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Old Aug 13, 2012, 09:02 AM
RC beginner
New York
Joined Oct 2008
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Mini-HowTo
$18 diy quad... COMPLETE! w/video

below is a photo of the dquad (diy quadcopter) which can be built for less than $18 complete with frame, rx, motors, and escs. it was inspired by the great success a year or two ago of my record breaking lowest cost multicopter rcg thread. this time i cut cost in half again thanks to the v929 fc board. it has turnigy/flysky compatible rx, 3 axis gyro, and 4 escs, all for $13. true revolution in the multi fc world. few bucks more for motors and props. it flies great and i have many modifications and experiments planned.

(edit: lower cost of multiwii based fc components instead of v929 board, udi instead of walkera props, and aliexpress/bidprocucts motors, now bring total cost down to around $10 and change!)

based on demand (some VERY demanding ) ive decided to make this a how-to thread. a great way to get your feet wet with multicopters w/o breaking the bank so lets get going:

first some info on glues. youll need polyurethane (pu, gorilla) glue, white (pva, school) glue, 5min epoxy, and pu floor enamel. a note about pu glue: on the hub its used straight for maximum strength. everywhere else its mixed with 10% or so white glue so it will foam up. the result is stronger and lighter than any other common adhesive including ca or hot glue. in fact tests show up to 40 times lighter. many complain "it foams up and makes a mess". lol! this is because you are using too much. foaming is in fact its great advantage in our hobby. why do you think they call them "foamies". foam is good. however it does take some practice to get it right.

now a comment about wood vs carbon fiber. cf has much higher tensile, compressive, and shear strength than just about any other material however it fails miserably in terms of adhesion. wood to wood is much stronger in this respect, specially when coupled with pu foam which is why i use them here. if you want to use cf you need to get some brackets and nuts and bolts too but your quad will weigh 4x as much. people underestimate the importance of "adding lightness" to these type models. not only handling but motor life and crash damage are affected. BIG TIME! i just weighed my first one and it comes to 23 grams with battery. thats a fraction what the v929 and other micro-quads weigh. you can tell the difference too as soon as it lifts off.

note that its a good idea to start on the paper tubes first because they take a week to make. lol! actually only a few man-minutes but 7-10 calendar days to dry. first you need a proper size form. this is by far the trickiest part of the whole project. too big, motors slide out and/or twist (not good). too small, they wont fit in the tubes. the motors should be EXTREMELY tight fit but not enough to split the paper. i found 7mm cf tube (junior arrow shaft) perfect for s107 pagers. for the 6mm motors a 1/4" dowel works with a little modding. if the form is too small you can build it up with tape or paper. if slightly too big sand it down.

tubes are made by rolling 2 layers of paper around the form with white glue in between. let set 24h then dip in oil base pu floor enamel. this is what takes a week to dry. but really it only takes a few minutes of your actual time to make enough tubes for 100 models. so not really that bad.

1. raw materials: 2 bamboo sticks, tongue depressor, and strip of paper.

2. cut sq wood hub, glue arms on with pu , and lay down on a paper with crosshairs for alignment.

3. you can make more than 1 at a time adding another layer with wax paper between. i usually do 4 at once.

4. clothespins to keep the ends aligned and a weight in the center. set overnight.

5. cut 3/4" prefabricated pu impregnated paper tubes and glue to end of arms w/pu foam. clamp and set 3h

6. glue 3/4" sq velcro hooks pad (lipo holder) to where arms meet w/pu foam and add "bumps" other side next to wood hub. set 3h.

7. attach 1/4" sq velcro hooks and loops to rx corners and glue to "bumps" on the frame w/pu foam. set 3h. great vib/shock absorber for stable gyro!

8. dab of 5min epoxy on end of motors for strain relief.

9. make ziptie legs by bending w/lighter. trim big end as motor retainer and fork small end so it stays on the arm. insert motors. clamp & glue w/pu. set 3h.

10. make braces from 1" bamboo split 4 ways. glue w/pu foam. if ladybird props are loose glue with straight pu and set 12h checking alignment often.

11. optionally adding a coat of pu enamel to hub and on arms will stiffen and waterproof. also resists dirt and stains. negligible weight increase.

12. solder #36 STRANDED wire to the pcb, check for shorts, then wire to motors. 1.25mm pz plugs makes connection easier but add couple grams/dollars.

