I am not sure but I think flame hardening only hardens about .002 or .003 deep as the flame is passed over the surface with a water spray directly behind the flame.  A German machinist I worked with had worked at a Mouser lathe plant in Germany. He said you can lay your hand on the way right after the spray goes buy.  If the metal was hardened to any depth you couldn't do that.  They are already ground and the flame hardening is done after. If this is correct the heat would not likely warp the cast iron but very little because cast iron has no stress to amount to anything having not been rolled or forged.  Don't take this to church it may not be right and maybe some else here knows.                    Doug

On 12/12/2012 01:21 PM, Thomas.G.Brandl@... wrote:

 

Also some of the 10Ks had hardend beds, too. I don't know SB's manufacturing processes. Latheman might know better. I do work with castings. Depends on the casting, forging etc. As for type, area as to how much is any extra material is left on. I would say generally, with a sand casting, a surface to be machined would have about 1/8 of an inch material extra left on it. Then that material would be machined off. I would say on a part to be hardened, about  0.005 to 0.020 would be left on before hardening. With a some hardening processes, there can be a hardness to a depth. It's been a while, but I remember about 0.030 to possibly 0.060. The hardness would get less the deeper it went.
                                                                Tom



From:        john kling
To:        southbendlathe@...
Date:        12/12/2012 01:13 PM
Subject:        Re: [southbendlathe] Re: Temper   was<
Sent by:        southbendlathe@...

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Some of the "newer" SB heavies have flame harden beds. Does the manufacturing process  involve milling the bed prior to hardening and then after hardening grinding the bed.

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From: "Thomas.G.Brandl@..."
To: southbendlathe@...
Sent: Wed, December 12, 2012 8:27:12 AM
Subject: Re: [southbendlathe] Re: Temper was<

 

Actually, that is how they flame harden a bed. Or at least how it can be done. You would have to regrind the ways though. One shop I worked at did rollers for some Over Head cranes. The wheels were put on a turning head. The part was heated with a flame from several nozzles. Then when heated a stream of water was poured on it. I remember them being cast iron parts.
                                               Tom



From:        john kling
To:        southbendlathe@...
Date:        12/12/2012 08:22 AM
Subject:        Re: [southbendlathe] Re: Temper   was<
Sent by:        southbendlathe@...

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I take it that it would not be a good idea to heat my lathe bed with a torch and then cool it rapidly with a garden hose.

---

From: "Thomas.G.Brandl@..."
To: southbendlathe@...
Sent: Wed, December 12, 2012 7:25:46 AM
Subject: Re: [southbendlathe] Re: Temper was<

 

        It can, and usually does to varying degrees. Also, it can introduce cracks.  Also, some metals grow after heat treating, some shrink and other stay about the same. It might not be a lot. Not what I would consider an expert on this.
      I think shape of the part and how the quench is 'applied' can distort a part. Let's take a knife blade or a sword. It needs to go straight in. If one side is put in before the other it will cool first. The blade will warp to that side. With bone charcoal coloring, they do have the problem of warping side plates. I think the put them in a jig or block to prevent warping.
                                                                      Tom



From:        john kling
To:        southbendlathe@...
Date:        12/12/2012 07:17 AM
Subject:        Re: [southbendlathe] Re: Temper   was<
Sent by:        southbendlathe@...

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Another question from hardening 101. Does hardening a piece of steel usually produce distortions or twisting in the process?

