Turning blued steel?

[Federico]

Hey everyone, so recently (about 4 months ago) I got myself a lathe. I have been practicing turning brass and all the basic cuts with some hss gravers and all went well.

 

Then I purchased some blued steel rods in various diameters and some carbide gravers. I can’t quite figure out how to cut this stuff. From what I have read you always need something harder to cut the metal. So I went with carbide and I sharpened it to a nice sharp edge with some diamond wheels. I can’t cut into the blued steel at all it kinda just scratches it and that’s it. I also tried annealing the blued steel and it chips for a layer but not really. Tried the hss on it as well and nada.

 

Basically I am really lost at this point. Would happily take any advice you all could provide.

 

Thank you in advance.

[khunter]

It's all about cutting angle, shape and sharpness of the tool, and speed. If it's truly blue steel and has not been hardened carbide should cut it. If you're heating the piece while "attempting" to take a cut you could be work-hardening the steel and defeating your purpose. There is tons of information about cutting steel, both on full size lathes and ours, but the theory is the same. If the steel has been tempered (hardened), you won't cut it, period. Tempered steel can be ground but not cut, it has to be annealed fully...sounds like you got it almost hot enough to anneal but only the surface, not all the way through the part. After cutting you re-temper to hardness, again there are tons of videos and such explaining that process, and each has a lot to do with the users own preferences.....in a nutshell, heat thoroughly, let cool on its own, anneal.......heat thoroughly, quench, hardened......and the type of steel also has it's own properties, so it's a lot of trial and error. 

A simple test is to take a file and lightly drag it across the work piece. If it marks it, it's probably not hardened, but if it takes excessive pressure to leave a mark, the steel is tempered and would have to be annealed before working.

Oh, and HSS gravers WILL cut soft steel (annealed), but you will have to sharpen much more often....

Edited January 25, 2018 by khunter

[khunter]

One other thought, the work should not extend past the collet any more than is necessary to do the work. If it's a longer piece, say for a stem or something, the free end should be supported by a center (male or female) held in the tail stock. The longer the piece, the more deflection, and you won't be able to put enough pressure on to make the cut without distorting the piece, but it would still get hot, and work harden the piece, etc etc.....

[Federico]

59 minutes ago, khunter said:

It's all about cutting angle, shape and sharpness of the tool, and speed. If it's truly blue steel and has not been hardened carbide should cut it. If you're heating the piece while "attempting" to take a cut you could be work-hardening the steel and defeating your purpose. There is tons of information about cutting steel, both on full size lathes and ours, but the theory is the same. If the steel has been tempered (hardened), you won't cut it, period. Tempered steel can be ground but not cut, it has to be annealed fully...sounds like you got it almost hot enough to anneal but only the surface, not all the way through the part. After cutting you re-temper to hardness, again there are tons of videos and such explaining that process, and each has a lot to do with the users own preferences.....in a nutshell, heat thoroughly, let cool on its own, anneal.......heat thoroughly, quench, hardened......and the type of steel also has it's own properties, so it's a lot of trial and error. 

A simple test is to take a file and lightly drag it across the work piece. If it marks it, it's probably not hardened, but if it takes excessive pressure to leave a mark, the steel is tempered and would have to be annealed before working.

Oh, and HSS gravers WILL cut soft steel (annealed), but you will have to sharpen much more often....

Hm, that is a little confusing. The bit about not cutting blued steel if it is hardened at all. Most things I have read on this forum say that you should be able to cut it no problem as long as it is a carbide graver.

The blue steel I have is from timesavers.com Blued steel is a hardened steel.

I agree that working with it in an annealed state would be easier, but for some reason, I am having trouble doing that. I hold it up to my butane torch for about 5 minutes it glows red hot for about 3 minutes then I let it air cool. 

This weekend I am going to try to resharpen my carbide graver and see if that changes anything and perhaps hold the steel to the torch for longer.

 

 

 

[khunter]

4 minutes ago, Federico said:

Hm, that is a little confusing. The bit about not cutting blued steel if it is hardened at all. Most things I have read on this forum say that you should be able to cut it no problem as long as it is a carbide graver.

The blue steel I have is from timesavers.com Blued steel is a hardened steel.

I agree that working with it in an annealed state would be easier, but for some reason, I am having trouble doing that. I hold it up to my butane torch for about 5 minutes it glows red hot for about 3 minutes then I let it air cool. 

This weekend I am going to try to resharpen my carbide graver and see if that changes anything and perhaps hold the steel to the torch for longer.

