Black mild steel

[silverfox]

Been told that this is better than BMS for frames. Need 2 pieces 38 x 1/8 x 4 1/4

any suppliers out there?

[baggo]

Hi Ron,

Live Steam Models at Little Eaton, Derby list black steel plate which I presume is the same. They do mail order I think.

Unfortunately they only do 3mm thick as do most suppliers nowadays. It's getting very difficult to get steel sheet in imperial sizes. No real problem, you just have to alter the length of the stretchers slightly to keep the outside frame width the same.

John

[silverfox]

Baggo,
Thanks, i have sent a email asking if they can cut frames to sizw.Much appreciated

Ron

[Tim Bayliss]

So that everyone is aware, the difference between black and bright steel - Black mild steel (proper name hot rolled mild steel) is material that has come directly from the HOT rolling process. It has black 'mill scale' all over it hence the common name. The scale can be hard and make life a little difficult. It will not be as acurate as to thickness, etc. as bright and will have radiused edges. It may also have rolling flaws - beware!! It is much cheaper than bright.
Bright mild steel (proper name cold rolled mild steel) is the same stuff with the mill scale removed and finish rolled on a COLD rolling process. It is accurate in size, will have square edges and a bright steel finish, hence the common name. There should be no surface flaws or marks. It is more expensive than black mild steel due to the extra rolling process.
In industry black m.s. is used for welding/fabricating, etc. and bright m.s. is used for accurate mechanical assemblies/toolroom work, etc.
Tim

[Tel]

Pretty much sums it up Tim, but me and my trusty Douglas shaper will stick to the black stuff thanks.

[Tim Bayliss]

You're right Tel. A shaper is the bees knees to true up and 'refinish' black steel and it's economocally advantageous (wow - big words!) enough to do it. It can be cleaned up locally with the trusty angle grinder but not with anything like precision.
Tim

[rodwilson]

baylisst said:

. A shaper is the bees knees to true up and 'refinish' black steel and it's economocally advantageous

Wow. My wife will never believe that I recently bought a machine that could save me money........

[jgb7573]

For cleaning the mill scale I use a 10% (approx) solution of phosphoric acid. When it comes out of the acid bath rinse off under water and immediately spray with oil. The surface is so clean it will start to rust immediately otherwise.

[circlip]

Good description of the differences Tim, you only missed one salient feature of why you should use black instead of bright for frames. If you use cold rolled , or bright, when you start cutting lumps out for axleboxes and sutch, the stresses in the material due to the cold rolling can cause it to distort. In the dark and distant days of proper muddle engineering, ie. pre 60's, the comics always used to tell us to normalize BMS by leaving it in the fire overnight. Try that in yer namby pamby central heating boilers!

[Tim Bayliss]

I didn't miss that point, I ignored it as it is not necessarilly correct. I believe that there are less likely to be serious stresses in cold rolled steel mainly because prior to the cold rolling process the steel is annealed (similar to normalising!) whereas hot rolled is as it comes from the hot mill, stresses and all. The cold rolling process doesn't impart very great stresses as the metal is worked in one direction.
In reality it probably wouldn't matter which you use, we're not considering a complex fabrication here, and I wouldn't dismiss either.
Tim

[circlip]

Tim, re read it, CAN, not WILL. No it's not a complex fabrication, but I wouldn't IGNORE mentioning it, it's only a problem if it happens to a newby and it totally pi**es him off from the hobby and nobody could be bothered to tell him. When you present ALL the facts it's their choice.

Can Silverfox tell us why he was advised black in preferance to bright?

[Tim Bayliss]

I don't know why you're having a go at me , Circlip. I indicate that I believe that either would do the job and am not prepared to recommend one over the other. For economy use black, for nice finish use bright. Best of both worlds (maybe?) use black and remove the mill scale as mentioned above (Job7573). But what I suppose I'm really saying is don't be mislead into thinking that the one is size-for-size any stronger/stiffer/more rigid than the other and please, lets not get too bogged down with this.
Tim

[GWRdriver]

Over here our Black Iron (as it is known in the shops) HRS plate, up to 1/2" thickness anyway, comes with a very smooth (but hard) black oxide finish which I like. I WANT the black oxide finish as it resists wear and abrasion, deters rust, and takes paint very well, and then there is this. It is widely used in many thicknesses, and by extension SCRAP material is widely available, often for the asking. (I can be very humble . . and impoverished . . when the need arises!) Except for the main frames and tanks, which are 1/4" HRS and sheet brass respectively, all the platework on my 2X TICH will be done in begged HRS scrap pulled fom under the shears at a local sheet metal fabricator. We also have the option of "pickled" black iron which has had the oxide skin chemically removed but this material isn't laying around as scrap.

It has been my experience that all rolled materials have included stresses to some extent but unlike cold rolled shapes, hot rolled material isn't nearly as anxious to pretzelize itself or leap up off the milling table once the skin is penetrated. That's a bit of an exaggeration but you get the picture.

[AndrewP]

'Pretzelize' ;D Thanks Harry that has put a picture in my head I'll never forget.

[silverfox]

Head above the parapet!!

The reason for choosing Black over bms was three fold
the first was that the endmill decided to go walk about whilst milling the hornblock, and now the mainframe has a very distinct s bend to it despite remedial woek with hammer nad mole grips!
Second, chap at the lub was describing his latest engine and recommended black, for the reason stated above, it doesnt want to de stress? itself. Hopefully plenty of packing and support will cure problem 1
Thirdly, discovered a few holes were mis drilled and although i managed to thread them and re drill, it didnt look right

so decided to bite the bullet and re do the frames. measuring several times ( with two digital verniers!!)before marking the hole and drilling the once (with the right size drill!

regards Ron

Am getting the steel (cut to size) from Live Stam models. wioll update as and when

Ron (the other one)

[circlip]

Not having a go at you Tim, but just for reference, have a look at the acidic Scottish doctors site re his Simplex build, OR the Japanese masters site showing his laser cut frames, both used beautiful BMS.

[GWRdriver]

'Pretzelize - Thanks Harry that has put a picture in my head I'll never forget.

Andrew,
Always willing to oblige. I conjured up that term many years ago after about my sixth attempt at making the crankshaft of my first Stuart 10. It seemed a logical description.
Your humble servant, etc.

[Noddy]

Wot you all so picky for?

If it's in the skip or on the scrap pile, grab it!

Acidic Scottish doctor.... Don't know what you mean Iain.

Keith

ps
Wot does BMS stand for, "black" or "bright"?

[GWRdriver]

Keith,
For many years I mistakenly thought it stood for "Blued Mild Steel" . . . .because I remember reading a passage in ME which mentioned that in Britain one has the the choice of blued (annealed) mild steel available as an alternative to bright steel and thinking how nice it would be if we had that choice over here. I have since been put straight.