L1418 steel?

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jack620

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I'm building a pair ML Midges and my plans call for L1418 as the material for the cylinder. A Google search provides nothing on this material. Is this a discontinued grade of steel? Can anyone suggest a suitable alternative to mate with the cast iron piston?
Cheers,
Chris
 

idahoan

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Was it maybe 12L14 which is a nice free machining steel available here in the states; I'm not sure what the designation would be in Australia, but the (L) mostlikely means that it is leaded (hence free machining).

Dave
 

Swifty

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The L would denote that lead has been added which would probably make it a grade of mild steel. Can't find anything on it either.

Paul.
 

jack620

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Thanks guys. It definitely says L1418. I have some 1" round bar in 12L14. Is that a suitable material for a cylinder?

Paul, where do you source your steel? I like Lockbar in Cheltenham.
 

idahoan

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I don’t see any reason why not; some guys say that rusts quite readily. I would use it if it were me.

Dave
 

lensman57

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I'm building a pair ML Midges and my plans call for L1418 as the material for the cylinder. A Google search provides nothing on this material. Is this a discontinued grade of steel? Can anyone suggest a suitable alternative to mate with the cast iron piston?
Cheers,
Chris
Hi,

I won't go to court with this but if they have followed standard designation then,
L means loww alloy, special purpose
1 means it is a low carbon steel
4 means the alloying element is molybdenum
18 should mean that either it is 18% carbon or there is 18% alloy there, I am not quite sure about this!!

The only reference that I could find is to do with worm gear production, meaning that it is a tough wearing steel, perhaps that is why they used it as liner.

If you are not going to use the engines for real prolonged flying then perhaps you should consider a free cutting steel ( EN1A pb ) or EN24 T ( UK designations ), the later could be surface hardened as it is primarily used for gears and shafts. I do not know the ML midge design but I hazard a guess that even cast iron could be used as a cylinder liner.
Isn't ehgineering fun?

Regards,

A.G
 

jack620

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Thanks Lensman. I thought the L meant leaded? I found the worm gear link too, but I had assumed L1418 was the part number given that there were no other hits.

I don't think we use the ENxx designations in Oz, but hopefully one of the more knowledgable Aussies will chip in an clarify that.
 

lensman57

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Hi,

EN1A pb is roughly the equivalent of the 12L14 US designation, it has a machinability factor of 150 against 100 for EN1A ( still free cutting ) and 50 for EN24 T, so it is super easy to machine and achieve great finish.

Regards,

A.G
 

Swifty

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Lensman, 18% carbon would make it a high grade tool steel, I don't think that the "18" refers to this.

Chris, yes, I also use Lockbar steel supplies, also Handyman Steel Supplies in Moorabbin.

Paul.
 

jack620

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Thanks again. I have machined 12L14 and I love it. So the question is, is EN1A pb (equiv.12L14) suitable for cylinders, or does the addition of the lead make it too soft for that purpose?

Thanks for that Paul.
 

Swifty

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I don't think that the addition of lead makes it any softer, it's added to make it easier to machine, but no good to weld. The lead stays in suspension and does not homogenise with the steel, this is evident when you try to weld it as small pock marks appear where the lead is burnt out by welding.

Paul.
 

jack620

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Thanks Paul. Just out of curiosity, what grade of steel do you use for cylinders? Or do you not use steel?
Chris
 

lensman57

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Hi Swifty,

I will dig out the information just to refresh my own memory.


Regards,

A.G
 

lensman57

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Hi,

The 18 denotes that there is 0.18% carbon in the steel not 18% as I first stated. BTW I was browsing through Timken site, they claim that they have over 300 standard steel alloys and some special purpose ones. What a minefield. In any case this steel seems to be an elusive one.

Regards,

A.G
 

jack620

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I'm starting to think this steel doesn't exist A.G. I'll wait to get some more feedback on the suitability of 12L14 before I proceed any further.
 

Swifty

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Chris, haven't made any engines like that. Whatever you use, make sure you lap the cylinder to get a fine finish. Just have to watch out for seizing between piston and cylinder.
Other members have a lot more experience on these type of engines, may just have to wait until they wake up on the other side of the world.

Paul.
 

jack620

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No worries Paul. While they are snoozing I had a brief look on Google. It appears plenty of people have used a 12L14 cylinder with an aluminium piston and cast iron rings. I assume from that it would be OK to use a CI piston in a 12L14 cylinder. My ML Midges will only be static models and most likely never clock up more than 1 hour of running time in their (or my) life.
Chris
 

Tin Falcon

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Lots of questions here but will attempt to keep it simple. Knowing more about the plans time period and country of origin could all lead to what the author of the plans interned.
looking up steel specs in an older Machinery handbook could yield the answer.
Here is a basic cross reference chart.

http://www2.coromant.sandvik.com/coromant/pdf/smallparts/catalogue/P144-148.pdf
another got to book for metals is
AEROSPACE METALS - GENERAL DATA AND USAGE FACTORS 1-1A-9


http://www.robins.af.mil/shared/media/document/AFD-091006-039.pdf


as far as lead-alloys the main benefit of adding lead is added maintainability the downside is it destroys the ability of a steel to be welded.


McMaster carr sells 41L40 witch is a chrome moly steel that has high strength but added lead for added machinability.
Tin
what size material do you need .
Tin
 

Ramon

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Hi Chris - mind if I jump in here again?

I have built several diesels now all bar one at 5cc and all have cast iron pistons. The first a 'Nova' used En1a leaded steel (12L14 equiv) for the one piece cylinder fins and liner. This was primarilly chosen because of machining the very thin fins required. Despite my initial doubts over whether this would stand up to running for any length of time the piston seal on this is as good as when first made and it runs well.

However, not quite sure that this was actually a good combination I sought advice on the ME forum the upshot of which the next two engines - 5cc 'ED Racers' - used a cast iron liner in one and a high tensile steel in the other. The 'cast iron in cast iron' soon lost its initial seal as it bedded in but still works ok. The high tensile steel version, though providing a lovely finish and seal proved tough to cut the porting.
Personally speaking I would not go down this High Tensile route again....

Just after these were made I found I had an article squirreled away up the loft. This was by a 'George Aldrich' who was recognised as an extremely knowlegeable person in the model aircraft world when it came to piston/liner fits particularly on competitive motors. Indeed in later life he earnt a living by re-working model engines.
The article extolled the virtues of using the 'CIS' system - ie Cast in Steel. The steel recommended was leaded freecutting 12L14

The next engines I made then - the Eta's - used this for all three cylinders - very easy to machine and lap, no distortion and very good verging on excellent piston/liner seals. They run extremely well.

The last engines made - the Super Tigres (described on here somewhere) also use this combination. Since making those I have become aware that several engine manufacturers also used this combination on commercial engines - perusal of the pages on MEN will confirm this and it has also been used in some home built racing engines where out right performance is obviously the goal but for me personally it was/is the article by 'GMA' that swings it for me.

Cast iron in leaded steel is a good 'bearing' combination and it appears that this is also true for this application. Given the engines we make are unlikely to ever be required to work long and hard my initial doubt over the longevity of piston seal has proved to be an uneccessary one.

The only thing I would say is that as the bore gets smaller the quality of fit of piston to liner needs to be as near perfect as you can get it. It maybe that on very small bores a much tougher (harder?) surface is required as any wear will be quickly noticeable but I would certainly not hesitate to use it (12L14) in the first instance.

I've described how I approach fitting these parts on the Tigre thread if that's any help - not my ideas originally - yes, you guessed it - those of GMA :)

Hope this goes some way to allaying any doubt you may have.

Regards - Ramon
 
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