917 180 degree V 12

[Vixen]

A little doodling.....with my computer.....

It scales pretty close!....

1" bore x 0.812 stroke
40 tooth 32 DP crank and power take off gears.

Crank is about 10" long.....

That looks to be a sound basis for the design. You can add more and more detail as the design progresses. A 3D model which you can rotate and view from any angle will allow you to spot any potential collisions before you commit to cutting metal. Nice work.

Remember it is all about the journey, so enjoy every step

Mike

[steamer]

Yes it is about the journey!    AND who you take with you on the trip!!!

The case thus far is a very simple piece...it'll get more complicated as I add detail, but as it's a "prismatic" part, I shouldn't need any super special fixtures....

That crank.....I'm still torn....what I'm going to do is make the Wallaby crank using the method I have in mind, and see how that goes before I decide to make the crank 1 piece or 2 piece.....
Any way you look at it, the oil passages will be ...nerve racking.....

Dave

[Vixen]

Dave
Those oil passages are always nerve racking, even if you have done it many times.
My method is to do it all on the mill, start the oil passage with a 2 or three flute mill cutter of the required diameter and follow with a good quality (new) short stubby drill of exactly the same diameter. Then progress in stages with longer length drills all of the same diameter. I try not to have much unsupported drill exposed because that is where the bend wants to occur. I peck drill and remove the drill to clear the swarf every few mm. My record to date is four 120mm deep, 3mm oil passages which all hit a cross drilling within a few thou.
Yes I know, thous of an inch and mm but I am an engineer so trust me !!!!!!! 

Mike

[steamer]

No doubt in my mind Mike!   

I'm going to try to mill the crank from solid ala the Duclos method...then perhaps give it a little lap.   I'll try that on the Wallaby...and see how it goes....

With the 917 crank...there are only 4 centers...so not too bad.

Dave

[Tennessee Whiskey]

I'm reading this thread like the SI swimsuit edition: can't do anything with it,  but,  sure do enjoy it  . Wonder if one of these would come in handy at build time
http://sherline.com/product/8650-cnc-cam-grinder/

Cletus

[steamer]

Sure would!!!! so would the $3600 too!     I'll mill mine......

Dave

[b.lindsey]

Sure would make a pretty cam though. 

Bill

[steamer]

Sure would make a pretty cam though. 

Bill

Hey Bill!     That would make a great item as my stocking stuffer!   Christmas is coming!!! hint hint!

[stevehuckss396]

Steamer!

Have you looked into offset turning your cam on the lathe? The advantage would be cutting all the lobes at the same time in one 360 degree rotation. Save you a ton of time. Specially if you are doing 4 of them.

[steamer]

I have , and probably will!    it's a good way to do it!

Dave

[b.lindsey]

Do I look like Santa Clause    I may have the figure, but not the beard and my hair ain't white yet   

Bill

[steamer]

Great thread for reference.

4 carbs feeding 12 cylinders......this was described earlier in this thread, and this thread shows this concept working and in action.


http://www.modelenginemaker.com/index.php/topic,4241.60.html

Dave

[Mosey]

Dave,
Have you seen the "How It's Made" tv show on Discovery where they make a Jaguar crank by cutting the blank from a solid bar with a large diameter toothed cutter in the lathe. The Camshaft is done similarly. One rotation of the blank and a nearly finished crank emerges.
could it be done in the home shop?
Mosey

[steamer]

Dave,
Have you seen the "How It's Made" tv show on Discovery where they make a Jaguar crank by cutting the blank from a solid bar with a large diameter toothed cutter in the lathe. The Camshaft is done similarly. One rotation of the blank and a nearly finished crank emerges.
could it be done in the home shop?
Mosey

I think you could if your machine is stiff enough.   Additionally, the machine in the video had 2 chucks,  headstock and tailstock.    That would add a lot of stiffness to the system, something traditional centers don't have.

Dave

[steamer]

http://www.roadandtrack.com/car-culture/buying-maintenance/a9955041/watch-a-porsche-917-flat-12-get-rebuilt-in-three-minutes/


I'm working a lot of hours right now, but I saw this and thought of you guys.....I'll get to it


notice the shims on the cylinder heads to get the cam boxes all aligned?.....

Dave