What type of bearings are used in high quality production machines?
I have a POS Powermatic PM 2700 5hp shaper that I bought new about 5-6 years ago and I need to replace the bearings for the second time. The first time I had a bearing seize, and Powermatic sent me a whole spindle assembly under warranty.
It seems like the lower bearing is in worse shape than the top bearing, probably because of the side loading the belt puts on the bearing.
I'm thinking about ordering a quill and shaft from Powermatic, and having a machine shop install high quality bearings on the shaft. The stock bearings from Powermatic are ball bearings, obviously of low quality. I'm thinking of asking the machine shop if they could use a high quality roller bearing on the bottom, and a roller thrust bearing on the top side. It seems like with the ball bearing, there just isn't enough support to make the assembly last.
It's not so much the type of bearings as it is the size. Your machine probably uses the same bearings the old 26/27's did? Fine for a lot of work, but not to be compared with the "high quality production machines".
For some perspective, this is the bearing from a larger Martin/SCM shaper….with the little guy sitting inside being the bearing from a Powermatic 27. The other pic is of the quill from a Powermatic next to a Martin. This is a large part of what makes a high quality production machine what it is.
Point being that there's no bearing that will make your light duty machine into a production machine. In my opinion your best bet is to replace the bearings and use the machine until you can find yourself a larger replacement. Oh and FWIW the bearings Powermatic used back then were of pretty good quality, not sure if they went cheaper on the newer 2700's though?
If you contact the people at Bearings Inc, they can get you a grade or three better than what you are replacing, as well as advise you on the better choices. They have outlets in most larger cities. They are very knowledgeable folks, but you better move fast as they are closing outlets all over the US with the internet underpricing them all. You may pay a couple of bucks more per unit, but you get solid knowledge and advise along with the part.
Jeff's point is clear - it ain't only bearings. I had a Powermatic shaper that had the quill's vertical movement in dovetailed ways. While the ways were adjustable, the whole thing had all the weight on one side, so the ways wore extremely fast, and they were almost impossible to lube. As a result, it was common for the guy that got stuck using it (instead of the preferred SCMI) to grab the spindle to see if it wobbled before he turned it on. If it was loose, then he'd go underneath and try to tighten the ways. The worst design ever for a shaper.
JeffD - You have a future in machine sales. Good machines, that is.
Well, got my machine apart yesterday and I wasn't too happy with what I found. Seems as though the shaft is undersized, or the bearings are oversized. It appears that the bearings are spinning on the shaft. Not happy. Looks like this machine will need a new quill assembly once a year.
Jeff is right on. The PM is a low priced Chinese machine. Generally you can find good SCM, SAC, Gomad, etc. shapers, used for little more than new PM. I've got all 3 of those brands and they are night and day different than the PM. (had a PM26) Time is $. Don't waste anymore on the PM, lesson learned?
Lesson learned, but unfortunately I'm stuck with what I've got. I picked up an OEM complete quill/spindle assembly on Monday, and dropped off the damaged assembly with the machinist. He's going to repair the damaged shaft, press on a stock sized ball bearing on the top. On the bottom of the shaft, a larger roller bearing will be installed. The bottom side of the quill will need to be machined to accommodate the larger bearing. The bottom will be getting a 40mm x 80 mm x 19mm roller bearing as opposed to the factory 40mm x 68mm x 15mm ball bearing. I'll post some pictures when I get it back.
I'm not sure the roller bearing is a good idea. Every quill assembly I've had apart uses ball bearings. The bearings are arranged so they can provide pre-load and keep the shaft from moving axially. Star washers, that provide an axial pre-load, allow the shaft to expand and contract when temperature changes occur. Tapered roller bearings could provide preload, but I've never seen them used on a woodworking spindle.
I'm not sure how much the lower bearing contributes to axial support with in the PM 2700 quill though. If you look at the picture I posted with the indicator in it, you can see the exposed lower bearing. Directly above the bearing is a wave washer, which I assume is to preload the upper bearing for axial loads.
Sounds like you may be too far along already, but I would re-think having a bunch of expensive machine work done on that one, and instead put that money aside towards a bigger machine. As long as you have the new quill assembly you should be able to get some decent life out of it, giving you some time to shop around for something a little beefier. Better than throwing good money after bad on a light duty machine anyway.
There's a lot of big shapers sitting out there with apparently very few buyers. Don't know where your located but there's a Delta R-15 shaper (that I think comes with the feeder too) near me the guy can't give away for $2k! Total buyers market these days….for shapers anyway.
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