460/660/395xp hybrid?

[Rich Fife]

Well, this is a little different build than all of my previous builds... I have a bunch of parts kicking around, some parts I forgot about.
I'm starting with an 046 case, a 395xp crank, a 660 big bore cylinder and either a 395 or a 661 piston... I won't know the exact route until I get the case together. Below are some of the parts as well as the progress thus far.

 

[Rich Fife]

A quick sketch of the cranks (046/395xp)

 

[Rich Fife]

Well, I decided to pull the 395 crank apart and do it the tedious way.
Once apart, I faced the ends of the pin to match the length of the 046 pin. I decided to 'polish' the pin...

 

[Rich Fife]

Now that the crank halves were separated, I needed to find a way to be able to turn them in a lathe. I figured the easiest way would be to make a modified lathe dog.

 

[Rich Fife]

After thinking about the lathe dog... I decided to add another "driver"...

 

[Rich Fife]

At this point, it was time to see how true it runs.

 

[Rich Fife]

With the run-out being WELL within spec... It was time to start thinning the halves.

 

[Rich Fife]

The finish wasn't the best but it's smooth and spot-on size.

 

[Rich Fife]

Tomorrow the plan is to have the crank back together, dialed-in and tig welded... more to come soon.

 

[fredx]

With the run-out being WELL within spec... It was time to start thinning the halves.

well within spec.-- what is the spec? .0015 TIR? Where do you find the specs / tollerances? Nice job so far!

 

[Rich Fife]

well within spec.-- what is the spec? .0015 TIR? Where do you find the specs / tollerances? Nice job so far!

Well within my spec... the shaft was at .0002" of runout. Which, if the shaft was originally turned between centers, it should be concentric or easily Well within .00025" from one machine setup to the next... (if everything is correct)... I'll have to do a video of the runout.
This is a perfect way to check to see how well the manufacturer did when making a crank half... or checking the alignment of the tail stock etc.
Only downside so far is the shafts werent as hard as I would've liked if i was going to use it for a replacement... however, I do like how soft (mid to high 40s on the c-scale) it is for turning/modifying in a lathe. If the shafts were induction hardened and then ground to size/spec... this would've been a Nice replacement crank for cheap. The casting was actually really clean, uniformly smooth.

 

[Rich Fife]

Started the other side of the crank...

 

[Rich Fife]

We made our cuts, hit our dimensions and cut the M8x1.0 threads.

 

[Rich Fife]

While thinning the crank we had a decent show of sparks.

 

[Rich Fife]

I had to use the old South Bend and cut the LH threads for the clutch. These threads are supposed to be M12x1.0... my lead screw doesn't have the correct pitch so I used 26tpi. Some might say that's wrong... and I'll agree but, it works. These threads are only 5/16" in length so the thread difference is very minimal and they work in a pinch.

 

[Rich Fife]

Clutch side shaft complete.

 

[Rich Fife]

The fitment of the flywheel and the taper on the shaft is uniformed. The clutch and accessories fit perfectly.

I'll have to match the counter weight lengths and then it'll be a matter of putting the crank halves together and dialing them in.

After that is complete, I'll have to assemble the saw and do a mock up for ignition timing.

 

[Rich Fife]

I'll be posting more videos that hopefully explain things better.

 

[Rich Fife]

Showing the fitment

 

[drf256]

Impressive work Rich. Thanks for the thread.