EW350 Roller Bearing Sizing?

[Mikerobe]

Hi all,

Back after a break that has been way too long.

I remember reading somewhere on here that it is possible to get 1/4" roller bearings in oversize steps. I think from Harley Davidson spares places? They came, I think, in 0.001" steps but I may be misremembering.

 On the EW350 I am working on both the flywheel clutch and gearbox roller bearing races are loose. The bearing surfaces seem to be ok.

I have tried to find guidance on how to size roller bearing to give the right fit of roller dia, outer race dia and inner race dia without much luck. If I get rollers that are too small I am not going to cure the problem of loose bearings. If I go too large then I can imagine that premature and rapid wear might result. 

Does anyone know how to pick an oversize roller that would be "just right"?

Look forward to your sage advice 

[BARRYM]

Hello Mikerobe, You may want to try these people they have a tremendous range, if you can't find what you want in there listing I would contact them as i think if anyone would know in the U.K they would. BARRYM.
This URL takes you direct to their roller bearings

http://simplybearings.co.uk/shop/advanced_search_result.php?sort=2a&search_in_description=0&keywords=loose%20rollers&x=0&y=1853

[oily bloke]

Hi Mikerobe,
Having had similar problems with the EW crankshaft I had the races and rollers converted to metric 8mm. not a cheap exercise as a specialist who is prepared to do the work is needed. This may or may not be practical for the clutch. The gearbox bearings are metric and are readily available and they are marked on the race as to the size and/or part number (6004 for example). Oversize rollers are hens teeth but a rule of thumb would be to measure OD of inner race and ID of outer race and deduct one from the other to give you a nominal size. Running clearance of 1 to 1.5 thou should give you the roller size needed. I was told that the hardening on original Douglas roller races was very thin, I was told 5 thou at most, but when my crank was done we checked the depth of hardness and found it to be nearly 20 thou inner and outer. That's nearly 2mm of total thickness which means you may be able to have the races ground oversize to accept metric. (A last resort mind). Your races, however, may not have been hardened this deep. If you have them ground beyond the hardening they will not be able to re harden them successfully. Best of luck. It would be intersting to me and others to know how you get on.

[Doug]

Barry,
Cough! Simply bearings might better be described as Simply Expensive!
-Doug

[Doug]

Actually it is a little hard to figure out if the cost is per roller or per pack.
-Doug

[BARRYM]

Doug I think your looking at the pack price. I have just bought 3/16 balls for headstock and rollers for gearbox from them and they were cheep!  cheep! cheep!
They have pages and pages of rollers going up in small increments of length, I didn't spend time comparing imperial against metric for diameters however, but I feel that it is worth the time and worth emailing them as they seemed obliging. BARRYM.

[roy]

Hi Barry, quite correct, just checked, a pack of 50 1/4x1/4 rollers £12.
Will keep name in spares file.

[Mikerobe]

Hi folks,

After another long break I have, today, finally tracked down the website I had found that did 1/4" od oversize roller bearings. They are:-

"AAOK"
http://aaok.com/
1802 N. Carson St.
Suite #108-2178
Carson City, NV 89701
USA

The bearings can be found in these search results http://aaok.com/catalogsearch/result/index/?q=1%2F4%22+ROLLER&commit=Go&p=1 (scroll down a bit to get the first of them).

Unfortunately all was not quite what I seemed to remember and they don't do 1/4" OD by 1/4" wide rollers. They do, however, do:-

0.025" OD by 0.360" in  std, +0.0006" and +0.001" oversize.
0.025" OD by 0.726" in  std, +0.0006" and +0.001" oversize.
0.025" OD by 0.490" in  std, +0.0002", +0.0004", +0.0006", +0.0008" and +0.001" oversize.
0.025" OD by 0.600" in  std, +0.0002", +0.0004", +0.0006", +0.0008" and +0.001" oversize

I have emailed them to ask if they can source 1/4" by 1/4" in oversize sizes, along with umpteen other US based Harley Davidson and Indian Vintage bike dealers/suppliers. If I get any positive replies I'll let you know.

