Friday, December 26, 2014

DH44 - HUNTER: LAYOUT AND INITIAL GRIND





The DH44 pattern has a great shape, but a fairly long handle. I'll do this one with a stainless bolster to work into the choil area. The steel choice is CPM 154 in 1/8".
 Over to the grinder with a 60 grit ceramic belt.
 The basic profile has been shaped.
 To the 4x36" belt sander for some longwise clean up.
 The basic profile shown against the pattern.
Now to the grinder for the primary bevel. A fresh blaze 60 cuts the way. I like to do one or two passes per side and flip over and do the opposite side.
 After the grinder, it's off to the hand sand jig for some finish sanding.
This is the result of some wet sanding. Careful attention to the plunge line to remove any coarse scratches there.


DH44 - HUNTER: VINE FILEWORK

 On the tang I wanted to add something a little special for this knife. The simple vine filework adds some flair for a little effort. I layout the spine with a small ruler and mark off every 10mm (3/8") or so.
On the left and right sides I  marked some half circles. Alternate left and right.
With a round file, cut each half circle. Point the file down at a 45° angle.

 With the half-round needle file cut the leaves. These are about 2mm above the half circles.
This is the result. You can shape the curves some more to produce a better shaped vine. More on the filework at my Basic Filework: Vine page.
 Here I am marked and punched for drilling the handle pin holes. These are both 1/8" and 3/16".
Holes drilled for the handle and bolster. Ready for heat treatment.

DH44 - HUNTER: HEAT TREATMENT

To prevent decarburization (oxygen reacting with carbon in the steel) a stainless steel foil is used to make an envelope. The edges of the foil get folded up and pressed to make a seal. Once the knife is sealed in, it goes into the oven.
My quench plates are readied. These large copper plates that I place in a carpenter's vise.
In about an hour the HT2100 heat treatment oven and the wrapped up knife is up to temperature. I hold this temperature for about 20 minutes to ensure a good conversion.
Out of the oven...
into the quench plates. Within a minute the knife is cool enough to handle.
This is the foil after the quench.
Opening the foil envelope reveals a hardened blade with a small amount of oxidization.







After the hardening process, it's into the tempering oven to soften the steel a small amount. For CPM154 the recipe I like is 2 hours at 200°C (400°F). Allow to cool and repeat. The aim here is a hardness of Rockwell 59.





DH44 - HUNTER: BOLSTER ROUGHING

For the bolster I am using some 1/4" thick by 1-1/2" 304 stainless steel. Although it is a bit tougher to work than 416, I feel it's superior corrosion and scratch resistance are worth the effort. Here I am tracing the left and right pieces on with a marker. Leave enough room between the pieces for a hacksaw to separate them later.
After some basic line work on the belt grinder, it's time to separate the sides.
 Now I bring them close to the lines with the belt grinder, again 60 grit and a pot of water here.
After both pieces are close to shape, I clamp them together with a vise-grip and grind them together so they match.
Aligned to the mark on the knife I clamp and drill to match the tang holes. A #30 jobber bit is best here. After the first hole, I insert a piece of 1/8" pin then check alignment and drill the second hole. Pins are used to temporarily hole the pieces while drilling through the last side.
Now the bolster pieces are drilled. We need to focus on the fronts. Remember, these are difficult to polish after they are installed on the knife.


DH44 - HUNTER: ETCH & BOLSTER

Clean the area to etch well. I use isopropyl alcohol or acetone. Let it dry 100% before tacking the stencil down
After etching, I like to wash the area with Windex to neutralize any of the electrolyte solution that may remain on the steel.
Here I am etching the steel type, in this case CPM154 on the obverse ricasso.
 Once the etching is clean and no more work needs to be done on the blade, we can go ahead and attach the bolster pieces.Notice I have drilled some shallow, random holes in the bolster pieces to increase the surface area.
Taping up the blade prevents it from being scuffed during the next operations



 


 I've attached the bolster pieces with a small batch of Acraglas and a gentle press in the hydraulic press to slightly expand the pins.

DH44 - HUNTER: BOLSTER & SCALES

The next day, after the Acraglas has set I grind the pins down with the belt grinder and do some initial shaping. Keep a bucket of water handy as we don't want to burn or blacken the Acraglas.
 Shaping with an aggressive round file will work here,
 Or a drum sander (or small wheel attachment on your belt grinder).
Once the bolster is coarsely shaped, choose and cut the scales. I used a regular compound-mitre saw to cut these on an angle. Just remember the bottom side can tear out. A super sharp 60 tooth carbide blade is recommended.
With the angles cut, I clamp and drill the holes for the pins. As usual, I like to use the slightly oversized numbered bits, in this case #30 and #12.
 The scales are drilled, now over to the belt sander to shape the flats.
Optimally, the pins are cut to about 1/8" over size so when it's all glued up about 1/16" is sticking out each side.
 Mix up another regular 5ml batch of Acraglas and a gentle squeeze.
Make sure there is a enough Acraglas to make a healthy meniscus on the filework. Wait overnight before shaping the handle.

DH44 - HUNTER: HANDLE SHAPING

It really does look awful at this stage, but stick with it and it will be beautiful with a little effort.
First I work the flats with the 4x36" belt sander. Grind the pins down and remove any excess epoxy. Note that I applied a small wrap of electrical tape to the bolster. I don't want to accidentally gouge this when shaping the scales.
 Here I am working the profile on the belt grinder and bringing it close to the steel.
 As we approach the steel the filework appears. It's great to see we had enough Acraglas in there to fill all the voids.
Shaping the underside with a round drum. The drum is also great for shaping around the finger choil and contouring the scales.
 Here we are ready to start wet sanding the scale and bolsters together.
Working with a block across both the bolster and scale will prevent any depressions in the handle. Nothing could be worse at this stage than to go too deep in the wood and make a ridge where the bolster and scale meet.
After some wet sanding up to 400 grit, I'll hop over to the buffing wheel with some black compound.


Some acetone and a brush will loosen up the excess epoxy in front of the bolster.