DONE !!!

white silkscreen arrows on the v929 pcb in photo 12b show direction of flight and what kind of props go where. color is up to you. i prefer orange/rear black/front because thats how my v929 was. but it can be done other way around. the v939 board dont have indications so youll need to use photo 12c to get it working.

a word about batteries. the stock v939 used 300mah lipo and that is probably best choice. smaller ones (parkzone 138mah) work and handling is a whole 'nother experience but run time limited to a few minutes and the cell gets a bit warm.. for a little longer run time 600mah (v929) also work but now its the motors that get hot. not critical but you might expect somewhat shorter motor life. i even tried 1300mah and while it does lift off the handlling was sluggish and motors will wear even faster. its up to you.

one warning about the motors. they are very delicate. epoxy on the end as shown in step 8 will keep the leads from breaking off at the case which is NOT repairable. another thing to be careful of is support the back of the motor when pushing props on. otherwise the back end can pop off which is also usually fatal. it can happen in a crash too so a few tiny bumps of pu foam inside the tube to act as stops will help that. make sure you can still slide the connectors through if you use them. another trick is to use a washer under the prop or push the prop all the way down to take up any slack. im wondering if a tiny touch of ca around the edge of the can will help too. even with care pagers have a finite brush life but they will definitely last longer with some preventive maintenance.

also be aware that if you cant get motors with black/white(ccw) and red/blue(cw) wires then you can simply reverse the wires on two of them. just make sure they end up turning in the right direction.

word to the wise. if you are confused by technical discussions or upset by off topic posts then better to go no further than page one. everything you need to complete the project should be here. let me know if theres anything missing.




8/20/2012 update:

as requested finally got a video posted: http://www.rcgroups.com/forums/showthread.php?t=1715500




9/6/2012 update:

parts list (all tested and in stock as of 11/12/2012):
fc board: http://www.banggood.com/Wholesale-Wl...5-p-49468.html
props: http://www.banggood.com/Wholesale-Ud...t-p-48799.html
motors: http://www.focalprice.com/YE384S/Rep...er_Silver.html (.8mm shafts require gluing prop but more dependable supplier)
http://www.ebay.com/itm/161047189500...#ht_1843wt_869 (1mm shafts and very powerful)
many other motors are cheaper but more testing is required. right now the total is under $15 so no rush to change these 2.
http://www.banggood.com/Wholesale-2-...r-p-63727.html these 720 have more power and EFFICIENCY than the 716 uses so far



9/21/2012 update:

below are some photos and notes on the v939 fc board as a smaller. lighter, and lower cost replacement for the v929 one. it works great and is actually better for the smaller (15cm) dquad frame because those minor oscillations are gone. and it seems considerably easier to handle. does a good job on the regular 30cm and large 60cm frames too. also tested udi u816 and v939 props which work at least as good as the walkera ones ive been using. a photo has been added of the new board. notice pu foam strain relief on antenna, connectors, and battery cable like i did on the previous board.

a few things are different. motor wires are reversed so its necessary to pull the shells off and push them back on rotated 180 deg. only takes a minute or two but if you dont do it props will spin backwards. theres some interference with smd parts but a little trimming with exacto fixes that. also letteriing is upside down now and motor wiring is not so obvious. but the antenna is still in the front. i spent many hours (hundreds of combinations) trying to make this work but finally with help from mikesrc and shafter got things right. i did make adjustments since then so the orange props are in the rear like on stock quads and it is more compatible physically. connectors are numbered for easy swap out in the field. it flies great.

and best of all total cost for parts is now $14 and change.




9/25/2012 update:

added pic showing the 3 different sizes (15cm, 30cm, 60cm) next to each other in response to some offline requests. im planning a really small 6cm version too (if hubsan can do it so can i. lol!).

also photo of the 60cm one on a scale that jesolins was asking about. notice its under 28 grams INCLUDING BATTERY. probably possible to cut the frame weight in half again by using foam. the question is will foam be able to withstand repeated crashes like the bamboo version. time will tell.




