Surface Gauge scribe material ?

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Wolfgang
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Re: Surface Gauge scribe material ?

Post by Wolfgang »

Round, hardened, and ground HSS blanks were known to me as reamer blanks. I'd never heard of drill blanks.
The second heating operation I described is known as TEMPERING. This reduces the hardness somewhat and drastically improves the toughness of the steel. Very important for tools subjected to impacts.
On second thought, a better way to temper thin, long, tools such as scribers, center punches, screw drivers, etc. is as follows:
Polish the hardened tool to a clean bright shine.
With a very gentle flame heat the tool AT SOME DISTANCE from the business end; say 1 1/2" from the end. Need to use a little judgment here.
Observe the colour change. The heated area may change to a blue colour, and progress to straw colour towards the sharpened end. Dip the tool into the quenching medium to cool.

What you have made is a tool with a very hard point, and a less hard but very tough shank.

If heat treating is a new skill for you, it is indeed worthwhile to do a little experimenting. And test the experimental bits for resistance to deformation by placing in bench vise and hitting with a hammer.
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Harold_V
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Re: Surface Gauge scribe material ?

Post by Harold_V »

Wolfgang wrote: Tue Mar 23, 2021 9:31 am Round, hardened, and ground HSS blanks were known to me as reamer blanks. I'd never heard of drill blanks.
It's all to do with tolerances. Reamer blanks are positive, while drill blanks are negative. Otherwise they are identical.

H
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pete
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Re: Surface Gauge scribe material ?

Post by pete »

Wolfgang's method of letting the color change, or in reality it's temperature move into the area where you want the heat to be for the required hardness is the classic one for sure. One addition though, you want to stop that color change very quickly the instant you see it on parts with a cross section that small. Lightening fast is what I mean by quickly. So how you set up and hold the parts while heating makes a big difference. I wouldn't use a mechanical holding method at all since it's far too slow to then remove the part and get it quenched. On a longer part like that, hand holding it back from where your heating the other end would be fine, but I'd want to do the heating very close to your quenching container. With thin part cross sections just moving it through the air for any distance from where you did the heating to the quench tank can cool the part enough to make a real difference in it's expected hardness.

Without any prior heat treating experience? Then for what it cost's this is the best reference I know of. https://www.teepublishing.co.uk/books/i ... treatment/ It would be ridiculous to reinvent the wheel by making numerous mistakes and wasting your time and materials when a few bucks makes the learning curve and success rate so much easier. Heat treating high carbon steels in a home shop using simple cheap methods is fairly easy and not all that tough to be successful at it if you start with known types of steel meant to be heat treated and a bit of knowledge. It's still pretty neanderthal compared to how it's done in industry today. Our methods work well enough so that's the only important part.
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Bill Shields
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Re: Surface Gauge scribe material ?

Post by Bill Shields »

Wow...a lot here to which I never paid attention....since I have never made a reamer or knowingly used a drill blank.

Been fat dumb and happy with drill rod for 50 years.
Too many things going on to bother listing them.
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Harold_V
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Re: Surface Gauge scribe material ?

Post by Harold_V »

Bill Shields wrote: Tue Mar 23, 2021 8:31 pm Wow...a lot here to which I never paid attention....since I have never made a reamer or knowingly used a drill blank.

Been fat dumb and happy with drill rod for 50 years.
Nothing wrong with that---it's just nice to know that there's a step up when needed. Drill/reamer blanks are not made from the same material as drill rod, and are highly likely to be round, due in part to being ground after heat treat, when they are much shorter. Long pieces through a centerless (that's how such things are ground) have a tendency to not be round due to issue with straightness. If you understand how a centerless works, that makes all kinds of sense.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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