Thread Tools
Old Feb 29, 2016, 02:41 PM
slowmatch is offline
Find More Posts by slowmatch
Registered User
slowmatch's Avatar
Joined Dec 2015
214 Posts
Discussion
Motor Identity for Rewinding?

Please can anyone help me identify these three motors? The two larger weigh 17g and are 24mm diameter. The smaller with 'three armed' case is 12g and 21mm.

They were given to me as scrap but I'd like to test and rewind them if its worth it?

Thanks!
Jon
slowmatch is offline Find More Posts by slowmatch
Last edited by slowmatch; Feb 29, 2016 at 02:47 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 29, 2016, 03:50 PM
Skylar is offline
Find More Posts by Skylar
我爱飞行 . . . I love flying
Skylar's Avatar
South Africa, GP, Pretoria
Joined Jul 2003
599 Posts
What are the stator sizes? At least one of them looks like a converted CD-ROM motor.

Skylar
Skylar is offline Find More Posts by Skylar
Reply With Quote
Old Feb 29, 2016, 04:54 PM
jackerbes is offline
Find More Posts by jackerbes
Jack
USA, ME, Ellsworth
Joined May 2008
19,564 Posts
Yep, all three are 9N12P (probably 12 magnets, but not sure) CD-ROM style motors.

The two that were probably commercial motors were probably rewound at least once in the past. The wind on 9N12P motors would be the ABCABCABC wind and that can be terminated either Delta or Wye.

You can get a wind image and all kinds of other info here on Skylar's wonderful Home Built Motors page:

http://www.bavaria-direct.co.za/

Here is a instruction manual from a 9N12P kit motor that was sold in the past and that will show you the process:

http://www.micronradiocontrol.co.uk/.../KH-278-v2.pdf

If the motor can be run now you can run them up and measure the RPM and voltage at the same moment in time to get a raw Kv on the motors. That and the turn count and termination info can be used with the Simple Turn Calculator spreadsheet to pick a new wind with the Kv you want to have. if you know the props you want to use we can help you choose a Kv, otherwise just count the turns that are on them now and wind them that way again.

If you want to check the windings as they are now you can do some simple checks with a DMM to see if they appear to be OK.

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Mar 01, 2016, 12:20 AM
Skylar is offline
Find More Posts by Skylar
我爱飞行 . . . I love flying
Skylar's Avatar
South Africa, GP, Pretoria
Joined Jul 2003
599 Posts
Quote:
Originally Posted by jackerbes View Post
Here is a instruction manual from a 9N12P kit motor that was sold in the past and that will show you the process:

http://www.micronradiocontrol.co.uk/.../KH-278-v2.pdf
Jack

That construction manual seems to be well written and quite complete, but the problem I can see is that it doesn't teach people to fill the slots completely. In fact, it sets a bad example. As you very well know, The correct wire thickness should be used for the slots to be completely full, or as full as is possible, otherwise efficiency and power will suffer.

I quite like the winding instructions in the second picture although it is not as complete as the one you linked.

Skylar
Skylar is offline Find More Posts by Skylar
Reply With Quote
Old Mar 01, 2016, 05:43 AM
slowmatch is offline
Find More Posts by slowmatch
Registered User
slowmatch's Avatar
Joined Dec 2015
214 Posts
Skylar,

The 12g three armed rotor one has a stator 18mm diameter, 4mm thick and the arms are 4mm.

The one with the mount (17g) is 20mm diameter, 4mm thick with arms about 3mm long.

The cd-rom one (16.5g) is 200mm diameter, 5mm thick with 4mm arms.

The do all have 12 magnets. They do look as if they've been rewound, and I think you could get quite a bit more copper on.

The cd-rom one has shorts to the stator, the other two appear to be ok. I haven't attempted to run any of them yet.


I don't have a particular application in mind but I quite fancy a high kv motor for a mini racer? Can anyone recommend wire thickness and turn count that would be achievable for a newbie winder and would make sensible use of a free motor?


Thanks
Jon
slowmatch is offline Find More Posts by slowmatch
Reply With Quote
Old Mar 01, 2016, 07:00 AM
jackerbes is offline
Find More Posts by jackerbes
Jack
USA, ME, Ellsworth
Joined May 2008
19,564 Posts
Quote:
Originally Posted by Skylar View Post
Jack

That construction manual seems to be well written and quite complete, but the problem I can see is that it doesn't teach people to fill the slots completely. In fact, it sets a bad example. As you very well know, The correct wire thickness should be used for the slots to be completely full, or as full as is possible, otherwise efficiency and power will suffer.