9/27/2012 update:

what with brandigan and jesolins talking about double motors and skitchens INCESSANT WHINING for more lift i came up with the octo frame shown below. no "dirty air" here.

also a couple people asked to see video of the 60cm (2 foot) dquad. i really dont have anything atm except a few short test flights where i was checking out different motors and props. basically wanted to see if it would lift and be capable of some hint of control. the only place i have nearby is the 7 foot wide frat house driveway so no fancy flips or funnels. wind was a problem too. also because these are only test runs i didnt bother to change the camera from 10" macro used for the closeups so things are a little fuzzy (if not warm and...). heres one showing the 60cm frame with aliexpress motors and udi props. by far the lowest cost setup:

http://www.rcgroups.com/forums/showt...0#post22839626

you can see that it has more than enough power and no tendency to shoot off in random directions. when i get a chance ill replace it with a real video.




10/3/2012 update:

heres a list of compatible radios compiled by that shopping genius mystman:
Quote:
Originally Posted by mystman View Post
FlySky FS-TH9X 2.4G 9CH transmitter
http://www.hobbypartz.com/79p-th9x-r...nel-radio.html
http://www.banggood.com/Wholesale-Fl...r-p-47904.html
http://www.aliexpress.com/product-fm...olesalers.html

Turnigy 9X 9Ch Transmitter w/ Module
http://www.hobbyking.com/hobbyking/s...Firmware_.html

FlySky FS-T6 2.4ghz Digital Proportional 6 Channel Transmitter and Receiver System *NEW*
http://www.hobbypartz.com/79p-t6-6ch-radio-lcd.html

FlySky FS-CT6B 2.4GHz 6CH Transmitter
http://www.aliexpress.com/product-fm...olesalers.html

Hobby King 2.4Ghz 6Ch TX
http://www.hobbyking.com/hobbyking/s...2_Mode_2_.html

Double Horse 9116 Helicopter Transmitter
http://www.banggood.com/Wholesale-Do...4-p-40985.html

WLtoys V911 RC Helicopter Transmitter
http://www.banggood.com/Wholesale-Wl...r-p-42822.html
http://www.tmart.com/New-24GHZ-LCD-R...k_p153751.html

WLtoys V929 V939 Beetle 4-Axis Quadcopter 2.4G Transmitter
http://www.banggood.com/Wholesale-Wl...8-p-47529.html
the syma x1 radio works too: http://www.banggood.com/Wholesale-Sy...r-p-48760.html

heres his list of quads with 9x compatible fc boards:






10/28/2012 update:

i tried to make some more videos of the diy octo sunday but wind and rain put a damper on that. and what with sandy howling away outside there might not be another chance for another week or two so im uploading some old test files instead like i did for the 2 foot quad. short and nothing fancy but it does show lift and yaw. maybe you can make out a couple 180s:

http://www.rcgroups.com/forums/showt...0#post23130774

whats interesting is its using the "weak" blu/red 1mm shaft motors from ali. so apparently if you stick enough of them on there it does work out. with s107 or the blk/wht ones its hard to keep the octo from shooting up into the sky. i may need to adjust some throttle curves or expo to compensate but this is not quite as easy on the er9x modded v911 tx as on the original 9x so.... maybe later.

i put another short video up that might be of interest. it shows how spinning one prop causes the other one on the same arm to turn also. this is because one acts like a generator with enough energy to power the other. anyway i thought this little trick was kinda cool. lol!



11/12/2012 update:

due to peer pressure ive decided to update the parts list. actually the same fc board is no longer available. that original v929 board was great but if the new 8 plug one i received is any indication they REALLY SUCK now. i flew a battery with the old board and then the new one and things went downhill as far as controllability. not really that bad but all of the v939 boards i tried seem to work better. and they are about half as big too. so it seems like a good idea to change the v929 fc to v939. cheaper, smaller, and flies better. the only drawback is having to re-bind every time. while im at it i replaced the walkera props with udi version. much lower cost and almost as much thrust. the v939 ones work good too. anyway heres the old links:

http://www.banggood.com/Wholesale-3-...1-p-47127.html
http://www.banggood.com/Wholesale-Wl...6-p-47484.html

i also added a few comments in post #688 to reduce weight and streamline the build. they are much faster and easier to build now compared to when i started out.




