Control Sheave Button Bearing

[br549]

UPDATE: While waiting for new button/bearing to arrive, I spent the past few days repairing the shaft of the control sheave, which I chipped in the process of removing the old bearing. After 4 applications and between coat sanding of JBWeld, I was satisfied with the result. I even added some dental floss reinforcing between coats 2 and 3 to help keep the repaired chips from being "bulged out". The OD of the control sheave shaft is not critical, so I didn't mind if it grew a little with JBWeld. Sanded off excess for smooth, fairly uniform thickness just in case an uneven thickness might affect balance.

Had same thought as JPG about keeping snout from being bulged out when new bearing installed, so made a close fitting sleeve out of a 1/2" PVC coupling by sanding the inside of the coupling until it fit the OD of the shaft. As an alternate, also cut a short section of 1" copper pipe, which was little large, but figured I could wrap electrical tape around the shaft to made a tight fit. Any bearings I have ever replaced were a tight fit, so I was ready now, and planned on easing the bearing into place using a c-clamp or woodworking vice and a socket with an OD just slightly smaller than the OD of the bearing, and another socket with an OD to fit in the open space between sheave ribs on on opposite end of the sheave shaft.

The new part arrived.

To my surprise it went right in without any forcing at all. Sleeves and sockets and c-clamp were not necessary at all. Oh well. In the process of sanding and scraping excess JBWeld out the recessed area where the bearing seats, I must have enlarged opening slightly. Before I took the old bearing out, the end of the shaft did seem to be bulged out a little, and my prying on the old bearing to get it out may have made the end of the shaft slightly out-of-round.

My assumption is that since the porkchop only PUSHES on the button bearing while turning the speed control dial to go to a slower speed, that the semi-loose fit of the bearing should not be an issue. When dialing to a faster speed, the control sheave is not PULLED open is it? The floating sheave at the motor actually closing (under the force of the spring at the end of the motor shaft), which as the drive belt adjusts, in turn makes the control sheave want to open ... right? Or should I be concerned about the semi-loose fit and add more JBWeld to inside of shaft where bearing seats, either before setting bearing in place, or set it in wet JBWeld while installing? Since my control sheave itself will probably need replacing if the bearing ever goes out again, I'm not too concerned about being able to get the bearing out in the hopefully distant future.

Have also included pictures of new button bearing, how it is staked together, and a shot of it next to my old button. Did not realize the top of my button had worn down so much, but it is 36 years old. In the process of cutting the old bearing inner race off of the button, I nicked the shaft of the button, so more JBWeld to the rescue, in case I want to try to re-build it with a new bearing. May not have enough material left to stake it to a new bearing, but I've got plenty of JBWeld left.

[ChrisNeilan]

The bearing should be a snug fit sand MUST be staked in or it will come out and fail. Staking means you take a punch and smack the outer wall of the sheave, That will cause a dimple in the sheave wall that will hold the bearing in place. Do this in three places if you can. If it is a loose fit from the beginning, you might want to use a little loctite to help hold it in. Also, don't stake it on the JB weld- you know what will happen!

[br549]

I guess I didn't know what staking meant. I thought the flaring of the small shaft of the button on the back side of the bearing was staking. I found this picture after a google search. Is this what you mean?

481.jpg (107.85 KiB) Viewed 10583 times

I don't know that I'm good enough to do that and not fracture the shaft. Would a small amount of JBWeld neatly applied between bearing and inside of shaft not accomplish the same thing? Not so much as to prevent bearing from turning of course.

[wa2crk]

Is the bearing concentric to the center of the sheave? If not, I would expect some vibration and possible premature failure. Staking is deforming one part to hold an assembly together. I think that I may have used the term in an earlier post in reference to the rear of the center "button". I should have called it a flair rather than a stake. Apologies.
Bill V

[ChrisNeilan]

Yes, the photo show staking, although you don't in this case need so many points. Three or four should do, there is not that much force on this bearing. I would avoid any more JB Weld. All you need to do is to stake it down, and you could probably use a small nail set if you don't have a punch. Avoid the fragile area. Worse case scenario you need a new sheave (and by the way, always buy them in pairs so they are matched). If you buy new from Shopsmith, I believe the bearing comes already installed. That bearing, by the way, is usually damaged when turning the speed control when the machine is turned off.

