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Gareth Bull 29-12-2013 12:28 PM

Linerlock tutorial (my way - pic heavy)
A while back I had the presence of mind to drag my camera into the workshop and take a few pictures while making a knife. What you're not seeing is the designing stage, I sketch on paper until I find a design that I like and then I refine it on my computer. If anyone's keen on some design input I'll try chip in but the making's the fun part so, without much further ado:

Here are the basic parts, roughly cut out. They’re all a little oversized so I can grind them all down together for a tight fit.

Step 1 is drilling all the holes in one of the liners; I’m using UNF-080 screw so I drill with a 1.25mm drillbit:

Step 2 is transferring those holes into the opposite liner. I clamp them together with a piece of G10 underneath for rigidity and also something for the drill to pop out the titanium into, that way I won’t drill into my clamps.

Step 3 is enlarging the holes in one scale to allow the screws to pass though easily, I used a 1.5mm drillbit here. I also countersunk the holes to accommodate the heads of the screws.

Now you can tap the liner with the smaller holes. This is a brilliant tapping jig that keeps everything absolutely perpendicular and stable, UNF-080 taps break very easily, this tool makes them last for ages. Only tap the holes you need for the next step (pivot and backstrap holes in this case) you'll need to pass a drillbit through the bolster and handle material holes later and if they were tapped you might ruin the threads.

Now that the holes are tapped, I screw the two liners together and sand them down so they match.

Next I grind a bevel on the titanium bolsters and a matching angle on the micarta. This creates a dovetail which helps keep the handle material down and looks great when you radius the handle later on. I set the rest on my disc sander to 45 degrees and grind the parts to a blade edge. I step the grits up to 600 so the parts fit tightly.

Here are the dovetailed parts; you can see how they’ll fit.

Gareth Bull 29-12-2013 12:29 PM

Now that the parts are dovetailed, I use a clamp to set where the bolster will end, the metal faces are parallel so both sides will be the same and give a super accurate look. Dead simple to make, took me about half an hour but it’s worth its weight in gold :)

I then clamp one of the bolsters to the liner with the blade edge of the dovetail pressed right up against it.

Drill through the screw holes. I plan to have a hidden pivot pin on this knife so I only drill a short way into the titanium through the pivot hole. Once you drill one side, flip it over and do the other bolster.

Here are the bolsters, you can see the half depth hole in line with the pivot, I’ll size this up later to accommodate the pivot head.

I then tap the bolster screw holes and screw the bolsters onto the liners. You’re now ready to drill the handle material.

Gareth Bull 29-12-2013 12:30 PM

I push the micarta dovetail into the angle under the bolster and clamp it in place. Make sure the parts are clean, you don’t want some stray grit to cause a gap between the parts. Drill through just like the bolsters.

I then counterbore the holes to fit the screw heads.

Screw the handle material down tightly and check fit. If you’re happy you can flatten the materials down to the same level. I also grind the protruding screws flush with each liner.

I then screw the liners together, grind the screws flush again and attach the bolsters and micarta again. Now it’s all one piece you can grind all the way around the profile to make everything match. If all goes well you should end up with tight a fitting dovetail that’s pretty easy on the eye :)

Gareth Bull 29-12-2013 12:30 PM

Next I enlarged the hole to accommodate the pivot head, I did this by sharpening a drillbit the same size as the pivot head to a flat angle.

Here’s how it fits – you want it to drop just under the surface of the bolster material.

Now that there’s space for the pivot, you can radius the handle material. Here’s the rough shape, you can see how the dovetail creates a curved join between the bolster and the micarta.

Both sides domed and polished up to 1200 grit.

Next I cut the lock. I covered this in how I make my framelocks but I’ll go over it here to be concise.
I drill two holes at locations where I want the long cut to start and end. I like using holes as when you join up the two cuts that free the lock, it just comes out neater. I scribe two lines between the holes as a guide so I can line up the cutting disc. I clamp the lock-side liner in my drill vice and use a Dremmel cut-off wheel (0.8mm thick), spinning at full speed to cut through the titanium.

Here you can see the long cut, it causes a pretty sharp burr on the opposite side so be careful.

Do the short cut the same way.

Gareth Bull 29-12-2013 12:31 PM

Here I’m drilling the hole that I will later press the ball into. I drill using a 1.5mm drillbit and press fit a 1.6mm ball into the hole, the tight fit keeps the ball in place. You want to drill all the way through, you'll need do do this so you can drill into the blade, through the lock so that the ball detent works correctly.

Here are the parts so far.

Here I’ve stuck the spacer material onto one of the liners (the one with the countersunk holes)

Drill through the spacer material

Assemble! Next step is to sand those protruding screws down.

Once they’re flush you can attach the handle materials again and sand everything down. Looking good so far, I want to blast the bolsters later on to contrast the polished micarta.

Spine shot

Here you can see the lock cut, nice and thin :D

Gareth Bull 29-12-2013 12:32 PM

I sent the blade in to my local engineers for surface grinding - this results in a truly flat piece of steel and also gets it down to the required size. The spacer needs to be the exact same thickness as the two washers plus the blade. In this case my blade is 2.5mm thick, the washers are 0.1mm x 2 so the spacer is 2.7mm thick. If your parts aren't parallel it will affect your action.

