# Crankshafts



## Foozer (Feb 3, 2009)

Using a small lathe as old and rickety as myself, have found that for any hope of maintaining accuracy turning between centers is the way to go. I can get the old hunk of iron to hold within 0.001 over 8 inches between centers so long as I don't sneeze. It is too this end that after some keyword searching the term "jig" made itself known loud and clear. Being too flipping cold to go out to the barn the idea looks good on paper.







The jig(s) should be within my limited abilities to make, each being a left and right hand one with the center point spacings identical to each end. Figure that once securely fastened can remove all the bits that are not of the crankshaft without loosing position as I experienced the pleasure of, using a three jaw. All I can see at this point is some sort of spacer will be required to fill in the gap left from turning the journal prior to the main shaft to take up the pushing force (technical term) from the tailstock and whatever stress the cutter transmits..

I am lousy at descriptive jargon, even after 20 years pounding rivets on the Triple 7's I never got the port - starboard lingo down.

I like pictures hence the picture, anyone see inherent boo boos on this route 

Thanks


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## tel (Feb 3, 2009)

Foozer  said:
			
		

> I like pictures hence the picture, anyone see inherent boo boos on this route
> 
> Thanks



Nope, that's a tried and true way of doing it.


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## 10K Pete (Feb 3, 2009)

Yep, agreed. The one time I did that I used something similar and it worked very well.

Pete


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## Maryak (Feb 3, 2009)

Foozer,

This is a jig I used for an overhung crankshaft. It's made from Aluminium.






Worked very well for me - Hope this helps. ??? ???

Best Regards
Bob


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## kf2qd (Feb 3, 2009)

Did something similar a few years back to grind an 8 horse Briggs crankshaft. if you use 2 of them make one side of the fixtures the same distance from the centerline of the 2 holes so you can lay it on a surface plate and make sure everything is parallel before you put it in the lathe - other wise you might have ever so light an angle between the throw and the shaft.


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## Foozer (Feb 3, 2009)

Maryak  said:
			
		

> Foozer,
> 
> This is a jig I used for an overhung crankshaft. It's made from Aluminium.
> 
> ...



Thanks to all for the feedback, as it has been said the board here is full of knowledge. Searching out subjects and reviewing the means to the end takes a bit of upfront time, time tho well spent. This world of +/- 0.001 is a far cry from +/- 0.030 I spent the last 20 at.


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## Foozer (Feb 3, 2009)

kf2qd  said:
			
		

> Did something similar a few years back to grind an 8 horse Briggs crankshaft. if you use 2 of them make one side of the fixtures the same distance from the centerline of the 2 holes so you can lay it on a surface plate and make sure everything is parallel before you put it in the lathe - other wise you might have ever so light an angle between the throw and the shaft.



Point taken. Fills in that gnawing feeling that there was something I missed. Figure the more margins of error worked out before hand will only leave the final excuses to operator error, Yup I did it again


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## m_kilde (Feb 4, 2009)

Hi All

I made this crankshaft by turning between centers, it is for a 3 cylinder steam engine and includes cams for controlling pistonrods for the steam valves






A very interesting project, as you can only find out the result after a very long time working of materials in just light cuts.






When you are finish and the shaft runs freely in all four bearings, you feel like you can walk on water


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## Maryak (Feb 4, 2009)

m_kilde

That IMHO is on hell of a piece of turning. :bow: :bow:

Best Regards
Bob


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## Paolo (Feb 4, 2009)

Very master piece....... :bow: :bow: :bow: :bow:
Best regards
Paolo


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## ChooChooMike (Feb 4, 2009)

Beautiful !! :bow:


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## Captain Jerry (Feb 4, 2009)

Wow!!!

That may be the most beautiful single piece of metal I have ever seen!! :bow: :bow: :bow: :bow: :bow:

Jerry


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## Kludge (Feb 4, 2009)

Oh, my goodness gracious sakes!   

That is an excellent piece of turning. :bow: :bow: :bow:

I think I'm gonna go into my corner and sulk big time. :-[

Oh, Stevenson valve gear?

Best regards,

Kludge


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## steamer (Feb 4, 2009)

In boat building speak....you spent some time in the "worry chair" making that! :bow: 

That took some serious fingertip technology and planning!...Nicely done!

Dave


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