small magnet stuck on a thin stick of balsa is used as arm to move the surface. The actuator directly stuck on the edge of the hinge. Magnets inside defective small speakers of mobile phones are also very handy.

I can give you photographs if you are intersted. But firstly let me know what is the receiver you are using to drive the actuator.

i m not sticked to any particular reciever but want to get a common knowledge

so please post pictures and details of what to and how to use to make one

interesting.... picture please.
This reminds me that cheap 'earphone' also contain useful magnets, but they are normal ones, not the powerful Neodymium ones..

-Ujjwal

Can you please post some pictures as a step by step process of making an actuator. Don't have any defective CD rom drives with me  though I could make a few drives go bad at the office in some old systems  ... >:D

Mobile phones have very small magnets.
Take a look at nokia 6085 there is indeed a magnet and sensor.

The magnet is in the display half to the bottom left of the main display side of the board. i.e. Looking at the phone open in front of you 0.5cm to the right of the left hinge and 0.5cm up.

Here are some of the photographs. I do not have a defective phone or a CD rom at present so I am unable post photographs of the same.

In the photo graphs of the magnets from left first is a mobile phone earpiece magnet which is there under the diaphram making field for the voice coil. second is the CD Rom Lens Magnets. which are right under the lens. the lens is supended on a magnetic field created by these magnets with a coil and focusing is done by varying the signal to the coil. third is the magnets from very small burnt out brushless motors. Small brushless motors have 12 -15 magnets in each. then some are broken speaker magnets to fit inside smaler coils. Magents in the size of 1.5mm to 2mm is there inside Laptop hard drive on the other end of the reading arm which maker the reading arm stuck to the fixed structure. this is of size similar to centering magnets.

These magents are very strong and removing them even if they have not been stuck with adhesive is difficult from the core. Then they are stuck with adhesive. you have to edge them out with very thin rigid screw driver tips gently as they are brittle also.

Photographs of the coils and a accutuator actually mounted on a micro plane is attached.

Take care to mount the magents poles perpendicular to the poles i.e. axis of the coil. fix the coil to the wing and the magnet stuck to an arm which futher stuck to the moving surface. take care to match the center of rotation of the magnets to that of the  coil generally  

Now Thats I call innovation and improvisation Mr Sai has been calling for ! May be you can fabricate these at commercial level and see if Mr Sai can market them!!

Kudos Sundaram. These kind of idea my have struck many of us, but only few like you actually implement these. The next obvious question - the servo driver. Since these wont take PWM for the throw, how did you made them proportional (or even tri-state) ? As more of electronic enthusiast and not mech, the Rx design intrigues me!

Firstly these don't have much comercial value only innovation value. Yeah after my retirement I can surely think of producing them in an industry in a comercial manner in large scale then they would have some comercial value :giggle: :giggle:.

I use them with plantraco receivers as they are proportional. however if you are using with cheaper IR/ RF receivers which are not proportional then you have to control by rapid flics of the control. Further you would also require a mechanical / magnetic centering. which can be very easily achived by the appropiate rigidness at the hinge or by a very very small piece of magnet stuck to the coil.

here is lot of info
http://www.rcgroups.com/forums/showthread.php?s=&threadid=17871
ashta

Long back I have tried this. But its a MACRO! Not MICRO  :)

http://www.youtube.com/watch?v=Nz6Wiz4nXgk

i have got some wire from a old brushed motor no longer of use and started to build one in my study break
i wound the coil around a pen,leving abt 10cm wire from each side,put some ca,toof it off and put some more ca
now i'll in my next break will measure the resistance and will tell u all to comment ans tell is it of any use?
also a have a set of magnets which i can use

-ANkur

help....-how to scrap the covering of the wire without cutting the wire??
i am not able to do it and thus no able to get the resistance...

please help me out
-Ankur

how much should be the resistance ??
and how to measure  it??
 btw i opened a dead clock and got some more wire
i wrap them around pens

but the problem arises in glueing them
when i put a drop of ca[fewikwik] glue the coil gets stuck to the body of the pen :banghead: :violent: and gets destroyed
i have made 4 and destroyed 5

so please help me out!!!

hi mate,
you need 'wood glue' or something like that,
a glue is too fierce and finds its way to every thing in sight..........even the thick one needs carefull handleing.
try a .pva' glue this is waterbased but sticks to most things and will penatrate the coil a little to give a bond
regards
don

so fevicol will work i think???

hi mate
perhaps not
here is from the wiki writeup
"

Fevicol is a synthetic resin adhesive, so easy to apply that even non-experienced carpenters can work with it comfortably. It can be used in bonding various materials, where one of the surfaces to be bonded has to be porous. Fevicol strongly binds wood, plywood, laminate, veneers, MDF and all types of boards, cork etc. It is also used in sport goods manufacturing and book binding. The bond gives handling strength in 8 to 10 hours and cures fully in 24 hours to become so strong that if hit hard on the bond the wood gives away without so much as even affecting the bond.

 it seems to want a poruse surface try some on one that was destroyed ..perhaps get a winding of somesort on a center and try it , put a paper or something on the core mould first to aid removal.
or a  glue you might use for foamies perhaps.
regards
don

ok will find and use pva glue !!!

i used camlin glue named krafty glue and it worked-it dries up also very quickly-1-2 mins thin layer to 1 hr thick layer!!!
thanks don
now can anybody tell me how to scrap the covering of the wire?
and how to measure its resistance[i have a multimeter but connot measure without scrapping...]

-ANkur

some pics of the coil i scanvenged from a old dc brushed motor to make the actuator

here are the pics of the actuators
i wound them around a ball point pen's body!!
the whitish material is the glue[camlin krafty glue] which i used for bonding the coil [not yet dried up in some of them so that residue!!]

now please tell me how to scrap the covering of the end of the wire so that i could join them to other electronics... and also check the resistance
and suggest which magnets to use with which actuators out of those magnets i m posting pics of
here are the pics of the magnet...
the pen which is kept is the one around which i wound the coils..
and the magnets are stuck to a 6" steel scale to get an idea of the size..
please help me out
 -Ankur

knock knock knock...anybody interested????????????????

I  made one today

more images

Ankur, I have Lots of Insulated wire.

For wires, you have not to open up the Small Motors. If you want locally, just go to your ceiling fan repairing shop and ask for wire. You need about 40-43 SWG wire. even 36 SWG may be used. If he has not this gauge, ask hm to purchase for you. The current insulated Cu price is Rs. 580/- today. Just Purchase 100gm not more and that is sufficient for you for experiment.

Above 40 SWG, loose wire not sold. You have to purchase complete bobbin. It comes from 100 gms to 500 grams.

For terminal soldering, Just take solder molten in Tip of soldering Iron. Plenty of Solder that may stay on tip. Dip the coil end to Soldering Paste. Then insert it into the molten solder slowly from the cut end. You may hear a cracking sound that comes from the bit. Actually, the insulation cracks and the Cu wire tinned through your solder. Just insert a small wire again till your requirement is over. That's Enough. Purchase thick solder wire of 1 meter from Electronics shop.

Thanks.

actully to remove the solder you can just dip the wire end in thinner and then rub it with a damp cloath its a bit easy and then solder it just a said above and do check the connectivity of the wire by a multimeter after soldering.

Hi Any progress made in the actuator build? Please let me know. Thanks

@ Ponappa

You can have a look on this link.

http://www.rcindia.org/self-designed-diy-and-college-projects/magnetic-actuator-(home-made-scratch-build)/