 

 

 

When I say hardened I refer to fully hardened (tempered). like a high speed drill bit or similar. A staking punch is another good example of hardened tempered steel that a carbide graver wont touch (experience lol)....If it is truly "blue" steel, and has not been tempered, either in manufacture or working, then yes, a carbide graver will cut it, all else being correct (shape, sharpness, cutting angle, speed, etc).

I recently read here that most prefer a slower turning speed for steel cutting, and this makes sense, as you would not be introducing unwanted heat from friction, allowing the cutting tool to do its job. Shallow cuts, slowly, and I wouldn't expect long curls of swarf like you see when turning softer metals like brass or aluminum. 

It's really all about practice and trial and error, every machinist will have his own preferred method to do the same task.

Another afterthought, cutting oil is probably a good idea as well, as it reduces the friction (heat) and enhances the cutting action of the tool.

Just my thoughts.......

[jdrichard]

I have cut blued steel with carbide gravers and with no issue at all. Where did you get this stock. Perhaps it is not truly blued steal.


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[Federico]

I have cut blued steel with carbide gravers and with no issue at all. Where did you get this stock. Perhaps it is not truly blued steal.


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I got it from timesavers.com. I am really starting to think the stock is the issue. I got home today annealed the rod to the best of my ability for about 10 minutes with my butane torch and the stuff is still very hard. I have to use a lot of force with the carbide graver to just get dust. I am thinking of ordering some pre annealed stock. Can’t figure out anything I could be doing wrong I cut everything else just fine so far.


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[khunter]

To go a cheaper route, just for practice, you could try regular round cold or hot rolled steel rod available at most home improvement stores in the welding section...It's not hardened (tempered), but much harder than brass and cheaper than watch stock you would buy online. it would be good to just practice with, but you'd need proper sized chucks as they come in inch sizes, 1/16, 1/8, 3/16, etc....

[jdm]

7 hours ago, Federico said:

I agree that working with it in an annealed state would be easier, but for some reason, I am having trouble doing that. I hold it up to my butane torch for about 5 minutes it glows red hot for about 3 minutes then I let it air cool. 

I have no direct experience but I think is possible that your heating temperature is too high, and isn't held long enough to be effective. Assuming that your "blued" is high-carbon steel you should heat to between 1,400 and 1,500 deg. F. and hold it for a minimum of two hours (some source says one). Note that a butane torch can reach 2600 F. 

http://www.zianet.com/ebear/metal/heattreat5.html

[rodabod]

I’d put your carbide graver away and use either an HSS or carbon steel graver. Shape the graver as per Donald De Carle etc suggest and finish it on an Arkansas stone. It should be so sharp that it scrapes your fingernail if you drag it across. 

The carbide graver is handy when you have burnished a surface with a steel graver and need to cut through the skin. They are more likely to chip, so makes more sense to work with a steel one at first. 

[Marc]

There seems to be some confusion over terminology here.

Tempering is NOT hardening, and the blue colour of blued steel come from the tempering process, not the hardening process.

Carbon steels are hardened by heating to a temperature high enough to change the crystal structure of the material from the Ferrite phase to the Austenite phase (about 800C to 900C), and then cooling it fast enough to prevent the formation of carbide precipitates. As the material cools it changes to a third crystaline phase called Martensite which is extremly hard but very brittle, sometimes referred to as glass hard, with all of the properties that the name implies.

Tempering is the process of heating hardened steel to a precisely controlled temperature that is much lower than the Ferrite/Austenite phase change temperature (between about 170C and 380C depending on the required state of temper) and then allowing it to cool slowly. This allows for a partial reversal of the Martensite crystal phase to the Ferrite phase which reintroduces an element of elasticity and ductility, reducing the brittleness thus making the steel tougher (as opposed to harder). Tempering could be considered to be a controlled partial softening process.

Different states of temper are referred to by colour as the colour of the oxide layer formed on the surface of the steel as it is heated in the tempering process is an accurate indicator of temperature (Google "steel tempering colours"), so blued steel is carbon steel that has been fully hardened (glass hard) and then tempered to a temperature of between 280C and 310C (purple to dark blue) to partially soften it to a state of toughness to suit its intended use.

That is only half the hardness story though. The precise alloy (carbon content as well as the inclusion of other metals) also results in different levels of hardness, which means that you can have a whole range of blued steel with a whole range of hardness properties depending on the actual alloy.