I quite like the winding instructions in the second picture although it is not as complete as the one you linked.

Skylar
We don't want these infant man knitters to get too good at all of this too quickly! We just have to hold back on some of the secrets until they have captured the basics!

But you are right of course.

If you look at the various manuals here there are some other Komodo kit motor instruction manuals and info that is an interesting piece of the CD-ROM motor history:

http://www.micronradiocontrol.co.uk/docs/komodo/

I'll bet all of that will go away some day. Just like the old Croco pages did...

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Mar 01, 2016, 08:07 AM
Skylar is offline
Find More Posts by Skylar
我爱飞行 . . . I love flying
Skylar's Avatar
South Africa, GP, Pretoria
Joined Jul 2003
599 Posts
Quote:
Originally Posted by jackerbes View Post
I'll bet all of that will go away some day. Just like the old Croco pages did...
True... That was a sad day for the DIY motor community.

Skylar
Skylar is offline Find More Posts by Skylar
Reply With Quote
Old Mar 01, 2016, 08:45 AM
Skylar is offline
Find More Posts by Skylar
我爱飞行 . . . I love flying
Skylar's Avatar
South Africa, GP, Pretoria
Joined Jul 2003
599 Posts
Quote:
Originally Posted by slowmatch View Post
The cd-rom one (16.5g) is 200mm diameter, 5mm thick with 4mm arms.

I don't have a particular application in mind but I quite fancy a high kv motor for a mini racer? Can anyone recommend wire thickness and turn count that would be achievable for a newbie winder and would make sensible use of a free motor?
Jon

I only have experience with the 20mm CD-ROM motor. I've rewound quite a few and still regularly fly one of them. It's a real powerhouse for such a small motor.

I'd recommend 15 turns of 0.45mm (25AWG) wire, terminated WYE (Star) for a Kv of approx. 2160. You could also use 2 strands of 0.3mm (28AWG) wire. With this wind, it'll be good for an APC 5.1x4.5E prop on 3S with plenty thrust and speed for a small plane.

If you require more RPM for an even smaller prop, consider 12 turns of two strand (2x) 0.35mm (27AWG) wire. Kv will be about 2700.

The winding scheme should be typical CD-ROM style, i.e. ABCABCABC for the 9N12P motor. Use any of the winding instruction manuals posted above.

Have fun.

Skylar
Skylar is offline Find More Posts by Skylar
Reply With Quote
Old Mar 01, 2016, 12:13 PM
slowmatch is offline
Find More Posts by slowmatch
Registered User
slowmatch's Avatar
Joined Dec 2015
214 Posts
Thanks Skylar,

I'm a bit limited by what wire I can get hold of at the moment. Currently buying short lengths on ebay! I can get 27swg which appears to be the same diameter as 26awg or near enough.
slowmatch is offline Find More Posts by slowmatch
Reply With Quote
Old Mar 01, 2016, 01:10 PM
Skylar is offline
Find More Posts by Skylar
我爱飞行 . . . I love flying
Skylar's Avatar
South Africa, GP, Pretoria
Joined Jul 2003
599 Posts
Quote:
Originally Posted by slowmatch View Post
I'm a bit limited by what wire I can get hold of at the moment. Currently buying short lengths on ebay! I can get 27swg which appears to be the same diameter as 26awg or near enough.
Jon

27SWG is 0.417mm dia. You should get 17 turns on each tooth. That should yield a Kv of about 1900. I say should, because a lot of other factors, like magnet strength and magnet size also determine Kv.

That's perfect for the APC 5.25x6.25E prop and you can expect about 145km/h pitch speed at 9A. You did say you wanted a racer, didn't you?

Btw, I wanted to correct you in your one post where you said you're after a high kv motor for a mini racer, but I didn't want to discourage you. Well, here is proof that high Kv is not always desirable for speed.

I have a 250km/h racer that has a motor with Kv of 1900 on 4S. You don't need high Kv for speed - just the correct motor/prop/voltage combination.

