What size stock material?

[zeeprogrammer]

Square or rectangular stock doesn't have sharp corners.

If I want a length of 1/4 by 1/4 material with sharp corners I can't start with 1/4 by 1/4 stock material.

What is the minimum stock size I would need to mill the least amount from to get to 1/4 by 1/4?

Does that hold for any size? In other words, what is the minimal amount of additional material I need to account for? Is there a general rule?

Thanks.

 

[Metal Butcher]

Square or rectangular stock doesn't have sharp corners.

If I want a length of 1/4 by 1/4 material with sharp corners I can't start with 1/4 by 1/4 stock material.

What is the minimum stock size I would need to mill the least amount from to get to 1/4 by 1/4?

Does that hold for any size? In other words, what is the minimal amount of additional material I need to account for? Is there a general rule?

Thanks.

Hi Zee. To make the corners sharp on out side edges, I file off whatever it takes. Materials that are sized with rollers are very inconsistent. And almost all of them are. To get an exact .250" x .250" (if it mattered) I would use 5/16" square material. Using 1/16" oversize should work across the board.

-MB

 

[GailInNM]

Zee,
If you are starting from round material, the corner to corner dimension of a square is the square root of 2 (1.414...) times the side dimension. So for your 1/4 inch square:
0.250 X 1.414 = 0.354
This would be the minimum round dimension.
Gail in NM

 

[zeeprogrammer]

Thanks Pat. I should've stated the material I'm interested in. For both aluminum and brass that I've bought, it seems to come in at, or just under, size. For example, when I order .250 square, I will measure .247 to .249.

Thanks MB. I think that's what I was looking for. I suspected 1/16" oversize would be the target. I wasn't sure if that applied to all sizes.

Thanks Gail. Using round to start with would be an alternative.

 

[Metal Butcher]

Zee, did you notice that its never oversize by two or three thousands. Would be nice to have a little extra to level off with a file.

I know...dream on. :

-MB

 

[zeeprogrammer]

I don't worry so much about it.
2 or 3 thou under/over is well within my natural machining error. :big:

 

[Jasonb]

Zee consider cutting it from wider flat stock or plate that way you only need to clean up two edges or one if its not been cut before.

I keep all the offcuts from larger items and these can usually be poped in the mill and brought to dimension quite quickly.

You are likely to need at least 1/16 (32nd each side) larger if machining from square stock though the amount af corner rounding does seem to vary from one source to another. The majority of rectangular stock sold here has square corners its just the square section stock that tends to be rounded. Unless you are not buying bright stock.

Jason

 

[zeeprogrammer]

Thanks Jason.

While I haven't bought much stock yet, I checked what I had and all of the square and rectangular material have rounded corners.

What is 'bright stock'?

 

[Metal Butcher]

Zee, "bright stock" Is a word used to describe precision sized material with a ground finish, in shapes such as round, square, or flat material, (usually tool steel) in the European countries.

Also referred to as 'silver steel' I believe.

If I'm wrong, than I apologize to Jason and all of are other European members and freinds.

-MB

 

[kvom]

Zee,
If you are starting from round material, the corner to corner dimension of a square is the square root of 2 (1.414...) times the side dimension. So for your 1/4 inch square:
0.250 X 1.414 = 0.354
This would be the minimum round dimension.
Gail in NM

Unfortunately this also means turning 36% of the material into chips, which can get expensive for some materials. And the percentage goes up the less square the desired shape is. For the axle boxes on my current loco build, I had to get round bronze bar and milled off over 50%.

 

[zeeprogrammer]

Thanks MB.

Thanks kvom. For that reason (waste) I would only resort to milling round to square or rectangular if it meant having to order material special and I had round on hand.

 

[GWRdriver]

Zee, "bright stock" Is a word used to describe precision sized material with a ground finish, in shapes such as round, square, or flat material, (usually tool steel) in the European countries. Also referred to as 'silver steel' I believe. If I'm wrong, than I apologize to Jason and all of are other European members and freinds. - MB

MB,
I don't know about Europe in general but in England, in the model engineering world, there is a term "BMS" which stands for bright mild steel, our equivalent of CRS, cold-rolled steel. So "bright" steel means simply cold finished. Ground finish alloy steel stock, which we refer to as flat-ground stock, they call "guage plate." Silver steel is their term for drill rod although useage tests and comparisons suggest that British silver steel and US drill rod have slightly different metalurgical properties and behave a bit differently.

 

[Jasonb]

As GWR says by bright I mean Bright mild steel or CRS, most flats in this have sharp edges unlike what we call black or HRS which has a black scale and rounded edges.

We can also get precision ground mild steel which is just normal mild steel with a ground finish but I've only seen this in rounds.

Jason

 

[Metal Butcher]

Harry, thanks for the explanation. Zee, sorry for giving you an incorrect definition of 'bright stock'.

Not to sound like I'm making an excuse, but it is a little bit confusing, at least for me since cold rolled steel is not 'bright' at all, unless it has a 'ground' surface finish.

