thickness planer blades, old metalwork files.....

B

Bushman5

Joined
Oct 31, 2007
Messages
9,833
Pops teaches junior high metal shop/wood shop and saves me all the old files and thickness planer blades.

the planer blades are extremely hard, a file or drill bit barely scratches them.......should i throw them into the gas forge to soften them up a bit before drilling and stock removing?

whats the process for this?

edit: the planer blades are 1/4" thick, 14" long, 1.5" wide, some are marked 01steel 02steel
 
Those are crap, you should send them to me:D I'll dispose of them properly.


Probably the best thing to do is anneal them. Heat them up in your heat treating oven and then just let them cool slowly.
 
keep in mind this is a school shop....no dedicated heat treat oven, just a big ol long gas forge.....

should i heat to any particular color to anneal? (i ask because there is no temp gauge on forge, its either OFF or full roar
 
If your school has a gas forge, they likely have a ceramics kiln in the art room :) lots of temperature controlled annealling goodness to be found there! and color, no thats tempering. Annealling is taking a steel to it's austinizing temp (around 1500-1600ºF! Look it up to be sure!) and letting it slow cool ( usually around 50ºF per hour) till at ambiant room temp. this relaxes the structures and softens the steel. :thumbup:

Jason
 
if you don't have precise temp control then use a subcritical anneal... longer time at lower temperature

nice score btw
 
ive found you can get files to a workable softness just by blasting the spot you need drilled with a small propane torch and then letting it cool.

ive also annealed springs and files just by putting them in a campfire and letting them cool overnight. they may not be "properly" annealed, but they can be drilled, when before they could not, thats good enough for me.
 
Bushman

Here is the method I use. I'm sure someone else will say there is a better way and there probably is, however this is a method I have personally used on many different occasions and I can say with confidence it works. The blades I have been using run from 62 to 65HRC before the process and end up about 20HRC.

I take the planer blades and make two stacks about 8 blades high with all the bevels in each stack, on one side. I then insert small steel finishing nails between the blades about every 4 inches to separate the blades and give them support so they don't sag during heating. I turn the beveled edges of each stack so they face the other stack. This is to get all the sharp edges turned in. I take the double stack and wrap it in heat treating foil and throw in a strip of paper as a getter to burn up the trapped oxygen. I set this foil package on a strip of 1/2" or thicker steel bar stock (type of steel is unimportant, it just acts as a thermal mass) and place it in my heat treating oven. A kiln should work fine, but the larger the kiln the more thermal mass you may need. I then bring the temperature up to 1750°F and let it soak for two hours. The temperature is the stack temperature, not the kiln temperature. The larger the thermal mass the slower the stack will reach temperature and the slower it will cool. After the soak, I kill power to my oven and let it cool to room temperature. I have always done this of an evening, and the next morning the stack is still quite warm, but can be handled with bare hands. If your kiln cools down in less then 6 hours, I would had more thermal mass to retard the cooling cycle.

D2 and other high carbon high chrome steels are prone to decarburization, so make sure you get the foil sealed tight.

Good luck

Jim Arbuckle
 
You must log in or register to reply here.
Back
Top