rebuilding a Oneway live center

[Shawn Pachlhofer]

I have what appears to be the Jet/Powermatic clone of the Oneway live center - it appears the bearings are shot.

I already obtained new sealed bearings at a local supply house.

Is it as simple as just disassemble, clean, lubricate and reassemble...or am I missing something?

thanks!

 

[Fred Belknap]

Shawn I can't answer your question, however I have an OneWay live center that has a rough bearing, it makes a noise but turns free. I contacted One Way about getting new bearings and they informed me that it couldn't be fixed in the field and needed to be returned to them for repair. They even sent me the paper work to get it through customs. I still have it and use it for mounting the reversing adapter and it works fine for that. I have a PM3520B and it came with the clone. One Way wanted almost as much for a rebuild as a new one would cost, I don't remember exactly but think it was around $90.

 

[Shawn Pachlhofer]

I have snap ring pliers, so I was able to get it apart - that's how I got the bearing number.

Replacement bearings were about $12 for the pair.

I think there was another snap ring on the inside holding the bearings and shaft together.

I'm going to go ahead and finish taking it apart and see if I can get it back together.

the bearings are double-sealed, so they don't need lubrication. but the assembled guts do need some oil to get it all to slide back together smoothly. Any suggestions for that oil?


if I fail - I have another genuine OW live center, so I'll still be able to turn...and I can send this one to OW or someone more knowledgeable for rebuilding.

 

[Andy Chen]

Shawn I can't answer your question, however I have an OneWay live center that has a rough bearing, it makes a noise but turns free. I contacted One Way about getting new bearings and they informed me that it couldn't be fixed in the field and needed to be returned to them for repair. They even sent me the paper work to get it through customs. I still have it and use it for mounting the reversing adapter and it works fine for that. I have a PM3520B and it came with the clone. One Way wanted almost as much for a rebuild as a new one would cost, I don't remember exactly but think it was around $90.

You have better luck than I did, Fred. I apparently needed new bearings on my Oneway live center (#3 MT) ~2 years ago, after 16 years. I called Oneway and was instructed to "just ship it back and we'll replace the bearing for you for $60 (something like that)." So, I packed it up and shipped it UPS because I trust them more than any other. Two weeks had elapsed and I received a notice that my shipment was held up at the Canadian customs and they wanted me to pay import duties or I can pay for the return shipping and get it back without the repair, or else they would toss it in 2 days. I said what the hell happened to NAFTA? Just ship the d... thing back to me. I called Oneway and was told I should have shipped it USPS because they would have taken care of the paperwork. Why the hell didn't the first guy tell me specifically which shipper to use? A turner friend learned about my experience and told me he'd take it to a machinist friend. Guess what? I got it back in a couple of days with new bearings for $20 (after having already spent >$60 on shipping it back and forth and heartache). A word of warning here. The original bearings were NOT sealed. The machinist was nice to replace them with higher quality sealed bearings. However, the live center actually would now rotate with drag. So the machinist replaced the bearings AGAIN and now it works like new.

Postscript: I recently had a couple of other issues with Oneway. I think if I EVER needed a lathe again, I will go to Brent!

 

[Ron Rutter]

Interesting. I checked my General ( i assume it is)today & it looks like it is just a press fit- no snap ring, at least not at the back. There may be a keeper of some sort at the front. With snap rings you could get away with a light fit but really they are always in compression mode so shouldn't come apart.

Andy. The friction from seals would not create any problem at all. You would have been better off with them! He probably just popped the seals out.
Ron.

 

[Clifton C]

rebuild

Shawn,
I was in the same boat. With the rebuild so close to the cost of a new unit, I figured if I screwed it up, time is all I’ve lost. However, all went well…
This is what I did sort of…
After disassembly and cleaning of parts.
Preheat oven to 200F. Lightly grease (cup or bearing grease) shaft and freeze for at least an hour. After the shaft has been in the freezer for about half an hour, put the bearings into oven, I laid them on some crumpled aluminum foil so they wouldn’t be resting on the wire rack, they are going to heat for at least a half hour.
Have a wood handclamp or something similar to clamp the shaft by the threaded part so the split end is sticking straight up. Have gloves…
The idea is to have the clamp on the counter next to the oven already adjusted
so the shaft comes out of the freezer, is clamped in the hand clamp, gloves on,
brass disk placed on shaft with spanner holes facing the right direction, (down)
one bearing pulled out of the oven, slipped on the shaft, pushed down, the spacer ring set on bearing, second bearing removed and slipped on next, all in 30 seconds, give or take a few seconds…The idea is to not terry…
Things to think about…
Probably should have the house to yourself.
Make sure the shaft is held solidly in the clamp so you have both hands for the
hot bearing.
Make sure the groove the-snap ring fits into has no burrs.
The end of the shaft with the split in it might have some burrs, if so, file.
Make sure the shaft is slick clean before the grease.
Make sure oven accurate .
Don’t over heat the bearing. (>230F is too hot)
And thats about it…
Let cool.
Reassemble.

