EN8M FLAT

[Dougie SwanParticipant @dougieswan43463]

Hi

Can anyone point me in the direction of a supplier of en8m flat steel

I’m looking for something close to 5/8 x 1 3/4

Or recommend a suitable alternative for a crankshaft

Thanks

Dougie

[JasonBModerator @jasonb]

M-Machine list a few flat EN8 sizes but not large enough. In the past I have cut flat twin cranks from round bar milling a bit of each side in turn to prevent warping. This ebay seller has been quite reasonable on costs in the past and he does black EN8 which should be less likely to move. Not sure what will work out cheaper a length of 50 or 60mm dia or a short 20mm slice of 160mm dia.

[Dougie SwanParticipant @dougieswan43463]

Thanks Jason

Is there much difference between en8 and en8m?

Dougie

[Dave HalfordParticipant @davehalford22513]

Rapid Metals do 170mmdia x20mm +vat etc for just over £13

Or they can cut a block in en24, but you need to ring them for that.

[JasonBModerator @jasonb]

The EN8M is a bit freer machining than EN8

[Clive Brown 1Participant @clivebrown1]

Granted that en8 is stronger than mild steel, but is there any real advantage in going to the extra cost and procurement difficulties of using it for motion work? Most designs, steam and ic. that I’ve seen call for mild steel, the vast majority of models  built over many years probably have used it and I’ve never seen any reference to mechanical stress failure resulting from its use.

Ps; there might be a case with small aero engines which regularly crash on their nose!

[JasonBModerator @jasonb]

A lot of IC engines call for EN8 for the crankshaft and that is where I have used it. My way of looking at it is that I’m going to spend a lot of time making a crankshaft so the extra piece of mind is worth the small cost difference and having to chop it out of bigger stock.

Having seen the results of a backfire twist a  3/4″ PGMS model’s crankshaft it is not just crashing you have to consider.

This is the crank in question

[Roger BParticipant @rogerb61624]

This C45k keysteel might be an option although it has the problems of odering from outside the UK:

https://www.rcm-machines.com/en/materials/steel/flat/c45k/stretched-steel-sheet-c45k-60-x-15-x-300-mm/rcstf60-15

I have used this for several crankshafts including a 20 cc diesel with a compression pressure of ~40 bar. It also survived ingesting a M3 grubscrew.

 

 

 

 

[Author]

Posts