Crankshaft turning jig

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cfellows

cfellows

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The attached pictures show a simple jig I built which holds a crankshaft so the rod journals can be turned in the lathe. A round steel rod has a radial slot milled in the end to hold the crank web. A setscrew holds it firmly in place. An axial flat is milled on one side of the cylinder such that the connecting rod journal will be centered on the jig center when the crankshaft end is pressed against the flat. A host clamp can be used to hold the crankshaft firmly against the flat.

With the crank mounted in the fixture, the whole thing is chucked in the three jaw chuck with the crank end positioned between two of the jaws. It's real simle to make and it works flawlessly.

Chuck

OpenColumnProgress1%20001.jpg

OpenColumnProgress1%20002.jpg
 
Chuck,

Thanks for showing the jig. I am doing a twin crankshaft on an engine on the current engine.

Kenny
 
Chuck
SWWWWEEEEEEEEEEETTT!! That little dude just made the top 5 on my to do list.... well maybe after the rotary indexing table for my mill that I'm in the middle of right now. I'd think maybe a set of them with different offsets would be a real handy little piece of kit.

Steve
 
I figure I can just make them up as I need them, then hang on to them for future projects.

One additional tip is to grind the tip of the setscrew smooth so you don't mar up the crank web.

Chuck
 
That's an outstanding idea, Chuck. Do you think this could somehow be adapted to make a four cylinder crank?

Best regards,

Orrin
 
Orrin said:
That's an outstanding idea, Chuck. Do you think this could somehow be adapted to make a four cylinder crank?
Click to expand...

Don't think this concept could be used for anything larger than a 2 cylinder. A four cylinder crank jig would require a whole new concept.

Chuck
 
bob ward said:
Would the crankshaft turning adaptors work for 4 cylinder cranks if you had an adaptor and a chuck at each end?
Click to expand...

Yeah, you could probably make that work. But you'd need different jigs for the outboard and inboard journals. The jig for the inboard journal would have to be longer and the depth of the flat would be different because of the outboard webs sticking out beyond the crank main journal. All in all, you'd need three jigs. One for the outboard journals and two (one for each end) for the inboard journals.

Chuck
 
cfellows said:
The attached pictures show a simple jig I built which holds a crankshaft so the rod journals can be turned in the lathe. A round steel rod has a radial slot milled in the end to hold the crank web. A setscrew holds it firmly in place. An axial flat is milled on one side of the cylinder such that the connecting rod journal will be centered on the jig center when the crankshaft end is pressed against the flat. A host clamp can be used to hold the crankshaft firmly against the flat.

With the crank mounted in the fixture, the whole thing is chucked in the three jaw chuck with the crank end positioned between two of the jaws. It's real simle to make and it works flawlessly.

Chuck

OpenColumnProgress1%20001.jpg

OpenColumnProgress1%20002.jpg
Click to expand...
I see this is a old thread but would you have drawings or a sketch of the jig
I am having trouble visualing the jig
If available email to [email protected]
Thank you
Robert Wager
 
I, and I assume we, can't see the original photos. Maybe if someone is using this method could post some photos that would be terrific.
 
The original post is eleven years old. The pics are probably lost in photobucket
 
This is interesting only because the cloud tracks every movement that we do yet it can't keep a couple of pictures in storage.
 
I would assume photobucket has cleared out any old / inactive accounts. Unfortunately there's a lot of useful information lost in the process.
 
Brookesy said:
I would assume photobucket has cleared out any old / inactive accounts. Unfortunately there's a lot of useful information lost in the process.
Click to expand...


That is why forums need to store pictures locally and more importantly picture owners need to keep backups. As for backing up I'm pretty terrible at doing so, so obviously I'm preaching but not practicing.

In the end the old adage about advertising sounding too good to be true applies here. Nothing in life that is free can be trusted.
 
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