<VV> turn my crank

[Tony Underwood]

At 10:41 AM 11/3/2006, Ron wrote:
>Why isn't metal spraying better?  It seems that the grinding would 
>be much less and the heat input would also be less.
>RonH
>
>>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.



I've not seen much metalspray repairs myself, but my machinist buddy 
has and he's not real impressed by metalspray.  I think he had a 
couple of bad applications come back which bit him...   It's his 
opinion that you need to have someone who's *really* good at what he 
does to do it and make the stuff stay without flaking off.    He said 
he'd sent out several commercial machine pieces with damaged journals 
to be metalsprayed, got the stuff back and wasn't satisfied, had 
problems when he tried to apply final polish, had flaking 
issues.   Other times afterwards, he'd sent out pieces for spraying 
which came back looking fine, no problems at all, but once bitten 
twice shy.   I ended up checking out an outfit here in town that does 
metalspray journal buildup, saw samples, looked damned good.    It's 
pot luck I suppose, although a reputable shop would likely have word 
of mouth info on how good their work actually is.

In a couple of cases my buddy said he had journals chromed in layers 
until they mic'ed out to spec.     That likely gets costly...


In any event, I'd have no problems with sprayed journals if done up 
nice... and as long as the journal isn't cut too bad... metalspray 
(according to my machinist buddy) works best when it goes on fairly thin.


tony..