Common Scrap Steel

[BronxFigs]

Most any engine I will build, will be from bar-stock, and steel scrap found in junkyards. Much cheaper than castings...and if I screw up a part, some cursing, but, no tears.

However, I'm a bit confused about hot rolled vs cold rolled steel, plate, and, bar-stock.

There is a difference, and I guess depending on what part of the engine you are using it for, you better pick the right steel. But what steel is good for what part.

For example, crankshaft, con-rod....what steel? Flywheel...does it matter? Will one steel warp when turned? Can internal tension be neutralized by heating and cooling before making chips?

This correct choices of material selection for each part has me very confused. In a scrap-yard setting, is there an easy way to tell hot and cold rolled steels apart. Everything is usually rusty, or, greasy.

Any rules-of-thumb?

Frank


EDIT: After posting these questions, I realize they will be virtually impossible to answer without letting you know what parts of the engine the steel will be used for, stresses, working-engine vs. model engines etc.

I wish there was a reference section on this forum that listed engine parts, and the material choices for that part. It would help me, that's for sure. For example: Crankshafts: Use these steels....
Con-rods: Aluminum, use these alloys....Steel, use these choices....
Valves, use these..... Etc.
Frank

 

[Philjoe5]

Frank,
Several of the questions you have raised have been answered at various times on this forum. My advice is to try to find machine shops that will sell drops. Then you will know what you're getting and what the shop is using it for. In my part of the world there are shops I can go to for help.

If you can't find any shops, try fellow modellers at local shows. I often get asked at shows, and try to provide any bits I can.

There are also on-line suppliers that provide stock and advice on applications but you have to consider shipping costs (Ouch!).

Scrapyards may sell cheaper, but a few wrong choices may cost you the savings or more in ruined tools. Ask me how I know this.

Cheers,
Phil

 

[Wagon173]

Plus one to phil's advice. New as I may be, I've destroyed a couple of tools also by chucking something I shouldn't have. The cost of materials isn't really that bad if you order enough for a 3 or 4 projects all in one shot. I'm also looking into buying a bunch of aluminum ingots and taking a crack at casting to offset the cost of bar stock and billets once I start moving onto bigger projects. I'd like to start casting brass also for the custom plumbing for my submarine. I'll leave steel well enough alone for now though. If you're in the Bronx, you should be plenty close to several metal suppliers though. If you want to go the online route, a neat place I found through this website is, http://www.budgetcastingsupply.com/

 

[MachineTom]

In making an engine the cost of material is not that large, Steel being the cheapest of all. Since our engines are made first for sight, second for function. The fit and finish is often what first impress's anyone looking at your project, yourself first. To that end, if you know what you material is, you can choose feeds, speeds and tools that will work the best on that material.

In addition to sites like ebay, MSC, Mcmater, I have found a place in CT Yarde metals. Online they have an area called Drop Zone, where they sell drops, odd sized cutoffs etc. Some stuff is just above scrap price, always limited supply that keeps changing. And a $75 minimum order. Most of the scrap yards around my town will not sell material at any price, and with no industry generating drops the pickings are slim.

A suggestion would be buy some 12L14 round or hex material from whomever, and you will not want to fool with mystery metal again. It is as strong as any mild steel, machines great, looks nice, but not as good as O1 drill rod, can be brazed, but is poor to weld. For flat steel A-36 is good stuff, to do anything with.

Some years ago I bought 20 ft of 1" D SS, for like $30, it is a pig to work with, needs lube to machine well, drills poorly. But sure was cheap, about 4 ft left, good riddance. I do love the boat prop shafts that I get, free 304SS, not the easiest stuff to work, but it shines with only a turned finish, will look like a mirror if polished, threads well, but is tough on tools, and leaves stringy chips.

 

[BronxFigs]

Wonderful to read all the caveats regarding scrap yard metals, and now that I read some of the warnings, buying correctly identified "drops" sounds like a good investment. I have tried to machine some steels found at a scrap yard in Stamford, Connecticut, and it was terrible to cut, and ruined good carbide inserts. So, what did I save? Bar-stock is, or, can be cheaper for some non-critical parts. That's why I concentrate on scratch-built engines. I need to use the metal sellers that you recommend.

