Thread Tools
Apr 14, 2002, 06:43 AM
Sticky Shepherd
Graham Stabler's Avatar
Thread OP

home made brushless motor

Just thought I'd mention this thread on the heli section

Contains a brushless motor made for a piccolo helicopter. This one is just a rewound 36speed cd-rom motor. The only construction required is the rewinding and the production of a small aluminium adapter that allows mounting and holds a bearing. The shaft may also need to be reduced to match the propeller or pinion used.

It should be noted that this type of "outrunner" motor gives high torque so you can turn big props without a gearbox.

This motor is equialent to a s300 but it weights 18g not 49g. The recommended esc is a jeti jes 06-3P which is around $70.

Sounds good don't it!

Last edited by Graham Stabler; Apr 14, 2002 at 08:04 AM.
Sign up now
to remove ads between posts
Apr 14, 2002, 06:45 AM
Sticky Shepherd
Graham Stabler's Avatar
Thread OP
And here is Ron van Sommeren's usual informational post, copied from said thread, loads of links:

Discussion & help
• The LRK-torquemax e-mail list for help and discussion on construction and design (English), monitored by yours truly:
To join the list, click ‘Join This Group’ in upper-righthand corner, or send an empty message to [email protected].
• If you can read a bit of German, check out the German LRK-torquemax forum, it’s *very* good: >> rc-forum >> elektro-motoren
• LRK-torquemax meet & Electric fly-in, June 23rd 2002, Nijmegen the Netherlands:

Construction articles & tools & pictures
• Construction articles I & II, they describe the classic LRK-torquemax for outside fuselage mounting:
• The bible, LRK for inside fuselage mounting, more construction articles, winding calculation tool, measurements, diagrams, a motor test rig, diy brushless controller:
• Building manual: (414kB, may take a minute to download)
This manual is for Peter Rother’s design but it has many, many useful tips, tricks and winding calculation examples.
All four are in English and German.

Don’t let the German language deter you, the pictures are worth more than a thousand words!
• picturs, tables, drawings, LRK in helicopters: (G)
•pictures, tables, by other builders: (G)
• pictures, tables, drawings, LRK in helicopters: (G)

• English version of winding calculation tool: (E)
• Winding calculation tool: (E)
• Removing windings from old motors: (G)

More LRK-torquemax builders’ homepages
• FW Ta400, 4.35m wingspan, 6 classic LRK's: (E)
This site can be a bit slow at times.
• pics & diagrams, LRK ‘inrunners’: (E)
• help & discussion mailing list, archive, pictures, drawings: (E)
• mailing list’s pictures and drawings archive: (E)
• stator glueing and insulation: (G)
• slow-flight, drawings, tips: (G)
• mini-LRK drawings (S400 replacement), tests: (G)
• winding/wire diameter/prop calculation tool, canard delta: (G&E)
• LRK ‘inrunner’ from old hard-disk: (E)
• LRK & piccolo helicopter: (G) (G)
• LRK 430/30, 43mm diam. / 30mm long stator (G)
• pole-magnet combinations:

Material suppliers
Magnets must have at least a 1.1Tesla fieldstrength!
•( USA) Magnets:
• Stator material, magnets, turned parts, shafts, ball-bearings, wire, kits & complete motors and a very good downloadable construction/assembly manual: (G & E).
• Stator material, magnets, turned parts, shafts, ball-bearings, wire, kits, assembly tools, complete motors: Soon in English too.
• List of magnet suppliers: (E)

Diy brushless controller
While on the subject of diy: Jo Aichinger from Austria has three versions of his do-it-yourself brushless Speedy-BL controller: SBL-classic, SBL-mini and SBL-sprint. These controllers work fine with LRK-torquemax motors, but other makes are also suited, albeit some better than others. Manufacturers are in the process of adapting the software for the high pole count LRK’s. The SBL-sprint has separate powerboards. Jo can supply the printed circuit board and programmed microprocessors.
The information is German only for now (classic also in English), but the tables speak for themselves. If you don’t want to hunt for components, buy it as a kit or ready-made:
Speedy-BL ESC construction pictures:
Apr 14, 2002, 08:50 AM
Registered User

Does sound very good, I was just over there and Mario said he had a couple companies that are working on similar size motors for the House FLY. I wonder if it would be his own design that they are building for him? And I guess this question should be for Mario, Are you willing to sell it for us Airplane guys? Life is getting to be pretty good, first my dream Rx with the DU system and now my dream motor.