[JPG]

The loop is not pulled IF the floating sheave is well oiled and the pork chop is not pulled too fast.

FWIW I was concerned with the snout being supported on the od when the old bearing was driven out.

The sloppy 'hole' is not good. Cross yer fingers.

[everettdavis]

This has been discussed through the years and one of the threads has a post on staking that was done by Bill Mayo. Bill is one of my many valued mentors here.

See: http://www.shopsmith.com/ss_forum/viewt ... 92#p172092

and browse the thread. Your use of dental floss is innovative. I have seen others use an automotive hose clamp to help support the metal during the Staking process.

If I am not mistaken, Jacob Anderson uses the flared area of a 6-Point socket to re-seat the bearing mount as it compresses the entire area surrounding the bearing.

A fellow in Canada wrapped it in carbon fiber, then used adhesive lined heat shrink tubing that compressed around the opening. Don't know how long it held up, but innovative...

If you have a metal shaft, or even a wood dowel, and a spare turning face plate you can make a great support for the sheave staking process.

The 515556 Control Sheave w/Hardware ... $56.65 OEM is available as is the eBay kit from BandsawTireWarehouse at 25.95, so you do save some money by rebuilding if the sheave is in good mechanical shape otherwise.

I have used the bearing kit, and I have had to discard sheaves when they were internally worn, or the bearing seat torn up by neglect.

Kudos for the repair attempt and sharing it here.

Everett

[br549]

Thanks to all for your insightful replies. I didn't realize this was such a common situation and well discussed topic. After reviewing the previous thread thru the link provided, I better understand now about staking and the concern for keeping the "snout" compressed while removing the old bearing by using a sleeve ... I had thought that the new bearing would be a much tighter fit going in and hence that would be the reason for using a sleeve and my reasoning for the dental floss reinforcement.

At this point I'm leaning towards trying to compress the entire end of the "snout" around the bearing, and a judicious amount of LocTite or JBWeld to help hold the bearing in.

Everett, you mentioned what you thought Jacob Anderson did ... I have looked online and he only shares his method if you purchase the bearing from him. Using a 6 point socket of the right size and slowly squeezing it using a clamp or vice sounds like a plausible approach for my skill level.

JPG, good to hear that there shouldn't be too much pulling force on the bearing via the retaining loop, and since I am the only user, I will keep it well lubed and dial it very slowly when reducing speed.

Fingers crossed, and I will let you know result. I may only be buying a little more time before full replacement of the control sheave may be necessary, but salvaging and repairing it just feels like the right thing to do.

[ChrisNeilan]

Good luck. Make sure that you keep the sheaves well oiled and you should be good. Also always turn the speed control slowly.... less stress.

[JPG]

Thanks to all for your insightful replies. I didn't realize this was such a common situation and well discussed topic. After reviewing the previous thread thru the link provided, I better understand now about staking and the concern for keeping the "snout" compressed while removing the old bearing by using a sleeve ... I had thought that the new bearing would be a much tighter fit going in and hence that would be the reason for using a sleeve and my reasoning for the dental floss reinforcement.

At this point I'm leaning towards trying to compress the entire end of the "snout" around the bearing, and a judicious amount of LocTite or JBWeld to help hold the bearing in.

Everett, you mentioned what you thought Jacob Anderson did ... I have looked online and he only shares his method if you purchase the bearing from him. Using a 6 point socket of the right size and slowly squeezing it using a clamp or vice sounds like a plausible approach for my skill level.

JPG, good to hear that there shouldn't be too much pulling force on the bearing via the retaining loop, and since I am the only user, I will keep it well lubed and dial it very slowly when reducing speed.

Fingers crossed, and I will let you know result. I may only be buying a little more time before full replacement of the control sheave may be necessary, but salvaging and repairing it just feels like the right thing to do.

Do that when INCREASING!!!!