I'll do some reading of past postings to find out what cranks, con-rods, and other critical parts are made from.

Thanks for all the great tips, and advice.

Frank

 

[aonemarine]

Well im a bit of a wack job, i test what im going to cut with my pocket knife to give me an idea of how hard it is. Works out well for me...

 

[Wagon173]

Well im a bit of a wack job, i test what im going to cut with my pocket knife to give me an idea of how hard it is. Works out well for me...

Lol, my knife cost me about what my drill press did. I find that one of the wife's diamonds works well

 

[thayer]

Bring a file along and save your knife and your marriage!

 

[Woodster]

You could do what i did yesterday and just walk into a local workshop and ask for "Bar ends", and offer to pay. 9 out of 10 times you'll get it for free. I picked up about 3 kilos (6lb or so) of bright mild steel, EN3, EN24, a foot of 1"dia 303 ST/ST, some 3/4 hex EN1A, a few bits of Mild steel plate and a few Ali bar ends up to 1.5" dia. All for nuthin'. Worked out that i've saved myself about £50!

Next step is to try and design an engine, a)Only using the stock i've got, and b)Without any milling ops as i don't have a mill or milling atachment. Should be a laugh! I can do some milling type ops on the lathe, all be it dangerous!!

 

[n4zou]

Frank,
Several of the questions you have raised have been answered at various times on this forum. My advice is to try to find machine shops that will sell drops. Then you will know what you're getting and what the shop is using it for. In my part of the world there are shops I can go to for help.

If you can't find any shops, try fellow modellers at local shows. I often get asked at shows, and try to provide any bits I can.

There are also on-line suppliers that provide stock and advice on applications but you have to consider shipping costs (Ouch!).

Scrapyards may sell cheaper, but a few wrong choices may cost you the savings or more in ruined tools. Ask me how I know this.

Cheers,
Phil

I quit that practice for that very reason. Scrap is a little less costly until you lose a cutting tool while cutting into a case hardened part of the scrap you purchased. I found a peace of heavy wall tubing I thought would be perfect for a cylinder. A 'hacksaw test' on an outside corner passed cutting it easily. I had no idea the interior surfaces had been case hardened. My boring insert was immediately destroyed when I attempted to cut it.

 

[BronxFigs]

I still think a reference section, or chart, listing critical engine parts, and the alloy choices that can be used to machine that specific part would be very useful.
Then I could look under: "con-rods" and find a listing of recommended Steel/Aluminum alloys that would work...ditto, valves, camshafts, cylinder material, piston choices, and recommended ring combinations, etc. It's nice to have choices, and some substitutions. This kind of concise reference, information would be invaluable to beginning builders like me. It's tiresome to ask, and to answer that same questions over and over. Searching the, forums sometimes, yields the information you need, but many times it doesn't. Too many vague thread titles tell you little about what's in the thread.

Thanks for the suggestions.

Frank

 

[Tin Falcon]

First of all relax and breath. some plans specify metal needed others do not . We are building model engines. not the replacement for the space shuttle.

for many model engines strength is not a major factor with the exception of the crank shaft and crank disk and pin you can make an engine out of plastic. I have done it.



IIRC the machinery handbook suggests common uses for common alloys.
the mcamaster carr web page and many other sellers will give properties and suggested use for metals.

if you want a good guide on metals read here


AEROSPACE METALS - GENERAL DATA AND USAGE FACTORS AFTO 1-1A-9

Avoid mystery metal .

the most important factor for a home shop machinist is machinability.


read here it may help as well.
http://www.homemodelenginemachinist.com/f27/selecting-first-engine-build-15183/

Tin

 

[Entropy455]

There are several large metal recyclers near my house – one of which lets me pick through their scrap, and charges me only 20% over scrap value for what I take. The overwhelming majority of steel that I find is ASTM-A36 hot-rolled, which is good stuff!



Sometimes I purchase 50 pounds, sometimes I'll grab a half-ton. I scored about 100 feet of 4.5” round-bar a while back, and was very pleased!



The sad part is I’m running out of room on my steel rack. I've got 150 feet of 1.25" round bar that I still need to put away, and I've got some large plate steel sitting behind the shop.



My wife thinks I collect too much steel. . . . . . . She's probably right. . . . .


