Options for finishing steel in a home workshop

[jackssmirkingrevenge]

Merci Francois for chiming in, your CAF post was very informative!

I suspect because of the lead content

This is my feeling tool, what makes it "slippery" for cutting tools also seems to make the rust slide off!

1018 is easy to work with razor sharp HSS toolbits, with the right feed and speed you can get a very decent surface finish.

How does it do with carbide inserts?  As much as 12L14 is a doddle to machine I would certainly like to add some stronger steels to the material stockpile.  How would you compare machining 1018 to 1045?

   

[WobblyHand]

Tee nuts done in the peroxide/salt mix.  Also a picture of the tee nuts in the rotary table, to get an idea of the original unblued finish.  Don't remember what the material is maybe 1018.

[jackssmirkingrevenge]

Tee nuts done in the peroxide/salt mix.  Also a picture of the tee nuts in the rotary table, to get an idea of the original unblued finish.  Don't remember what the material is maybe 1018.

Excellent, that's the finish I would have liked!  It looks like I'm going to need to let some lead-free steels into my life

[WobblyHand]

If the solution stops bubbling it is spent, you need to replace it.  Also, just use a nylon toothbrush to "card" the rust.  You are trying to simply remove the loose stuff not scrape it away.  If you keep scraping it away, well, it's going to take forever to blue!  The 12% peroxide is concentrated, it seems to last a while.  I don't remember how many times I renewed the solution, maybe once?  I only made a little at a time, because, well, I had little idea how well it would work!

I see a bunch of people saying to use steel wool to card it.  Beware, almost all steel wool has oil in it, so it won't rust.  The oil will get on your parts and inhibit the reaction.  If you were to get steel wool, you'd need to either remove the oil (pain in the neck) or try to find some stainless steel wool which won't rust.  But finding stainless steel wool isn't easy!  And you still need to clean the steel wool anyways to ensure there's no oils on it.  An old toothbrush seems to work fine for me.  It will turn dark, so you won't be tempted to reuse it!

[happymecanic]

Merci Francois for chiming in, your CAF post was very informative!

Ça me fait plaisir Jack . Glad to be of some help, but I must say Gippeto (Al) was my mentor on this subject.

How would you compare machining 1018 to 1045?

I personnally find 1018 is easier to machine (at home) with good quality HSS toolbits and cutting oil, than with carbide inserts. At the machine shop where I work, I'll often switch to carbide inserts made for stainless steel to get a better surface finish. We also use high-grade, small-radius (CNMM 430 I think) inserts for aluminum for tight tolerance parts. These inserts are typically much sharper than common ''all-purpose'' inserts. 1018 is somewhat soft, you really need to cut it, not ''deform cut'' like with conventionnal inserts. Shallow passes are quite nightmarish on that material, it's not always easy to break the chip.

On the other hand, 1045 machines very well with ''regular'' grade carbide insert, the chip breaks pretty well and you get a nice surface finish without too much fuss. Typical inserts we use for roughing are CNMG 432 EMU AC820P, and for finish it's CNMG 431 WF 5015 (Sandvik-Coromant), also called ''wiper inserts''. With these you can get an almost mirror finish, and it's easy to stay within 0.0002'' tolerances. If you have a good machine, 0.0001'' accuracy is very feasible.

Another steel I like for home machining is StressProof 1144. It's dubbed ''easy machining'', and it is indeed, but it's a bit more expensive than regular carbon steels. But if you need a very accurate part, Stressproof is unbeatable for dimensionnal stability and surface finish. I never tested it with rust bluing though, but I guess it may give good results, as it's a medium-carbon steel.

Hope that helps you a bit (pun intended ).

[jackssmirkingrevenge]

I must say Gippeto (Al) was my mentor on this subject.

It was probably seeing something Al made that prompted me to start this thread in the first place

Hope that helps you a bit (pun intended ).

It does very much, appreciate the detailed professional insight as I have no formal training in this area.  I will definitely be stocking up on 1045 and will also give 1144 a try, cheers!

[WobblyHand]

Comparatively speaking 1045 is not easy to machine, especially on a small lathe.  1144 is so much easier to machine.  1144 is easier to machine than 1018, and 1018 is easier to machine than 1045.  I'd recommend 1144 and 1018.  Later, when you have your technique worked out, you can try 1045.  Or 304 stainless.  304 work hardens quite readily.  But 303 stainless is a dream to machine.

Search for machinability.

[WobblyHand]

This link contains a decent set of charts of various types of steel machining indices.  https://www.machiningdoctor.com/machinability/steel/
At least it will give you an idea of easier vs more difficult. 

I was lured by a cheap price and bought some 4340.  (Had no idea of the machining index when I bought it.) It was not that easy to machine.  Made a lathe spider out of it. 
Picture is of the lathe spider installed on my 10x22.  Made the brass tipped screws as well.  You also can see part of my ELS install, with the stepper motor mounted inside the lathe casting.  The stepper drives the lead screw, rather than being gear driven.

[Ronno6]

On the original topic, I use Jax metal black for iron and steel.
I have always liked the results......
2 or 3 applications, then on to Birchwood Casey or Outers bluing products.

[WobblyHand]

On the original topic, I use Jax metal black for iron and steel.
I have always liked the results......
2 or 3 applications, then on to Birchwood Casey or Outers bluing products.

