Why Do We Love the Little Red Motor? (Emax CF2812)

by jetpackninja | November 13, 2013 | (15) Posted in Tips

Why Do We Love the Little Red Motor (Emax CF2812)?

There are plenty of decent motors in the 370 class. As I browse the forums (mostly the CrashTestHobby forums on RC Groups) I think it's funny to observe the love/hate relationship that people have with this little motor. The purpose of this article is to give some info on why CrashTestHobby recommends this motor for all of their small wings and small and midsize trainers.  I've seen posts that claim the little red motor is a decent six dollar motor, but a crappy ten dollar motor. I really wonder where these comments come from. In my experience these motors work great across a wide variety of applications.

Price point
At the time of this writing, these motors can be had for six bucks and some change. A lot of new flyers will try to get into the hobby as cheaply as possible. At around six dollars these guys are almost disposable. This is probably one of the main reasons these motors are our favorite for our combat planes. 

Availabilty
Hobbyking sells this motor as the fc 28-12 and it's available in the US warehouse. If you are in the states and don't like ordering from across the ocean, it can also be had from many suppliers in the US. Prices vary, they can be found on ebay, PlaneInsaneRC, HeadsUpRC and Value Hobby just to name a few. 

Weaknesses
There are some gotchas with this motor. Once you are aware of it's shortcomings and take a little time and effort to work around them you can have a motor that will work great and last a long time.

  • Mounting plate- the base of the motor is held into the mounting plate by two little grub screws. These motors are often delivered with the screws loose. Blue locktite is your friend here. Pull the two little grub screws, a generous drop of locktite in each hole. Put the screws back in tight, but careful not to overtighten. If you lose one (or both) of the screws you can replace them easily with a 3mm socket head screw. Be careful not to overtighten, it is possible to crank down on the screws so hard that the bearing gets squished.
  • Bearings- the bearings are cheap, they can be replaced if needed. A drop of bearing oil on the front and rear bearing every now and then and they will last for a long time.
  • Thin motor leads- the wires that exit the windings are very thin and are also fragile. The first thing to do to prevent them from breaking is to make sure the motor is mounted securely (see above). What we see very often is that the motor will try to spin in the mount causing stress in the wires. Another thing that can help with this is stress relief. I like to wrap a very small zip tie around where the leads exit the windings, I also like to secure the leads to the plane either with hot glue (or goop) or another small zip tie.
  • Naked motor leads- Most places that sell the little red motor don't supply or put on the little 3.5mm bullet connectors that we all know and love. You are going to need to source them from the web or your local hobby shop. Soldering them is a little bit more difficult but still easily accomplished. If you want to try a different option you could check out the CrashTestHobby site and use a modified Deans mini connctor like Lee does. 

Rewinding and experimentation
This is where this little motor really shines and truly shows it's value. The design of this motor makes it really easy to rewind. I know of people who will actually take a brand new motor, strip the windings and then rewind them. This is one of the few places in this hobby where you get something for almost nothing. A little time and the right wire and you can take a burned out motor and end up with one that works better and is more reliable. I have one motor that has been rewound several times before I figured out the right kind of wire to use. I gave up on the cheap wire from radio shack and use only wire that has a high (200c) temperature rating. It looks like the sweet spot for this motor is nine turns of 23 or 24 gauge wire. I've seen other winds succeed and work well with this motor. Experiment and have fun.
Check out this thread on RC Groups if you are intested:
http://www.rcgroups.com/forums/showthread.php?t=1456812 

I've seen these motors work well on so many different planes. Just some that I know of off the top of my head... Brushless conversion Hobbyzone Supercub. Scythe and Assassin Combat plane. Roswell foam delta. Coroplast and dollar tree F22 planes. CTH Pelican and Albatross trainers.

Address the items in the weaknesses section and for about six bucks you've got what I think is a great motor. It works well across a wide variety of planes and for pilots with a broad range of skill levels. Please also feel free to comment. I'm sure there are other great motors out there, maybe I just haven't found the one that I like better- yet. 

