Milwaukee router 5625 bearings replacement

--- >>> UPDATED <<< --- Still, might be worth to read...

About a week after I've changed the brushes, the router went zzzzzzzzzzzzzzzzzzzzzzzzz... I sort of knew this was going to be some time soon!

I've managed to take plenty of pictures while replacing the bearings but when they actually failed, I hurry myself at disassembly to make sure of what parts I may need other than the two bearings. It was a Friday afternoon and I had to get the order on it's way. I was wise to do so since the collet shank (sometime referred as the chuck) had its inside threads damaged. Long story short; when I rebuilt the motor I've took care to take pictures that depicted the disassembly stage but I may have missed something too obvious to me.

The bearing can be purchased at your local bearing supply or you can get them from MK service center.



Once you have the cover, the electronic feedback module and the brushes off (that part is covered in my previous post about the brushes service), you need to tap out the motor frame (black plastic) from the motor housing (aluminum). Then you reach for the field insulator inside to have only the housing with the armature assembly still attached by the collet shank. At this point, you're ready to remove the collet shank and then press the armature out of the lower bearing. As recommend in the MK 5625 service parts list, you should soften the locking compound with mild heat to aid the disassembly of the collet shank. No need to make the collet shank red! Just make it hot; that's a few seconds while turning the armature at the other end. Be ready with your tools which should be 3/8" allan hex key and 1-1/8" wrench. There's (if your a lucky one) an inside hex fit for the allan key at the end of the armature shaft. The MK 5625 service parts list have very worthy informations regarding your tool; you can get it on the MK web site.



When the collet shank is removed, you need to press the armature shaft out unless there was no locking compound and it slide off with a hand pull which wasn't my case.



After that's done, press the lower bearing out of the motor housing...



The upper (small) bearing can be pulled off with the appropriate puller or if you're like me and don't have all the tool you may need some day, you can press it out... remove the tachometer first by pulling it out with your hand only.



That's it!... for half the work!

The next step is to clean the armature shaft where the bearings fit along with the lower bearing seat on the motor housing.

You need to install the lower bearing in the motor housing first. The lower bearing only needed to be slide on in my case, both in the housing seat and on the armature shaft in my case; you may need to press them in. Make sure the armature and the collet shank threads are surgically clean (screw on the collet shank dry prior to be ready; it should be easy to turn until it reach the bearing) and put two drops of locking compound on the threads 180 deg. apart when ready to screw on the collet shank. I decide to put locking compound on the housing seat too because there's only two small screw to retain the bearing in the housing once assembled. Screw back the two lower bearing retaining screws with the contamination shield (black plastic grid).

The upper bearing have to pressed in. Put back the tachometer with the help of your fingers only.



Don't forget to drop the field insulator back inside the motor housing before placing the motor frame back on the housing. Help yourself to align the upper bearing with your fingers...



The rest is pretty easy since it's just placing back the remaining parts. Again, I strongly caution about over tightening anything, mostly where you'll screw in plastic. I do recommend to run the tool at low RPM for the first 15 minutes without any load to set the bearings. Check for any overheating and abnormal sound.

Check out the complete set of photos that I've placed on my public gallery at Google Picasa Web Album. There's pictures of exploded views of the main components which layout the parts pretty much as they go inside. My armature shaft thread were damaged and I show how I managed to "repair" them.

Keep in mind that this is not any kind of "official Milwaukee service" procedure. I'm not neither an engineer nor a qualified electrician but rather the "average do-it-yourself handy guy". I only wanted to share this easy (for me) procedure to service this Milwaukee router motor.

The bearings are fairly cheap but I can say that I've decided to install something different from what MK provided. The bearings that I got from MK are sealed which can do the job but I've chosen to get a shield type to keep it cooler under high RPM. If you decide to install something else as I did, bring the original, or make sure you can provide the specs, to your local bearing supplier and either know what you do or discuss with the technician what is the best to get for the application as there's probably many bearing that can fit in but may not work in the long run. In fact, the critical specification to be cautious about is the clearance; enough but not too much...

The whole procedure take around an hour the first time I did it.

Let me know if something doesn't seem right or doesn't make sense (leave a comment or use the Get in touch link in the Links section) and I'll make it up to your suggestions and recommendations.

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I plan to try to find the proper preload spring for the upper bearing so I can get rid of the free play from the lower bearing clearance... I'll post if I find it.