Old Delta/Rockwell bandsaw - bearing lubrication?


I picked up an old Delta/Rockwell 10" bandsaw a while ago (model 28-113) for peanuts - I don't think this model was ever considered particularly good (it's got the plastic wheels), but it'd be OK for the kind of stuff I'd use it for.
Anyway, the bronze driveshaft bearings were completely shot - but when I pulled them out so I could replace them, I found that the one on the drive pulley side completely blocks the grease fitting pathway!
It seems impossible that it was always like that; there's a cavity within the saw's cast frame which still had some grease in it (albeit not much). So I assume that the bearings have been replaced at some point in the saw's life; did the original (on the grease fitting side) maybe have a notch to allow grease in? Or perhaps a hole, and grease could flow between the bearing and driveshaft into the cavity (but this seems unlikely as the clearance between bearing and driveshaft is so small)?
Another possibility is that according to the parts break-down (e.g. http://www.toolpartsdirect.com/cgi-bin/schematic.cgi/rockwell/28-113 ), replacement bearings were supplied over-size and the frame would have to be reamed to get them to fit - in which case was there perhaps originally a channel in the frame between the grease fitting and internal cavity, and reaming took this out (and whoever did the work didn't cut a new one)?
The bearings which were fitted were 10/16" ID and 13/16" OD (and 12/16" OD seems much easier to obtain, again perhaps suggesting that the saw has over-size replacements), and I've got some new ones to put in - but in order to fix the lube problem properly it would be useful to know what the original setup would have been.
cheers
Jules
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#64. To be of any use 63 would have both an external groove and a bore to allow oil or grease to pass into the bearing. This groove to align with the hole into which the oiler fits. Internally the bearing would probably (damn, late at night, lost worms) have a spiral channel to distribute lubricant to the shaft. You say above 'driveshaft bearings' but the drawing shows only one bearing. I wonder if at some time in the past the original bearing has been replaced by two sleeves; which could allow a space in between for lubricant dispersal but in this instance has been poorly manufactured/fitted? Too long a sentence but I hope you'll get my drift. Looking at the drawing, the oiler seems to be set at an angle. I reckon someone has fitted new sleeves to this at some some and has blocked the oiler pathway. Could the frame be modified to take sealed bearings? Just my 2d's
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On Tue, 15 Oct 2013 01:35:59 +0100, Nick wrote:

Hmm, there would have to be *something* supporting the shaft at the wheel end, though; the shaft runs around 3" through the frame, so a single bearing at the opposite end to the wheel (which is under stress from blade tension) wouldn't last long. I did find a couple of diagrams for other Rockwell/Delta saws of the same era, which seem to show the same shaft, and use two bearings (both with the same p/n as the one listed for my saw). I think they just managed to miss it off the diagram for the saw that I have.

Yes, that's what I'm thinking - it does say on the diagram that replacements are supplied over-size and the frame has to be reamed for them to fit; I expect someone just didn't take into account the need to also cut a new path for the lube.
Whether there were internal spiral grooves or anything on the originals, I don't know - although the couple of photos of the same part that I've found online don't seem to show any (and it seems unlikely that Delta/ Rockwell would expect someone to machine those themselves - although I suppose they did expect them to ream out the frame!). For now, I've cut a channel between the grease fitting and the internal chamber, and I'll see how that goes (it won't be much work to dismantle and check for wear after x hours of use)

See my reply to the other guy; there isn't enough material in the frame, although external bearings with a carrier might be technically possible (but just not worth the effort in a saw of this class).
cheers
Jules
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On 10/11/2013 6:29 PM, Jules Richardson wrote: ...

I think it's the latter; that you're supposed to drill the hole before installation. The point of the cap on the "oiler" if it's as the one I've seen that's a set screw is that you put some grease in there and then the screw forces it down into the area and then the shaft rotation carries some into the annular space. One should, of course, coat the interior fully before inserting the shaft.
That's if the bushing is solid bronze; alternatively, if the bushings supplied are sintered they use oil instead of grease and it's supposed to work it's way thru the pores.
Unfortunately, as the other poster suggests there likely isn't sufficient material to support any sealed bearing which would be the cat's meow if so...
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On Mon, 14 Oct 2013 20:08:14 -0500, dpb wrote:

These are oil-impregnated bronze, but I don't think that they're porous - the oil just helps them to last longer, but they still need greasing. Searching for the original p/n (920-75-011-2796) turns up a couple of images, both of which appear to be plain bearings/bushings - no holes, grooves etc.
I don't understand how grease is supposed to get to where it's needed, but I have seen this setup - a grease chamber and plain bearings at the ends of a plain shaft - before; e.g. the right-angle drive on my tiller and the back axles on my pair of lawn tractors are like that. It just seems a bit wasteful as what's the point of having a big chamber full of grease when only a little bit of it is doing useful work (it's different for the tractors and tiller as the gears sit in the grease)? Maybe as the bearings get warm they're supposed to "wick" more grease from the chamber or something.
Anyway, what I've done for now is cut a small ("internal") slot in the saw's frame between the grease point and the interior grease chamber; that will allow me to pump grease into the chamber with the bearings fitted (from where it will be forced between the bearings and shaft, although I'll still pre-grease everything before assembly, of course). It would just be nice to find someone who has taken one of these saws "in original condition" apart just to see what the setup is!
Maybe it was just supposed to be routine maintenance every x months to force more grease into the chamber via the grease point, and this in turn would force fresh grease into the bearings. Of course, hardly anyone likely did so...

