<VV> turn my crank

[Ron]

Why isn't metal spraying better?  It seems that the grinding would be much 
less and the heat input would also be less.
RonH

----- Original Message ----- 
From: "Tony Underwood" <tonyu at roava.net>
To: <virtualvairs at corvair.org>
Sent: Friday, November 03, 2006 11:18 AM
Subject: Re: <VV> turn my crank


> At 06:22 PM 11/2/2006, AeroNed at aol.com wrote:
>>
>>In a message dated 11/2/2006 7:55:19 P.M. Central Standard Time,
>>tdrinkr at yahoo.com writes:
>>
>>what is  done when a crankshaft is
>>turned? And what are the consequences of doing  this?
>>I.e. will over-sized bearings be  needed?
>>
>>
>>
>>
>>The crank is placed in a lathe so that the main and rod journals are 
>>located
>>in the center of the spinning lathe. A cutting tool, basically a sharp  of
>>steel, is used to remove a small about of the journal. The amount of the
>>material removed depends on how bad the journal is originally. The goal is 
>>to  cut
>>all of the journals to the same diameter. It is not uncommon to have the 
>>mains
>>at one new diameter and the rod journals at another.
>>
>
>
>
> There's a bit of a trend lately, with damaged cranks, with the shop 
> checking the journals and if only one is damaged, they weld up on that one 
> journal and turn it back down to STD so that the replacement bearing set 
> remains STD as well.
>
> This only works if the rest of the crank journals fall within factory 
> specs.   A good shop will also insure that there's no warping or other 
> issues.    I've known cranks done this way to work out fine, no problems. 
> It's also generally a little cheaper than setting up the crank to turn all 
> the rods; easy to do all the mains but the rods require resetting the 
> crank 6 times.    I watched a guy weld up like this, work piece was 
> chucked in the lathe, spinning very slowly, he went after it and laid down 
> a bead like he was feeding rope onto a spool, finished the weld in almost 
> no time, looked fine...  turned the journal back down to STD at the same 
> time on the same lathe, entire process from start to finish took less than 
> a half hour, from the time he picked up the greasy crank to the time he 
> stuck it on the outgoing rack with a billing tag on the snout.    Of 
> course, he'd been doing this sort of thing for a while...  ;)
>
> Either way, it's a good idea to stick with reputable shops if you have a 
> crank turned, and check the work out for yourself after it's done, can't 
> hurt.
>
>
> tony..
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