Rewound sporting a zip tie

 

Chopped shaft, riding pusher on an F22. I usually don't shorten the shaft anymore unless it's going on a front mounted setup

 

Coroplast F22 with a happy little red motor

 

COMMENTS

earthsciteach on November 13, 2013
Ninja,
Good article on the motor that I have purchased more of than any other. Toss in the 2822's (same motor, but I think terminated differently) and you have two motors that fly SO many planes. My tricopter was powered by the 2822's and they worked brilliantly.

David W. suggested epoxying the motor leads. This really extends the life of one of these motors, particularly under harsh conditions, such as combat, and the inevitable shenanigans that happen when flying with knuckle headed friends.

I wonder how many of these motors I have downstairs that I could rewind...
Log In to reply
jetpackninja on November 13, 2013
Agreed. Proper stress relief of some kind really goes a long way to help these guys last longer. I think I accomplish what David is talking about with the little zip ties. Lee from CrashTestHobby wants to do an instructional vid for his website. If we ever get around to doing one of those, I'll probably do a write up specifically for the rewind process. Take a look downstairs and see what you have. Too bad we don't live closer, we could take a weekend and have a rewind party :cool:
Log In to reply
Royall on November 15, 2013
As a new RC hobbyist, It would be a nice thing to see how rewinding a motor is done. Does Flitetest have any tutorials on this? Mahalo nui loa!
Log In to reply
jetpackninja on November 17, 2013
Royall- Not sure but I hope to get and article put together soon but it will be pretty specific to these little red motors. For now this link is the closest thing I have.
http://www.rcgroups.com/forums/showthread.php?t=1456812
There's also a Flitetest thread but it's also pretty specific and not as active.
http://forum.flitetest.com/showthread.php?713-Rewind-HobbyKing-cf2812-motor
Take a look around RC Groups, there are some pretty informative threads over there and some spreadsheets and stuff if you want to get into rewinding. The little red motors are a good place to start, they make it easy for ya
Log In to reply
sailorJohn on November 13, 2013
I find I bend more shafts than anything and the mounts are not durable. I found a lamp socket base that I made do with, but the set screw binds the bearing. Alternative mounts have been pretty pricey, depending on what you need .But it would be possible to make one.
Log In to reply
jetpackninja on November 13, 2013
I've bent a couple of shafts myself (I bet there is a joke there somewhere). But have also had good luck replacing them. With the front mounted motors, I have also sometimes cut the shaft and mounted the prop saver right against the bell. With the pushers I just leave the shaft full length and haven't managed to bend one (yet).
Can you post a link to the lamp socket? I might wanna give that a shot :)
Log In to reply
sailorJohn on November 14, 2013
small drawers in LOWES lamp parts section.
Log In to reply
jetpackninja on November 14, 2013
Cool- I'll check 'em out :)
Log In to reply
gsgraber92 on November 13, 2013
I love these little motors for all the reasons you mentioned above. They are cheap, powerful and versatile. I have them on all my Swappables, a foamboard F22, and a D.W. Tricopter 2.6. I think they spin up nicely. I use them with the Skywalker 20A Esc. I am in the Midwest so I usually get mine at ValueHobby and get them in two days. Thanks for the article, good stuff!
Log In to reply
jetpackninja on November 13, 2013
Never had any kind of problem with ValueHobby. They get stuff to Utah in a couple of days as well. Never had to talk with them on the phone but they must be good people ;) I also like the Power HD 1711mg servos that I get from them. I use them as a drop in replacement for the hitec hs82mg...
Log In to reply
SteveRoby on November 14, 2013
Bending shafts ????
These have the strongest shafts of any small motor Ive tried. Very strong compared the the butter shafts of many Hobbyking motors. VERY Strong but not unbendable.
Ive have a stack of motors with bent shafts, heaps of bent orange HKing motors, only 1 bent red motor.