Yes, I don't think so either - I did look at sealed bearings, but the OD is just too big. It could probably be done using a bearing carrier mounted to the frame (although there's not much clearance on the pulley side), but realistically I only got this saw for light use (I've got $15 in it right now*, including the new bearings) and if that changed I'd be better spending a few hundred on a decent saw rather than putting $50 into a saw that would still be left with cheap plastic wheels :-)
* add $10 for a 1/2HP motor, but I want to make sure it all runs true before getting that far.
cheers
Jules
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"Jules Richardson" wrote in message
I picked up an old Delta/Rockwell 10" bandsaw a while ago (model 28-113) for peanuts - I don't think this model was ever considered particularly good (it's got the plastic wheels), but it'd be OK for the kind of stuff I'd use it for.
Anyway, the bronze driveshaft bearings were completely shot - but when I pulled them out so I could replace them, I found that the one on the drive pulley side completely blocks the grease fitting pathway!
It seems impossible that it was always like that; there's a cavity within the saw's cast frame which still had some grease in it (albeit not much). So I assume that the bearings have been replaced at some point in the saw's life; did the original (on the grease fitting side) maybe have a notch to allow grease in? Or perhaps a hole, and grease could flow between the bearing and driveshaft into the cavity (but this seems unlikely as the clearance between bearing and driveshaft is so small)?
Another possibility is that according to the parts break-down (e.g. http://www.toolpartsdirect.com/cgi-bin/schematic.cgi/rockwell/28-113 ), replacement bearings were supplied over-size and the frame would have to be reamed to get them to fit - in which case was there perhaps originally a channel in the frame between the grease fitting and internal cavity, and reaming took this out (and whoever did the work didn't cut a new one)?
The bearings which were fitted were 10/16" ID and 13/16" OD (and 12/16" OD seems much easier to obtain, again perhaps suggesting that the saw has over-size replacements), and I've got some new ones to put in - but in order to fix the lube problem properly it would be useful to know what the original setup would have been.
cheers
Jules
After reading the other replies......How about needle bearings that is what I call roller bearings??? WW
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On Tue, 15 Oct 2013 09:27:56 -0600, WW wrote:

Yes, I think they're the same thing. They should be narrower than ball bearings, but I did notice on one Delta saw that they fitted a needle bearing for the top wheel only on earlier ones, but then changed it to a sleeve on later ones, so I wonder if they had problems with the needle bearing not taking the load (or maybe it was prone to sawdust getting in and then wearing out quickly... or maybe they were just trying to cut costs :-)
J.
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On 10/15/2013 10:27 AM, WW wrote: ...

needle bearing isn't the same as a roller bearing, no...both are rollers as opposed to a ball, yes, but much different...but a good idea and can even actually find something that might just work...
<(Amazon.com product link shortened)>
--


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On Tue, 15 Oct 2013 11:43:54 -0500, dpb wrote:

Hmm, I'd always thought that they were basically the same thing.
http://en.wikipedia.org/wiki/Rolling-element_bearing#Roller_bearings
... seems to say that a needle bearing is a sub-class of roller bearing (so it's perhaps fair to call a needle bearing a roller bearing, but not necessarily the other way around :-)

B0026GTP7U> I think that picture's wrong, and shows a plain sleeve bearing - googling the same part-number turns up other sites selling the same part, but with pictures of a bearing that obviously has rollers. Weird.
cheers
Jules
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WW wrote:

dpb wrote:

"Jules Richardson" wrote:

Needle bearings and roller bearings are totally different animals.
It's been a long time since I was involved in bearing application design, but for openers there is at least a 10:1 price difference and most needle bearings I'm familiar with do not have an inner race, they use the shaft.
Lew
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On 10/16/2013 6:43 PM, Jules Richardson wrote:

They're both based on rollers rather than balls, yes, so I'll concede the point... :)
But, I think of them as substantially different owing to the dissimilarities in structure so generally don't call one the other meself...
Anyway, on looking at the picture I agree they've got the wrong picture; I assume the product is probably as described. I though at first glance it was enclosed/sealed which would be ideal for the purpose but think on further and more close looking it is the bushing, too.
Another link I found has several of what look to be right I/OD of various loading ratings...probably no different than what you've found but I'll post the link anyway...
<http://www.globalindustrial.com/c/motors/bearings/needle-roller-bearings?ptegory%3D8Q1U%2Cattr+borefwmminch%28text%29%3D15.875+\%285\%2F8\%29>
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