So here are the parts:

Design glued to the blade:
Now, the areas denoted by the letters are important. You don't want to remove too much material here. You can always grind more off - adding steel is far harder :D
Area A: this is where the stop in will sit in the closed position, take too much steel off here and your blade will touch the spacer - serious no-no.
Area B: this will be your lock face, leave more than you think here, it needs to be angled later so leave some steel to work with
Area C: This is the anvil for the stop pin. Grinding steel off here will move the point up in the open position. Again, leave yourself some breathing room.

Centre punch and drill through what will be your pivot hole. I drilled with a 1.5mm drill, this will fit the screw I'm using to hold the handle together right now. It'll allow you to put the knife together and see if you drilled in the right spot.

While we've got the knife apart we may as well do a couple more details. Here I'm jimping the lock, it looks cool and helps when disengaging the blade. Clamp the liner in the vice with something to protect it. I used some thin leather so the jaws won't marr the titanium. I did it at an angle to follow the dovetailed bolster - devil's in the details right? For those who haven't seen one - that's a jimping file I'm using, you line it up and go to town - it does all the work and every cut is evenly spaced.

The result:

Gareth Bull 29-12-2013 12:32 PM

Because the blade is so thin, I'm grinding a small notch into the opposite liner that will allow your thumb to get in and access the lock. To do this, tilt the liner to about 45 degrees and grind with a small diameter wheel. I used an old Trizact belt - cuts well and polishes up easily.


After a quick buff:

Now to put it all together and check everything, starting to look like a knife!

You want the spine to stick out a bit, I'll grind this down later so it's all flush.

View from the lock side. Also a little stock to remove here, you can see the jimping and the cutout for your thumb:

Gareth Bull 29-12-2013 12:33 PM

So, next chapter:

First thing I did was size the holes up to 4.2mm and ream them up to 4.5mm. Reaming makes for a smoother tighter fitting pivot hole - this is another thing that will help improve your action.

Now that the holes are the correct size to fit the pivot, we can accurately drill the mating hole for the ball detent. The location of this hole is very important and actually should be worked out in the design stages. In the image below, the ball needs to be within the red circle, if it's outside the ball will run off the blade during opening and closing which is not what you want.

Now that the first hole (the one in the lock that, the ball will be pressed into) is in place, assemble the blade, the locking liner and the spacer:
I get the blade into the position I want it to be in the closed position and draw a line along the back of the blade with a fine sharpie (you can scribe it but it means one more scratch you'll have to sand out!)

I then remove the spacer and rotate the blade a couple degrees past closed. You can see the gap between the spine and the sharpie mark:
This is how you want the parts when you drill through the liner, into the blade. This will cause the blade to be under tension in the closed position.

The tension I'm talking about is created by the offset. It's important because without it your blade would wiggle a little when closed poteintially baring the tip of your blade - definitely not what you're after.
Here's a close-up view of the offset you're looking to create:
Get this offset right and your blade will snap shut nicely and stay closed in the pocket.

Drilling into the blade:
You want to drill a minimum of half the diameter of the ball or more. Less could affect how the ball seats, you can drill all the way through if you like, I often do.

Gareth Bull 29-12-2013 12:34 PM

Now we can grind the blade (some makers do all their grinding post-hardening, I like to get a bit done before hardening, just personal choice here - do what you're comfortable with).

Technically you should be able to grind before leaping into folders, but I know I'm the impatient type so:
Grinding stages:
A: edge marked
B: grinding down to the edge at a coarse angle - this will mean your grit won't be hitting a perpendicular face and dulling your belt faster than necessary
C: Full hollow grind - the rough grind you did previously makes this easy to see and work down to. I only grind about 90% so you still want to see a little of the coarse angle.

Coarse angle:

From the edge:

Pre-hardening grind. I still need to crisp up the line and raise it a little but it's a good start, not much to fix. Note the thin silver line along the edge - that's what's left of the coarse angle I ground on earlier:

Gareth Bull 29-12-2013 12:35 PM

Time to switch on the kiln! THIS was one of my best investments, not only does doing my own heat treat appeal to the OCD voice in my head but I can harden a blade up on a Friday night - might be a bit of a nerd.... oh well.
Green number is the kiln's current temperature, the red number is the target temperature. Little red ligh shows the elements are on :)

While the kiln is pre-heating I make a stainless steel foil packet - this stuff will cut you faster than anything I know - like a paper-cut on steroids :D I fold an over-sized piece in half then close up the long side first. I do two folds to make it airtight and tap the seam with a rubber mallet to make sure it's tight.

Now one of the ends, again, double folded:

Clean the blade with alcohol before placing in the packet:

Press out as much air as possible (it'll oxidize if you don't, this way the blade comes out a frosted grey that's very easy to polish)

The blade steel I'm using is RWL-34 so I heat to 1050*C and hold for 10 minutes, I then quench between two chilled steel plates (no photos - not enough hands!). As I type this it's chilling in liquid nitrogen overnight and I'll do the first tempering cycle (1 hour at 180*C) in the morning. I'll follow it with 4 more hours in the liquid nitrogen and another tempering cycle.

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