liner stock in tube form?

[petertha]

I'm gathering a materials list for my next project, an opposed twin. The cylinder liners measure 38mm OD x 35mm bore x 57mm length. On my radial I bought cast iron solid rod & was happy with the machining & final result. But obviously a high percentage becomes swarf. & even more on this 1.5" nominal bar size. I thought about pre-drilling the core out with an annular cutter from both ends to reduce time & waste, make use of the core slug. Its not the end of the world but just wondering out loud if there is another option that should be considered? Are there appropriate alloy tubes? I've seen 4140 but not sure about heavy wall & on a bit uncharted waters if its a desirable liner material.

[Jasonb]

Look for "Durabar" Hollowbar. but not sure if they go down that small.

[john mills]

i have used hollow bar  close to those sizes but local manufacture i believe is no longer it will depend on what local suppliers have .
when i was running a cnc lathe  making rings and seals they just used solid bar and machined it .big pow full industrial machine
it was quicker to use a size of bar that most parts would come from and machine it away lots of swaf but it was cost effective
John

[Jo]

Hollow bar in cast iron needs to have a wall thickness of 1" to prevent internal features forming during the casting process.  The diameters you are talking about are less than two wall thicknesses which is why on our models we find ourselves machining out of solid  .

You can definitely get suitable bronze hollow bar of the sort of diameters you are talking about but I am not sure about what alloy, other than aluminium bronze, would make a good liner.

I suspect solid cast Iron bar is going to be cheaper and easier to come by than anything else  .

Jo

Edit: I read Alloy as Aluminium alloy, the one you referred to is steel. Yes a steel alloy could be used as a liner.

[Jasonb]

If you wanted to go down the steel route then I have seen several engine designs that specify DOM (Drawn over Mandrel) steel tubing, something like 40OD x 30ID would yield what you want though it is actually a seamed tube.

Or you may even be able to find some honed hydraulic tube in 35mm bore which typically has a 3.5,5, 7.7 and 10 mm wall. and you would not need to touch the inside.

[Zephyrin]

there is a large choice of seamless steel tubes!

I have used small bit of 20x25 mm tube for cylinder liners. the internal geometry and surface was better than I could achieve with turning. the steel was rather soft, and easy to machine to the dimensions of the engine block.
cylinder from pneumatic or oil cylinder locks could do it maybe...

[vtsteam]

Hollow bar in cast iron needs to have a wall thickness of 1" to prevent internal features forming during the casting process.  The diameters you are talking about are less than two wall thicknesses which is why on our models we find ourselves machining out of solid  .

These iron castings I made for cylinder stock have about 3/8" wall thickness:





I've cast thinner and smaller, notably an experimental casting 1-1/4" OD,  3/4" ID on a removable steel core using a soot (carbon) release.

[crueby]

For larger bores, there are also a wide range of automotive cylinder liners in cast iron available. I have not seen them down below about 2", though maybe they are for smaller engines (like chainsaws).

[Roger B]

I have core drilled various cast iron and aluminium parts using hole saws.

[gldavison]

I made some liners for my Snow engine several years ago from thick wall, seamless, stainless steel tube.  It was suppose to be 1" ID, but I had to bore it too 1.062" to get a clean bore. I used Vitron o-rings, and that was 10 years ago. It still running great.

Gary

[Mike R]

I initially tried making the cylinders for my radial from 4140 as was called out on the drawing.  I had a terrible time machining it on small flexible machines.  It left a terrible surface finish and I eventually gave up and went with other material. This was a few years ago and I've become a better machinist since then but I still think it doesn't play nice in home hobby shops. 1144 machines much better and I found my local supplier wasn't charging much different for it versus 12L14.

[steamer]

Cast iron or 1144SP....at least on this side of the pond

1144SP has a 100K to 125K yield, and has a machinability rating of 83%   ( 12L14 is 100%)    It takes a great finish and is tough as nails, but machines really nice.   HSS will do if you don't push it too hard, but it responds well to carbide in light machines.'

I use it all over the place...   Good stuff!

Dave

[vtsteam]

Just thinking.....old cast iron radiators came in many different forms, but some of them had tubular sections with about  3/4" ID, and maybe a decorative set of ridges on the outside, and say 3/16" or better wall thickness.

I have one now in my scrap melting pile: each radiator section has 3 tubes of maybe 16" usable length. Times as many sections as the radiator has. That's about 4 feet per section times say 12 sections, or 48 feet of 3/4" ID cast iron tube. Might be a lifetime supply if you make small engines.

[crueby]

I like that hole saw method - did it need to be a particular type, or will the ones they sell for cutting doorknob holes in doors work okay? Seems like a great way to still have some usable material from the bar.

[steamer]

Just thinking.....old cast iron radiators came in many different forms, but some of them had tubular sections with about  3/4" ID, and maybe a decorative set of ridges on the outside, and say 3/16" or better wall thickness.