At the moment I am not sure how useful this is. I need to go and double check my measurements of the various bearing races.  In the mean time..... Would it be feasible to shorten, say, the 0.360" or 0.490" bearings by grinding them down?*  Or would this introduce a pile of other problems? For example: Going through the hardening on one end would cause strength / wear issues? Ground end would be sharp and need chamfering? Given the relatively low mileage I am likely to do I am not sure quite how serious these issues would be.

If nothing else I have proved to myself that I wasn't going entirely mad and the web site I thought I had found and lost has been found again. Also these fellows may yet solve my problem or, perhaps having found them, solve someone else's.

Cheers Mike 8-{>

*Have access to precision surface and cylindrical grinding facilities.

[Doug]

Mike,

The rollers are likely made from 52000 series steel, which is a through-hardening high chromium steel particular to bearings elements and races. So you do not need to worry about going through the hardness.

I have shortened rollers (to make use of the HD and Indian oversize rollers generally available), and it simple enough to do. You need a fixture to hold them in place on the grinder as individually they do not have enough mass for the magnet to hold securely. A piece of 1/4 steel flat with 1/4 diameter holes reamed through it does the trick nicely. Then you have to thoroughly demagnetize them, which is actually the biggest nuisance.

The other alternative is to face them in a lathe using a CBN (Cubic Boron Nitride) tipped tool. CBN is the second hardest material to diamond. You can only cut a few thou at a time, but hard steel cuts like butter. However the CBN tool insert is expensive, very prone to chipping, and impossible to resharpen by what most folk have in their workshops.

You do need an edge break or chamfer. Otherwise loading along the edge of the roller will cause the edge to chip and release hard debris into the bearing. Not good. If turning with CBN, you can machine the chamfer or edge break. If grinding, I have broken the edge using a deburing wheel, or using a small grindstone in a Dremel Moto-tool. Having something to spin the part slowly and uniformly at the same time is a great aid.

-Doug


[fix typos.  10Jun11. -Doug]

[Mikerobe]

Have a reply from AAOK they don't have anything sadly. The closest match on a Harley to 1/4" by 1/4" is part number #2289-17 which is 1/4" x .270" long and not something AAOK stock. They have offered a possible source but they only list the std part and not oversize parts.

I have also tracked down the original post, which I thought was on this forum but now appears not to have been (or the info I think I read posted here may have come from this source) that sent me off on this possibly wild goose chase. It came from the Antique Motorcycle Club of America website:-

http://www.antiquemotorcycle.org/bboard/showthread.php?9906-Roller-bearings-0.25-x-0.50-needed-Peugeot

Where one of the posters says "The nice thing about Harley rollers is that they are generally available in .002 " ". I suspect he may have meant 0.0002" increments from my searching to date.

Further down the thread these people are mentioned http://www.vintagebearings.co.uk/. I hadn't come across them before so have now emailed them to see if they can help.

Cheers Mike 8-{>

[Mikerobe]

Hi Doug,

Thanks for the quick and detailed reply

Mike,

The rollers are likely made from 52000 series steel, which is a through-hardening high chromium steel particular to bearings elements and races. So you do not need to worry about going through the hardness.

Ahhh haaaaa! that sounds promising

I have shortened rollers (to make use of the HD and Indian oversize rollers generally available), and it simple enough to do. You need a fixture to hold them in place on the grinder as individually they do not have enough mass for the magnet to hold securely. A piece of 1/4 steel flat with 1/4 diameter holes reamed through it does the trick nicely. Then you have to thoughroughly demagnetize them, which is actually the biggest nuisance.