Everything on this rack was purchased as scrap, for pennies on the dollar (including the steel to build the rack). I also picked up a good selection of 303 and 304L.

 

[BronxFigs]

Thanks everyone. Very helpful suggestions. The reference links will give me all the information that I will need, I'm sure.

Frank

 

[Wagon173]

First of all relax and breath. some plans specify metal needed others do not . We are building model engines. not the replacement for the space shuttle.

for many model engines strength is not a major factor with the exception of the crank shaft and crank disk and pin you can make an engine out of plastic. I have done it.



IIRC the machinery handbook suggests common uses for common alloys.
the mcamaster carr web page and many other sellers will give properties and suggested use for metals.

if you want a good guide on metals read here


AEROSPACE METALS - GENERAL DATA AND USAGE FACTORS AFTO 1-1A-9

Avoid mystery metal .

the most important factor for a home shop machinist is machinability.


read here it may help as well.
http://www.homemodelenginemachinist.com/f27/selecting-first-engine-build-15183/

Tin

I'll give a hundred bucks and a free bikini car wash to the first person to build a working model space shuttle... My milkshake brings all the boys to the bench.

 

[Tin Falcon]

Hey I only made a part for the space shuttle one a long time ago.
Tin

 

[ConductorX]

I'll give a hundred bucks and a free bikini car wash to the first person to build a working model space shuttle... My milkshake brings all the boys to the bench.

Estes Rockets sells a model space shuttle you can build, launch, fly and recover by parachute. I built and flew two of them. I also worked as a NASA contractor on the Space Shuttle External tanks in New Orleans.
1981 - 1991.

Estes Rockets
http://www.estesrockets.com/

I did a quick search and it appears they don't offer the Space Shuttle model any more.
Sorry

Found one on ebay
http://www.ebay.com/itm/Vintage-Est...Model_Kit_US&hash=item4ac3e17953#ht_38wt_1057

"G"

 

[aonemarine]

I built the estes model space shuttle a long time ago. On its first launch the motor slid forward in the fusealodge and burned a hole the the side causing the shuttle to spin out of of controll and crash in flames. Shortly after the real shuttle did about the same.....

 

[Brian Rupnow]

Anything subject to a lot of rolling friction such as shafts, should be made from steel. Hot rolled or cold rolled mild steel is the preferred steel to use. Cold rolled is a very nice steel to use for shafting, as it has no mill scale on the outer diameter and requires no external machining, and the outer diameter is very accurately sized. Hot rolled steel has a nasty black scale on the outside that must be machined away, and it generally is supplied slightly oversized to allow for this. The best material for cylinders is grey cast iron, as the high carbon content in it allows a certain amount of self lubrication. Likewise, pistons can be made from grey cast iron for the same reasons, although with a fast revving engine the mass of a cast iron piston can cause oscillation problems, so it is acceptable to use aluminum for pistons. Anything which a shaft revolves in, another very high friction area is best built of bronze----however, many of us substitute brass, and while it isn't quite as good a bearing material as bronze, it is much better than "steel on steel". Grey cast iron can also be used for bearing blocks, again because of its high carbon content which helps with the lubrication. The main body of an engine which everything else bolts to can safely be built from aluminum with no problems. There is one caveat to remember though---Most home shops are not set up to weld aluminum, so if anything absolutely must be welded to it, then use mild steel. Connecting rods can safely be machined form 6061 aluminum, although it is preferred that they have a bronze or brass bushing in the ends. Crankshafts, whether they are built up or machined from solid should always be made of steel. Valves can be made from cold rolled steel or from drill rod. Flywheels should be as heavy as possible for a really smooth running engine, and consequently be made from mild steel or brass. Baseplates for engines can be made from aluminum. Camshafts should be made from steel. Cylinder heads which bolt on can safely be made from aluminum. Carburetor parts can generally be made quite safely from either brass or aluminum, except for any shafts such as throttle shafts which rotate should be made from steel.--Valve seats can be made from steel or brass. Any connecting linkages are generally made from steel, although in highly rust prone engines such as steam engines, brass is preferred. Cylinder rings for internal combustion engines should be machined from grey cast iron.-Brian.

 

[va4ngo]

Thanks for an excellent summary of material usage brian