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Saturday, December 3, 2011

How to replace the bearings in a Porter Cable 7518 router

Our victim
If you're like me, you use your router a lot.  Unfortunately, most recently made routers are not of the quality that they once were, and sooner or later, there is a pretty good chance that your router is going to start making the creepy rattling noise as it runs that signals the death of one of the bearings guiding the spindle.  These bearings are not made as well as they once were, as evidenced by the failure in my PC 7518 Router.  Though I do have to admit that I've put it through some pretty heavy use.  So I knew that sooner or later, I would need to replace the bearings.  Unfortunately, it was somewhat sooner than later.
So this is how we do that.




Tools required:
#2 Phillips Head Screwdriver
1 1/8" Impact Socket
Impact Wrench
Allen Wrench
Bearing Puller**
Bearing Press**
Hammer

**These are not essential, but they sure help.  I managed without them, and at the end, I will talk about how I removed the bearings without any specialized equipment.  I do not recommend you do this if you have access to the proper tools.  My way isn't pretty, but it worked fine for me, but the proper tools make life a lot easier.


Nachi 6005ZZE Bearing
First, and most importantly, find a good quality new bearing.  This is a Class 3 bearing I purchased locally for around $10.  I have heard very good things about this bearing from several sources, so I am optimistic it will work well.  It is a Nachi 6005ZZE.  You'll notice that I am using a metal shielded bearing, as opposed to the neoprene or rubber shielded ones on it originally.  Having spoken with Nachi's rep, he assured me they are just as durable in a dirty environment, so we'll see how these hold up over time.



Dis-assembly proceeded as follows:

1. Remove screws.
1. Remove 4 screws holding top of plastic cowling.  Remove cowling.  This will expose the wiring to the brushes, the speed control and the on/off switch, as well as the rear bearing.  I recommend taking a picture at the wiring at this point, so that you have someone easy to reference when you are reassembling the wiring.  For ease of access (and because I hate fighting cords), I disconnected the power cord from the switch and set it aside.









2. Remove more screws.
2. Remove the 4 screws holding the brushes in place.  There will be 2 on each side.  Remove both brushes. I went ahead and pulled out the insulating sheets around the brushes so they wouldn't get dropped or lost.  They look like folded pieces of paper.  Do not lose these!  Having a small container (I reuse old yogurt containers) to hold your small parts when working on a project like this is absolutely invaluable.  At this point, check the condition of your brushes.  If they are worn low, replace them while they're out.  Mine were still in good shape, so I left them in place.




3. Remove even more screws.
3. Remove the 2 screws holding the cast retaining ring and top bearing in place.  Remove the set screw threaded into the top of the main shaft.  Removing the set screw allows the four flanges on the shaft to release their hold on the top bearing.  Carefully lift off the aluminum retainer and the bearing.  Check this bearing for signs of wear.  While this was out, I pressed out this bearing and installed a new one.  The failure of the top bearing had induced a little more play in this bearing than I was comfortable with. I had a spare on hand from another project, also made by Nachi, so I went ahead and used it.




4. Remove the rest of the screws.
4. Remove the 4 screws holding the plastic motor housing to the aluminum body.  The next step was one of the harder parts in disassembling the router.  I recommend taking a sharpie, at this point, and making a small hash mark across the joint of the metal and plastic to mark where they line back up.  Not terribly important, though.  Next, you will remove the plastic housing.  It will pull directly off, but a little twisting action helps to loosen it up.  It will be seated fairly well, just keep working at it until it comes free.  Set that aside, you will be working on just the metal section for a while.

You should now be left with just the motor body, with the main spindle still installed in it.
Whoops, more screws to remove.
5. At this point, remove the three screws holding the bearing retainer ring in place.  Remove the ring and set it aside.  A word of caution here that I will repeat later: Do not use this retainer ring to try to press in the bearing below it.  Seat the bearing, THEN install the retainer.  In that order.  The aluminum doesn't have the strength to force the bearing home, and you'll most likely snap one of the flanges on the side before making any real progress.







Your motor should look like this after removing the collet.
6.  Now is the time to break out the Impact Wrench.  I have a Kobalt that I picked up on clearance from Lowe's, and it works great.  Any type will work.  The important thing, as I discovered, is the sharp impacts which break loose the collet threads.  The reason being that we don't want to damage the armature (the part of the shaft that the brushes rub against, and the only real place to grip the shaft to remove the collet) so clamping it in a vise is out of the question.  Put on a heavy leather glove, grip the armature in your hand, place the impact wrench on the collet (should be 1 1/8"), and loosen the collet.  It should take just a couple of seconds to break loose, at most.  Unscrew it fully and set aside.  I was skeptical that this would work, having read about the trick elsewhere, but hardly any torque was applied to my hand and was very comfortable to do.  If you are worried about it, talk a friend into holding it for you instead.  (Kidding about the friend part.  Mostly.)

