Crankshaft re-grind

[dthompson1941]

I have a 1949 A7 longstroke engine (Engine # ZA 1451 HC)) that I am rebuilding (the plunger frame is essentially done) and I have an issue with the original crankshaft. It is in need of a re-grind of both of the crankpins: one of them is at -0.020”, but the other is already at about -0.040”. An experienced local machine shop here (Tampa, FL, USA)  can built them back up and regrind them to whatever I want, even back to standard, but it costs a pretty penny to do it.  Also, Draganfly’s supply of bearing shells is limited, so I have to proceed very carefully (called them  and, -.030”, and -0.40” shells are in stock, -.010" are attainable, but no others, and almost no chance of getting them anytime soon). And of course, they haven't had a used crank in there for years.
My first question is a bit pie-in-the-sky: if at all possible, I would like to salvage the original crank so is the build-up my only option? My second question is: does anyone know of another crankshaft out there that still has some room for a regrind of the crankpins? 
This is one of the last roadblocks  to my completing the rebuild, so any advice or help you can provide would be greatly appreciated.

[terryk]

Cranks and engines come up occasionally on ebay so keep watching. I guess it depends on how much of a hurry you are in.

The subject of building up cranks has been discussed on this forum in the past I think the easy consensus was to try to get another crank. In saying that I have had shafts for other things built up and the built up part was so hard that it couldn't even be filed. I want to try it one day on a crank to see how it goes as I have a few cranks that are ground too far. I think it would be fine. How about you be the trend setter and do it. Make sure you let us know after you have done a year or so of riding.

Try other suppliers for bigend shells there are plenty in the UK. The timing side bush/bearing can be made to suit whatever size you grind the crank to.

[wilko]

Well I do know they don't make 60 thou over .

[olev]

Bert Monroe was casting pistons out of baked bean tins back when the bears were bad.
I've heard stories of people rebuilding bigends using leather in the war.
How do they make these things? Is it that hard?
cheers

[BSA_54A10]

Well , yes you can make a big end out of leather or even engineering felt, but it would not have lasted long even in a veteran with 4;1 compression.
Lots of people who knew next to nothing cast pistons in their back yards and a lot of engines siezed when they expanded way too much due to not being degassed.
A friend has a lathe with a bed made from 2 lumps of rail track, hand scraped to near perfect flat using an old file ground down & a sheet of glass with some old grease because they could not afford bearing blue.
People used to work with their hands all day every day so they developed eye hand co-ordination comensurate with their trade.
I rocked up to a members place one night with a long plank ( for loading BSA's of course )to be cut down to fit our respective vehicles.
In the dark he looked at it the promptly cut it with a hand rip saw and both pieces were about 15mm short of our decks, it was also dead square both ways.
He works with his hands.
Like doctors , we ony see the successes, failures went back into the furnace.
And the stories of Bert melting aluminium in a backed bean tin are myth.
He used either a cast-iron solder pot or glue pot.
Al-Si alloys melted in tin plate would dissolve so much tin they would make horrid tin -silicides and be impossible to machine.
Back in those days every mans workshop had a glue pot ( and they stunk ) for glueing wood and a solder pot for soldering gal iron roofing & guttering with dipping irons

[jachenbach]

I spun the clutch side main bearing on a Triumph many years ago. Had the crank welded and reground and continued to ride the bike another 10 years. Still running to my knowledge. When I was a field geochemist, out drill bits would wear out (drilling rock). After being built back up and reground, they were better than original. So I guess it comes down to the filler material that the welder uses and the ability of the machinist to regrind it. Assuming a reputable shop, I would not hesistate to have it built up and reground.

[dthompson1941]

Many thanks for the feedback on my crankshaft inquiry- I'm going ahead with the crankpin build-up by Falicon Crankshaft Components, Inc., who are crankshaft specialists located nearby in Clearwater, FL, USA. I dropped by there with my crankshaft last week and left feeling confident they will get it right.
They asked me to first pull the flywheel off the crankshaft, and so I removed the six bolts (with difficulty!), but the flywheel is still holding on tightly. I'm assuming it is a press fit and I'm planning on setting up a jig to press it off. Before I try this, I thought it might be a real good idea to ask if any of you have any experience with this problem; thanks for any advice you can provide which will keep me out of further troubles!