That sounds eminently do-able. We can probably sort out a suitable jig and have a tool demagnetising doodad. We process quartz and ceramics at work so we are reasonably well set up for tools even if most of them are a bit long in the tooth. We tend to stick things we are processing down using a range of waxes so we might be able to get away without making a jig

The other alternative is to face them in a lathe using a CBN (Cubic Boron Nitride) tipped tool. CBN is the second hardest material to diamond. You can only cut a few thou at a time, but hard steel cuts like butter. However the CBN tool insert is expensive, very prone to chipping, and impossible to resharpen by what most folk have in their workshops.

Also have access to a lathe and CBN tool tips/holders. This is sounding better and better. I know about the inserts and the associated issues so it shouldn't be too much of a problem.

You do need an edge break or champfer. Otherwise loading along the edge of the roller will cause the edge to chip and release hard debris into the bearing. Not good. If turning with CBN, you can machine the champher or edge break. If grinding, I have broken the edge using a deburing wheel, or using a small grindstone in a Dremel moto-tool. Having something to spin the part slowly and uniformly at the same time is a great aid.

-Doug

Could use the lathe to chamfer the bearings. I am guessing the CBN tool would still leave too sharp an edge if you were to try and put a small chamfer on with it?  Would a hand held stone be enough? Would a jury rigged dremel or similar hand held tool with a grinding tip be better?  Failing that we do have a cylinder grinder so could probably sort something using that. I'll have a word with our workshop guy on Monday See what devious plan we can come up with.

I had better get back to work on the numbers and see if the oversizeness is suitable. If it is I'll get some rollers ordered up.

Thanks again

Mike 8-{>

[Doug]

This is sounding better and better.

Better yet, do you have a CNC lathe? Then you can have it turn a corner radius, along with multiple facing passes to work the length down. If you do a 45 degree chamfer, you will not need much of an edge break. Probably breaking the edge with a stone while spinning it at high speed in the lathe would be sufficient. It is not so much the sharpness of the edge as the angle to provide adequate support (see illustration.) A radius would be less likely to create a track where the edge of the roller runs. You can also vary the chamfer slightly roller to roller. 



-Doug

[LATDOUGNUT]

Hello,

May I offer a time tested tip how to radius quickly and effectively cut down bearing rollers. You need to buy a fine grain abrasive/rubber grinding disc (150 mm diametre would be enough, 1/2"wide). Mount it on your toolpost grinder. Then take a round stick of hardwood, drill from both ends at precise 1/4"diametre so that you can insert/push in the roller 2/3 of the roller length in the hole. When you offer the roller with the stick (thus giving leverage and perfect control) to the rubber abrasive under 45 degrees angle, after a few turns by hand, you will get a perfect radius! Why? Because rubber is resilient, not as harsh as stone, the embedded abrasives will still cut steel effectively and smoothly.  After a few rollers your hand movements will become professional and you will be doing rollers quickly enough not to become bored. Using a stick with both ends will let the roller cool down while you are working on the other end. Properly done -- you will almost not be able to tell the finished end from the original radiussed one without a magnifying glass!

Old American rollers by the way did not have radiussed edges, (well maybe very slightly) but they were chamfered at a steeper angle, leaving a protrusion in the centre which would rest against retainer.

The running clearance of a roller bearing is also dependant on the length of the rollers, usually 0.03 to 0.04 mm total. A useful tool to open up the bearing race is Flex-Hone -- you can literally work within microns with this tool and you may not always have precise enough micrometre to measure progress! You have to use Boron carbide Flex-Hone tool to work on hardened steel effectively. Silicon carbide may be too soft. Flex-Hone will introduce diagonal cross hatch -- a perfect surface to distribute oil and provide longer service life than just ground bearing surface...Remember that the rollers are finished by lapping and they may look like polished. I remember having seen how old fitters used to lap them by hand -- a handful of rollers put between two cast iron pans with fine paste and the whole assembly was rotated in different directions...Nowadays this is all done by machines automatically!



Good luck with your rollers!