Porter-Cable Router W/Bad Bearing
Sequim Tool
| Posted in Power Tools and Machinery on
I have a PC 7539 in my router table It’s the big 3 1/4 plunge router. Two weeks ago as I shut it off and it came to a stop the bearing let out a howling sound. I unplugged it and turned it over by hand. The bearing was bad. I disassembled the router, called the PC Service Center and order new bearings.
The bearing was a 6005LU made by NTN. This bearing has a max speed of about 18000 RPM. The LU part of the bearing # is the type of seals it has and LU seals are good to 9500 RPM. Not good
I got the new parts from PC, the replacement bearing was a 6005DWA1 by NSK If you look it up you will find it’s same as the NTN it’s seals have a max speed of 9500 RPM. Still not good.
The Porter Cable 7539 top speed is 21000 RPM
Edited 1/8/2007 6:40 pm ET by Sequim Tool
Replies
The limitation of the speed is based on the grease used, not the seals. The rating is based on continuous operation under normal loads. The bearing for this application must be sealed because intrusion of wood dust would result in premature failure of the bearing. It is also sealed to hold in the grease.
Therefore, although the router may run at higher speeds, it doesn't run continuously and probably not under the normal loading conditions (or not for very long.) I'm not familiar with the first bearing you mentioned, but NSK is a highly respected, high quality brand and should last quite a long time.
The max speed for the bearing was 15000 RPM running with grease, 18000 in oil with a service factor of .75 so the max speed for the bearing balls and race is 11250 RPM but still the seal was only good to 9500 RPM when it went the dust got in. The bearing is 25mm X 47mm X 12mm it's just to big to go 21000 RPM in any oil or grease.
I use the same router in my table. Do you use an auxilliary lift?.
I use a bearing lubricant out of Lee Valley, it work well, and will even pick up a bearing that is starting to growl, but not gone yet. Loot s of hours on that router, and so far so good.
No lift kit just a knob. I have to reach under the table. It takes three hands. I have the router back working with the new bearings. One thing about Porter Cable you get good service if you need parts and on-line parts list too.
I like your knob, did you take a spring out of the handle? I took one out to make it easier to lift . Do you lock the break open? I like the router but it isn't the one for a table, to hard to setup.
The spring are still in, I do lock the clamp. The router in the table is my 1 1/2 HP porter cable and it very hard to set, I think I will make a lift kit for it. I just fixed the 3 1/4 PC and had not put in back in the table. I have no heat in my shop and to day it got up to 42 in side as we had 6" of snow.
I think I will buy one of those new Triton router that was reviewed in ffw, and have one in he table and one out. The PC is nice but not in a table.
I got the 3 1/4 PC router for my table 18 years ago but it only had about 10 hours running time when the bearing went bad. I just got the PC 690 router with the multi base kit. I have always liked PC tool. I bought my first PC 1/4" drill motor 48 years ago. But after this bearing thing it may be the last PC.
Sequim,
The disparity you mention seems to be a fact of life.I have changed bearings in my Elu routers several times and noted that the upper speeds are in excess of the stated max rpms for the bearing sizes fitted. I use the SKF bearing manufacturer's hand book in which max speeds are stated for bearings running in grease and bearings that are oiled.
I don't abuse my machines, (eg indiscriminate air blasting) but am resigned to the fact that bearings on routers in particular fail relatively often. At least they are cheap. And I like preventative maintenance.
As an aside, I see that SKF also does a range of bearings "for precision applications" which have higher rpm tolerances-but I am sure these are much more costly .
Thanks Phil I like your work, I too have made afew planes and chisels. I worked in a shipyard and made tools for the shipwrights. Big slicks, chisels, planes and blades.
That is a very nice looking plane and your attention to detail is not lost on me:in particular the way you have (spent lots of time on handwork) shaped the cap. I think you should make more ....Let us see pictures of your shop-what metal working machines do you have?Philip Marcou
In the shipyard I had everything a complete machine shop. Now retired I have a 9" south bend lathe I use for woodworking tooling and a very small mill, all very old. Till I get a new shop built I working in the garage.
Do you single point all your brass parts. I made up form cutters and plunged all the parts but it takes a lot of HP. My 9" is to small plunging.
Ball bearing steel is grade 52100. old bearing are good for making chisel and plane blades. in the shipyard I'd take big old bearing cut them up and make tool for the shipwrights and me.
That is most interesting to me, as I also have a 9" model A South Bend. I also have an Emco Super11 with milling machine combination.
I have been thinking of form tooling for some applications- the Emco probably can cope with smaller stuff, but I keep procrastinating.So at this stage it is all single point, and batching where possible. Often do one thing on Emco and the next process goes to the South Bend, to reduce fiddling and re-setting....
I am aware of bearing steel. In Zimbabwe I had a friend whose father was a big shot on the railways-he supplied me with forged bar stock for knife-making, produced from what must have been huge roller or ball bearing rings.I brought none of it here, regrettably, as I now have a Browne & Sharpe surface grinder which would make short work of smoothing those bars.(But I have lots of good D2 bar stock)Philip Marcou
Your lathes may be to small. Find an old turret lathe they are very cheap.
I grind a form cutter and use it to make lots things with the same kind of detail.
I run the at the slowest speed, flood with coolant and plunge in. I grind most form cutters with on rake just flat on top
See the cutter I made the plane knobs with made the base for the 1/2 shot glass.
The door pull knob I used two 1/2" cutters.
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