what is l24 steel?

[werowance]

hi, i am reviewing plans for the bj cicada engine and notice that it calls for "L24" steel for the crank and some other parts. was just wondering if this was hard steel like drill rod or soft steel like 12l14?

it also calls for 2024-t3 aluminum for other parts - in particular the rod, anything you all can think of that would be a decent substitute? i read someone else suggesting bronze, but i dont have any of that handy either. i do have plenty of scrap 6061 aluminum if that would be usable.

what do you all suggest?

 

[Jasonb]

The best combination to go with the cast iron piston would be 230M07PB which in the US is 12L14

2014 is another suitable ali for the rod, you need a higher tensile for this part so the 6061 will not be suitable unless you want the holes to stretch!!

The crankcase, head, carb and infact all the other aluminium parts can be done in 6081 or 6082 with the exception of the rod mentioned above and as it does not have a press in front bearing then I would also make the Front paring part #2 out of 2014/2024 as well due to its better bearing qualities

You could up the OD of the bearing nose to 0.500" and bore it 0.318 and then press in a 0.250" bore bronze bush in which case it could also be done on 6081/2

 

[werowance]

i think i have found out that L24 steel is a actually a wrought iron product? can anyone confirm this as true?

if it is, for the crankshaft that the cicada plans call for, what could i substitute for it? i will have enough fine grain cast iron that i will order for the cylinder hopefully to make it from, and i already have enough 12L14 and also plain old cold rolled laying around. would any of those be suitable for the crankshaft?

 

[Swifty]

You will find it designated on this page http://books.google.com.au/books?id...ved=0CCgQ6AEwBA#v=onepage&q=L24 steel&f=false.

If I was making this engine, I would use 4140, which is a high tensile steel.

Paul.

 

[werowance]

ah, ok, so not iron. tool steel i see, thank you for that link to that will be handy.

 

[Swifty]

ah, ok, so not iron. tool steel i see, thank you for that link to that will be handy.

L24 would not be classified as a tool steel, it's just a low carbon steel, 1% carbon, with some manganese and silicon.

Paul.

 

[werowance]

ok, looking to buy the 4140 steel for the crank, and i am mostly seeing "pre-hardened" since i dont know how hard 4140 can get unless its like drill rod when hard and is a bugger to cut on the lathe after hardening, i ask, should i look for non hardened 4140 or will pre hardened still cut ok?

also when i started a search for 4140 i am seeing alot of pins for equipment like for back hoes and such, since i happen to have several track hoe boom pins in my scrap pile, wonder what they are likely made of? i have cut those and they are hard but are turnable. anyone think those pins might be acceptable? if not ill just get the 4140 online once i find out if i need pre hard or non pre hard

 

[Swifty]

"4140 in the hardened and tempered as supplied condition has good to very good machinability and operations such as sawing, turning, drilling, broaching, hobbing, milling and tapping can be carried out satisfactoraly using machine manufacturers recommendations for suitable tool type - feeds and speeds."

The above quote is from one steel supplier, all it means is that the steel is pre treated, you will be able to machine it without a problem with HSS or carbide. Just watch your speeds and feeds and you will be OK.

The backhoe pins that you have are probably acceptable for use.

Paul.

 

[MachineTom]

Pre Hardened 4140 is nice stuff, Around 25-30 R-C,It cuts nice bimetal saw blades suggested,HSS for tooling works well. My experience 40 years ago with backhoe pins was they were almost file hard, way way above PH 4140.

4140 can be hardened to very hard material. I like 1144 commonly called Stress Proof, Very strong, not brittle, does not work harden.