Small V8

[Peter.]

That is some very nice work Steve!

cfellows: If I were to attempt a built-up crank I'd probably machine the pegs & holes with some small clearance then machine a jig of main journals from a substantial solid to hold all the pieces concentric then silver solder the assembly in one.

 

[Lakc]

That is some very nice work Steve!

cfellows: If I were to attempt a built-up crank I'd probably machine the pegs & holes with some small clearance then machine a jig of main journals from a substantial solid to hold all the pieces concentric then silver solder the assembly in one.

Thats how I tried the only multi-piece crank I attempted. It was an utter failure in the silver soldering aspect, but I will take the blame for that over the method itself. It did have the benefit of no offset turning at all, as the pins just fit into the throws which were conventionally turned.

From an engineering aspect, I worry about eventual fretting and fatigue at the joined sections. I recall a German avaition engine that used sectional crankshafts, it was joined with an inner pipe type section with left/right hand threads, and a Hirth joint to absorb the torsional stresses. I am looking forward to see how this pans out, quite a worthy effort!

 

[stevehuckss396]

By the way, how are you going to make the square holes? Doesn't look like you have enough room between the webs to use a broach... they're kind of long.

Im going to mill the squares with a 1/16 endmill. I did the same thing on the Bugatti crank and the square pegs went good. It was the disk that recieved the arm that stunk. This design has 1/2 the pieces that the bugatti had. Now some 4 years later my skills have improved (somewhat) and I hope this one will be alot better.

 

[stevehuckss396]

Hi Steve,
the problem I see is holding the accuracy of the locator hole so that when the crank is assembled it will be concentric throughout. If the squares and pockets aren't within very close limits the crank won't be accurate and I don't know how much rigidity it will have.

If you notice the center is drilled. I did that to use as a center finder when milling the square. I found center and then used the DRO to move around the part in a square. Should be darn close. The same will happen for the square pockets. The vise and V block are of above average quality so i believe it held the part as "straight up" as I'll ever get it. Keeping the fingers crossed.

I think I am still going to try a one piece with this 1144 bar. I like this stuff!!

 

[deere_x475guy]

Like I have said before my friend...you never cease to amaze me....very nice!!!!!! :bow: :bow: :bow:

 

[cfellows]

Im going to mill the squares with a 1/16 endmill. I did the same thing on the Bugatti crank and the square pegs went good. It was the disk that recieved the arm that stunk. This design has 1/2 the pieces that the bugatti had. Now some 4 years later my skills have improved (somewhat) and I hope this one will be alot better.

Me thinks you've acquired a fair amount of patience as well. Gotta give something like this a go for a 3 cylinder engine I want to build.

Chuck

 

[stevehuckss396]

Me thinks you've acquired a fair amount of patience as well.

That's fair. I don't seem to be in a big hurry like i used to. Also if a part needs a fair amount of setup and i'm too lazy to do it, I just go in for the night and do the work the next time i'm out there. I find that i'm not looking for that "short cut". You know, the ones that never work out.

BTW 4 down, 8 to go!!

 

[stevehuckss396]

And as I have to do all the turning jobs on this little “living room toy” lathe here (….ha ha ha….)

Achim, Sir!!

I have seen samples of your work and you would have a hard time convincing me that the "living room toy" lathe is holding you back. Your work is very impressive.

This crankshaft is experimental. I may be doing all this for nothing but I need to see how hard it is to do. Who knows!!

 

[kustomkb]

That's a very impressive crank you are holding there Steve.

I hope all continues to go well!

 

[dsquire]

That's fair. I don't seem to be in a big hurry like i used to. Also if a part needs a fair amount of setup and i'm too lazy to do it, I just go in for the night and do the work the next time i'm out there. I find that i'm not looking for that "short cut". You know, the ones that never work out.

BTW 4 down, 8 to go!!

Steve

Your text above that I have quoted tells us all why you are so successful with the delicate machining of the small engine parts. Patience, patience, patience. It works every time. Wishing you the best of luck with the rest of the engine, I'll be watching. :bow:

Cheers

Don

 

[stevehuckss396]

Hello all!

I spent some time making chips today. I cut all the crank pieces except the front nose piece. Then using the center hole. I found the center of the piece.

I used a 1/16 end mill and cut the square in the end of one of the center sections. At .010 per pass it took me 22 laps around the square to break thru.

I pressed the center section together with the rear section and with the 2 outside bearings held down the center bearing showed a few tenths runout. I took a short video of the test results. The crank disks show almost .002 runout so the journal must be about the same but I believe the runout in the bearing is taking up some of the error.

The video is very poor. The indicator is .004 full swing both ways. The needle is moving about .0004
[ame]http://www.youtube.com/watch?v=plfazkKtb8Q[/ame]


I think it would be worth cutting a few more squares and see what happens. If I can keep the runout to a few thou, I'm going drill and pin the crank and give it a try. Here is a picture of the next piece being pressed on. I used two, 3/8 inch tool bits and a deep socket. Not fancy but it worked very well.

 

[zeeprogrammer]

So depressing. I have a long long way to go to achieve that level of workmanship.

 

[Lakc]

I see I am not the only one who uses lathe toolbits for their squareness.

 

[Peter.]

I'd be careful doing that - I've found several of mine in the past to be less than perfectly square.

 

[stevehuckss396]

I GIVE UP!!! for now

This crankshaft is a failure. Seems when i held the pieces in the fixture, they were not aligned on axis so the crank arm axis is not parallel with the center line axis of the crankshaft. That means that the rods will wiggle in the cylinder bores and i cannot except that. I think what i'm going to do is carry on with something else and come back to the crankshaft at a later date.

 

[zeeprogrammer]

for now

You scared me.

Otherwise, I would have no worry that you'll get it.
I'll wait...anxiously...but I'll wait.

 

[deere_x475guy]

Ditto here, I thought the same thing at first...I know and understand how it goes..sometimes you just have to change focus for awhile...You will get er Steve. One thing you at least know what went wrong and can take corrective measures next time around. I am sure the rest of the gang feels as I do and really appreciate all your hard work and step by step details in the build.

Thanks again Steve!

 

[Maryak]

Steve,

Hang in there ;D

My computer failure this week combined with my mate holidaying in Canada have me in some form of burn out at the moment so I know where you are at. My concern is if I don't get back in the saddle soon the horse will go on without me.

So comes Friday it's Yippee Kayo and out with the whips and on with chips. :

Best Regards
Bob

 

[stevehuckss396]

You scared me.

Hahahaa!! I'm sorry!

I have spent this entire month with nothing to show for it. Time to move on to some valve cages or something. Need to get the energy in the shop back to positive!!

I started building one of those mini cannons that shoots BB's using flash powder. When i'm done (end of the week) I will get going again.

Zee, Deere, Maryak, I shall be back!!

 

[kustomkb]

Hey Steve, sorry the crank didn't work out. That's a lot of patient work that went into that.

Have fun with the projectiles and show us a video!

I've got something going to distract me from the hoglet too...