Apr 15, 2002, 02:22 PM
Senior Gravity Checker
All the links seem to be for a 12 pole motor.

The cd-r drives are nine poles...

How do you calculate # of windings?

How are you gearing these motors....I think you lose 8% efficiency with the first gear set...why not direct drive?

i'm interested in a fixed wing an m100 brushed motor...

Apr 15, 2002, 02:45 PM
Registered User
Your right the CDR drives are 9 poles. From the info I have seen so far they say 16-19 turns of 26 gauge wire. I am working on my motor now still have to run the wire on the stator. Here is a good link of the 12 pole

at 18 gram I believe this is the next step in motors. I am not sure of the workable rpm but if it is the same as the larger LRK's then its around 5500 rpm.
Apr 30, 2002, 07:42 PM
Registered User
pgoelz's Avatar
I have flown my 16T (#26 wire) and 19T (#28 wire) CDROM motors successfully.

The 16T flew in my Wattage Hawk with a Jeti/AF 06-3P controller and the 19T is currently flying in my Piccolo with the new Castle Creations Phoenix (new firmware with brake disable).

The 16T coupled with the accompanying weight reduction yielded somewhat longer flights and lower performance compared to the stock S380. However, the performance was still respectable. The only real problem was landing on the prop and knocking the stator out of the mount.

The 19T flies VERY well in my fixed pitch Piccolo with the Phoenix controller. Performance and run time in this application is comparable to the AF010. Since the run time is the same as the AF010 and the weight is lower, I have to conclude that the motor efficiency is lower than the AF010. But the price is even lower!

I will be installing the 16T in my collective pitch Piccolo as soon as Patrick develops the heli governor for the Phoenix. In a preliminary test, the 16T flew the CP Piccolo FAR better than the AF010. However, I was using the Jeti 06-3P, which is a very poor choice for a heli. It was not possible to keep the head speed constant enough to dial it in well and get a good feel for run time. However, the motor was capable of driving the head speed well over 2000 RPM in a hover even past the half way point in the discharge curve. The best the AF010 can do is about 1700 RPM.

In both helis, I am flying 8 Maxell 700 mAH NiMhs and using an ECO8 ten tooth pinion.
May 01, 2002, 06:49 AM
Registered User
I found that thread as well so I pulled out a power surge Infra 52x drive.

its got a 9 pole brushless. very silimiar the the one in the pic. the only problem is I can't get it apart!
I got the out casing off (the part with the maget around the outside) but I can't seperate the interior magnets from the back...
anyone done this successfully?
also mine got some circuit board attached?? I owuld need that coz I lopped a huge chunk off lol
May 01, 2002, 07:17 AM
Registered User
mrtim's Avatar
So am I looking for any old cd rom drive or is there a certain CD speed needed? I work with computers so I would have an endless supply of 4 and 8 speed drives...
May 01, 2002, 07:24 AM
Sticky Shepherd
Graham Stabler's Avatar
Thread OP
It isn't easy and I haven't got any super method for you. When you say interior magnets I assume you mean the laminations with the wire wrapped around. The only magnets are the ones in the "cup". Getting the stator plates off the pcb/base is probably the hardest part. Mine had a brass insert that tapped out fairly easily from the back but the back plate which was on the other side of the pcb was much harder as supporting the plates is very difficult. Next time I think I'll just saw/grind the back plate off leaving a tube in the motor. The pcb can then be slid off and the stator supported properly before tapping the tube out with a drift.

Hope this is some help. I cocked it up first time so am no expert.