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From: "Thomas.G.Brandl@..."
To: southbendlathe@...
Sent: Wed, December 12, 2012 7:11:10 AM
Subject: Re: [southbendlathe] Re: Temper was<

 

        I would say you have the general concept. You have a hardened steel, that you want a bit softer, but not back to its anealed state (soft). So, heat is replied. You can temper the entire part or just parts of it. Basically, a temperture is atained and the carbon is changed thus softening the steel. Straw is the least amount of tempering or the hardest. Gray is about the most, getting to a near annealed state. With a chisel or gouge, usually only the tip of the tool is hardened. Then the shank is heated and let the heat go towards the tip. Then the enitre part or actually the tip tip is quenched to stop the heat flow to the tip. It is the end you still want hard, but not brittle.
     With Samuri swords they 'mask' off the blade edge with clay I think. Then heat the back. They scallop the clay along the bladed edge. Then the blade is tempered. This gives a hard edge, but a flexable back.
                                                             Tom



From:        David
To:        southbendlathe@...
Date:        12/12/2012 06:45 AM
Subject:        [southbendlathe] Re: Temper   was<
Sent by:        southbendlathe@...

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Re: tempering, I think I read somewhere, maybe HTRAL, that you reheat to straw color and then plunge the back end into oil or water. This draws the temper up the tool. By back end, I mean the end that won't be doing the work. In the case of a chisel, the quenching for tempering is not at the chisel point but at the handle end.

Can someone confirm this?

--- In southbendlathe@..., Thomas.G.Brandl@... wrote:
>
> Stress releiviving is a bit different than tempering or 'drawing
> colors'. It depends on the part, as to size weather a propane torch or
> such will be adequite. Heat treating can be complex, so this is a basic
> primer. First the metal has to have suficient carbon content. IE 40 points
> of carbon, like 4140. The 40 denotes the carbon content. the 41 is the
> alloying of the steel.
> The steel is heated to a cherry red in most cases. Then 'quenched'
> or rapidly cooled. It depends on the metal as there are oil hardening,
> water hardening and air hardening steels. Probably other ways too. With
> water hardening it is best to use a salt brine solution, as to keep air
> pocket off the steel.
> OK, the steel is hard, brittle too. You want the hardness, but the
> brittle part isn't good to most needs. The steel must be heated to a
> tempreture, but not to hot. So, say a straw yellow about 400F, or a blue
> or a brown. For small parts it is best to heat on a plate. Then when
> reaching color it is generally OK to quench again.
> Some things you want to run the colors. Say a chisle or gouge.
> You want the shank soft, but the end hard, even brittle. So you heat the
> shank, then watch the colors draw down the shank. When the tip is getting
> yellow, then you stop the draw, or run by quenching.
> Now there can be stresses in the steel, from heat treating,
> machining or handling. Basically, heat up to less than your tempering temp
> for an hour or more. This relieves the stress. You will not soften the
> steel as you haven't gone past your tempering temp.
> There are other ways of hardening. Basically case harndening. This
> can be done at home on mild steels. The part is heated to cherry red, then
> dipped, dunked or rolled into a carbon type material. One brand is
> Kasenite. Also, bone meal is used. Those colors on fine fire arms are bone
> charcoal. Then that is heated red and quenched. No need to draw, as you
> want the hard ness, and the case is only .020 to 0.061 deep. Other ways
> even for high carbon steel to be case hardend.
> Again, this is very basic.
> Tom
>
>
>
>
> From: Mark Hofer
> To: southbendlathe@...
> Date: 12/11/2012 03:42 PM
> Subject: Re: [southbendlathe] Temper was< > Sent by: southbendlathe@...
>
>
>
>
> Everything I've read on hardening and then tempering (for example 'Tool
> Steel Simplified') has indicated cooling after heating to tempering
> temperatures (light straw being ~400°F) should be slow, like leaving it
> in lime or ashes. I have not seen any instructions suggesting it should
> be quenched again. I thought doing so would simply reintroduce stresses
> which the tempering was inter alia removing?
> M
>
> On Dec 11, 2012, at 12:48 PM, Eggleston Lance wrote:
>
>
> Depends:
> Type of steel <% carbon>
>
> How big a piece?
> Can you insulate it to retain heat?
>
> You heat to cherry red.
> Quench
> Heat to dull red, polish to shiny,
> look for straw coloration on the steel, quench.
>