What materials to stock?

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razzle

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Hello, long time lurker here. Been wanting to ask this question for a while. I was hoping to get some recommendations on materials to have on hand for building basic model engines. i dont have anything specific in mind to build right now but have been watching youtube videos on some of the more advanced model engineers and see that they appear to have stock they use regularly. i already have quite a bit of bar stock (aluminum, brass, 12L14, and drill rod) in small diameters. but am wondering what i should get for sheet materials or anything else that would be good to stock. i dont get much time in the shop and when i do get out there it is frustrating to pick a project to work on and find that i dont have the right piece of material.
I guess that i am looking for recommendations on:
Brass bar. Shapes? Sizes?
Brass sheet. Thicknesses?
Steel sheet. Thicknesses?
Aluminum?
Plastics?

Looking to start with Elmer's engines and build skills but i would like to get into steam engines at some point.

Thanks all.
Russ
 

danallen

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It's pretty tough to stock material without having a specific project in mind. No matter what you buy you will need something else. 1/4 and 1/2 inch aluminum plate is pretty handy for making jigs and holding fixtures.
 

Brian Rupnow

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When I build an engine, I buy round bar or flat bar in lengths that are twice as long as I actually need for that engine. After you've built a few engines, you will see that the same sizes of material come up again and again. Of course I have two or three metal suppliers right here in Barrie.
 

Zeb

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For small stuff and if you're in the US, I went to Hobby Metal Kits (thanks to a forum member tip!) and was happy with prices/shipping. Lots of hex bar stock for making custom engine bolts.

For larger plate, the best, cheapest way is the local scrap yard (Pacific Steel here). Every now and then I'll dive in their recycling bins for $2-3 a pound. A couple years or so of doing that and I have plate in almost any thickness (and a Huey compressor stator housing for my standing desk footstool. hehe). CNC shops generate a lot of waste on thick plates (1-2" thick). Round stock is hard to find, but I managed to get Ø5" 60XX extrusion on a lucky day.

My preference was going to town on a couple PM research engines as a warmup. Their flywheel castings are going to be a lot cheaper than machining raw, round aluminum stock (as with Elmer's). You'll also be left with some scrap for other projects. Just kinda depends on what you want to do and how much you want to spend.
 

ShopShoe

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Brian Rupnow said it well: when you have a project, order extra for "the next time."

Personally, I tend to stock materials slightly thicker or larger than my finished sizes are likely to be, for "machining allowance."

In my location, there is not so much in the way of variety of materials available, so I tend to order extra items so I have them in stock. When going in new directions, I may order two options and try them out before putting them into a real project.

The size of my projects and machines also plays a role in what I get.

I have ordered from OnlineMetals and taken advantage of their "random length" option to save money ("random length" being close to, but not exactly 1 foot long, the result of them having bar ends to get rid of.)

I started my machining life with a variety of materials, so I stock more than metal: I have Delrin, Nylon, PTFE, Phenolic, Acrylic, etc.

Since I do a lot of "fixit" stuff, I also keep a large variety of fasteners, Plastic Pipe, Rubber Stoppers, cast iron pipe fittings, brass fittings, etc.

I generally have brass in small rods, 5/8, 7/8.. Brass flat bar in 1/4 x 1/4, 1/4 x 1/2, Aluminum in larger rods ( to "cut off a slab") 1/4 x 4 inches wide, 5/8 x 6 inches wide. Aluminum in larger rectangular bars. I have bearing bronze in 5/8 and 7/8 rods. I have a piece or two of 303 stainless I have yet to use. I have some sheet aluminum and 18 and 16 guage steel sheet. I have structural steel from local sources I sometimes machine, but mostly use for fabrication of larger projects.

--ShopShoe
 

Henry K

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Having, or creating, a reasonably complete 2D CAD drawing, with dimensions, is the best way to know what kind of stock you will need for your project. You can even compare it with what you have "in stock" and can then figure out what you need to buy. Companies like McMaster, and others, deliver to me (New Jersey) overnight with standard shipping and small pieces on many items are available. This overnight delivery reduces the cost of your inventory and enables you to get exactly what you need instead of substituting what you have for what you need.
DoubleCAD XT5 is a very nice and free 2D CAD program from TurboCAD. If you are a student at a qualifying institution you can even get a variety of AotoCAD products for free with a renewable 1 year license. Have fun making drawings and chips.
 

