When to replace router bearings?

I have done a couple of the handhelds in the past. I am wondering if it is time to do my router table router. It is a PC 7518. I havent put a dial indicator on it, my main 'diagnostic' is listening to it, and in particular as it winds down after being shut off. When new bearings the routers wind down smoothly. After time, there is a speed range where it 'chatters' and makes a rough sound as it winds down. I understand resonate frequencies etc etc.

I always took this as an indication the bearing was going bad. But dont actually 'know' this.

Any insight from the gurus here? How do you know when a router bearing needs replacement?

(have the bearings sitting in a drawer for over a year... always keep a spare set)

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Originally Posted by Carl Beckett

I have done a couple of the handhelds in the past. I am wondering if it is time to do my router table router. It is a PC 7518. I havent put a dial indicator on it, my main 'diagnostic' is listening to it, and in particular as it winds down after being shut off. When new bearings the routers wind down smoothly. After time, there is a speed range where it 'chatters' and makes a rough sound as it winds down. I understand resonate frequencies etc etc.

I always took this as an indication the bearing was going bad. But dont actually 'know' this.

Any insight from the gurus here? How do you know when a router bearing needs replacement?

(have the bearings sitting in a drawer for over a year... always keep a spare set)

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Just spit balling, if there was a defect, worn spot, in the inner or outer race of the bearing wouldn't it make more noise during operation? Brian

Do not buy the replacement bearings too soon. While they sit on the shelf the grease is drying and separating. How long is too long? who knows. A few years is fine but decades may be to long.
If I buy a machine that is fifty years old I assume the bearings will fail soon due to grease failure. Of course modern grease is probably better and I always use sealed bearings while older machines used shielded ones who dry out sooner.
Bill D.

Getting parts for PC routers can be difficult and/or expensive since they quit.
At least the bearings look somewhat universal throughout the Stanley Black & Decker brands.

Carl if it were me I would change your bearings. The change in sound on wind down is one of the main ways that I use to determine if bearings need to be changed on machines or smaller power tools. Things like table saw arbors I check without power as well. With the saw unplugged I grab the arbor and lift it up/down or turn it by hand listening and feeling for a crunching sound.

Your suspicion about vibration during coast down is likely correct. I have read, more than once, that this is a reliable sign of wear in bearings. My 1880’s shaper did this slightly when I bought it third hand-a bearing replacement fixed that. (No discernible difference in the finished cut however)

I have the same PC router in a table. Bought new in 1997 if I remember right. As my hearing is almost totally shot (two hearing aids for the past 35 years) I don't hear any tools wind down. I usually put my hand on something close to the tool to feel vibration while its slowing down. And I haven't put new bearings in it yet (and have no idea if I need to). I have put new bearings in about 5-6 motors now in the 1/2 to 3 hp range. Never in a router though. Is it hard as they are small? Randy

I changed bearings on a Freud FT2000E, the one nearest the collet was noisy/gritty. It was no big trick, I just removed the brushes to make getting the rotating part in and out easier. The OEM bearing was shielded, I replaced it with a sealed bearing. I imagine being in a table results in more dust and chips falling on the bearing than would be the case if the router were used upright.

I recently opened up my 1617 because it started making a weird noise on spooling down. I pulled the brushes and I could still feel the roughness as I spun it by hand, so I assumed it was the bearings. A closer look at the brushes however revealed that one had a small chip and broke off a small corner of it. When I further disassembled the router and cleaned out both bearings (without removing them) that roughness I was feeling disappeared. After reassembly it went back to it's normal sounding self.

Point is that before assuming it's the bearings, it could be a small piece of a brush causing the noise. Much easier fix.

Note that brush type motor will not make any special noise on slowdown since it has no centrifugal switch to kick on. But the brushes will make a constant rubbing sound.
A good way to tell is to time the coasting time and compare it to the original time which you of course measured and wrote down after the bearings were broken in.
Bill D:D

You can get the bearings from NAPA auto parts and they are real easy to replace. The hard pat is getting the nut off. I used a 1/2ninch impact hammer to spin the nut off the nut comes off before the arbor spins

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Originally Posted by Bill Dufour

A good way to tell is to time the coasting time and compare it to the original time which you of course measured and wrote down after the bearings were broken in.
Bill D:D

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lol

this is great!

Sometimes cleaning and regreasing will save a bearing.

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Originally Posted by Tom Bender

Sometimes cleaning and regreasing will save a bearing.

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The bearings in a PC 7518 are sealed