A couple of smart taps with a mallet will pop this loose.
7.  Once the collet is removed, it is time to remove the armature (the main spindle).  Stand the router motor up so that the collet end is on top, and the armature and shaft is hanging free underneath.  For me, I stood the body on a pair of 2x4s that were on edge, that gave me about an inch of clearance below the armature.  Take a small block of hardwood, place it on the shaft where you just removed the collet from.  Grap the armature to hold it (it will fall out if you don't) and sharply rap the hardwood with a mallet or hammer.  The armature should pop free.  It make take a couple of blows.  Make sure your strikes are square, and not too hard.  We want to remove it, not break it.  The hardwood will protect the metal from being marred by the hammer you are using.  Alternatively, you can use a wooden mallet, but I'd rather not mar the face of a mallet by beating on a piece of steel.  Your call.

Old bearing, next to the new Nachi replacement.
8.  The next step is to remove the bearing.  Using a bearing puller, or the method I talk about at the end, remove the bearing from the motor housing and set aside.  This is what this entire process was meant to replace.  You can see how dirty and worn my old one was.  It was definitely time to replace it.  Most of the lubricant was long gone, it really was kind of a sorry sight to see.

At this point, you should be left with a completely disassembled router.  Switch out the bearing, and begin the reassembly process.  The most important thing to note, as you are going through this process, is to fully seat the bearing, and make sure it stays there while you are installing subsequent parts.  You can follow this dis-assembly guide in reverse order and should meet with success.

Motor disassembled.
You may notice that most of the pictures show the new bearing in place, rather than the old.  I started taking pictures after I was done disassembling the motor, as I realized there may be other people like me that had the same troubles, and decided to write this tutorial.  Here's a picture of the old bearing, with the rubber seal removed, to show how dirty and worn the bearings were.
Wood dust will eventually work its way into anything.

Cheap bearing puller:
 So you don't have a bearing puller at home?  Don't worry, you aren't alone, and it certainly doesn't mean you can't do this yourself.  A bolt with an appropriately sized washer will do the trick just as well.  Here's what I did.

Tools:
(2) Ratchets, with extenders
Bolt (4+" long helps)
2 Washers-OD (Outside Diameter) just larger than the ID (Inside Diameter) of the bearing.
2 Nuts-To fit the bolt.

Tighten in the direction of red, bearing travels along yellow.
Setup as in the picture above.  I mocked this up to give a better idea of how I did this.  The gray represents the body of the router, cut away to show the bearing.  The first blocks below that are spacers, followed by a solid block with a hole drilled through it for the bolt to pass through.  Thread the bolt through, with the washer on top of the bearing, and outside the bottom block.  Tighten the nut down while holding the bolt stationary (so it doesn't just spin).  As you tighten, it should pull the bearing in the direction of the yellow arrows, out of the body.  If you reverse the process, and put the block on the opposite side, you can pull the new bearing into the motor and seat it that way, but this can put some undue stress on the inner ring of the bearing.  A better option is to use your drill press, if you have one.  Remove your drill chuck, put a wood spacer over the bearing, and press the bearing into position.  Use the old bearing as a spacer if necessary to fully seat the new bearing.  It should end up recessed into the body about 1/16". 


Good luck!  I hope this saves you a trip to the tool repair shop and a few dollars in the process.  This basic process applies to most routers, and may be particularly useful on some of the more inexpensive routers that chew through their bearings a little more quickly.  You can refurbish an old router pretty easily if you have the right attitude.


9 comments:

  1. Is the collet reverse threaded? Or is it rightie tightie, lefty loosey? I have arrived at this point and I can't get the collet loosened. Any advice appreciated. Can the shaft be held by a bolt in the head where the set screw goes and a wrench applied to the Collet? After your mirth subsides, reply to talchess@gmail.com. thx

    ReplyDelete
  2. The best bearings would still be the metal ones. Tested and proven to give the best results. white metal bearings

    ReplyDelete
  3. Regardless of the materials, all bearing needs care to insure the proper working of the machine.
    white metal bearings

    ReplyDelete
  4. Thanks so much for this article. I'm struggling with dismantling my router now and needed your insights. Much appreciated.

    ReplyDelete
  5. Thanks Eric. Your step by step article was just what I needed. I've sent the routers in for repair in the past and spent $75 plus shipping and waiting. This is only going to cost me bearings for about $30.

    Kevin

    ReplyDelete
  6. Thanks for info. Very helpful for disassembling my 7815. The top bearing on mine was a loose fit -- the original used bearing retainer compound. So I found some small 2.6ml bottles of the green stuff online (Quebec!) for about CAD$9 delivered.

    Cheers

    ReplyDelete
  7. Whoops.. 7518 router, not 7815!

    ReplyDelete
  8. Great post! I really appreciate this information. I can't stop to comments on this imperative blog post. Wish you best of luck for all your best effort.


    Find the Cable Puller

    ReplyDelete
  9. Great post! I really appreciate this information. I can't stop to comments on this imperative blog post. Wish you best of luck for all your best effort.


    Find the Cable Puller

    ReplyDelete