I recently purchased an APS 63100 outrunner motor (https://alienpowersystem.com/shop/brushless-motors/63mm/aps-63100-outrunner-brushless-motor-140kv-4500w/) to subsequently transform it into a fully waterproof motor. The aim is to get the highest possible torque than an equivalent inrunner motor.
However, at the very beginning it was necessary to completely disassemble the motor, and immediately the first problem arose - it was not possible to loosen the grub screws (M4 x 10mm) in order to extend the shaft (10,00mm). I even broke a good quality Allen key on the first attempt, I was unhappy about it. I was beginning to accept that I would have to drill out the grub screws, then create a new thread for a larger screw (M5 or M6) etc etc.
After much thought, I finally decided that the glue that the bolt is glued with must be reliably loosened by the elevated temperature. After all, the heat will also expand the surrounding aluminium, which will significantly help loosen the bolt, as the thermal expansion of aluminium is about 50% greater than steel. So heating the rotor face to 70 to 80 °C should be sufficient (most plastics start to soften at this temperature), and it is very easy to cool the neodymium magnets to avoid reducing magnetisation. And this technology proved to be the right and best solution in the end, in 5 minutes the screw was loosened.
Now the technology itself:
- You will need to do this
- cotton cloths (oalso two hair elastics used by women)
- a good quality workshop vice
- two aluminium flanges for the vise (to prevent damage to the shaft surface)
- very cold water
- a very good quality Allen key (possibly with extension lever, arm, etc.)
- Preparing the motor rotor
- soak both cotton cloths in cold water
- place one wet cotton cloth inside the rotor to sufficiently cool the magnets (but not the inner surface of the rotor face)
- wrap the second wet cotton cloth around the entire outer surface of the rotor face (and secure with hair elastics)
- place the aluminium flanges on the jaws of the vise
- clamp the rotor shaft firmly in the vise (between the aluminium flanges)
(Note: In both photos you can see a round aluminum washer, this should only be used if the rotor face is straight to the edge, like the motor face from tacktun https://foil.zone/uploads/default/optimized/3X/3/5/355dda5f5ba882eefe5e1f864aa2354218aaa95e_2_562x750.jpeg The aluminum washer thus transfers heat only at the position of the grub screws and the shaft. The aluminum washer can be replaced with a copper washer, which conducts heat better, but is more expensive or difficult to buy. …hope you understand what I mean)
You set the iron on the highest power (without water of course), after it has heated up, you carefully place it on the center of the rotor face.
Once the rotor face is heated to the desired temperature (you have to guess, you may have to find out just by wetting your finger, repeatedly) quickly remove the iron and loosen the screw with an Allen key.
This procedure (according to points 2 and 3) will probably have to be repeated several times, because the heated rotor face cools down very quickly!
A similar procedure can be followed when extending the shaft, replacing bearings, etc.
It is advisable to have a helper on hand when working. Just estimate the flange temperature with a wet finger. However, there is a risk of damaging or stripping the magnets if the temperature is exceeded. The shaft can be protected from corrosion by a thin layer of grease to prevent it from corroding (from wet canvas). Similarly, it is necessary to protect the surface of the workshop vise to prevent it from corroding (from wet canvas).