Difference between revisions of "Tools/forge/induction"

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(Created page with "What we're going to do Making a small utility knife I've made 3 blades so far, all successful but am not an expert Show the metal, micarta, rivets, wood. Show the knife...")
(Start editing down to just induction stuff)
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  Keeping the spine flat
  Keeping the spine flat

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  Marking out the area of "hot things" when leaving
  Marking out the area of "hot things" when leaving
Cutting off the rod
Can use the cold-cut saw on fully annealed metal, never hardened
If hardened, use the angle grinder!
If working on stainless/chromolly etc remember to use dust mask
Making sure to cut away all the weld material as it's not knife steel
Using the belt grinder and/or forge to re-shape the end of the rod for reuse or cut-off
Welding the tang onto the rod
Same deal as last time
Focus on welding the flats thoroughly into the rod
Remember to normalize

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Drawing down the cutting edge
Using the round-headed hammer, not the blade heads
Hitting below the mid-way point of the blade
Initially hitting harder near the edge, then evenly everywhere
Working the edge down to about 0.5-1mm thick, NOT sharp
Beat on the edge of the anvil as you get towards finishing
Watch out the for the banana bend, fix it if it happens
You CAN beat on the edge of the blade but try letting it cool a little first
Use care to keep the spine straight

Normalize and Anneal
Normalize and Anneal
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  Getting the blades out of the vermiculite and cleaning up.
  Getting the blades out of the vermiculite and cleaning up.
Setting up the grinder, cleaning dust away
Using the blue belts and what the difference is
Using the water bucket while grinding, keeping the blade cool to avoid damage
Safety gear, googles, dust mask, hearing protection, watch out for getting caught on belt!
Using a file to sharply define the notch
Grinding the spine
Smoothing off the back of the tang and curving it
Doing all the boarders of the tang, then flatting it
Make sure it's flattened all the way to the edges unless there's a deep forging error
Doesn't need to be flatted across the whole surface and may even grip better
Doing the flats of the blade, keep the blade flat relative to the tang and perpendicular to belt
Blade doesn't need to be 100% perfect as it's going back in the forge for hardening
Grinding the primary bevel, let the knife tell you what angle it wants
Be extra careful of heating!
Movement necessary to get the point sharpened
Putting it up to a sharp edge but probably will have burrs
Don't bother smoothing off corners or polishing
Cleaning up the grinder when done

Revision as of 10:45, 10 September 2018

What we're going to do

Making a small utility knife
I've made 3 blades so far, all successful but am not an expert
Show the metal, micarta, rivets, wood. Show the knife
Describe the basic forging, making tang, drawing out blade, grind, harden, grind, handle, sharpen

General Safety

Clothing, overalls best, nothing flammable, avoid synthetics
Heavy boots, toe-capped preferred
Welding gloves
Ear protection while hammering
Good air circulation, monoxide hazard and detectors
Clearing the area around the forge of all flammables
Everyone knows how to use fire extinguishers?
In case of fire, TURN GAS OFF!
What types of extinguisher to use on what sort of fire
We cannot extinguish metal fires, use the vermiculite to smother
NEVER use an extinguisher on the forge it's self, it has nothing flammable anyway
Hazards of the oil for quenching
Hazards of metals high in nickel, chrome, cadmium etc, and protection needed
Arc-eye hazards of welding

How steels behave and heat treatments

Use the diagram to explain things
The states the steel can be in, what is critical temperature and why it matters.
               Form above critical
 Plannish under critical
       Using a magnet to test for critical, but learn to use colour
How different types have different hot-hardnesses
Stainless needs a lot more heat
Damascus needs even more
Cover annealing, hardening, normalizing
       Effects of under-heating and over-heating – Stress cracks, decarburization, crumbling
       Effects of oxidizing and reducing flames – Scale, Temperature, Decarburization
What steels we have available
 1095 – Standard, easy to work with, sharp, OK toughness, rusts
               EN47 - +£5, TOUGH! OK sharpness, rusts, harder to work
 Others I can get if you want to go further but don't have right now

