Lapping in big ends

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Lapping in big ends

Post  hippy dave on Tue 13 May 2014, 12:37 pm

Hi all can you give me some pointers on the lapping in of the big ends iv got the timesaver powder but no real idea were to start, sorry if im being simple, cheers allQuestionLaughing

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Re: Lapping in big ends

Post  lynnr on Tue 13 May 2014, 1:10 pm

Hi Dave


No problem.

To start.
Mark each set of bearings and designate HP and LP.
Make sure all parts are free from Burrs.
Try fitting the big ends and see if the bearing halves come together.
If not you may have to gently file the curved edges and or the fillets on the crank pins. (Mine needed a bit as the brass jammed on the crank side)
Once the halves are fairly well down.
Mix a small quantity of the rough powder with a standard motor oil.
add a little to the surface of each bearing half and assemble lightly. I did this with the crank in place to allow rotation.
Using the rod start rotating gently, try to keep a good lineup.
The powder will slowly degrade, as designed, so you need to look, feel and add more. Once you get a uniform surface, work your way down a couple of grades on the powder while you are feeling for good fit and rotation.
Clean the halves well. MAKE SURE the oiler hole is clear. As grinding residue will crawl up it and block it.
Add a bit of clean thickish oil to the bearing. You should get a good film when the halves are fitted in to it and pulled apart. Also when the assembly is done up you are looking for a "slurp" feel and sound when you rotate.
At this point if all is well. There should not be any witness marks. ie scuffs and groves anywhere in the big end.

Remember you are after a good fit. No rattle or knock. Do not worry overly if things get a bit tight. As long as everything is smooth she will run in quite quickly once running.

Hope this helps.


Last edited by lynnr on Tue 13 May 2014, 1:13 pm; edited 1 time in total (Reason for editing : Added a bit.)

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Re: Lapping in big ends

Post  hippy dave on Tue 13 May 2014, 1:36 pm

Cheers Lynnr will start on that tomorrow thought that was the idea but was,nt sure plus didn't know about mixing it with oil makes a lot more sence now, thanks againVery Happy

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Re: Lapping in big ends

Post  iain on Wed 14 May 2014, 1:34 am

having used this on a full size it is very quick to do.

I'll be waiting until i'm assembled on the boiler before doing this. Take out any minor misalignment issues.

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Re: Lapping in big ends

Post  Adam Brown on Thu 15 May 2014, 4:16 am

From Timesavers Booklet on the subject - please PM me for a copy

DIRECTIONS
For Mixing and Using
Timesaver (Precision Finish) Lapping Compound
(Materials Recommended)
Mix Timesaver with oil (see specific application) as you use it and only in quantities needed for
the particular job on hand. Mix thoroughly to obtain an even mixture and keep well stirred.
The following instructions suggest proportions and types of oil to use for specific applications.
Variations, however, may be made to meet existing conditions. Timesaver Lapping Compound
will not charge the metal or continue to cut.
Bearings
(Procedure and Materials Recommended)
No. 40 Course (Yellow Label) For roughing in and removal of excessive amounts of
metal.
No. 60 Medium (Yellow Label) General lapping.
No. 80 Fine (Yellow Label) For finish and removal of small amounts of metal.
1. Round Bearings (Babbitt and Bronze)
Newly poured bearings are usually too tight to permit the shaft to bottom. If this is the case,
relieve side pinch with a scraper only enough to permit the shaft to bottom in both halves.
Mix compound with thin oil (SAE 10 or 20) in proportions of about one part Timesaver
Compound to 3 or 4 parts of oil, by volume. Spread the mixture evenly on bearing halves.
Shim properly to maintain alignment.
Bolt up cap, not too tightly, but just so shaft can be easily turned by hand. Rotate shaft
manually or under power at a speed of not over 100 R.P.M..
Gradually take up on bearing, removing shims if necessary, as high spots are removed. At
intervals add a small amount of oil and gradually take up on bearing halves making additional
applications of the lapping mixture if necessary.
Caution
Never permit bearing surfaces to become dry or gummy at any time during the
operation. The lapping mixture, on the bearing surfaces, must be kept in a semifluid
state to obtain even distribution, rapid action, and uniform removal of metal.
Add oil if necessary.
When a full bearing surface has been obtained, tighten cap to final position, add plain oil and
continue to lap for a short period. This operation produces the final finish and proper oil
clearance. This position should not be changed or varied following the cleaning operation or
during the final assembly. Flush out with thin oil.
Timesaver lapped bearings have the proper oil clearance and should not feel as tight as a
scraped or machined bearing as no allowance is necessary for the wearing down of high spots.
Solid Bearings and Bushings
Fit bearings snugly to shaft. Apply Timesaver and oil mixture to the bearing and shaft. Insert
shaft and lap with a twisting motion, adding oil or lapping mixture if necessary until proper
clearance is obtained. Flush out with thin oil.

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Re: Lapping in big ends

Post  storey on Tue 21 Apr 2015, 11:53 am

Hi Guys, which compounds did you use ? The fine or very fine ? And are the 3oz cans sufficient ?

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Re: Lapping in big ends

Post  lynnr on Tue 21 Apr 2015, 12:10 pm

Timesaver as above instructions.

Small tins are fine. You don't need a lot when you work the way down through the grades.

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Re: Lapping in big ends

Post  storey on Tue 21 Apr 2015, 1:08 pm

Thanks Lynn, ordered the Kit with all grades. When I finish painting the Belly Tanks I will get in touch about the stencil

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Re: Lapping in big ends

Post  Vapor on Wed 22 Apr 2015, 12:26 am

Hi Guys/Girls

Where do you order these "Kit" of lapping powder from please.

Ian

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Re: Lapping in big ends

Post  lynnr on Wed 22 Apr 2015, 12:59 am

I got mine from Frost auto restorers But if you do a internet search for timesaver lapping. You will find a few places. Also think heritage steam also do it

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Re: Lapping in big ends

Post  Vapor on Wed 22 Apr 2015, 1:15 am

Thanks Lynn,

What happened to I think it was Seddon & Black are they still going do seem to hear anything about them now days.

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Re: Lapping in big ends

Post  lynnr on Wed 22 Apr 2015, 1:40 am

Now called Craftmasters steam supplies. Also do the paste.

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Re: Lapping in big ends

Post  Vapor on Wed 22 Apr 2015, 1:42 am

Ok Thanks Lynn, wondered why I had not heard the name on the forum for a while.

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Re: Lapping in big ends

Post  bjwlancashire on Wed 22 Apr 2015, 3:57 pm

Vapor wrote:Ok Thanks Lynn, wondered why I had not heard the name on the forum for a while.

Hence why Mr Brown posted the instructions above. I did get mine from Seddon & Black in the past.

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Re: Lapping in big ends

Post  Vapor on Wed 22 Apr 2015, 11:34 pm

Well I suppose I could be excused then as I don't know who Mr Brown is or was.

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Re: Lapping in big ends

Post  bjwlancashire on Thu 23 Apr 2015, 1:53 am

Vapor wrote:Well I suppose I could be excused then as I don't know who Mr Brown is or was.

He of Craftmaster Paints fame too. He is posting painting tips in a special section on this forum. Maybe he is not as famous as he would like! Wink

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Re: Lapping in big ends

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