Stresses in machined crankshafts – Whittle V8

[Steve WithnellParticipant @stevewithnell34426]

I managed to get a long way down the track in machining a crankshaft for the Whittle V8, before I broke it!

 

Anyway the point of the post is that before I scrapped it, the part rang like a tuning fork. The fact that it broke rather than bent when it hit the toolpost suggests a lot of stress going on (and that I’m a muppet…) The material is EN8.

 

I’m on with my second attempt at making the crank – should I consider any form of stress relief? I did think about annealing the material and then re-harden, but suspect that will put the stress back and cause other problems.

 

Regards

 

Steve

[Steve WithnellParticipant @stevewithnell34426]

[Gray62Participant @gray62]

Hi Steve,

I suffered a problem with my first crankshaft for the Whittle V8, although I bent mine rather than it breaking. I am making mine form EN16 which seems to machine a little more forgiving than EN8. That said, I have roughed it out and left it to ‘relieve’ for a while. I found that the main problem was finishing the centre bearing as having finished the other cranks, the resulting lack of rigidity caused the centre bearing to ‘bounce’ against the tool.

I am now looking at a jig to finish all the bearing surfaces in the mill so that all of the crank si supported during the final finishing operations. I feel that machining in the lathe is doomed to problems.

There are many threads regarding this issue, here is one,

http://whittlev8.wordpress.com/

 

Google Whittle V8 and you will find many threads on this subject, there is also a yahoo group for this engine build.

PM me to collaborate on this, I amin Hampshire if you are local I would gladly meet up to discuss the build

regards

 

Graeme

[David Clark 13Participant @davidclark13]

Hi There

Model Engineer issue 4405 has the start of a series about building a doubled up version of the Whittle V8.

On sale in about two weeks or so.

regards David

Edited By David Clark 1 on 19/05/2011 20:23:33

[Author]

Posts