cc

 

[Clifton C]

rebuild

Here are the parts and pieces, shop made spanner and snap ring pliers are quite useful.
Not sure I would attempt without.

 

[Shawn Pachlhofer]

luckily I have a pair of toaster ovens in the garage that I use for stablizing

otherwise - yeah, I know what you mean - I have already been forbidden from using the kitchen oven ever again for anything other than food.

 

[George Van Beynen]

Thanks for the information guys. I saved it for the time my live center fails.

 

[hockenbery]

Thanks for clear explanation with photos.

I might be needing to refer to this...
Al

 

[Raul McCai]

Are those bearings all conventional balls in conventional races?
Or is at least one of them taper rollers like so:
http://upload.wikimedia.org/wikipedia/commons/6/69/Tapered-roller-bearing_din720_ex.png

An angled or taper roller bearing typical to what you see in an automotive wheel assembly would take the thrust loading so much better than a plain ball in a race.

 

[Ron Rutter]

Are those bearings all conventional balls in conventional races?
Or is at least one of them taper rollers like so:
http://upload.wikimedia.org/wikipedia/commons/6/69/Tapered-roller-bearing_din720_ex.png

An angled or taper roller bearing typical to what you see in an automotive wheel assembly would take the thrust loading so much better than a plain ball in a race.

Raul.If the manufacturer had any concern in this regard he would have used a deep groove ball bearing.

 

[Raul McCai]

Raul.If the manufacturer had any concern in this regard he would have used a deep groove ball bearing.

Having been in manufacturing at R&D, New Product Design, Engineering, and Marketing; I know better.
You'd be appalled at the forced error and compromises at engineering that are imposed by marketing. Marketing simply demands a cost per item and engineering has to find a way, bad choices notwithstanding, because marketing has decreed that it shall not cost more than X dollars and cents to produce. If it does, they'll just find other engineers and fire the ones who won't comply.

Didn't used to be that way. Once, long ago, all of America's best manufacturing companies were funded, built, and run by engineers.

 

[Dale Miner]

Are those bearings all conventional balls in conventional races?
Or is at least one of them taper rollers like so:
http://upload.wikimedia.org/wikipedia/commons/6/69/Tapered-roller-bearing_din720_ex.png

An angled or taper roller bearing typical to what you see in an automotive wheel assembly would take the thrust loading so much better than a plain ball in a race.

Tapered roller bearings work in pairs, and need a means of setting the clearance or preload, and then need to have a way to seal the dirt out of the assembly. It gets complicated and expensive to make a proper tapered roller bearing assembly. I'm not sure that given the size of a One way live center housing, a suitable pair of tapered roller bearings could be found. The bearings in a One way live center hold up for a long long time and it seems to me that the cost to lifetime ratio is excellent. If we knew the bearing numbers that are used, we could tell if the bearings are deep groove (I'll bet they are), and could easily tell what the parts cost to rebuild the center.

I start just about everything between centers and rough the outside shape that way including chunks that weigh upwards of 80 to 100 lbs. Seven years now and the center is still smooth. No complaints on the design or manufacturing considerations from me.

 

[Raul McCai]

It gets complicated and expensive to make a proper tapered roller bearing assembly.

Yes, it does.

 

[KellyDunn]

After a number of years my live center began making noise. Same as with others Oneway said $60 to rebuild. I had a friend just buy me a new one at a symposium a few years ago. Seems Oneway went with a cheaper bearing cause it makes noise. I tried to take apart my other one. Maybe I will try harder. Thanks for this thread.