3/29/2013 update:

low cost diy nano flysky/turnigy rx ic for multiwii
--------------------------------------------------------------------------------

in http://www.rcgroups.com/forums/showthread.php?t=1798913 i mention if theres enough interest i will make available an ic that, when used with a7105 or xl7105 discussed there, will implement a flysky/turnigy compatible rx w/ppm output. perfect for a diy nano-quad or nano-tri based on multiwii or other open source firmware. due to lower cost of fc components compared to the v929 board ive been able to reduce expense to considerably less than the origriial $18.

only 3 components required:
-1pc $3 xl7105 module
-1pc avr flysky ppm chip
-1pc 1n914 diode to drop lipo voltage
-1pc .1uf cap

pinout is as follows:
-pb2=csl
-pb1=sck
-pb0=dio
-pb4=io1
-pb3=ppm/bind (not bad. only 5 signals)




7/2/2013 update:

i added a pic of one of the quad brushed escs that were used in prototypes here before integrating into the mw circuit. used to convert diy or commercial fc like crius or those from hk to brushed. wiring is from the mw diagram in flysky rx thread.




7/26/2013

motors have been a big topic of discussion here so im adding photo and link for some new 720 "hollow cup" (lol). i just tried them out in my standard 30cm frame and there seems to be HUGE increase in power compared to the 716 weve been using. a little more weight, but a LOT more lifting. im not sure but after running a few lipos through they seem to be more efficient too. ie not only more power but longer flight time compared to the smaller ones.

only a dollar and change ea using up some points. its a good idea to buy 3 sets, not only for the big discount but, pays to have a couple spares what with wear and popped end caps. (btw a tiny dap of ca helps with that last one)



photos:
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Old Aug 13, 2012, 09:49 AM
I Toast Planes
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That is incredible! Can you post a video of a flight?
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Old Aug 13, 2012, 10:39 AM
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I believe those are DC brushed motors?

Does it need tweaking? or is it turnigy/flysky compatible out of the box?

Thanks
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Old Aug 13, 2012, 10:48 AM
THE PUBLIC IS THE PROBLEM
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Got a parts list???

this is interesting....
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Old Aug 13, 2012, 10:52 AM
RC beginner
New York
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Quote:
Originally Posted by Raj Quest View Post
I believe those are DC motors?

Does it need tweaking? or is it turnigy/flysky compatible out of the box?

Thanks
9x compatible like all wlt products.

no tweaking at all. in fact the spot on the pcb for pid gain pots is unpopulated in latest versions. it just runs perfectly right out of the box. a far cry from my experience with the kk board which i do consider one of the best deals around but not plug-n-play by any stretch...

actually all our motors are dc but if you mean brushed, yes. they are 6mm pagers from "solar grassshopper toy". about 50 cents ea on ebay which was another radical departure from the brushless used in last years $40 tricopter. this along with no extra escs are biggest reasons i was able to cut cost in half. i also used s107 motors in another version but it added couple bucks to the cost. they did however allow me to lift a camera when the grasshopper motors could not.

as mentioned in the other thread i cant easily do facetube type videos but will try to take some this weekend when i go home and upload to the rcg gallery.
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Old Aug 13, 2012, 11:21 AM
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With 6mm pager motors, GWS 3020 should work fine?
what might be the AUW?
and all props are mounted DD?
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Old Aug 13, 2012, 11:32 AM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,263 Posts
Nice job Dave! Now lets make it brushless. Can you find any fcb signal to the FETs that would work with a brushless ESC? Or we can use something like TheSteve brushed to brushless converter that worked for the Walkera UFO#4 quad and some others. Any check on the gain pot contacts being functional?
Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index
Quote:
Originally Posted by dave1993 View Post
below is a photo of the micro-quadcopter which can be built for less than $18 complete with frame, rx, motors, and escs. it was inspired by the great success i had a year or two ago in my lowest cost multicopter rcg thread. this time i cut cost in half thanks to the v929 4-in-1 board. it has turnigy/flysky compatible rx, gyro x3, accelerometers, esc x4, etc all for $13. true revolution in the multi fc world. it flies great and i have many modifications and experiments planned.
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Old Aug 13, 2012, 12:07 PM
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Originally Posted by jesolins View Post
Nice job Dave! Now lets make it brushless.
thanks jim. unfortunately bldc is not in the cards this time around. it would be hard to get one motor, converter, and esc for that price let alone 4. my cutoff was $20 here. having built several mutlicopters at this point im convinced the smaller they get the more expensive they are. my $40 tricopter was 2 meters and most of the really tiny ones then were at least 4x that. i never could have built a really small one for that price. not until these cheapo pagers and v929 rx came along.

