Internal Hone

[Mark CParticipant @markc]

I have a small cylindrical bearing that needs altering to C3 clearance, I was going to have it done out but at £20 for the race I thought I might give it a go in the workshop. I know a lot of people do bores with hones but the race is 26.5 mm diameter and 10 mm wide making it short compared to an engine cyl.

I was wondering if anyone has any experience of honing such a short diameter and how they went about it? For information, I need to add 0.007 mm (roughly 2 or 3 tenths) to the diameter.

Mark

[Mark CParticipant @markc]

Best method for internal hone over short length

[Michael GilliganParticipant @michaelgilligan61133]

Mark,

Not much experience, I'm afraid

… I sold my Delapena because it wasn't being used.

Biggest problem will be avoiding "bell-mouthing", so it's probably not a freehand job [which is all the Delapena was intented for]

… Here is an article that may help.

MichaelG.

[jason udallParticipant @jasonudall57142]

How did you intend to immobilise/drive the inner race to hone it?

Once done why not machine a stack..with first/last as sacrificial..to the gods of bellmouth

[jonathan heppelParticipant @jonathanheppel43280]

Why the C3 clearance? If you're just following factory recommendations I wouldn't bother. Such a tiny amount would make very little difference to the service life of the bearing, if that's your concern. Doesn't C3 refer to the clearance between inner and outer race? That would be a tricky job indeed, and well worth £20.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Marc C – PM .

[Mark CParticipant @markc]

Sorry, the cost of the bearing assembly is £20, having it altered was more like £50…. I reckon for that I would have a go and still take a chance on a second standard bearing if it goes to pot!

The idea is to alter the outer race to give extra running clearance and the bearing is "n" type with detachable outer race. the reason for trying is not just replacing like for like, it is a very tight fit in the housing and as it is on the business end of an armature, it gets quite a large temperature difference across the bearing, hence the increased running clearance.

Michael, thanks, I did not think about holding the race before (I planned on sticking it in the 3 jaw!). I will probably make a housing that it can sit in, just clear so the diameter is free and nip it in with a retaining flange (should that be convex or concave &nbsp I will then make a lap (again, I thought they were the same thing hone=lap interchangeable but you live and learn – and I am supposed to be qualified….) along the lines of a tube with longitudinal slots in a soft material like aluminium and put it on an support such that I can compress it progressively to increase the diameter. I have never tried anything like this so I was curious how much material comes off and what sort of fit the lap needs to be in the bore to start with. I figured the speed would be very slow – 50-100 rpm

Mark

[Ex contributorParticipant @mgnbuk]

Why not adjust the mating part & keep the standard bearing standard ? Modify the bearing & next time you replace it you will have to modify the replacement – modify the mating part now & next time a standard bearing will fit straight in.

Nigel B.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Marc C ,

2 to 3 tenths will come off in 30 seconds to two minutes continuous working if everything set up correctly .

Process makes a nice hissing sound when working properly – forgot to mention incidentally use plenty of very thin oil as well .

Nobody ever believes me but there is no need to make the lap adjustable when taking out very small amounts from a bore .

The matter of that housing and holding flange requires serious consideration .

Certainly flat on flat but other things to get right as well . Flange has to sit flat on both bearing shell and housing to avoid distrortion stress and fretting .

This means that housing has to be finished and microlapped to be same length as bearing shell less a chosen very small amount for a nip .

Finish on mating surface of flange needs to be very fine and with a lay that is different to that on both housing and bearing .

If flange is to be bolted in place then has to be adquate thickness so as not to distort under bolting down loads .

For a high efficiency minimum weight design use variable thickness – for instance pads at the bolting positions and thinner section elsewhere – taking care of course to have the pad edges with radiused fillets blending back into the parent metal or preferably with complete flowline profiles .

Medium carbon steel would do at a pinch for flange – hardened to same level as bearing shell and stress relieved .

Lot’s more to consider but that’ll do for now .

Smiley’s not working pro tem – maybe add later .

Regards ,

Michael Williams .

Edited By MICHAEL WILLIAMS on 26/03/2014 10:26:16

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