I believe I finally solved the problem with the spindle on the PM833 running hot enough to almost burn your fingers while trying to change tools.
There are two problems that cause the spindle to run too hot:
- The stock oil seal can rub on face of the spindle bearing.
- The stock oil seal is too tight.
The stock oil seal size is 45 x 72 x 10. The solution is to replace the stock size with a 46 x 72 x 10 and remove the garter spring from this seal. Be sure to apply Isoflex bearing grease to the rubbing surfaces of the seal as well as the part of the spindle that make contact with the oil seal. This will result in an oil seal that makes light contact with the spindle and reduces heat buildup. Install this oil seal using the 3D printed “oil seal installer jig”. This will ensure that the oil seal is not fully seated and will not rub on the bearing face.
BUT… since this large diameter oil seal makes only light contact with the spindle, some contaminants could possibly pass through the seal since it is looser fitting than the OEM seal.
To solve this problem, put two garter springs on a 45 x 72 x 10 oil seal and install this seal in addition to the fist seal, but leave bout 1/16” space between the two seals. The second seal will fit tightly around the spindle and act as deflector to stop any particles from passing through it.
This seal will hug the spindle and spin freely. Do not apply grease to this oil seal and clean any contact point between this seal and the spindle with alcohol.
The first seal will make light contact with the spindle eliminating heat build up, the second seal acts as deflector to keep debris away. I have run this arrangement at 5000 rpm for extended perious and the spindle never gets hotter than about 85F.
Oil Seal Installer Jig:
STL: Dropbox
STEP: Dropbox
There is one additional bonus of using the jig to install the oil seal, since the oils seal is not fully seated, it can be removed easily with inexpensive wrench like this:
Amazon.com: WORKPRO Oil Filter Wrench Set, 9" & 12" Adjustable Oil Filter Pliers Oil Filter Removal Tools, Ideal for Engine Filters, Cars, and Trucks, 2-piece : Automotive
One final note. Another reason the spindle runs hot is if there is too much grease on the bottom spindle bearing. It is very important to use as little grease in the bottom bearing as possible. I used a syringe to put a tiny bit of grease between each roller. I then placed the roller section (cone) of the bearing in the outer race and used my finger to rotate the inner race with respect to the outer race for about 12 revolutions. I turned the bearing over to inspect and was amazed to find a bunch of grease expelled out the bottom. I used a small dental like tool to remove any excess. The result was an even coating on all the rollers etc. I believe there is enough grease, but not too much.