When your car or plane is using brushless motors, it’s not uncommon to see one fling a magnet as a result of the abuse.
We’ll show you how to quickly and easily fix it so you can get back on the road or in the air. A new motor may be an option, but it may be more convenient to fix the one you already have. Brushless motors come in many varieties, and I’ve found that some are better than others. While some are overpriced, others may be downright awful. The middle of the road is the best place to be if you’re like me.. Learning how to fix a common problem, such as a loose magnet, is a valuable skill that few of us have access to. My preference is for NTM or SK3 motors, rather than gold-plated and ridiculously overpriced motors. For the most part, the NTM and SK3 motors I’ve owned have proven to be solid performers. My older motor recently decided to throw its magnet, which can happen for a variety of reasons;
Due to the high temperature, the glue in your motor has begun to weaken and the magnet has begun to detach from the rotor.
Over time, glue breaks down, leaving a deboned magnet behind.
Shock in the form of a fall or a collision
Turnigy Propdrive’s later versions of NTM motors are bulletproof and have better performance, finish, and fittings than the first generation, which had a reputation for tossing magnets. Even if you accidentally drop a magnet, it’s simple to fix, so you should at least try. Otherwise, you’re wasting your hard-earned cash. If you’re a hobbyist, you probably already have the materials you need at home. We’ll use an NTM 50-50 motor as an example, but the procedure is universal and can be used on any size outrunner motor.
- Devices That You Must Have
- Solvent for thinning paint
- An empty glass jar with a lid on it (Big enough to fit the bell)
- A can of lacquer to be sprayed (Type is irrelevant)
- CA glue, thin (Cyanoacrylate)
- Super Glue CA by HobbyKing (50g / 1.7 oz) Baking Soda that’s Extra Thin
The first step in disassembling the motor is to remove the c-clip from the back of it and then split it in half. Set aside the stator and other loose parts in a small plastic tub for safekeeping. Fill the jar with thinners until the rotor is fully submerged, then place it in the jar. Thinners will begin to break down the remaining glue, making it easier to remove the magnets. It’s fine to leave the rotor in the thinners for 24 hours or more. The epoxy and paint on the rotor will be dissolved or softened as a result. Flat-head screwdrivers can be used to gently pry the magnets loose. Magnets are extremely delicate and can be damaged by even the tiniest of impacts. Allowing magnets to come into contact with one another can lead to broken magnets, which can render your repair pointless. Alternating north and south pole magnets are inserted into the casing one after the other. Magnets should be marked on the backside to ensure they are installed correctly and without error. When all the magnets are in place, all you have to do is use a red or black marker to mark the front and back surfaces.
Remove any remaining paint or glue from the rotor and thoroughly clean the surface. Using sandpaper for the final clean-up creates a rough surface on which the adhesive can adhere. Sanding will remove any lubricants or other substances that could interfere with a strong bond, as will the earlier procedure. Once the paint has been removed from the bell’s exterior, coat it with lacquer. Without protection, the steel bell will rust. If the surface is not shielded from moisture and fingerprints, tarnishing will occur quickly. Spraying the inside is unnecessary, as it will be glued in a matter of minutes. To begin, select one of the magnets and slide it into place. The magnets should be aligned at the correct angle using the shaft. The grooves on NTM rotors help to align the magnets. The remaining poles can be installed after the first one has been completed. After double-checking alignment, carefully apply a few drops of thin CA between the gaps to secure them. If you want the glue to go into the magnets, you’ll want to use a thin CA adhesive. In order to further secure the magnets, we’ll need to apply thin CA to all of them and allow it to cure before applying a thicker glue to fill in the gaps between them. Baking soda can be used to fill in the rotor’s magnet void. Only about three-quarters of the baking soda should be used. Apply thin CA to the baking soda in the gap once the desired height has been reached. The combination of baking soda and CA glue creates an extremely strong bond that can be used in a wide range of applications. Baking soda transforms CA, which is typically brittle, into a product with a wide range of uses. You should tackle each gap sequentially. Here’s a tip… The rotor is kept stable and from rolling around by two strips of blue-tac on either side of it. Reattach the rotor to the motor and test its freedom of rotation. The rotor should be removed if it won’t spin freely, and the offending CA and baking soda should be ground off. Reassemble the motor and take it for a spin once the rotor is spinning freely. Motor repair isn’t difficult, so you should give it a shot. Keep an eye out for someone at the field who wants to throw a ball. To give it back to him, or use it for practice, you could repair it. An extremely strong bond is formed between the baking soda and CA glue.