May 01, 2002, 08:53 AM
Just an average RC'er
Jim McPherson's Avatar
I'm currently experimenting with these as well. I used a dremel tool to grind away the brass inserts that seem to hold every part in place. So far what I'm doing is widening the brass bushing then expoxying 3mm bearings to it so that I change from bushings to bearings. I ordered a pinion shaft from stock drive products that is steped from 5mm to 2mm. I plan to install some 5mm bearings in the motor and use that shaft. 2mm pinions are farily easy to find in the 64 pitch I need on my heli's, and there are good prop adaptors in that size as well. I steped on the cup last night bending the shaft mounting hole and the backside of the cup so I'll be looking for some more parts.

I'd love to see some pictures Paul of your setup, it sounds like your ahead of the rest of us here.
May 02, 2002, 12:40 AM
Registered User
graham- well they are electro magnet so I was sorta right
in the centre of the motor there is a brass looking circular thingo. i'm guessing thats whats holding it in.
is the backplate used for anything??? I might just slice it off
May 02, 2002, 04:11 AM
Sticky Shepherd
Graham Stabler's Avatar
Thread OP
Genrally you will machine your own backplate with the correct mounting holes and to hold bearings. The old back plate is probably chuckable. On my motor the back plate is what held the plates and the brass piece fitted inside so it depends on the motor what you need to do.

May 02, 2002, 04:58 AM
Grand Poobah of Nothing
Trizza's Avatar
I'm still tracking down cd-rom drives - think I've found a source now so I'll be trying to make some of these motors in the mid-year holiday. Need to get a job so I can get a brushless controller too...
May 03, 2002, 05:37 AM
Registered User
pgoelz's Avatar
Sorry, I've been busy with a new job (yay!) and haven't had time to take pictures. However, I suspect that every motor is a little different.... especially in how it is held in place and in exactly what you need to do to modify it.

The two motors I have used (from different manufacturers) both use the same mounting methods, though. The lamination stack was fitted over a brass piece that passed through the backing plate and circuit board. When it was in place, the open end was staked into place and the bronze sleeve bearing was pressed into place. To remove it from the backing plate, I ground off the end that protruded from the rear of the backing plate. This simultaneously released the motor from the plate and exposed the bottom end of the motor so I could remove the plastic retaining washer that the shaft snapped into. Unfortunately, this does not leave a lot of the brass piece to press into a new backing plate, so there may be a better way.

Since the brass piece seems to be staked into place at the exposed end, it might be possible to carefully drill out the staking and slide the stator off the brass piece and then make a new one from stock 6mm ID brass tubing. That way the bearings would fit without any adapter and you could have plenty of mounting area.

Rewind the motor with between 15T and 20T depending on your appliation. I like my 19T motor for the Piccolo, but 18T might be a wee bet better at using up the very last of the pack capacity. Go to Radio Shack and get the three pack of enameled magnet wire.... or find another source of wire. You will need #26 and #28. The windings are would as three sets of three.... wind one pole, skip two poles and wind another, skip two poles and wind a third. Repeat this twice more. Then, connect the start end of each set together. The finish ends are the three phase wires that will connect to your controller. And yes, you can reverse this and connect the finish ends together and use the start ends to connect to your controller.

I saw a post earlier that mentioned using the Hall effect switches on the circuit board to drive the motor. This is something I have been thinking about too.... I see no reason why you could not use them to drive three FETs and then drive THAT with a conventional speed controller. But if you can get your hands on the CC Phoenix, it works so well you will not want to bother.
May 03, 2002, 06:10 AM
Grand Poobah of Nothing
Trizza's Avatar
In breaks I've been reading up in my University's library about motors and controllers, and found some VERY VERY simple brushless controllers which effectively allow them to be controlled just like a brushed motor - voltage control and pulse width. Basically it was 3 MOSFETS, each had a hall effect sensor switching it. There were more components but I was truly astonished at how simple it was.

I'll try to remember to go into the library again and copy it out next time if anyones interested. I can draw it up in OrCad and do a screen capture of it for everyone.

Quick Reply

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Home-made LRK-torquemax Brushless motors. rsieminski Power Systems 5 Feb 05, 2002 07:30 PM
home made brushless motor tomr Electric Plane Talk 7 Oct 01, 2001 10:59 AM