 

[Bill Boehme]

And thats about it…
Let cool.
Reassemble.

cc

You might add that it would be good to rehearse things as there is no second chance. Make certain that the spindle (the part with the threaded cup and point) needs to be clean, free of any burs or scuffing, and lightly greased. Use room temperature grease (don't grease it before freezing it). I would be a little apprehensive about heating the bearing -- not because of any possibility of damage, but because in some cases when dealing with bearings with small diameter inner shells and deep races, heating can actually make the hole size shrink. It may sound counterintuitive, but if you are interested, I can explain why that can happen. As far as I know, manufacturers data doesn't tell you when this might occur with a particular bearing. Also, roller bearings are not the answer for a live center, it angled ball bearings might work, but not likely as a retrofit here. Check out the Robust live center.

 

[Clifton C]

Sprained brain

Bill,
You are most correct on the rehearsal thing, however, you do have a few seconds. If you slip on the first bearing, look down and happen to see the brass disk laying on the counter, your first thought might be to say something like “Oh fiddlesticksâ€. (another reason you might want the house to yourself) However, the bearing will, in the first second or two, still slide off the shaft, if that happened I would probably put the first bearing back in the oven and grab the other one. Did I mention gloves, use gloves. Again you have more then milliseconds, maybe a second or two, but I don't think you have five to ten.
As far as greasing the shaft, I grease it before I put it in the freezer,
my reasoning is that after I clean it, it is bare metal, when it comes out of the freezer condensate forms almost instantaneously, so greasing first prevents this. Even cold, the light coating of grease does not impede the sliding on of the hot bearing. As in turning, more then one way to skin a cat, I mean banana. (I think PETA is monitoring my posts)

I think I mentioned cleaning and deburring, but no harm in repeating.
You want things to go smoothly, with no hangups. So, thinking thru each step of the procedure is a good thing.

So, the original post was about rebuilding a Oneway style live center.
Not reengineering, i.e., tapered and or roller bearings, just replacing the original bearings with direct replacement bearings.
The bore of these bearings (6202LB) expand when heated.

I would be interested in learning about the apparent paradoxical relationship of bearings. How small bore bearings may contract when heated.
It seems to me, just as a quick and dirty mind thought experiment, all thing being the same, that if I had a line of bearings lined up, all starting at room temperature, neither really really cold nor really really hot, the largest bearings ever made on the right, graduating to the smallest bearings ever made to the left, measured the bore, heated them, measured again, the ones on the right would have expanded, and somewhere down the line to the left I would find that the bores have contracted. So, somewhere in the line, is one bearing that has, to it’s right, all the bores that have expanded, and to it’s left, all the bores that have contracted. So, “That Bearingâ€, neither expands nor contracts when heated. Or, “That Bearingâ€, may expand or contract, depending on how it feels…So, now I’m stuck.
I think I’ll go clean my shop…
Ok, I’m not that stuck…But I am curious.

cc

 

[Bill Dalton]

Check out the Robust live center.

I did and after a couple of weeks use, sent it back, they were kind enough to refund my money. I will not say anything bad about the Robust Live Center because I think they make great products. There are some definite pluses to their live center, but the one I got had way to much play in it.

 

[Don Doyle]

I think I may be married to her twin!
Don

 

[Shawn Pachlhofer]

well I'm off Friday, and she'll be at work...

 

[Cliff Walsh]

Live centres

I manufacture live centres, and have not had any failures over the last ten years. I use ordinary sealed bearings - three of them each centre. Most manufacturers use one or two bearings. There is no need to use deep groove bearings for wood lathes. If there are three bearings in your centre, then you have a good quality centre.

 

[Bill Boehme]

I manufacture live centres, and have not had any failures over the last ten years. I use ordinary sealed bearings - three of them each centre. Most manufacturers use one or two bearings. There is no need to use deep groove bearings for wood lathes. If there are three bearings in your centre, then you have a good quality centre.

I would agree if people used common sense tailstock pressure, but I have seen some ham fisted demonstrators throw all of their ability into cranking in as much tailstock pressure as they could muster. I don't know how much axial force this amounts to, but it certainty is more than the rated axial load of the bearings. While there is plenty of cushion in the load ratings of bearings, I think that it is definitely possible to abuse them. Does their warranty on your live centers cover more than manufacturing defects?