I have one now in my scrap melting pile: each radiator section has 3 tubes of maybe 16" usable length. Times as many sections as the radiator has. That's about 4 feet per section times say 12 sections, or 48 feet of 3/4" ID cast iron tube. Might be a lifetime supply if you make small engines.

Steve,  Beware!    there is a big difference between "cast iron" and Durabar from the perspective of material consistency, strength, and machinability.    Generally stay away from "Cast Iron" and stick with a Meehanite iron.   Meehanite is a trade name for the process of a very good iron that machines well and has great properties.    Cast Iron is what ever they find on the foundry floor!.....and trust me you don't want to machine it!    It's nasty.   Save the cash up and get the durabar.    You'll thank me.

Dave

[vtsteam]

Well Dave I cast my own iron. Since cylinder liners were mentioned, generally for models at least, the cylinder itself is support for the liner.

I generally use disk rotors as melting stock, but might modify that with a small amount of radiator metal which has a fairly high phosphorus content for more fluidity. I do test my iron when anything critical is needed with the old hammer in vise test. Generally anything I cast is way over-built anyway. Nothing as technical and refined as your Porsche engine!

[vtsteam]

Just an FYI re. disk brake rotor cast iron and home casting strength, a cast crankshaft and destructive test:

<a href="https://www.youtube.com/watch?v=iNo5N7-zBis" target="_blank">http://www.youtube.com/watch?v=iNo5N7-zBis</a>

and a pressure test of a home foundry cast iron steam cylinder:

<a href="https://www.youtube.com/watch?v=-Tp30p84Wf8" target="_blank">http://www.youtube.com/watch?v=-Tp30p84Wf8</a>

[petertha]

Thanks for input & advice.
- sorry I had not realized 'alloy' might infer something different but yes I meant cast iron or steel
- I've machined 1144SP for my radial crankshaft. It was tough stuff but finished predictably with nil post machining distortion. I don't see it in tubular form, so probably no advantage if solid rod is only option
- re the 4xxx series I've also heard mixed reviews depending on the specifics or maybe heat treating. Cost wise not much different than CI at least where I can shop
- the comment on why no hollow CI makes good sense, didn't consider that. I saw hollow Durabar but it was like 4" OD with 1" OD

So I suspect CI it is. I'll experiment with drilling out the the core with annular cutter. I did that on my aluminum cylinders & worked well.

btw this is what I used on my radial. It has not run. Waiting for winter to end. But, knock on wood, seems to be holding pressure if I did the tests properly.
https://www.speedymetals.com/pc-4277-8388-1-12-rd-gray-cast-iron-class-40.aspx

[steamer]

Sorry Steve I didn't know you cast your own my impression was that you were thinking of sawing some out of a radiator .
Brake rotors worked well for.my steam launch engine. 
The Construction of the Steamlaunch “Rushforth” http://www.neme-s.org/The%20Construction%20of%20the%20Steamlaunch.pdf

Dave

[vtsteam]

You were right the first time Steamer, I did mean trying radiator casting tube as possible cylinder liner or material for small simple steam engine models, assuming one doesn't have the money or access for more expensive stock. I've built a small piston valve uniflow single using only cast iron plumbing fittings steel pipe and nails for raw materials, as a fun challenge. Runs quite well. A small pic of it is my avatar here.

If I were building a Bentley, I would be buying every bit of material, and only the best. But much fun can be had by raiding the scrap bin or the local hardware store bins for modest engines. And for some people it's as much fun and a challenge as anything else.

That is a beautiful boat you've got there, file bottom sharpie in hullform it looks like, and it must be a great pleasure steaming along. I'm envious! 

[steamer]

Well    A long time ago in a galaxy far far away I was working for a machine tool company for a man named Bobby Rainville.     He was my boss and my mentor, and my friend.

I was in the engineering office, and he barged in from the production floor and said   "Get your glasses and come with me!"

OK!

I was a bit taken a back, Not knowing why we're marching with alacrity out to the production floor, I was thinking what was this all about?  Clearly Bobby was kinda cranked up about something.

He brought me over to a big VTL   ( 52" table), The machine shop covered 13 acres, and on this VTL was a big faceplate casting having the OD turned....the operator was clearly more pissed off than Bobby!

Bobby said walk around the back of the table and tell me what you see!....OK!    Now I didn't know this part, or the machine it was going on....and I still wasn't sure why he was so fired up!

I looked at the partially machined OD of the faceplate, and astonishingly, I could plane as day see the outline of a railroad spike buried in the iron, and it was breaking tools because it was harder than woodpecker lips as it had been carburized and quenched during the pour.   Don't know if it was in the mold, or in the crucible, but it was certainly right there!   

You see it?!....Yup!....OK come here!

