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Drill Blanks with Lathe?


bscherokman

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Just one thing to remember about tools.

 

If you use High Speed Steel (HSS) tools they are much more tolerant of heat than carbon steel tools and you will not loose the temper if they run at less than red heat. So, the warnings about running grinders cool and slow do not apply to HSS tools. The temper on a really hard carbon steel is drawn if the steel exceeds 215 degrees centigrade (420 deg F, gas mark 7). The steel will not be softened if the temperature does not get up to its tempering temperature, it will be softened only if it's exceeded.

 

There is a down side to HSS tools though. They do not seem to hold an edge in quite the same way as a good carbon steel. For the absolute best work possible carbon steel tools are an imperative. For lesser work, you take your pick.

 

For info, the list below (of tempering temperatures, steel colours and uses) is drawn from Marv Klotz's web site ( http://www.myvirtualnetwork.com/mklotz/ ) with editing and Gas Mark temperatures added by me - because I try to temper my tools in the kitchen oven if possible (ie when Tracy's out of the house!).

 

Tempering Colour: FAINT YELLOW; 420 degF; Gas Mark 7; Use: KNIVES,HAMMERS

Tempering Colour: VERY PALE YELLOW; 430 degF; Use: REAMERS

Tempering Colour: LIGHT YELLOW; 440 degF; Use: LATHE TOOLS, SCRAPERS, MILLING CUTTERS, REAMERS

Tempering Colour: PALE STRAW YELLOW; 450 degF; Gas Mark 8; Use: TWIST DRILLS FOR HARD USE

Tempering Colour: STRAW YELLOW; 460 degF; Gas Mark 9; Use: DIES, PUNCHES, BITS, REAMERS

Tempering Colour: DEEP STRAW YELLOW; 470 degF;

Tempering Colour: DARK YELLOW; 480 degF; Use: TWIST DRILLS, LARGE TAPS

485 degF; Use: KNURLS

Tempering Colour: YELLOW BROWN; 490 degF;

Tempering Colour: BROWN YELLOW; 500 degF; Use: AXES, WOOD CHISELS, DRIFTS, TAPS >= 1/2", NUT TAPS, DIES

Tempering Colour: SPOTTED RED BROWN; 510 degF;

Tempering Colour: BROWN PURPLE; 520 degF; Use: TAPS <= 1/4"

Tempering Colour: LIGHT PURPLE; 530 degF;

Tempering Colour: FULL PURPLE; 540 degF; Use: COLD CHISELS, CENTER PUNCHES

Tempering Colour: DARK PURPLE; 550 degF;

Tempering Colour: FULL BLUE; 560 degF; Use: SCREWDRIVERS, SPRINGS, GEARS

Tempering Colour: DARK BLUE; 570 degF;

Tempering Colour: MEDIUM BLUE; 600 degF; Use: SCRAPERS, SPOKESHAVES

 

 

Regards

 

Richard

 

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Just one thing to remember about tools.

 

If you use High Speed Steel (HSS) tools they are much more tolerant of heat than carbon steel tools and you will not loose the temper if they run at less than red heat. So, the warnings about running grinders cool and slow do not apply to HSS tools.

A qualification. Though it is indeed accurate that HSS tools, by definition, can withstand temperatures up to red heat, what is almost always overlooked is that they can be severely degraded not by the heat of grinding but by the quenching frequently applied during grinding after the tools get hot -- an operation completely absent from their operating enviroment (e.g. mounted on a lathe toolpost).

 

So, HSS tools can't be damaged by the heat of grinding (up to red heat) per se, but they can be damaged during the whole operation of using a grinder to shape and sharpen them.

 

--Daniel

"The greatest mental derangement is to believe things because we want them to be true, not because we observe that they are in effect." --Jacques-Bénigne Bossuet

Daniel Kirchheimer
Specialty Pen Restoration
Authorized Sheaffer/Parker/Waterman Vintage Repair Center
Purveyor of the iCroScope digital loupe

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... HSS tools can't be damaged by the heat of grinding (up to red heat) per se, but they can be damaged during the whole operation of using a grinder to shape and sharpen them.

True. Don't quench HSS.

When I grind HSS tools and my fingers get a bit warm, I tend to continue after putting on welding gloves.

 

Regards

 

Richard.

 

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For drilling blanks, this is my preferred method - quick & cheerful (there's no pressure on that visegrip BTW - it's just to hold against rotation):

http://i3.photobucket.com/albums/y59/ruaidhri/FPN%20Stuff/Drilling.jpg

 

Just my 2 cents.

 

Cheers,

Ruaidhrí

 

I use a similar technique when drilling my blank to add scrificial pieces on the ends.

Since they are cut on a table saw and have a flat side and are relatively square, I mark centers and put a dimple in the center with a punch.

I suspend the blank between the live center and the bit and raise the tool rest to the bottom of the blank.

The tool rest stops the blank from spinning as I advance the ram in the live center.

 

"Where the spirit does not work with the hand, there is no art". -- Leonardo da Vinci

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