Terrible bearings, the way the motor attaches to the mounting plate isnt the best. But overall a great motor for the price. Ive just bought 6 more.
Log In to reply
jetpackninja on November 14, 2013
Yeah- the only shaft I managed to bend was on a front mounted motor on one of my trainers. I had the prop saver way out on the end of the shaft and clipped a telephone wire. I haven't found the shafts to be any weaker than any other motors of this size with a 3mm shaft. I added a pic to show how I set them up now on the front mounted setups.
Log In to reply
ranwell on November 14, 2013
Great little motors, new shafts & bearings are cheap as. I get shafts from Giant Shark, around 35 cents each plus postage when they are in stock as they go pretty quick & bearings on ebay for around 50 cents each.
http://www.giantshark.co.uk/product/169645/spare-shaft-for-emax-cf2812-22-3mm

Log In to reply
cholfeltz on November 14, 2013
Love these motors, and Mt Timpanogos in the background! I see your from Utah flying in Utah county. Nicely done. I need to get down there and fly with you guys! (I'm up north in Murray) I was actually just saving this link so could practice re-winding some of my motors, good tips on this!
Log In to reply
jetpackninja on November 14, 2013
Have you manged to make it to one our sWARm events? If not, you definitely want to get that onto your calendar. Our sod farm reportedly has been sold but I'm pretty sure we are still going to be there for the spring sWARm, Check us out on our Utah County flying thread on RC Groups, drop in a say hi. We keep track of where we are flying and lots of other stuff in that thread. We will probably be at the Sod Farm until the ground gets soggy and then mostly be a Art Dye park in AF.

http://www.rcgroups.com/forums/showthread.php?t=1335791&page=501#post26620159
Log In to reply
Foam Addict on November 14, 2013
Thanks Ninja, I've been looking for something like this for ages!
Now I can rewind those 28-12s I have laying around!
Log In to reply
colorex on November 14, 2013
Hey JPN, I've been looking to use the HK FC2822 version of these on a hexacopter, could you tell me anything about them for this specific field?
How well are they balanced? Do they have bearing issues often? Do they dislike dust?
Log In to reply
jetpackninja on November 14, 2013
The bearings usually aren't a problem unless the motor mount gets screwed down too tight. The bearings are low quality but work fine, a drop of oil every now and then takes care of that issue. I've heard some folks complain of balance issues but I haven't noticed any problem. As for dust I don't think it's a huge issue (any more than with any other motor). Mine all get abused pretty regularly (COMBAT) and it's not unusual for one of my trainers to bury itself in the dirt, I just knock the dirt off and keep going.
Log In to reply
colorex on November 14, 2013
Thanks for the reply! Hopefully I will get my order placed soon and I'll also get some spares, just in case. But the truth is if you buy two spares, three motors break.
Log In to reply
Jtbluefeather on November 14, 2013
I just got into the hobby and when I started I bought about six motors of different kinds including this one. It's my favorite go to for the Swappables, and I just got a few more for a tri-copter build. They are also great for my kids planes, almost disposable is right. Now that I know they can be rewound, I'll have to try that when they break! Thanks for this article.
Log In to reply
sneaky on May 7, 2014
I use this motor and its big brother on a few swappables. It works great. But on planes like the baby blender that tend to nose over on landing, the motor quickly gets loose in the mount. I always use locktite on the two mount set screws. Any advice on how to keep the motor from loosening?
Log In to reply
jetpackninja on May 22, 2014
Lots of blue lockite :)
On the motor mounts I usually replace the little grub screw with a hex head cap screw.
I get them from home depot in the hard to find cabinets, it's the smallest size metric screw they carry. Scroll up to the close up pic and you'll see the screw on the f22s' motor
Log In to reply
Neskair on January 16, 2016
Thanks! Nice article.
Log In to reply
jetpackninja on December 18, 2017
this article is getting a little old ;)
I have since found a couple of other motors that seem to work as well as this guy but we still use these almost exclusively on the Assassin and other similar sized planes.
They are just too good of a motor for the price to pass up and once acquainted to it's shortcomings they are pretty amazing.
Log In to reply

You need to log-in to comment on articles.


Why Do We Love the Little Red Motor? (Emax CF2812)