John Wilson's KITH WIP - folder COMPLETE

[Johan Nel]

Top marks for the kudu horn to emphasise how special a hand made pocket knife can be.

I am having a relook at this thread, but on the computer screen today, which allows for bigger, better viewing and I really like the colours that I can see in the horn. I think it has the potential to polish out in beatuful colours.
Note to self: * Start collecting kudu horn when next you go on a hunt...

 

[John Wilson]

Well John, I am hoping to make a slipjoint folder in the foreseeable future

As you should. Every gentleman needs a pocketknife, Johan! What I like about slipjoints is that the same basic design can be made numerous ways. It’s all about the blade-to-spring fit. You can shape the rest of the knife any way you please.

 

[BrandantR]

Awesome tutorial, John!

 

[Smallshop]

Excellent tutorial John.

 

[John Wilson]

We left off at the layout stage. Now I’ve cut out the blade and back spring and profiled them on the grinder. I’ve taken the edges of the profile to 220 grit. On a fixed blade I’d go to 60 or 120 grit on the profile edge before heat treat, but dimensions really matter on a folder and we have lots of fitting to do prior to heat treat. 220 grit gives you a nice clean dimension at the cutout line and is pretty much your final dimension because there are no more scratches to sand out along the edge of the profile. Any steel removed past this point is about fit and mechanics. We don’t want to have to sand away grinder marks during mechanical fitting- that would change our fit way too much.

I talked about leaving some meat in key areas. The notch on the back of the blade where the back spring will rest is one such area. We remove that extra meat with a file guide and hand files.

A file with a safe side allows me to cut on only the surface I want to cut.

I progress to finer files to finish the cut and then use a needle file to finish the inside corner.

 

[John Wilson]

That looks pretty good. I hit the filed area with some 320 grit to get rid of the file marks and then polish with green chrome on a buffer for a few seconds. This is far from complete, but it is smooth enough to begin fitting to the spring. (No deep scratches that will affect measurements.)

A quick double check with the print and I’m satisfied with this step.

 

[John Wilson]

Here’s a handy tip to remove adhesive and stuck on paper: WD40. I like this much better than acetone.

 

[John Wilson]

The blades and springs have been cleaned up on the disc grinder to 600 grit.

I measure their thicknesses and pair each blade with a back spring. From this point forward nothing is interchangeable. I am working on three knives, so I mark each pair with a center punch. Pair #1 gets 1 dot, etc. This will help me keep them straight and paired to its proper mate.

 

[BossDog]

Great thread.

 

[Motor City Mike]

Great job with the pics and explanations

 

[Johan Nel]

I am watching this thread with bated breath and at the same time I am realising that an undertaking such as this may still be beyond my ability for the time being.

 

[John Wilson]

I am watching this thread with bated breath and at the same time I am realising that an undertaking such as this may still be beyond my ability for the time being.

It most certainly is not. Trust me when I say that, because I thought the very same thing. There are a great many steps, but none of them are difficult to accomplish. Anyone who has ever fitted a full guard to a blade can make a slipjoint. In fact, the only steps which require any special tooling are yet to come- those steps are: 1) relieving the liners around the pivot point with a milling machine. And that step can be avoided by thinning the blade in relation to the back spring and then using washers, and 2) spot welding the bolsters to the liners, which can be accomplished in the usual fashion if one doesn't have a spot welder.

The two key ingredients to slipjoints are attention to detail and slowing down. I really must emphasize that everything I am doing here is taken from Don Robinson's book. Mr. Robinson's approach is that thorough and straightforward. I take no credit whatsoever for this WIP, and honestly feel quite guilty because I feel like I'm presenting his ideas as my own and I want to make it clear that everything I am doing here I owe to Mr. Robinson.

 

[Dennis Morland]

This thread is awesome!!

 

[John Wilson]

After a day of working on customer orders I have some time for the KITH knife.

In the last post I had cut and profiled the blade and spring and sanded them to 600 grit to get the thicknesses of the blade and spring to be the same.

Now we get to the meat and potatoes of what makes or breaks a slipjoint: Rise and Fall.

What separates a custom from a store bought slipjoint is primarily fit and finish. A big part of that is how the backspring fits. We want the backspring to be perfectly flush to the back of the knife when the blade is both in the open and closed positions. Also, this knife will have a half-stop. The spring will snap flush when the blade is halfway open/closed.

Therefore the spring must be in exactly the same mechanical position in all three blade positions. To make this work we use a Rise And Fall indicator. Basically it’s a fixture that holds a dial indicator against the back spring. As the blade is rotated we can see exactly how far the backspring rises and falls.

We need to start with a baseline. That is the open position. We’ll zero the dial here and see what happens when we rotate the blade.

 

[John Wilson]

Well, that ain’t good...

The spring has risen .050 in the half stop position. Hey, this rise and fall indicator is pretty convenient. That tells me exactly how much too long the tang is. It’s easy to go too far. I’ll knock most of that excess off at the grinder but not all of it. The name of the game is to sneak up on your final dimension.

 

[John Wilson]

After several trips to the grinder we got very close. Then a trip to the vise to hand sand the scratches off. Back to the Indicator to check...

repeat...


repeat....

Voila!


“Uh, John... excuse me but that’s not perfect.”

Good eye, and right you are. We are looking to be within .002 before heat treat. After heat treat things will get sanded and polished and that’s when we will polish everything into final dimensions.

 

[John Wilson]

Let’s check the closed position.

The blade is making contact with the spring. That is no good. We’ll relieve that area on the small wheel and then check again.

 

[John Wilson]

Sand, check, sand, check...polish... good to go.

 

[John Wilson]

Check all positions: Looks good. We’ll call this step complete.

 

[Motor City Mike]

Excellent job with the pics and the description.

Fantastic WIP!

I think I'll try and make a slippy thanks to your WIP.

Great job.