 

[Cliff Walsh]

Rebuilding a Oneway live Centre

As you say, ham fisted operators do abuse lathes, but the one thing that helps the centres stand the attempts at abuse is leverage. The wheels on the tailstock that is rotated to advance the quill are relatively small, so the leverage is small, also. Secondly, ordinary ball races can stand a lot of side pressure, a fact I discovered by accident years ago. My wife & I drove a Borgward each (remember them?) for years; me for more than ten. I was the spare parts agent and part time mechanic. A customer wanted a replacement thrust bearing for the clutch, so I dismantled the part and obtained a replacement bearing from the local bearing shop. Then I discovered that the bearing was not a thrust bearing, nor was it a deep groove bearing. It was a stock standard bearing, and had performed well for fifteen years and over 100,000miles!! In that time, it was the only thrust bearing I had to replace. So, how long will three bearings, side by side, last?

 

[Cliff Walsh]

Live Centres

I replied to your post, Bill, but it disappeared! It must be somewhere.

 

[Bill Boehme]

Looks like it showed up. Maybe the electrons were tired and took their time.

 

[Hu Lowery]

steel tends to shrink more than it stretches when heated

Bill,
You are most correct on the rehearsal thing, however, you do have a few seconds. If you slip on the first bearing, look down and happen to see the brass disk laying on the counter, your first thought might be to say something like “Oh fiddlesticksâ€. (another reason you might want the house to yourself) However, the bearing will, in the first second or two, still slide off the shaft, if that happened I would probably put the first bearing back in the oven and grab the other one. Did I mention gloves, use gloves. Again you have more then milliseconds, maybe a second or two, but I don't think you have five to ten.
As far as greasing the shaft, I grease it before I put it in the freezer,
my reasoning is that after I clean it, it is bare metal, when it comes out of the freezer condensate forms almost instantaneously, so greasing first prevents this. Even cold, the light coating of grease does not impede the sliding on of the hot bearing. As in turning, more then one way to skin a cat, I mean banana. (I think PETA is monitoring my posts)

I think I mentioned cleaning and deburring, but no harm in repeating.
You want things to go smoothly, with no hangups. So, thinking thru each step of the procedure is a good thing.

So, the original post was about rebuilding a Oneway style live center.
Not reengineering, i.e., tapered and or roller bearings, just replacing the original bearings with direct replacement bearings.
The bore of these bearings (6202LB) expand when heated.

I would be interested in learning about the apparent paradoxical relationship of bearings. How small bore bearings may contract when heated.
It seems to me, just as a quick and dirty mind thought experiment, all thing being the same, that if I had a line of bearings lined up, all starting at room temperature, neither really really cold nor really really hot, the largest bearings ever made on the right, graduating to the smallest bearings ever made to the left, measured the bore, heated them, measured again, the ones on the right would have expanded, and somewhere down the line to the left I would find that the bores have contracted. So, somewhere in the line, is one bearing that has, to it’s right, all the bores that have expanded, and to it’s left, all the bores that have contracted. So, “That Bearingâ€, neither expands nor contracts when heated. Or, “That Bearingâ€, may expand or contract, depending on how it feels…So, now I’m stuck.
I think I’ll go clean my shop…
Ok, I’m not that stuck…But I am curious.

cc

I think it is a property of most steels that it shrinks as it cools more than it stretches when heated. Watching them true twenty foot long joints of pipe in a plant they heat the outside of the bow, making the bend in the pipe worse than ever. Then when it cools to ambient temperature the pipe straightens so that it has less bend than it had before heating. They may have to work back and forth a little but a man used to truing pipe can true a rack full of pipe in pretty short order.

Auto body repair from the days of fairly thick mild steel, beating the metal between a hammer and dolly stretched it, heating it with a torch shrunk the metal. A good body man with some patience could straighten out most sheet metal to where no more than a skim coat of filler was needed. It is even possible to take it further and use no body filler.

Taking advantage of this we often heat steel that is an interference fit over another piece then put it in place as you describe. I have seen collars on shafts tight enough that a 100,000psi press didn't budge them.

Being a true red blooded male I assembled my chuck and insert before reading the manual. I didn't like how far the insert stayed from being seated so I took it back apart and froze the insert for a couple of hours. Walked it down considerably further than before freezing. Reading the manual later I see that the insert has to come out to clean the chuck properly. OOPS!!

Hu