Crank snout turning nut

[Patcon]

We call that "tuition" around here. The cost of learning...

[Patcon]

@Captain Obvious

So I received the new tool. Short story is it won't work!

The internal Id they said was much closer than it is. Also the internal shape is all wrong. So back it will go

It would have been nice if it had worked because it will accept a degree wheel under the knurled nut

So I need a device with an Id like this

I believe that 1.373" with a key way that .205" wide

As an aside the LD28 crank sitting on another bench has the same snout OD. So this tool should work on pretty much everything L series

[Captain Obvious]

I get 1.378 OD off that mic (not 1.373). So it looks like that crank snout is 35mm.

So the one you ordered from Summit looks like aluminum? That would be easier for me to work with. Wouldn't last as long, but certainly easier to produce.

[Patcon]

I am not sure aluminum will be strong enough. Pretty sure it's steel because it weighs a couple of pounds

Expound on your mic interpretation

I figured it a 1-2" mic

so by default 1.something

little hashes put it 1.3...

approximately 3/4 makes it 1.37

Then 3 marks past zero makes it 1.373, correct?

[Captain Obvious]

OK. I thought it might be aluminum. I know I found a bunch of aluminum ones when I was searching around, but wasn't sure if that's what you had.

As for the micrometer... You got most of it right.

It's a 1-2 inch mic, so yes, it's 1+something.
And yes, the numbered hash marks make it 1.3 something.
And yes... The un-numbered hash lines are each 1/4 of the major hash lines

But since each of those minor hash lines is 1/4 of .100, it works out to twenty-five thousandths  (.025). And as you turn the thimble (the part that spins), you are counting up thousandths to add to the previous .025 hash mark.

So if the zero on the spindle lined up perfectly with the third minor hash line, you would be at 1.375  (1.3 + .075). But you're actually three thousandths beyond that 3/4 hash mark, so you have to add three more thousandths. 1.375 + .003, or 1.378

I whipped this up to hopefully help:

[Captain Obvious]

And forgot to mention... The other small numbers with the lines that run parallel to the thimble are vernier lines to estimate between the other lines.

So since your .003 doesn't line up exactly with the fixed line on the sleeve, you could use the vernier lines to get one more digit of accuracy. You are alllllmost at 1.378, but an RCH below that. Eyeballing it, I estimate it to be a tenth of a thousandth smaller than 1.378, or 1.3779. You can't see it around the back side of the mic in the pic, but I bet the small "9" line is lined up-ish with one of the marks on the thimble.

But for what you're doing, we don't need to split thousandths. 1.378 is good enough for me.

(As a side note... 35mm is 1.37795 inches)

[Patcon]

Thanks

[Captain Obvious]

Glad to help.

I'll take a look at what I have for raw materials around here and let you know.

[Captain Obvious]

So I found a chunk of stock that would probably work for a crank nut. It's not as thick as I would have liked, but it's what I got. However, before I got too deep into it, I wanted to verify measurements:

I'm going to make the ID to be a slip fit over a 1.378 shaft. Couple thousandths over.

You had previously mentioned that the key is .205 wide? I'm thinking "as long as the slot is wide enough that the device fits over the key, it will work". The goal would be to keep the amount of slop to a minimum, but since you're just using it to turn the crank, it really doesn't matter. There could be 5 degrees of slop and it would still work, right? I'm thinking you'll want to rock the force back and forth to get the motor unstuck, so slop like that would be "uncomfortable and feel cheap", but it would still work.

So how about the DEPTH of the slot? How far out of the crank does the key stick up?

And we already talked a little about the flats on the outside for using a wrench. Would just two flats on opposing sides work for your BFA? That would be the easiest to make. Square would be second easiest. And I could do hex, but it's just more work.

[Patcon]

Looks like the depth is less than 0.100" on several of the cranks that I looked at

Two flats is fine, if that's easiest

[ETI4K]

CO: Are you cutting the keyway with a broach?

[Captain Obvious]

Broaching would certainly be the fastest and easiest. The problem, however, is that I don't have a broach that width. I know I have 1/4  (.250), and I think I have 3/16 (.1875), but I'm positive I don't have .205

I'm thinking I might broach to 3/16 and then finalize the width of the slot on the shaper. That would be a lot faster than hogging all of it out on the shaper.

So to answer your question... I haven't completely decided yet? Haha!!