How does the OneWay live center come apart?

Candidate for the article section.

Stuart Johnson

Can this thread be saved as a how to tip in the article section?

Re: latest measurements

Doug Ladendorf

Very thorough and useful information Dave. Thanks for taking the time to share.

Doug

Re: latest measurements

Dave Paine

Thanks Doug, more documentation ahead to complete the thread.

Today I went to a local branch of Bearings and Drive Unlimited. I have been to this place before. They had the original Nachi brand and SKF brand in the 6202 bearing. I decided to go with the SKF. I was surprised to see the SKF states Made In Italy.

I may have paid a few dollars more to purchase local vs online, but they were only $9 each.

The new bearings have no play, smooth rotation on the finger. Not spinning freely due to the new grease.

The old bearings have a lot of side-to-side play, which I think may be due to the race prematurely wearing due to the pressure from the bearings being pressed into a too small opening.

The new bearings have the same fit as the old, so will need to be pressed on the inner shaft.

I have not decided whether I will machine the housing, or use a small brake hone. I want to get an easier fit, but not too loose.

The original bearings had a code 6202 - NKE. The "NKE" seems to be specific to Nachi and means "Single contact face".

The SKF bearings have a code 6202 - 2RS. The 2RS means two rubber faced seals. Not sure if this is specific to SKF or used by others.

Stay tuned for updates.

Re: Fixing the housing

Dave Paine

Yesterday I went to a local bearing supply house, Bearings and Drives Unlimited and purchased new SKF 6202 2RS JEM bearings.

Today I decided to machine the housing to get a better fit - at least one that does not bind.

I wanted to mount the housing via the MT2 taper since this is how it is mounted in the wood lathe so if I improve how true the bearings are in the housing, the assembly should run closer to true in the wood lathe.

First step is to mount a 4 jaw chuck and true up the MT2 extension using the inside surface.

I re-checked the runout. Ranges were smaller than on the 3 jaw chuck, but still the rear machined area was worse.

I then added layout dye on the machined areas. This helps to see where material is being removed. I am trying to remove only a thou or so at a time.

This is after the first pass, nothing removed from the front machined area some removed from the rear.

I checked fit with a new bearing after each pass. Stopped when I could get the bearing into the front machined area but snug fit.

Rear area has no dye. Front area has some dye left.

I then did a dry fit with the bearings and large diameter spacer connected with a lag bolt and nut so I had something to pull on the back side.

I am able to get the assembly flush with the housing. A lot easier fit.

I will update with final pictures after I have pressed the bearings on the shaft and re-assembled. Need to visit my friend to use his arbor press.

This thread just gets better and better

John K Jordan

Thanks for the excellent pictures and step-by-step. I love to see how people fix things. There is no substitute for having good tools, except perhaps knowing someone who does!

I know how my own horizons expanded with metal lathe and mill on top of the cutting/welding toys, er, tools.

JKJ

Re: Final steps

Dave Paine

My housing is still tighter on the rear machined area than the front. I removed a small amount of metal from the rear area only until I was able to lightly tap the bearing assembly in place.

I used a carriage bolt through the assembly to allow me to be able to unscrew this due to still being a little tight.

Small washer and nut so I can use the bolt to tap the assembly into place. Assembly is as deep as I can go - hitting the carriage bolt head at the bottom of the housing.

I removed the nut and added a big washer to span the housing, then the smaller washer and nut. Two nuts jammed together at the end so I have something to hold the screw while using wrench on the nut to remove the assembly.

Off to my friend to press the bearings onto the shaft.

Showing this to remind people what NOT to do - press on the bearings and spacers WITHOUT the brass cover. Doh!!!!!

We had to press the bearings apart. At least pressing on and off the shaft goes easily.

The live centre together INCLUDING the brass cover.

Since my bearings are still a bit tight, I do not want to risk damaging the threads on the brass cover. I stripped a couple of threads in the disassembly phase.

In the above picture I have hand screwed the brass cover until touching the bearing. I then use my piece of aluminium to protect the thread and the sharp tip so I can use a mallet to tap the assembly further into the housing. I can only go until I contact the brass cover.

A couple of iterations then I use the pins in the aluminium to screw on the brass cover. I screw only hand tight.

Finally together then back home to test on the wood lathe. A quick test to rotate by hand. Feels nice and smooth. Before the repair the assembly felt rough when hand turned.

I mounted a project just to have some pressure on the live centre. No noise from the live centre when rotating under load. Before the repair I would have a growling sound when under load.

I am glad I replaced the bearings before I had a failure. With my luck I would have been in the middle of a project.

This took far longer than I expected, but I am happy with the outcome.

I hope this thread is of use for others who need to do the same repair.

Re: Final steps

Clifton C

Dave,

So glad you persevered and had the skills...Thanks for sharing. If I'd had your experience on the first one I did, it would have been my last. But at least now I know who to sent it to if I run into that problem...