All that being said, I have never needed to anything other than HSS gravers to cut blue steel stock. As @khunter says "it's all about cutting angle, shape, and sharpness of the tool". I struggled cutting anything at all to start with and just about all I could do with blued steel was scrape off the blue oxide layer and make a shiny line. It turned out to be because I was trying to sharpen my gravers freehand, an envyable skill that I just haven't managed to acquire, and as a result I was just not getting a suitable cutting edge on the graver. That changed though when I got a honing guide. The difference was instant and dramatic, and the swarf began to fly.

Once you have sharpness and technique sorted out the only practical differences between HSS and Tungsten Carbide gravers in watchmaking applications are ease and frequency of sharpening. HSS is easier to sharpen but looses its edge quicker so needs more frequent touching up, Tungsten Carbide is harder to sharpen but holds its edge longer. It is also more prone to chipping.

 

[jdrichard]

I use carbide and sharpen with a diamon Metal sheet I bought from China 2000 grit. I find cutting a balance staff with carbide graver better as I don't need any pressure and I can use a 0.2mm rounded tip for the cone part of the pivots.

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[measuretwice]

what Marc said. 

If you are not able to cut this with a carbide graver, imo you need to look at the edge or tool geometry.    Can you post some close up pics of the tool?

Edited January 26, 2018 by measuretwice

[measuretwice]

20 hours ago, Federico said:

I agree that working with it in an annealed state would be easier, but for some reason, I am having trouble doing that. I hold it up to my butane torch for about 5 minutes it glows red hot for about 3 minutes then I let it air cool.

 

To anneal, carbon steel needs a long cool down - like 24 hours for a full anneal.  A tiny part like that is being essentially air quenched (it may not be A2, but it is still being quenched at least partially) as you are doing it and might be harder than the tempered stuff you started with.  If you do want to thoroughly anneal something small, the trick is to pack with some larger pieces, get them all to red hot, hold for a bit then place the lot in ashes (amazing insulator) in a steel box.  To take it back to so called blue steel, heat to red, quench, the temper back to blue

Edited January 26, 2018 by measuretwice

[vinn3]

anealing is not hard to do.    hardening is the real chalenge. also,  there is different ways to  "quench". somthing you can read up on.  good luck, vin

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[Federico]

I tried cutting an old drill bit by hand and it seemed to make a chip just fine so I think my stock is simply too hard. I ordered some stock from Diesupplies.com They have W-1 Stock that is in annealed form for 100% machinability. I think that should help.

14 hours ago, khunter said:

To go a cheaper route, just for practice, you could try regular round cold or hot rolled steel rod available at most home improvement stores in the welding section...It's not hardened (tempered), but much harder than brass and cheaper than watch stock you would buy online. it would be good to just practice with, but you'd need proper sized chucks as they come in inch sizes, 1/16, 1/8, 3/16, etc....

@khunterLike music wire?

@rodabod thank you for your advice, unfortunately, I have tried with no success. The stock might be my issue.

@Marc Thank you for the clarification on the vocabulary that matches exactly what I have read so far. Thankfully I do not sharpen my gravers by hand. I tend to refuse to do work that a machine can do for me so. Here are the tools I am using: Firstly I use a GRS Tungsten Carbide Graver and to sharpen them I use all 3 Grits of Jura Swiss Diamond wheels. I have read that the better the finish on the graver the better the cut and the cleaner the finished product will be, so I try to get a mirror finish on it with the 3 wheels. I use my 3-way cross slide and a quick change tool holder to get perfect and accurate grinds on the graver.

56 minutes ago, measuretwice said:

what Marc said. 

If you are not able to cut this with a carbide graver, imo you need to look at the edge or tool geometry.    Can you post some close up pics of the tool?

2

I am using a parting tool looks like this here only miniaturized:

 

@vinn3 Yup I have read up on those, Water, air, and oil hardening. Currently, I am reading William E Bryson's Heat treatment book.

[khunter]

2 hours ago, Federico said:

I tried cutting an old drill bit by hand and it seemed to make a chip just fine so I think my stock is simply too hard. I ordered some stock from Diesupplies.com They have W-1 Stock that is in annealed form for 100% machinability. I think that should help.

@khunterLike music wire?

@rodabod thank you for your advice, unfortunately, I have tried with no success. The stock might be my issue.

@Marc Thank you for the clarification on the vocabulary that matches exactly what I have read so far. Thankfully I do not sharpen my gravers by hand. I tend to refuse to do work that a machine can do for me so. Here are the tools I am using: Firstly I use a GRS Tungsten Carbide Graver and to sharpen them I use all 3 Grits of Jura Swiss Diamond wheels. I have read that the better the finish on the graver the better the cut and the cleaner the finished product will be, so I try to get a mirror finish on it with the 3 wheels. I use my 3-way cross slide and a quick change tool holder to get perfect and accurate grinds on the graver.

