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Can I grind my own crank?

blakews2217

NAXJA Forum User
Location
Alton, Illinois
I work in a machine shop ( my fathers). We have the ability to turn/ sand and polish metal. Is there anything specific to grinding/turning the crank down?


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You may be able to turn the main bearings but the offset rod bearings may be different story.
How do you plan on chucking the crank for each rod bearing?
It's your dad's shop, ask him if they are equipped to do so .
 
You may be able to turn the main bearings but the offset rod bearings may be different story.

How do you plan on chucking the crank for each rod bearing?

It's your dad's shop, ask him if they are equipped to do so .



We have 4 jaw chucks where each jaw is moved independently so we can do off center turning. I was more worried if there is a certain direction to turn/polish it. I believe I herd something about polishing in the direction of crank rotation.


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Wondering why you want to undertake the project, for the novelty of making your own parts, you cannot find exactly what you want, or to save money ? Unless your shop already grinds cranks and has the specialized equipment, you not will save any time or any money. The shop I work for fabricates and repairs exhaust systems for small planes, and I buy all my automotive headers and exhaust systems at the auto parts store. One of the fabricators built the exhaust manifold and exhaust for his hot rod. It is all custom, but he spent many many hours on the project.
 
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Is your equipment liquid cooled? What's the tolerance of your equipment? Do you already have a stone for that?
 
Yes everything we have ( except for the little lathe) is liquid cooled. I was curious as to save a little money because the 258 crank in my stroker motor will probably needed turned to .020 under. ( it’s already .010 under.) When I tear it apart I’ll have to put a micrometer to it. I guess I’ll quote to see what my local engine shop will do it for. Maybe barter some other machine work for them.


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We have 4 jaw chucks where each jaw is moved independently so we can do off center turning. I was more worried if there is a certain direction to turn/polish it. I believe I herd something about polishing in the direction of crank rotation.


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A 4 jaw chuck will let you do off center turning, but what are you going to put in the jaw ?? It's not like you can put the crank throw in the jaws.

The only thing you can 'chuck up' are the snout & the hub, and I doubt that will get you what you need to machine the throws correctly, and even if it does, the time needed to set it up would cost more than having the crank turned by a shop that does it regularly.
 
You need a centerless grinding setup for doing crank shafts. Grinding a crank requires a specialized piece of equipment. I am a tool and die maker, trust me.

I understand wanting to save some money, but it isn't worth the hassle. I used to flame spray crank shafts to build them back up for racing motorcycles and snowmobiles, but I always had the finishing grinding done on a specialized machine.
 
Its really cool that you are working in your Pop's machine shop! If you were to go to the automotive machine shop and talk to them, they would probably give you the 50-cent tour and answer any questions you can think to ask.
 
Its really cool that you are working in your Pop's machine shop! If you were to go to the automotive machine shop and talk to them, they would probably give you the 50-cent tour and answer any questions you can think to ask.



Me and him built this stroker back about 5 years ago. Long story on it. When we had the crank ground the first time he thinks we spent about 400-500 for them to do it. I’ll have to dig through my receipts. Or get a new quote. I may find another throttle body and see how far I can bore it before it’s too thin.


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to me, the fu@k with factor exceeds any gain. but if you want be able to say "we turned the crank in the shop" then sure
 
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