I need to put a list together. Here's a common one that still confuses some I'm sure.

Silver solder; in the USA= Soldering with a low temperature 800F or less with soft silver bearing solder, using a propane torch.
Silver solder; in the XYZ= Brazing with a high temperature 1100F or more with silver bearing bronze brazing rod, using a OA welding outfit

In the US the definition of 'soldering' and 'brazing' is a 'process' based on temperature, not the filler material. The terms (word) are not interchangeable.

It would help if all the members would simply post the country their from, on their avatars.

-MB

 

[GWRdriver]

MB,
Most of my early indoctrination in model engineering and metalwork came from reading the Model Engineer magazine and that's how I became familiar with British terminology. At that time model engineering globalism hardly existed, certainly not on the scale we enjoy today, as we both were "foreign" to each other. (Those were the days when if I drove up to a garage in my MG-TC they would pretend not to be open!) When I first saw "silver steel" called for in an article I had no idea what that was, but eventually as I read on I learned the intended use and treatment of it and then I was able to say Aha! - That's drill rod! Eventually more discussions and explanations of silver steel vs. drill rod (and other materials) appeared in ME and Live Steam and it became clearer. "German silver" was another metal I was unfamiliar with at first but that turned out to be what we (in the US) call nickel silver. Two nations, divided by a common language! I still call these materials by "our" names though.

With respect to soldering/silver-soldering/brazing question, in the USA, in model engineering and live steaming, when one uses the term "soldering" alone with no other modifiers, the assumption is that this is soft soldering using a low termperature (425F+/-) tin or lead based solder. The term "silver soldering" is accepted to mean high temperature (1100F+) brazing with a high percentile content (45%-55%) silver bearing solder. "Brazing" with no other modifiers is assumed to mean high temperature (1100F+) joining with fluxed brass or bronze rod. "Silver brazing" or "hard soldering" are assumed to be the same as silver-soldering. What continues to confuse and then frustrate some people is the current practice by some mfgs, repackagers, and retailers to sell low-temp tin-based solder having a 2%-5% silver content as "silver solder", which it is not, at least in the sense that we understand it and use it.

 

[zeeprogrammer]

Thanks GWDriver, Jason, and MB.

It is certainly confusing to us novices.

I'm putting together a metal order...and thought about getting some bronze.
Nope.
I have much to learn...too many choices.

 

[GailInNM]

Before anyone grabs a section of 5/16 square CRS and decides to whittle it down to 1/4 square I would assume that you want it to be straight also. ALL rolled materials have stresses built into them. After milling off one surface of our straight square stock it will be found that it is bowed away from the fresh cut surface. Then after milling off the opposite side it bows back some. To mill a square piece that is straight you have to mill a little off each surface and then do it again a time or two and creep up on it. This has been the downfall of many a person on this board who tried to make a one piece crankshaft and did not do the cuts in the proper order. Lots of cussing has resulted from pretzel shaped crankshafts.

The worst about this is cold rolled steel. Hot rolled steel is much better and the best of the common steels is 1144 Stress proof. This applies to round rolled stock as well square and rectangular. Extruded brass and aluminum also exhibit this behavior but not nearly as bad as steel and it is not normally noticed.

Regarding the waste from starting with square or round stock. In Zee's example of 1/4 inch square as our finished dimension, the amount of material to be removed is about the same starting with 3/8 round or 5/16 square.
If using brass, the cost will be about the same for the stock. They are both about the same cost per foot.
If you use 12L14 the cost of 5/16 square is over twice the cost of 3/8 round, so it is much cheaper to mill from round. It is harder to roll square than it is to roll round. Since this is a hobby, our time is free after all. ;D

Gail in NM

 

[GWRdriver]

Thanks GWDriver, Jason, and MB. . . . I have much to learn...too many choices.

Zee,
We're all about the same, none of us were born knowing it, we all pick it up one tidbit at a time from somewhere or someone else. In the last ten years or so I've noticed a general tendency among US live steamers and engine builders to make things, material selections in particular, more complicated and overly technical, more exotic than they need to be for the job they are going to do. I guess the best way to say it is we are building steam locomotives not spacecraft. I think most people I know eventually settle in on a small vocabulary of metals which they like to work with, which do the job they are needed to do, and which are available, and after that they don't go searching around for the latest and greatest exotic alloy, just to have the latest and greatest.

 

[zeeprogrammer]

Thanks Gail. I'll be using aluminum and brass but your point is well worth remembering.

Interesting point too about the cost of milling square versus round.

Thanks GWDriver. That's exactly where I am. For my interest in this hobby, I want just a few choices. One aluminum, one brass, etc. I'm not as interested in understanding the nuances of different metals (blasphemous that may be). So when people say 'brass' or 'bronze'...I'm wondering which is the most popular or useful and I'll probably stick with that.

 

[shred]

FWIW, brass can bend as stresses are released too... I had a piece banana on me a while back that really surprised me since I didn't know brass would do that.