Vietti

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Second the suggestion of Hobby Metal Kits and they support the hobby, Furnished lunch at the BH show and are super nice.

John
 

Richard Hed

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Many of the guys here are purists in that they want their materials to be of the better quality that matches the material to the use. This is a good thing, but it can be over done also. There are many small parts that it doesn't really matter what type of material they are. If you can stock up on this kind of stuff from your local metal recycling center (junk yard or whatever it's called nowadays), you will have a cheap supply of it for such things as bases, screws and bolts, rods and many other things. Where you needs specialty materials is for bearings, sleeves, pistons, cylinders. I have a friend where I can get lots of stuff. He has a bin of throw away stuff at his machining shop which he lets me go thru from time to time.

Also, there are two junk yards, one a recycling, the other is a metal's only place. I can get incredible stuff at both places, and often know what the material is too. You should be looking in these type places. Keep it cheap then you will have the extra $$ for when you needs something special. I buy a lot of stuff also from Alcobra which is in Spokane and other places. You can get it on line and have it sent or go to the Alcobra if you live close enough. I recommend them over Master-Carr. There are other places too:
Ryerson
and many others. Just look up metals and scrapyards.

My biggest prob is getting bronze when it is the correct material for some part. It's not that it is so difficutl to get, it is expensive and I am not always sure if bronze should be used or if brass will do as easily.
 

dnalot

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Just stock up on button batteries, sharpies, cutters and Band-Aids. Everything else as you need it then get a little extra. It adds up over time.

Mark
 

Henry K

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Free metal from you local machine shop (especially steel) can be a mixed blessing. You can save some money but the parts you may want to make could take 2 to 10 times the labor of purchased free machining steel and have poorer surface finish depending on your machines. Free aluminum is another story, if the parts you want are aluminum - go for it.
 

Richard Hed

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Free metal from you local machine shop (especially steel) can be a mixed blessing. You can save some money but the parts you may want to make could take 2 to 10 times the labor of purchased free machining steel and have poorer surface finish depending on your machines. Free aluminum is another story, if the parts you want are aluminum - go for it.
I wouldn't use the unknown metals for important parts but there are lots of parts that can use almost anything.
 

SmithDoor

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Most machine shops use the bars to the nubs.
They also buy short bars from junk dealers.

My self I would purchase round stock 1144 and Hex 12L14. Flat and shapes stock A36 hot roll.

It keeps bar stock simple.
All bar stock is in 3 or 4 foot bars to fit on shelf

Dave

Free metal from you local machine shop (especially steel) can be a mixed blessing. You can save some money but the parts you may want to make could take 2 to 10 times the labor of purchased free machining steel and have poorer surface finish depending on your machines. Free aluminum is another story, if the parts you want are aluminum - go for it.
 

razzle

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@SmithDoor Do you use the A36 for machining projects? I haven't tried it yet and have read that it is poor machining material.
Machine shops and scrapyards are few and far between around here. I pretty much order materials on fleabay or from online.
 

Richard Hed

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@SmithDoor Do you use the A36 for machining projects? I haven't tried it yet and have read that it is poor machining material.
Machine shops and scrapyards are few and far between around here. I pretty much order materials on fleabay or from online.
8u
iWhere do you live?
 

SmithDoor

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Yes at one time I had tons of 1/2" , 3/4", 1" and 2½" plate.

To machine It takes a 7° to 15° rake angle to machine like butter.
A36 welds great too.

Dave


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Do you use the A36 for machining projects? I haven't tried it yet and have read that it is poor machining material.
Machine shops and scrapyards are few and far between around here. I pretty much order materials on fleabay or from online.
 

awake

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@SmithDoor Do you use the A36 for machining projects? I haven't tried it yet and have read that it is poor machining material.
Machine shops and scrapyards are few and far between around here. I pretty much order materials on fleabay or from online.
IIRC, A36 is more or less the same as 1018, which is often generically described as either cold rolled steel (CRS) or hot rolled steel (HRS). (Of course, CRS and HRS differ in important ways, but in terms of alloy, I believe both terms generally refer to 1018.)

I make a lot of parts out of 1018 / CRS / HRS / etc. - a lot of parts. Why? Several reasons: 1) I have a very large supply of free scrap material; 2) I often fabricate some portion of my projects via welding, TIG or stick, for which 1018 excels; 3) I am cheap, and 4) did I mention the material is free?