I walk back over and he points to the title block on the print for the faceplate...which lucky for me wasn't mine!....and it stated in the material block   "gray iron"

Bobby then went on a tirade about NEVER EVER   capitalizing because well Bobby was friend and a "Cunuck" and he'd get wound up occasionally.  ( his words not mine)

Never NEVER put gray iron on the print.    You will put!   Meehanite GC40 stress relieved to 220 BHN+/-20 %!   Then you'll get a nice piece of material, and not make these guys kill themselves trying to save a casting!    Yes sir!  I replied....now doubly grateful it wasn't my part   LOL.    

Later when he wound down a bit, he pulled me aside and said he was just really frustrated that the person who did that, who knew better, and wanted to make sure the young Engineer in a galaxy far far away, didn't befall the same fate!

And I will never forget it!   ....35 years later.....

So that's where that came from Steve.    The boat was a lot of fun to build!, and alot of work!.  to say nothing of the engine and boiler.    I still have it, and hopefully this year it will be back out on the water.

Dave

[Dave Otto]

Great story Dave!

Dave

[vtsteam]

Good story Dave. But the foundry did not provide what was requested. The foundry was at fault, and frankly so was the engineer who qualified it, if what was to be normally expected from that foundry in grey iron was faults and inclusions so gross as to be readily identified as a hardened railroad spike in a casting. No reasonably competent foundry would have had rairoad spikes floating around in an iron melt, and have somehow poured them into a mold.

There is nothing wrong with including a percentage of steel or iron scrap in a cast iron melt as long as the metallurgy is adjusted and the process accounts for it. Scrap has been used forever in iron and steel manufacture, as evidenced by the massive scrap drives during the wars, and the car crushers we can see at today at any large scrapyard. That metal is not buried somewhere or dropped at sea, it is reused. And it can be reused for high quality iron and steel, when refined.

Steel can be converted to cast iron by the addition of coke or other carbon and reheated above the melting point of steel, which is higher than that of cast iron. Cast iron can be converted to steel by removal of carbon and heating above the melting temperature of steel. These processes are reversible and commonplace.

Iron ore contains far more impurities than a rairoad spike does, and requires far more effort and energy to convert to a named steel or even Meehanite, which btw, is a trade name for some specific licensed processes.

Normal specifications determine the minimum and maximum amounts of a limited number of alloying and impurity elements in any steel or iron spec, usually less than a dozen. But specs do not in any way require how a foundry or steel manufacturer achieves that specification. Only that the specification is met.

Foundries are also responsible for the processes of cooling, casting, stress relief, etc. But foundries are free to blend scrap and so-called virgin pig metal in any way as long as the spec is achieved. Virgin metal comes from highly impure ore, so it is not a "pure" source in any way.

Your boss was typical of many engineers, who do not have a full understanding of melting practice, and who react to a problem by requiring an over-specification rather than risk being called onto the carpet themselves when something in the plant goes south. That is understandable, as self protection. And if cost is no object, specifying Meehanite for everything reduces the possibility that a railroad spike will be found in a casting.

It doesn't eliminate it however, if he continues to use the same foundry, and doesn't investigate further.

[steamer]

My point was Meehanite is a process.   Follow it and machine tool makers get what they want   beyond that   we'll knock yourself out  Make it from whatever you like.

Have a nice day

[vtsteam]

My point was Meehanite is a process.   Follow it and machine tool makers get what they want   beyond that   we'll knock yourself out  Make it from whatever you like.

Have a nice day

This was the point you had made:

"Cast Iron is what ever they find on the foundry floor!.....and trust me you don't want to machine it!"

I disagree.

[Admiral_dk]

Sorry Steve - but this was a Quote from the former Boss - and Not Daves statement ....

+ it was a Heat of the Moment statement .... I'm pretty sure sure He new better ....

Best wishes

Per

[vtsteam]

Actually it was, in the prior post, but it's not a problem as long as it's okay to simply disagree about processes and materials and explain one's reasoning. I have a lot of respect for Dave and his work, period.

[petertha]

Just going through my old notes & links & stumbled on my original 'maybe' idea. It was this 4130 seamless tubing available by the foot (reasonable length for model engineer types). At 1.5" OD it comes as thick as 0.120" WT. Not sure how it would machine or lap or hold its shape though. As it turns out a friend stumbled on a drop of Durabar offcut just the right size. Which around these parts is equivalent to saying I stubbed my toe on a gold brick sticking out of the snow, I suppose I should grab it LOL.

https://www.aircraftspruce.ca/catalog/mepages/4130tubing_un1.php

[mcostello]

Had a local  grey iron foundry buy up a semi from a disgrunteled semi driver who said "he would sell the whole truck if they would buy it by the pound." They told one of Our employees they would throw it all in the melt but the tires and gas tank. Later the employee hit a ball bearing in a casting and lost a tool.