Author Topic: Turning a bearing  (Read 348 times)

Offline vintageandclassicrepairs

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Turning a bearing
« on: May 15, 2018, 05:45:29 PM »
Hi All,
I'm not 100% sure if this is the right place to post this, but if it needs moving please go ahead

As part of a rebuild project on a 1923 Harley Davidson engine that I am currently involved in, the crankshaft drive side main bearing required attention
Originally the factory setup was a bearing race fitted to the alloy crankcase, 1/4in rollers sat in cages in two sets and ran directly on the crank main shaft. In order to set these up properly several sets of rollers are needed in steps of 1/10,000in.  :scratch:
The last person who was at this engine fitted a pair of R16 ball bearings one with a seal that's wider than the other,
When I refitted the flywheel assembly into these and checked to timing side for run out, it was "wobbling" :Doh:

I removed the flywheel assembly again and rechecked my work on aligning it, and all is good !!
I went back and re read the factory book on rebuilding these engines and one section in it goes on about "setting" the alloy cases to get the bearing housings in line
This involves setting bars and a big hammer :bugeye:
I found another publication where the author modified the casing and shaft  to fit a metric  self aligning roller bearing 22205, by boring the casing from 2in. to 52mm and grinding the shaft from 1in. down to 25mm
I decided instead of modifying the case and shaft I would see if it was possible to machine the bearing to imperial outer and inner dimensions

To hold the bearing inner and outer rings absolutely true would be vital to make this a success
I chucked up a piece of 75mm round alloy bar and bored a recess in the end face that was a tight fit on the 52mm outer race, a tapped hole in the centre of the bar held an alloy disc to clamp the bearing against the recess. I have some DCMT tool tips in P25 grade that will machine the  bearing race steel
I then cut away the alloy that was holding the bearing true, I took it really easy cutting the bearing ring, 5 thou off the diameter per cut, making a ball of steel wool in the process !!

To hold the inner race I made another alloy disc, relieving the outer part a little, this was held  by four 6mm bolts threaded in the end of the alloy bar outside the bearing outer
I turned a 10mm length at the end of the 75mm bar down to 25mm a tight push fit for the bearing inner, then clamped the bearing in place
I then drilled and bored the alloy out of the inner race
I did not have a boring bar to take the DCMT P25 tips,  :bang: so I hacked an old boring bar to hold one.
Taking very light cuts and taking lots of measurements as there was only 0.4mm to remove I snuck up to the 1.000in size, It was difficult to see into the bore when the boring bar was in there

I was really happy to achieve the sizes required without scrapping the expensive bearing   :beer: :beer:
The photos hopefully show the progress through the job,
Tomorrow, onto the phosphor bronze timing side plain bearing

John




Offline pycoed

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Re: Turning a bearing
« Reply #1 on: May 16, 2018, 06:28:12 AM »
I love that - great stuff! (But can you imagine the next owner's predicament when he takes this bearing into the bearing shop for replacement & finds they don't exist?)

Offline awemawson

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Re: Turning a bearing
« Reply #2 on: May 16, 2018, 06:43:07 AM »
Sometimes you just have to do what you have to do  :clap:

Nice job  :thumbup:
Andrew Mawson
East Sussex

Offline Joules

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Re: Turning a bearing
« Reply #3 on: May 16, 2018, 08:13:38 AM »
Well done without grinding, that swarf looks evil.  In years to come when it comes back for repair, this will be a Harley Didsumfing  :scratch:
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline seadog

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Re: Turning a bearing
« Reply #4 on: May 16, 2018, 08:20:59 AM »
I did something similar with a Commando engine I rebuilt. The drive side crankcase was split where a gorilla had driven the main bearing in. I had it welded and re-machined and started to pop it back together. Strange, when I tighten the crankcase bolts the crankshaft stops turning  :Doh:
After a bit of measuring, it transpired that the bore wasn't deep enough, so the outer race was nipping the bearing up. Rather than give it back to the engineer and wait another 4 weeks for him to correct the problem, I went for the quick and easy (dirty) solution. Pop next door to the injection mould manufacturer and borrow their surface grinder   :thumbup:

Sold the engine to a french chap a couple of months later for a hefty profit :ddb:

Offline kayzed1

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Re: Turning a bearing
« Reply #5 on: May 16, 2018, 03:12:57 PM »
I do like that, i have one or six very old engines running around with very odd bearings in them...but haho they are still on the road.
Lyn.

Offline vintageandclassicrepairs

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Re: Turning a bearing
« Reply #6 on: May 16, 2018, 04:49:09 PM »
Hi All,
Thanks for the kind words. they are needed !!!
Every part I turn to needs work  :bang:
The aim is to get the flywheels and conrods central in the cases with about 5 thou end clearance
The original bearing housing is approx 20.6mm (13/16in.) and the new bearing is 18mm wide
so a spacer is needed, I am trying to see if I can fit a custom seal into this spacer, maybe move the bearing 1mm towards the flywheels to gain some space in the housing?
The original setup was a tin hat that held a felt washer, 4 screws hold it to the outside of the engine

I'm just in from measuring up the different parts, the width between the case bearing housings is  0.240in more than the width of the flywheel assembly,
The old bush I removed today has a 0.090in. thick thrust face, A thin shim was fitted between it and the flywheel (forgot to measure it!)
I have a new bush turned up but needed to do the measurement's to calculate the thrust collar thickness before parting it off,
A good sleep and things might look better tomorrow !!
John

Offline vtsteam

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Re: Turning a bearing
« Reply #7 on: May 16, 2018, 09:33:52 PM »
Would there likely be enough miles on it again to ever replace the bearing, in the coming era of autonomous vehicles? And if there were that much wear, won't there still be people with lathes and brains to fix it again? Hmmmm. Maybe I shouldn't ask...... :wack:

Nice job of work!  :beer:
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline Pete49

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Re: Turning a bearing
« Reply #8 on: May 16, 2018, 11:52:15 PM »
Going from what I see lathes will only be seen in museums and brains?? well maybe rent them out once more than motor functions are needed  :)
oops..........oh no.........blast now I need to redo it

Offline vintageandclassicrepairs

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Re: Turning a bearing
« Reply #9 on: May 18, 2018, 07:59:52 PM »
Hi All,
Quote
Would there likely be enough miles on it again to ever replace the bearing

The bronze bush on the timing side of the engine was either the original or when replaced they managed to use the original hole for the dowel pin that prevents the bush from turning in the housing, (almost impossible to do and not recommended)
I have machined the bush, cut the oil grooves and fitted it to the case,
I do not have a suitable pilot to fit the expanding reamer that will line ream the bush to the roller bearing, the bush bore will not be a "standard" size, I need to machine one up as time is pressing
Honing to size might be preferred to reaming, but this would need special tooling (that I do not have)

The engine and motorcycle are being prepared for the 2018 USA Motorcycle Cannonball event
It will cover almost 4000 miles from Portland Maine to Portland Oregon
Average daily mileage approx 350
This is a fairly serious ask of 95 year old mechanical components,
It will be put together with the best available parts and attention to detail that I can achieve

John