I am using a parting tool looks like this here only miniaturized:

 

@vinn3 Yup I have read up on those, Water, air, and oil hardening. Currently, I am reading William E Bryson's Heat treatment book.

 

No music wire is too hard, just plain round stock, either cold rolled or hot rolled. They have it in the hardware sections of most big box home improvement stores, in 3 ft sections. 

[vinn3]

20 hours ago, Federico said:

I tried cutting an old drill bit by hand and it seemed to make a chip just fine so I think my stock is simply too hard. I ordered some stock from Diesupplies.com They have W-1 Stock that is in annealed form for 100% machinability. I think that should help.

@khunterLike music wire?

@rodabod thank you for your advice, unfortunately, I have tried with no success. The stock might be my issue.

@Marc Thank you for the clarification on the vocabulary that matches exactly what I have read so far. Thankfully I do not sharpen my gravers by hand. I tend to refuse to do work that a machine can do for me so. Here are the tools I am using: Firstly I use a GRS Tungsten Carbide Graver and to sharpen them I use all 3 Grits of Jura Swiss Diamond wheels. I have read that the better the finish on the graver the better the cut and the cleaner the finished product will be, so I try to get a mirror finish on it with the 3 wheels. I use my 3-way cross slide and a quick change tool holder to get perfect and accurate grinds on the graver.

I am using a parting tool looks like this here only miniaturized:

 

@vinn3 Yup I have read up on those, Water, air, and oil hardening. Currently, I am reading William E Bryson's Heat treatment book.

 

that is the proper tool (for parting only).   use it on annealed steel.  as mentioned above, "drill rod" comes annealed, BUT,  be sure to ask for the proper quench medium for hardening. !  drill rod will save time and aggravation.  vin p.s.  the stem must be hardened.  cheers

[measuretwice]

There is so many factors a play, I had a few more random thoughts to throw in the mix and possibly get you toward success.   

It is always possible that you got a dud piece of material or a dud cutting tool.  Unless you are using developed world stuff, complaints about horrible quality of offshore cutting tools is frequent.  It could be nothing more than a crappy piece of carbide.

Next,  details on the wheel and sharpen procedure for the carbide.   Carbide compared to steels is very brittle - little things like having the wheel run off the edge will mess you up - tiny bits of carbide will fracture at the edge.  Another no-no  is cool the tool by quench so you can hold on to it - this will create micro fissures from the thermal shock that quickly lead to the edge fracturing off - carbide is great under compression is but is fragile.

 

22 hours ago, Federico said:

Yup I have read up on those, Water, air, and oil hardening. Currently, I am reading William E Bryson's Heat treatment book.

The one you might consider is Hardening, Tempering, and Heat Treatment by Tubal Cain (the British author, not the internet utube character who's taken on the name.... or for that matter not the biblical character either lol).

The reason is its written for homeshop applications with modest equipment.  Reading a commercial book might get you convinced that you need to spend $1000's or it will never work which is simply not true for common carbon steels (it is for hss though!).   For example, I've been making specially cutters for all manner of work and rarely use more than a propane torch and can of oil to harden and temper.  I have the temperature controlled oven some will say you must have, but the reality is its not worth turning it on to do simple stuff from O1, W1 etc. 

 

22 hours ago, Federico said:

Thankfully I do not sharpen my gravers by hand.

 

hmmm,  a couple of points.  Generally, you might be cutting yourself off from your best work if you eschew handwork; its very often necessarily to get the best results.   Specifically, with a cutting tool, the cutting edge is a product of two planes and to get there requires a bit of handwork.  The idealized cutting edge is two perfectly smooth and uniform planes coming together - just like how a woodworker sharpens a chisel.  The bottom AND the bevel edge are lapped to a mirror finish.

How to bring this about?  I too use equipment where ever I can - the angle ends get put on using a uni-vise in a tool and cutter grinder (point being I'm not lacking in sharpening equipment but it still doesn't preclude the hand work).  I set it up and do a bunch, however you are still left with two issues even if you use the finest (and slowest) diamond wheel:  1) The end is only 1/2 of the number of planes you want perfect - you still have to stone/lap the side of the graver leading up to the cutting edge and 2) you will have burrs from grinding, these need to be stoned off bit the the edge maintained.

