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Cutting a single keyway on crank snout


Derek

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My newly acquired diesel crank has a little key way damage from an exploding damper. Since I have machines I have options. At the very least I have to touch up the groove with the tig welder and then mill the groove with a key cutter. I figure since I'm going to the trouble of setting it up in the mill I might as well convert it to a single key.

Now the options kick in!

1) Weld damaged slot Pick up the existing slot in the mill and connect the grooves for a single key.

2) Don't weld the slot and oversize the entire key way and the install a step key. I may have to make the key but that's not a problem. Realistically I could mill the slot then fixture the new key with super glue and then mill it in place. This is the way I would like to go unless someone in the know has a better idea or sees a problem with this approach.

 

Thanks

Derek

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I don't see the problem with using a step key, but there isn't really a problem with welding the slot and recutting the keyway, either. The mill setup will be the same amount of work either way, half an hour of measuring and jigging, then two minutes to make the cut.

 

I LOVE machining! Everyone looks at you like you're a madman when you spend hours on a difficult setup and then take seconds to make the cut!

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I don't see the problem with using a step key, but there isn't really a problem with welding the slot and recutting the keyway, either. The mill setup will be the same amount of work either way, half an hour of measuring and jigging, then two minutes to make the cut.

 

I LOVE machining! Everyone looks at you like you're a madman when you spend hours on a difficult setup and then take seconds to make the cut!

 

I hear ya. It's all in the setup. I love the ones where you get 90 percent there with the setup and then realize "that'll never work".

 

The main reason I'm thinking step key is the strength of the key way is somewhat determined by the fit. When I try to make the connect cut if I'm off a hair it may be problematic. Then again I can make the cut and if it's not right I can open it up and do the step.

 

Derek

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It will work fine. I wish you were closer because I want that done on my crank but I think it would quickly lose cost effectiveness after shipping. :[ If you do it, can you note down how many hours it took you so I can get an idea on what it will cost me at my local machine shop? Thanks Derek!

24zip1g.jpg

28h3a5i.jpg

 

If you feel like being super cool you could add 2 more dowel pins on the flywheel end and mill the crank 6mm, tap the flywheel bolt holes 6mm deeper too:

x4g8ec.jpg

 

Although as discussed, it's not mandatory for higher RPM use at all. If you have the machines though it is pretty cool... B)

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