Does it machine poorly? Well, it is not as "machinable" as tempered aluminum or "free turning steel" (e.g., leaded steel such as 12L14), and it generally does not give a silky smooth or mirror bright finish straight off the lathe or mill. That said, I don't find it difficult to machine with the HSS tooling I mostly use (or the carbide I occasionally use), even on small machines. With experience, I can get a more-than-good-enough finish straight off the lathe, mill, or shaper. If I need the polished surface, it is easy and quick to turn it .001" or so over sized and bring it down to a polished surface using a strip of emery paper.

The issue with A36 / 1018 is that it is a bit more "gummy" than either "free turning steel" (which has lead and or sulfur in the alloy to provide lubrication and ease of splitting off metal) or than a somewhat harder steel such as 1144 (aka "stress proof"). As a result, machine tooling can "smear" it a bit rather than shearing / cutting it. Naturally, keeping the tooling sharp is helpful, as is attention to good tool geometry (as Dave comments above).

Note that aluminum can be insufferably gummy, depending on the alloy and temper, far worse to machine than 1018. Even with tempered aluminum, I find "chip welding" to be a significant danger (especially drilling / tapping), but it is rarely a problem when machining 1018.

With regard to the issue of welding - some aluminum alloys can be welded with TIG (or MIG using argon), and some cannot - but welding aluminum is quite a bit more challenging, at least for TIG (I don't have MIG). In general, free turning steel is considered "not weldable" - meaning you may be able to glob a weld on it, but it will be ugly and you shouldn't trust the results. Meanwhile, I find 1018 / A36 to be one of the easiest materials to weld.

As always, it comes down to personal preferences, capabilities, tooling, etc. FWIW, I made my first model IC engine almost entirely from 1018: Introducing ... the "Steel Webster"
 

SmithDoor

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I have work with A36 for 50 years.
A36 can machined to look the same as 12L14. It is how you sharpen the tool bits. Very sharp and high rake angle 7° to 15°

Dave

IIRC, A36 is more or less the same as 1018, which is often generically described as either cold rolled steel (CRS) or hot rolled steel (HRS). (Of course, CRS and HRS differ in important ways, but in terms of alloy, I believe both terms generally refer to 1018.)

I make a lot of parts out of 1018 / CRS / HRS / etc. - a lot of parts. Why? Several reasons: 1) I have a very large supply of free scrap material; 2) I often fabricate some portion of my projects via welding, TIG or stick, for which 1018 excels; 3) I am cheap, and 4) did I mention the material is free?

Does it machine poorly? Well, it is not as "machinable" as tempered aluminum or "free turning steel" (e.g., leaded steel such as 12L14), and it does not give a silky smooth or mirror bright finish straight off the lathe or mill. That said, I don't find it difficult to machine with the HSS tooling I mostly use (or the carbide I occasionally use), even on small machines. With experience, I can get a more-than-good-enough finish straight off the lathe, mill, or shaper. If I need the polished surface, it is easy and quick to turn it .001" or so over sized and bring it down to a polished surface using a strip of emery paper.

The issue with A36 / 1018 is that it is a bit more "gummy" than either "free turning steel" (which has lead and or sulfur in the alloy to provide lubrication and ease of splitting off metal) or than a somewhat harder steel such as 1144 (aka "stress proof"). As a result, machine tooling can "smear" it a bit rather than shearing / cutting it. Naturally, keeping the tooling sharp is helpful, as is attention to good tool geometry.

Note that aluminum can be insufferably gummy, depending on the alloy and temper, far worse to machine than 1018. Even with tempered aluminum, I find "chip welding" to be a significant danger (especially drilling / tapping), but it is rarely a problem when machining 1018.

With regard to the issue of welding - some aluminum alloys can be welded with TIG (or MIG using argon), and some cannot - but welding aluminum is quite a bit more challenging, at least for TIG (I don't have MIG). In general, free turning steel is considered "not weldable" - meaning you may be able to glob a weld on it, but it will be ugly and you shouldn't trust the results. Meanwhile, I find 1018 / A36 to be one of the easiest materials to weld.

As always, it comes down to personal preferences, capabilities, tooling, etc. FWIW, I made my first model IC engine almost entirely from 1018 (the only exceptions were the bearings and the bronze valve guides): Introducing ... the "Steel Webster"
 
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