Boring Bar for Making Tobacco Chambers

[LatakiaLover]

FYI if Kurt is using HSS then he doesn't need to worry about the heat, you cannot draw the temper of HSS under normal circumstances.

True Sheffield steel, for sure. Does that apply to Chineseium, though?

[KurtHuhn]

FYI if Kurt is using HSS then he doesn't need to worry about the heat, you cannot draw the temper of HSS under normal circumstances.

For comfort though you will want to cool it otherwise you will burn your hands.

I understand that carbide bits can be heated without losing temper, but not really sure that is true for HSS.
However, your point is good about comfort.
DocAitch

The basics are, if you see color on the steel, it's too hot. Light straw will generally show up about 350-400 Freedomheit, and that means you've drawn back the hardness of the steel somewhat - though for this purpose, it's mostly not a problem, as it should remain in the high 50s on the RC scale. If it goes blue, it's done. Start over. You made spring steel at that point.

The intricacies of heat treating can be complex - jerks like me take it for granted due mainly to experience. It's definitely an interesting thing to study and learn about though.

[caskwith]

You are talking about "tool" or high carbon steel there though Kurt, HSS is a different beast. Not only does it require high temperatures to anneal it, it also needs to be done for the correct soaking and cooling times and even then it is never really "soft". These times and temps depend on the specific alloy of HSS, some being easier than others but for our purposes they are essentially the same.

For anything that you are doing at home grinding tools etc don't worry, you will never make a significant impact on the hardness of the tool. All you really need to do is keep it cool enough to handle for comfort and safety.

Case in point, you can braze or silver solder a piece of HSS onto a piece of mild steel and it will retain full hardness. This is great if you want to make a special purpose tool.

[caskwith]

FYI if Kurt is using HSS then he doesn't need to worry about the heat, you cannot draw the temper of HSS under normal circumstances.

True Sheffield steel, for sure. Does that apply to Chineseium, though?

I have used HSS blanks made of the cheapest chinesium I could get on aliexpress and for our purposes it works just fine. Certainly I get better edge retention on my higher quality blanks but since you want a sharp edges for pipe work you are going to be touching them up regularly anyway so I think expensive HSS is a bit of a false economy, better to invest in having a quick and simple sharpening system.

[KurtHuhn]

You are talking about "tool" or high carbon steel there though Kurt, HSS is a different beast. Not only does it require high temperatures to anneal it, it also needs to be done for the correct soaking and cooling times and even then it is never really "soft". These times and temps depend on the specific alloy of HSS, some being easier than others but for our purposes they are essentially the same.

For anything that you are doing at home grinding tools etc don't worry, you will never make a significant impact on the hardness of the tool. All you really need to do is keep it cool enough to handle for comfort and safety.

Case in point, you can braze or silver solder a piece of HSS onto a piece of mild steel and it will retain full hardness. This is great if you want to make a special purpose tool.

For our purposes, that is true. The rest of the conversation devolves into some pretty serious and boring discussion on metallurgy.

[oklahoma red]

FYI if Kurt is using HSS then he doesn't need to worry about the heat, you cannot draw the temper of HSS under normal circumstances.

True Sheffield steel, for sure. Does that apply to Chineseium, though?

Chineseium! Good one! I also like "Kung Flu". Gotta make Xi's arse pucker some more.

[kasperbunk]

I am quite a newbie on holding my tools sharp. I do not yet own a bench grinder. Is it possible to sharpen up my tool bit (straight round nose shape) on the table disc sander? What are you guys doing for a quick touch up?


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[KurtHuhn]

I am quite a newbie on holding my tools sharp. I do not yet own a bench grinder. Is it possible to sharpen up my tool bit (straight round nose shape) on the table disc sander? What are you guys doing for a quick touch up?

You can use any kind of grinding device - belt, disc, wheel, whatever. Some will be better suited due to speed or media used, but all will work in some fashion.

[professor_throway]

You are talking about "tool" or high carbon steel there though Kurt, HSS is a different beast. Not only does it require high temperatures to anneal it, it also needs to be done for the correct soaking and cooling times and even then it is never really "soft". These times and temps depend on the specific alloy of HSS, some being easier than others but for our purposes they are essentially the same.

For anything that you are doing at home grinding tools etc don't worry, you will never make a significant impact on the hardness of the tool. All you really need to do is keep it cool enough to handle for comfort and safety.

Case in point, you can braze or silver solder a piece of HSS onto a piece of mild steel and it will retain full hardness. This is great if you want to make a special purpose tool.

For our purposes, that is true. The rest of the conversation devolves into some pretty serious and boring discussion on metallurgy.

Something this lurker can actually comment on. HSS gets its strength from fine carbide precipitates that form. There are a whole range of compositions but the ones that are most relevant in HSS are M6C where the M is a metal atom. SO one metal atom and one carbon covanlently bonded in an fact centered cubic crystal lattice. The makeup of M is different than that of the alloy is is about 40% Fe, 30% Mo, 17% Tungsten, and 6% each Cr and V. The important thing is they are incredibly stable. You need to hold HSS at 900C for about 15 hours to dissolve these carbides. So unless you take your tool way past cherry red and even orange into the yellow or light yellow range >100C you will not significantly degrade the hardness of HSS.

[KurtHuhn]

Something this lurker can actually comment on. HSS gets its strength from fine carbide precipitates that form. There are a whole range of compositions but the ones that are most relevant in HSS are M6C where the M is a metal atom. SO one metal atom and one carbon covanlently bonded in an fact centered cubic crystal lattice. The makeup of M is different than that of the alloy is is about 40% Fe, 30% Mo, 17% Tungsten, and 6% each Cr and V. The important thing is they are incredibly stable. You need to hold HSS at 900C for about 15 hours to dissolve these carbides. So unless you take your tool way past cherry red and even orange into the yellow or light yellow range >100C you will not significantly degrade the hardness of HSS.

Good info, thanks! I have ruined some hss in the past, but since building a proper heat treat oven, it hasn't been an issue.