Skylar
Skylar is offline Find More Posts by Skylar
Reply With Quote
Old Mar 01, 2016, 01:29 PM
slowmatch is offline
Find More Posts by slowmatch
Registered User
slowmatch's Avatar
Joined Dec 2015
214 Posts
Skylar, thanks, that helps. I should have been clearer - was thinking to use 2S 800mah batteries I have here already. But thanks for the reminder, I will look at 3S
slowmatch is offline Find More Posts by slowmatch
Reply With Quote
Old Mar 01, 2016, 03:35 PM
Skylar is offline
Find More Posts by Skylar
我爱飞行 . . . I love flying
Skylar's Avatar
South Africa, GP, Pretoria
Joined Jul 2003
599 Posts
Jon, that will work too. The CD-ROM motor on that little Stick in the picture runs on 2S 460mAh. The motor is wound 10 turns 3 strands (3x) 0.4mm wire for a Kv of 3250.

For 2S you can probably do 8 turns of 2 strands 27SWG wire. The Kv will go up to about 4050. Just keep the prop size to 5" or slightly below and watch the heat. (All numbers are calculated, not guessed).

Skylar
Skylar is offline Find More Posts by Skylar
Reply With Quote
Old Mar 01, 2016, 04:51 PM
slowmatch is offline
Find More Posts by slowmatch
Registered User
slowmatch's Avatar
Joined Dec 2015
214 Posts
Ok thanks, that gives me a great starting point
slowmatch is offline Find More Posts by slowmatch
Reply With Quote
Old Mar 05, 2016, 08:12 AM
slowmatch is offline
Find More Posts by slowmatch
Registered User
slowmatch's Avatar
Joined Dec 2015
214 Posts
Hullo chaps,

I've been given another motor, this one is 18mm diameter and 8.6g with no wires. It looks like one of these discontinued motors from Robotbirds: http://robotbirds.com/catalog/produc...oducts_id=2191

But I have no documentation and there are no markings on the motor. It had 24 turns so I presume it is the lowest kv model at 2280kv or maybe 2500kv. I'm not sure which of the four it is.

Stator dimensions are 14mm diameter, 4mm thick and slots are 2mm long.

Unfortunately I don't have a micrometer but the wire is less than the 33swg I used on my 1811 10g rewind.

The stator is also glued into the base/motor mount and I reluctant to damage it by forcing it. I think its possible to rewind it as it but it will be fiddly.

Any thoughts on a starting point for rewinding? Modestly low kv would be good for a small scale model on 2S. But a practical number of turns is more important than ultimate efficiency on this one.


Thanks!
Jon

EDIT: Actually I think it may be the C18-15-17
slowmatch is offline Find More Posts by slowmatch
Last edited by slowmatch; Mar 05, 2016 at 09:29 AM.
Reply With Quote
Old Mar 05, 2016, 12:04 PM
Ron van Sommeren is offline
Find More Posts by Ron van Sommeren
homo ludens modellisticus
Ron van Sommeren's Avatar
Netherlands, GE, Nijmegen
Joined Feb 2001
13,599 Posts
9slots, 12 (or 6) magnetpoles
→ ABCABCABC

Too late to determine Kv, but next time, i.e. if motor is still ok
Several simple methods for determining Kv
www.bavaria-direct.co.za
→ motor constants

Now you can use the quick'n dirty wind method.
Sticky: (Re)winding and building motors, tips & tricks, checks & tests
→ opening post
→ #14 Calculating number of winds for desired new Kv

Prettig weekend Ron

Prettig weekend Ron
Ron van Sommeren is offline Find More Posts by Ron van Sommeren
Last edited by Ron van Sommeren; Mar 05, 2016 at 12:47 PM.
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Rewinding candidate motors for HP murdnunoc Electric Motor Design and Construction 18 Oct 20, 2015 06:06 PM
Discussion Suppo 1000kv motor rewind for gimbal? Scottychop Electric Motor Design and Construction 0 Aug 14, 2015 02:26 PM
Discussion Rewind multirotor motor: More thrust for less Power leonard3k Electric Motor Design and Construction 26 Jun 11, 2015 07:58 PM
Sold 3000kv blue wonder motor for rewind Free Johnnymeg Aircraft - Electric - Power Systems (FS/W) 1 Apr 08, 2014 05:12 PM
Discussion F450 motors and PHANTOM motors 100% identical? Biacman Multirotor Talk 0 Oct 27, 2013 04:21 PM