Modern Vespa

As I inch toward kicking off my major P200 build, I'm accumulating bits and pieces of tooling, knowledge, and parts. One of my design decisions is that I want to run a 62mm crank, which is great, but requires that you grind 1mm off the crank case to fit the crank.

This is something that people normally either send out to a machine shop or just obtain a CnC mill to do, neither of which were easy options for me.

So instead, I built a jig for grinding out crank cases.

I was texting with CM2 last night about it and had the idea of how I could build a jig to do it myself. The funny thing about it was that he imagined more-or-less the same design as I did while we were discussing it.

So anyways...tonight I headed over to the hardware store and bought a 5/8" bolt, some 5/8" nuts, and a 1/2" nut for the grand sum of $2.45, and headed home to see if I could realize my vision.

And I did. Using an old main bearing and some scrap angle iron, I was able to build a jig that holds the flex attachment for my dremel and rotates in the main bearing housing. The arm slides in and out to allow different size cutting heads and diameters, and the entire housing sits on the bolt, which I welded into an old bearing to provide centering.

Tomorrow, I'll actually put it to the test on my trashed Stella cases, then work on a mount for the fly side cases. I think they'll be similar, I'll just change up the attachment of the bolt. It'll probably be something similar, only leveraging a two-part bearing for centering and bolting in place.

the 1/2" nut isn't quite the right thread for the Dremel, but it was what I could get at the store. I'll get the correct pitch and cut that one off once the time comes.

More to come on this, but I'm pleased with where it's at right now. Not bad for $2 in parts (I didn't use all the nuts) and a couple hours of my time.

It's a movement!

Great, well done Cheap and easy. Not peeing on your fireworks but there is a but: With many of the 62mm cranks the main case side doesn't need machining, just the flywheel side case.

Ohhhhh
Ahhhhh

Exciting things afoot.

I'm already working (well, thinking) about how to do the fly side. The clutch side was just easier so I could prove out the concept. Fly side will be more-or-less the same, just need to center on an old two piece bearing sleeve, which means prying one off an old crank and getting another bolt.

I didn't really didn't think the whole thing through when I started, but it'll get there.

mad scientist mode ON, word

I already snuck out to the workshop and confirmed that I can use the same bearing mounting technique for the fly side. I even punched the bearing out of the case, ground it down enough to pressure fit, and confirmed it.

If I'd just thought to get two bolts at the hardware store, I'd be posting pictures of the fly side now.

That's cool. Looking forward to your updates.

I once contemplated setting up a slide vice drill press milling arrangement. Don't know why it never happened.

Could you build a big flapper wheel and sand off a mil or two? Use the bearing to hold a rod of some type in the center and spin the other side with a drill?

I'm not sure I quite understand what you're describing, but the idea of sanding off a millimeter sounds like less fun than winding my contraption around the crank case a few times.

Sketch a picture if you can. You can see what my high-qwality engineering diagrams look like, so no need to be shy.

Substitute your center bolt, adjust wooden center diameter as needed. Made a few of these over the years for various projects.

Hah! I should have taken my dogs for a walk because the weather was nice, but I just sat around and worked all day instead.

Oh, yeah. And finished my jig.

I made a few quality of life improvements and have a few more still to do, but it's very viable even in its current form.

You can see where the cutting wheel hung up for a moment, but even that I could live with.

Ingenious man. Love it.

That came out really good.

Yeah, I was really pleased with my results.

I'm going to go back and finish off the fly side, then sand it a little to see what the final result looks like, but so long as I don't mess up the execution I think it's quite workable.

Just saw the vid.
Nice job!

Gracias!

It might not be quite as accurate or versatile as a CnC mill, but it's a lot easier to store

It doesn't need to be that accurate for what you are doing but it will make fitting up easier and it doesn't look like ass.

This is a boring thread.

<<<<I'll see my way out the door lol

You should try the ves-pi thread. At least I talk about strippers over there

Well what you did was boring.