maybe a REALLY small bldc could be built with those tiny 2 phase dealies. a few attempts at sub gram plane using helmuts diy 2 phase taught me how much work is required down there. im trying to imagine that many hours multiplied x4.

if cost is no oblect i think kreatures brushless nano-quad is impossible to beat. probably cost hundreds but even so i cant wait to see how things work out when his boards come in.
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Old Aug 13, 2012, 12:13 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
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Hi Dave,
Roger that. Here is a 2008 post of a Gent flying a flea sized quad(jk)
http://www.rcgroups.com/forums/showp...postcount=1780
Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index
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Old Aug 13, 2012, 12:22 PM
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Quote:
Originally Posted by Raj Quest View Post
With 6mm pager motors, GWS 3020 should work fine?
probably not. even gws 2.5" fried the motors on my first attempt with those. the ones in the photo are cut down walkera ladybird props. i just reduced size until the motor could be held in my fingers for at least 30sec. they did not need trimming with the 7mm s107 motors though. and man.. what power!

cost is another issue. the walkera props are only around 50 cents which is hard to beat even for gws. my first attempt used aero ace motors and props which work great but hard to find now and literally 50 times higher price now if you do find them.

Quote:
Originally Posted by Raj Quest View Post
what might be the AUW?
iirc the one in the photo came out to somewhat less than an ounce with pz 138mah.

Quote:
Originally Posted by Raj Quest View Post
all props are mounted DD?
yes. this is essentially an mqx with ladybird arms like in elvills famous hybrid thread in the indoor area. i think dragging in those speed boats killed that thread but fortunately not until i already caught the "bug".
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Old Aug 13, 2012, 12:39 PM
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This is going to be a real cool and quick project...
Really looking forward to get going....
thanks to you!!
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Old Aug 14, 2012, 02:29 AM
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dave,

Thanks for all the info...

V929 control board: http://www.banggood.com/Wholesale-Wl...6-p-47484.html

and prop: http://www.banggood.com/Wholesale-3-...1-p-47127.html
is already on its way

would like to use s107 7mm main motor........

is there any way that I can use the following propson DD without using gear-box):
http://www.banggood.com/Wholesale-4-...d-p-47491.html
BUT.. which motor then??

what do you think is the max amps the on-board-brushed-motor-ESC can handle ?

Thanks,
R
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Old Aug 14, 2012, 05:31 AM
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I've found some cheap 6mm (10pcs $7.90) & 7mm (10pcs $8.90) coreless motors on Aliexpress.

6mm : http://www.aliexpress.com/product-fm...olesalers.html
7mm : http://www.aliexpress.com/product-fm...olesalers.html

If you choose 1mm shaft with the 7mm motors Ladybird or UDI propellers should work.

Will they work as quad-main motors?
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Old Aug 14, 2012, 05:45 AM
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Quote:
Will they work as quad-main motors?
looks great....
Hopefully someone who has used it before can help us with that ??
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Old Aug 14, 2012, 01:59 PM
RC beginner
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Quote:
Originally Posted by Raj Quest View Post
im sure those will work but they are too expensive for me. for low cost yet high power i suggest s107 or maybe the motors mystman linked to. s107 are a dollar and change ea (in sets of 3) to keep total cost below $20. i pulled 6mm pagers from the solar grasshopper to get cost below $18 but there are drawbacks. power is so low it barely lifts off for one thing. for another its tricky finding a good source. and the props need trimming which is not the case with the s107. so its a cost tradoff.

Quote:
Originally Posted by Raj Quest View Post
yes. truly a miracle of modern engineering. just a month or two back the only similar item available was the walkera controller at 3x the price.

Quote:
Originally Posted by Raj Quest View Post
This is going to be a real cool and quick project...
Really looking forward to get going....
thanks to you!!
glad you like it. if your only experience so far is with conventional quads you are in for a treat. even a surprise to me after flying the v929 past few weeks. i was going to buy its little brother the v939 but not anymore. so easy to build and fun to fly you wont believe it.
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Last edited by dave1993; Aug 20, 2012 at 09:22 AM. Reason: better motors?
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