Its ideal to understand how metal is cut (the unread 1st chapter in every machining textbook).  Its always the same - the tool creates pressure that creates a shear plane ahead of it - its the same whether its milling, grinding, drilling or turning on the watchmakers lathe.  As the size of the chip gets smaller, the edge must corresponding get sharper else it would bounce along instead of creating the pressure needed to establish the shear plane.  This is an important point - since we are making very tiny chips, we need very sharp tools

imo you get a better edge with a bit of handiwork and since you are having trouble, the thought is do it the best way and see if that eliminates the problem.  If you've got a microscope, it gives great insight onto how good or not  an edge is

 

Quote

I am using a parting tool looks like this here only miniaturized:

This confused me a bit....is the issues hand held gravers aren't working, or that a fixed cutting tool isn't working?

Edited January 27, 2018 by measuretwice

[Federico]

There is so many factors a play, I had a few more random thoughts to throw in the mix and possibly get you toward success.   
It is always possible that you got a dud piece of material or a dud cutting tool.  Unless you are using developed world stuff, complaints about horrible quality of offshore cutting tools is frequent.  It could be nothing more than a crappy piece of carbide.
Next,  details on the wheel and sharpen procedure for the carbide.   Carbide compared to steels is very brittle - little things like having the wheel run off the edge will mess you up - tiny bits of carbide will fracture at the edge.  Another no-no  is cool the tool by quench so you can hold on to it - this will create micro fissures from the thermal shock that quickly lead to the edge fracturing off - carbide is great under compression is but is fragile.
 
This confused me a bit....is the issues hand held gravers aren't working, or that a fixed cutting tool isn't working?

My graver is a GRS carbide graver I have 3 so I will sharpen another and see what happens.

Agreed on the sharpening bit Must have at least 2 sides for a cut to happen. With the tool I am using it is 3.

Fixed tool on cross slide. However I have also tried by hand with no success on the material.

With HHS graver I harden and temper first then sharpen so I don’t get micro fractures on the edge. I am not sure if you can harden carbide. From my understanding carbide is not really a metal so I am not sure if it can be hardened and tempered. Or can it? Will look that up..


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[measuretwice]

11 minutes ago, Federico said:

With HHS graver I harden and temper first then sharpen so I don’t get micro fractures on the edge. I am not sure if you can harden carbide. From my understanding carbide is not really a metal so I am not sure if it can be hardened and tempered. Or can it? Will look that up..


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bad carbide was probably a long shot....but it does happen and if all else has been tried....

You shouldn't try to heat treat HSS, there's no need, it comes hardened and ready for use.   Its very difficulty hardening and tempering hss (like impossible) as the temps required need to be exact.  Unlike carbon steel, its just not a DIY thing I'm afraid.   Carbide afaik cannot be hardened or heat treated, its made by sintering and is what it is.

If the tool is mounted, its dead on centre height?  Sometimes easier said that done for very small diameters....and I know its pointing out the obvious but stranger things have happened

 

Edited January 27, 2018 by measuretwice

[Federico]

 
You shouldn't try to heat treat HSS, there's no need, it comes hardened and ready for use.   Its very difficulty hardening and tempering hss (like impossible) as the temps required need to be exact.  Unlike carbon steel, its just not a DIY thing I'm afraid.   Carbide afaik cannot be hardened or heat treated, its made by sintering and is what it is.
If the tool is mounted, its dead on centre height?  Sometimes easier said that done for very small diameters....and I know its pointing out the obvious but stranger things have happened [emoji4]
 

Yup dead straight on to the center of the stock. I learned that is very important when I was practicing on the brass.


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[vinn3]

On ‎1‎/‎26‎/‎2018 at 12:11 AM, rodabod said:

I’d put your carbide graver away and use either an HSS or carbon steel graver. Shape the graver as per Donald De Carle etc suggest and finish it on an Arkansas stone. It should be so sharp that it scrapes your fingernail if you drag it across. 

The carbide graver is handy when you have burnished a surface with a steel graver and need to cut through the skin. They are more likely to chip, so makes more sense to work with a steel one at first. 

good  show.  vin

[jdrichard]

good  show.  vin

I love my carbide gravers for making balance staffs.
0.2 round and flat
0.4 round and flat
2mm triangle x 3 blades.

Absolutely no chipping yet on blued steel and sharpening easy on 3" by 6" diamond plate from china (1000)


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[vinn3]

23 minutes ago, jdrichard said:

I love my carbide gravers for making balance staffs.
0.2 round and flat
0.4 round and flat
2mm triangle x 3 blades.

Absolutely no chipping yet on blued steel and sharpening easy on 3" by 6" diamond plate from china (1000)


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I sharpen woodworking tools on the oil stones.  vin