Welding onto the dop rods

Anyone competent does their own, anyone else I do
Emphasise use a LOT of weld material
Need to normalize the welds
They are GOING to break, what to do when they do
 Watch for starting of cracks
 Pick it up IMMEDIATELY with grips, place onto hot-safe surface

Lighting the forge

Describe the forge and it's parts
       How the tunnel can be opened longer for bigger objects
Never use brick choke and rear door at the same time
Check it over for damage
Vacuum out tunnel – clean before use, not after
Plug it in!
Checking the gas & air valve positions are closed
Start the blower
Let a little air into the forge
Cover the dramatic differences in gas and air settings
Turning on gas at the bottle and burners
Opening the main gas valve and using the lighter to get it lit
Adjusting the gas and air valves to get a flame the right size and slightly reducing
Demonstrate high/low, oxidizing/reducing, show what they look like
       Large flames are more stable, small flames may result in burner over-heat, check this often
       Demonstrate high/low flames
Starting up the second burner if you have a need to for a long object


Why we need to normalize
What it does
Proper procedure
What happens if we're not hot enough, or too hot!

Flattening out the rod

Heating to a suitable colour, testing with magnet if you need to
Squaring it off but not all the way to the dop rod
The need to keep it roughly oblong
Just getting the feel of beating on the metal, try both hammers, see what it's like
Don't touch metal to anvil till you're ready to strike
Correct any error immediately, don't let them grow

Forming the Tang

Consider the shape we're working towards
Think of width you want, 15-20mm? And thickness, 3-4mm
Need to get the thickness about right but go a touch over on the width
The need to come to both dimensions at once and not over-work in one direction
We can't fix over-thinning
Don't need to get the end neat, we're going to be grinding it off
Looking at the metal as it cools, seeing what needs to change
Drawing out using small hammers, large hammer on step, large hammer on side, edge of large hammer
Cycling draw out and flatten
Keep thinning, flattening, drawing out till there's room for a good grip
Try to get the surface nice, so we can do less grinding
Establishing the notch on the edge of the anvil and beating out the burr, don’t make it too big
Reducing the tang width a bit if you can
Keeping the spine flat


Repeat the normalization cycle
Furnace cooling as an option for normalization but not annealing

Shut down the forge

Air off – Gas off – Air on
Leaving the air running to cool the forge if needed
The forge may stay hot enough to start fires for up to 2 hours
Marking out the area of "hot things" when leaving

Drawing out the blade

Bringing the blade to a similar size to the tang but longer
Keeping the bar uniform, don't try to narrow the cutting edge yet
Using the notch to define the boundary where to stop working
Cutting of excess if needed
As always, correcting any problems as soon as they appear
Trying to get the surface smooth, 5 minutes hammering can save an hour's grinding
Try to avoid twisting, use the grips and fix to fix it if it happens

Forming the point

Beating behind the point to start the drop but only just behind
Avoiding "fish-lips"
Forming a symmetric point using the edge of the anvil
Letting the length increase to maintain the thickness
Being careful as things get thinner, reducing hammer force
If an edge gets folded over, have to cut it off, can't fix
Thin the point a little but don't make it delicate

Dropping the point

Explain how the metal will try to move once we forge the edge
Dropping the point to prevent banana-shaped knives
Using the horn of the anvil to make the drop not the edge
Beating the blade back flat if needed and keeping forming the drop

Normalize and Anneal

This is the last chance to smooth out any gross surface defects or geometry errors
Using a little less heat than before as we're not trying to cause bulk movements
Planishing using the smaller hammers to smooth things as best we can
Normalize for at least 2 cycles and maybe more
Fix geometry before cycles
Using the vermiculite to slow down cooling to achieve maximum softening or furnace cool

Shutting down the forge

As before for shut-down
Letting the forge cool down enough before putting it away
Hand-in-tunnel test
Don’t try to clean inside the tunnel, put it away dirty
Watching out for condensation dripping off the gas bottle
Getting the blades out of the vermiculite and cleaning up.