Crank Grinding Fillet Question

[Ishiftem]

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I was wondering if this crank is ok to run. I had it ground .010 under on the rod journals and the man stopped short of the radius leaving a step. This is a 409 crankshaft which has the same rod journals as a BBC. I already have narrowed bearings (acl race) but will still have to scrape the edge of them because the contact right before the step on a couple. Is this going to be a problem having the step as far as cracking? 7000 rpm and a 670 gram piston with steel rods.

[Schurkey]

the man stopped short of the radius leaving a step.

You need a different "man" to grind your cranks.

[Ishiftem]

Obviously!

[Dave Koehler]

I am hoping this was a low bidder grind. That work is shameful.

[Dan Timberlake]

Like others said, the details/geometry of the feature connecting the journal to the good looking original radius could be a pretty big problem.

How do the journals measure for size, roundness and taper ?

Assuming it checked crack free with wet mag particle before grinding, I'd be inclined to think about hand dressing/blending the edge of the radii into the cylindrical journal.
No crank grinder could "pick up" the new journal and just cut the radius. Might be able to create a slightly under cut relief similar to this -
https://files.engineering.com/download. ... nator_.png

I'd probably try a 1/4" Ø grinding stone just kind of layed into the step and crank radius. And on a practice crank first.
The grinding scratches from a 1/4" Ø grinding stone would be in the "right" direction for potential for crack initiation. The region "under' the journal is especially vulnerable to crack initiation ( which is usually the beginning of the end).
https://encrypted-tbn0.gstatic.com/imag ... c&usqp=CAU

[Ishiftem]

Well I guess it will have to go another .010 under to fix it. What he did do is great but I guess he turned out to be a short cut hack who makes money with his mouth and pencil instead of doing quality work. He quoted me $190 to grind the rod journals and charged me $324. Of course he “didn’t recall” telling me $190 and says he only charges for his time. I sent him a very polite message asking about the situation twice and no response. Now I’ll have to pay again to have it done a second time and buy another set of bearings. Unfortunately these situations have become the norm. Really makes me want to quit this car shit all together. In 30 years I have only found one person who does good work and takes care of the rare slip up immediately and politely. Wait, there is a second. So two in 30 years. Unfortunately one is a chassis guy and one does everything engine related except grind cranks.

[Dave Koehler]

325 for a grind 101 without issues? incompetent and slow based on his time.
Where does your one favored guy send his cranks?

[enginepieces]

This makes me sick to look at. The man need s his crank grinder taken away. They sell a radius gauge that you use and dress the stone to the radius needed. Then the stone is checked for the correct radius before grinding. There are good machinist out there you have to look long and hard to find them. Keep looking there always busy.

[BillK]

Just curious where you are located ? The guy that has been doing mine for a while is so busy he cant keep up. I keep telling him he needs to charge more $324 just to do the rods ??????? Wow.

[Ishiftem]

I’ll send it to my trusted guy to redo. He sends it out and he is really busy so I figured I wouldn’t bother him. That was a mistake on my part. The hack will get one more chance to make things right or it’s small claims court. I don’t care if it costs me money as long as it costs HIM money.

[Schurkey]

The hack will get one more chance to make things right or it’s small claims court. I don’t care if it costs me money as long as it costs HIM money.

You may need the shaft as-is, for evidence.

Can you find another shaft to get ground so that you have one to use?

[Ishiftem]

I doubt they would let me in carrying a 65 pound crank. I can see it now,”he has a bomb!”
Another crank is a non starter. I’m out of money after filling my gas tank.

[Ishiftem]

So I brought the crank back and he had a good explanation for why he did it. It’s an eagle crank and he said the fillet is not a perfect radius. So he would of had to choose what he thought was the closet radius which might cause him to cut into the cheek to clean it up and not leave a step in the fillet. Since this may open up the rod side clearances he didn’t do it. Makes sense to me. So he said he would do it again and grind the radius this time no charge as long as I understood the rod side clearances might be larger. I figure larger side clearance is the better than a stress riser.

[Dave Koehler]

uhh, nope

[Ishiftem]

uhh, nope

No on his explanation or no on looser side clearances are better than a stress riser?