I'm sure you know,  but others may not.  Products like Jax black for iron & steel contain some pretty toxic chemicals, including nitric acid, selenium compounds and copper sulfate.  They are fine to use with taking reasonable care.  The used product is typically considered "toxic waste" and should be disposed of with that in mind.

The DIY cold blue is hydrogen peroxide and table salt.  Neither are considered toxic, but one could argue they are not good to drink! 

@Ronno6 do you have any pictures of your Jax blackened steel parts?  It would be interesting to see how they look.  Thanks.

[Ronno6]

I will see when I return home next week..........

[douglasr]

I like the results I get from Brownell’s Oxpho cold bluing. Fast, reasonably durable, and much better than super blue imho.

https://www.brownells.com/tools-cleaning/paint-metal-prep/metal-bluing/oxpho-blue/

[KWK]

I like the results I get from Brownell’s Oxpho cold bluing. Fast, reasonably durable, and much better than super blue imho.

https://www.brownells.com/tools-cleaning/paint-metal-prep/metal-bluing/oxpho-blue/

Cold blue offers no rust prevention at all.

[WobblyHand]

I like the results I get from Brownell’s Oxpho cold bluing. Fast, reasonably durable, and much better than super blue imho.

https://www.brownells.com/tools-cleaning/paint-metal-prep/metal-bluing/oxpho-blue/

Cold blue offers no rust prevention at all.

What about a hot blue, like molten potassium and sodium nitrate?

[KWK]

We all WISH we could do that at home

[jackssmirkingrevenge]

This link contains a decent set of charts of various types of steel machining indices.  https://www.machiningdoctor.com/machinability/steel/

I had seen that one, I suppose there is some subjective factor as well especially on a manual lathe.

In other news I have splurged out on some 1018, 1045 and 1144 round bar so with any luck I will be able to do some practical testing by next week.

[WobblyHand]

We all WISH we could do that at home

It seems that some tree root remover still contains potassium nitrate and at least in the past you could buy sodium nitrate at garden stores.  I have some of both.

I have a spare Lee 4lb melting pot, I may give it a try.  I believe that the pot can melt a 50/50 mixture without trouble.  You better believe that I'll be doing this outdoors.  Don't want a chance of burning my house down.  Need to make some trinket to try it on.  I'll use some plain steel wire to dunk the preheated part into the part.  From what I've read, it's all blued in a minute or two.

The only thing is to remove the solid nitrate material from the pot when cooled.  Sodium nitrate absorbs water from the air.  So I need to store the remaining material in a moisture proof container. If you don't remove it, I bet that the steel pot will rust like crazy.

[KWK]

We all WISH we could do that at home

It seems that some tree root remover still contains potassium nitrate and at least in the past you could buy sodium nitrate at garden stores.  I have some of both.

I have a spare Lee 4lb melting pot, I may give it a try.  I believe that the pot can melt a 50/50 mixture without trouble.  You better believe that I'll be doing this outdoors.  Don't want a chance of burning my house down.  Need to make some trinket to try it on.  I'll use some plain steel wire to dunk the preheated part into the part.  From what I've read, it's all blued in a minute or two.

The only thing is to remove the solid nitrate material from the pot when cooled.  Sodium nitrate absorbs water from the air.  So I need to store the remaining material in a moisture proof container. If you don't remove it, I bet that the steel pot will rust like crazy.

Just make sure you don't breath while you do it. PROTECT YOUR LUNGS

[WobblyHand]

We all WISH we could do that at home

It seems that some tree root remover still contains potassium nitrate and at least in the past you could buy sodium nitrate at garden stores.  I have some of both.

I have a spare Lee 4lb melting pot, I may give it a try.  I believe that the pot can melt a 50/50 mixture without trouble.  You better believe that I'll be doing this outdoors.  Don't want a chance of burning my house down.  Need to make some trinket to try it on.  I'll use some plain steel wire to dunk the preheated part into the part.  From what I've read, it's all blued in a minute or two.

The only thing is to remove the solid nitrate material from the pot when cooled.  Sodium nitrate absorbs water from the air.  So I need to store the remaining material in a moisture proof container. If you don't remove it, I bet that the steel pot will rust like crazy.

Just make sure you don't breath while you do it. PROTECT YOUR LUNGS

Not arguing, frankly having stuff this hot is a little scary, especially hot molten oxidizers. 

Does this heated mixture out gas, or make fumes?  The question is what am I protecting my lungs from?  Then I might know what precautions to take.

[jackssmirkingrevenge]

First attempt with 1018, definitely intolerant of less than sharp tools but with new carbide inserts I got a reasonably adequate finish:



I tried the peroxide/vinegar/salt solution and results were quite disappointing, this was after around ten repetitions of the process:



I still seem to have difficulty getting the oxide layer to "stick".  The red oxide turns a promising shade of blue-black on boiling, but most of the finish just seems to wipe off once the part is removed, simply using a paper towel.

One thing I noticed I wasn't doing previously was drying the part completely after boiling, which does appear to help "fix" it to some small extent, but the majority of it still just comes off with a light wipe.  Given that the mechanical properties of 1018 are slightly inferior to 12L14 and it's not as pleasant to machine, these initial results aren't too great.  Perhaps I'm not cleaning the part well enough beforehand, however I was fairly meticulous with brake cleaner and used gloves to avoid handling the parts with bare hands, I'm not sure why it isn't working.