Subject: Re: Spring tempering

From: [email-masked]
Date: Fri, 14 Jun 1996 12:18:52 -0400

George,
In order to temper a sprng it would help to know the type of spring, the
composition of the spring, the use, etc. Short of that, springs are usually
tempered back to a nice bright blue. There are multiple sources for the right
temperature. Be careful most of these sources refrence carbon steel. Alloying
elements do change the color response. I am a purist when it comes to
temperature so I use my oven. Most have temperature controls that go high
enough for most applications. They are also more accurate than the eyeball.

Good luck,

Hochewa

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From: George Ezell <[email-masked]>
Date: Fri, 14 Jun 1996 12:11:30 -0500

> enough for most applications. They are also more accurate than the eyeball.

George, you neglected  to tell us what your spring is made of, ie, stainless,
tool steel, carbon steel.
Michael

Yeah, I did forget that part!
Well, its definatly not stainless...Judging from the spark test, the quench test,
and the way it moved under the hammer, and the fact it came from a chevy, I'm 
gonna call it 5160 (really scientific, I know).
	If its not 5160, its pretty close...350 degree temper makes a good blade,
and a VERY light straw color, so I'm gonna guess about 500 degrees will be hot
enough...By the way, its the bow for a crossbow...never seen a quality hand-made
crossbow before, so I figured I'd make one.  I'm dreading the trigger mechanism!
	George
PS...Fancy forging and O-1 tool steel do not go together very well...

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From: [email-masked] (Frost, Jerry)
Date: Fri, 14 Jun 1996 22:48:13 -0800

> PS...Fancy forging and O-1 tool steel do not go together very well...

George:

The trigger mechanism is no sweat, a simple rolling block connected 
directly to the trigger works sweet, same thing they've used for 
centuries. There are fancier ones that don't work any better.

The mechanism is a trigger on a disk, drilled in the center for the 
pivot. Think of the letter "P" or a Tinker Toy stick stuck in one of the 
round connectors. With the trigger pointing straight down, there's a 
V-notch cut parallel with the pivot hole across the back of the circular 
section.

The trick is to make the rolling block work like a cam. When it's 
cocked, the string needs to be below the pivot, the tension in the 
string will hold the trigger in place. When you pull the trigger, the 
V-notch will raise the string above the pivot, the trigger will snap 
back on it's own and the bolt's gone.

Once you see how it works you can start trimming away the unnecessary 
parts of the disk. Easier still, find an old Barret at a garage sale and 
make a new prod (bow) or copy it.

The thing to sweat with what you are doing, is the string, even a gut 
string can take a slice out of BONE if it breaks and they usually break 
when fired. 

A couple friends and I made a crossbow from a trailer spring when we 
were kids. We kept reinforcing the parts that broke until it would hold 
together for a few shots at a time before the string (3/16" HC cable) 
would break. It had no trouble firing a bolt (3/8" cold rolled) through 
a 14" Chinese elm. We never hand fired the thing, even cocking it was 
scary. Dad caught me grinding the prod down to lessen the draw weight 
and torched it.

Hmm, I never did thank him for that. Wonder if he's still up?

Please, be careful.

	Frosty
-- 
If it ain't forged
It ain't real
wrought iron is
The FROSTWORKS