John Wilson's KITH WIP - folder COMPLETE

[John Wilson]

That is a very slick bit about heating the weld spots to red to make them disappear.
Now I'm off to research "spot welding", to see what that entails as I know little about different types of welding.
Excellent work and tutorial!

Harbor Freight sells a great little spot welder. Catch it on sale and with a coupon and it’s dang cheap.

So easy a caveman (me) can do it!

 

[Motor City Mike]

Outstanding WIP!!

 

[John Wilson]

We’ve gone about as far as we can without heat treating the blade and spring. But, since we’re still annealed there’s no time like the present to get the blade and spring to their final thicknesses. I don’t have a surface grinder. We’ll be doing this step manually on a surface plate. The thought of removing several thousandths on a surface plate after the parts are heat treated certainly sounds like a bad proposition to me. Let’s do it now before we forget.

I use 320 grit and my trusty Mobil 1 Synthetic. The steel is soft and this really doesn’t take a whole lot.

We want the blade thickness at the pivot to be the same as the spring thickness. The blade pivot is the only part of the blade that will ever come in contact with the liners. The rest of the blade will be a wedge when we’re done with it. However, the entire spring needs to be a uniform thickness. After all, it’s also the back spacer and is what makes the liners parallel. Parallel is important here, or else the pivot will be wonky.

Sand, measure, repeat.

Remember the mantra, “Don’t get OCD, Grasshopper”. The blade and spring will have to be sanded and polished after heat treat. The blade will get hand sanded after grinding. So get any egregious scratches out now, but don’t go crazy. A 320 grit finish is A-OK at this point.

 

[Johan Nel]

John,
I assume the thinnest object will be the frame of reference. So if the blade pivot is thinner than the spring, then the spring will be thinned and vice versa?
Second question, is it possible to deal with areas of varying thickness on an object in handsanding it on a flat surface, or do one compensate for variations somehow?

 

[John Wilson]

John,
I assume the thinnest object will be the frame of reference. So if the blade pivot is thinner than the spring, then the spring will be thinned and vice versa?
Second question, is it possible to deal with areas of varying thickness on an object in handsanding it on a flat surface, or do one compensate for variations somehow?

That is correct. Everything has to be thinned to match whatever the thinnest part is.

Usually things are rather wedge shaped. I have found that applying direct finger pressure to the high spots when sanding on the plate does well enough to bring things into flatness.

If the difference is more than 2-3 thousandths of an inch, touching it up lightly on a 220grit belt helps knock it down quickly and then final sanding on the surface plate brings it in nicely.

Am I getting “surface grinder” results? No, certainly not. But I am getting them within .001” to .0015” difference without too much fuss. Call me sloppy, but we’re going to beat pins with a hammer to set it all in place. I’m not convinced that fussing over 4 digits after the decimal point is anything that yields a difference in the real world.

I’m open to feedback and correction, of course.

 

[Johan Nel]

That is correct. Everything has to be thinned to match whatever the thinnest part is.

Usually things are rather wedge shaped. I have found that applying direct finger pressure to the high spots when sanding on the plate does well enough to bring things into flatness.

If the difference is more than 2-3 thousandths of an inch, touching it up lightly on a 220grit belt helps knock it down quickly and then final sanding on the surface plate brings it in nicely.

Am I getting “surface grinder” results? No, certainly not. But I am getting them within .001” to .0015” difference without too much fuss. Call me sloppy, but we’re going to beat pins with a hammer to set it all in place. I’m not convinced that fussing over 4 digits after the decimal point is anything that yields a difference in the real world.

I’m open to feedback and correction, of course.

Tony Bose seems to agree with your method and he is no slouch...
I have something very exciting in the pipeline which I will discuss in a seperate thread, but be forewarned that you may be swarmed with questions soon...

 

[John Wilson]

Tony Bose seems to agree with your method and he is no slouch...
I have something very exciting in the pipeline which I will discuss in a seperate thread, but be forewarned that you may be swarmed with questions soon...

I only hope that I’m qualified to answer them. I will freely share whatever I believe to be true at the moment! ha!

 

[John Wilson]

On to heat treat

The blade and spring are AEBL stainless. They are encapsulated in a foil pouch and into the oven they go.

 

[John Wilson]

Time to prepare the sub-zero dry ice slurry.

My local grocery store sells dry ice which is very convenient. What is not so convenient is that they sell it in block form. Luckily for me my kids have a sno-cone machine. It’s actually an ice crusher for frozen margaritas but they don’t know that, and good thing- who wants their kids drinking frozen margaritas all day? Not me. They have homework.

I smash the block into pieces with a hammer and the margari... sno-cone machine makes quick work of shooting it into a small cooler. I add alcohol or acetone and mix it very scientifically with a long screwdriver to make the slurry.

Now we wait for the oven to finish with the blade and spring.

 

[Kevin Zito]

One of these days I’m going to make a slip joint, and I’m going to start on page one of this thread. Thank you!

 

[Dennis Morland]

One of these days I’m going to make a slip joint, and I’m going to start on page one of this thread. Thank you!

Exactly!!

 

[Smallshop]

sno-cone machine makes quick work of shooting it into a small cooler.

genius...

 

[John Wilson]

We did the rough grinding on the bolsters. Let’s put some pins in the two sides and samd everything down to the finished dimensions on the grinder.

A 60 grit belt does a good job of hogging off the extra, and then a 120 or 220 grit belt gets the scratches out.

Once that’s done we take the sodes to the surface plate and get rid of the burr that is all around the edge from grinding.

 

[John Wilson]

Here’s something I like to do. I like to knock the 90 degree corner off the inside edge of the liners. For one thing, nobody was ever happy to discover sharp edges anywhere other than on a cutting edge. For another, there no reason to have an edge that might mar the blade as it nests in the handle.

A few final strokes flat on the surface plate will blend in the chamfer.

 

[John Wilson]

A quick assemble to make sure we haven’t ground away too much. Looks good.

We fit up the scales. I epoxy them into place. I’ll drill the center hole later when the epoxy is cured.

 

[John Wilson]

Grinding the blade on a tiny folder presents a challenge. My old file guide does double duty here: it provides a foolproof way to get the plunges the same on both sides and it also provides me something to hold onto during grinding.

60 / 120 / 320. I’ve gotten accust to making big kitchen blades. Grinding a tiny folder blade is a blessing and a curse. Such a tiny blade grinds in minutes, which is really nice, but the flip side is there’s not a lot of room for error.

 

[John Wilson]

Dry fit after grinding.

It looks like a hot mess right now because of the epoxy.

Fit looks good and we have good Walk and Talk. Walk and Talk is the nice audible snap you get in each blade position. This knife had a half stop and the blade snaps smartly into all three positions.

Spring tension feels perfect to me: nice and strong but the knife is not hard to open and close. I’m very happy with it.

 

[John Wilson]

Side Note

Spring tension is primarily a function of the thickness of the back spring. For my material and the size of this design, I find that the correct spring tension is pretty predictable when the thickness of the spring from back to front is about the same as it’s thickness. It’s a ballpark. Sneak up on the final thickness by grinding and checking the feel with the knife assembled.

This spring comes from another knife I’m making. The spring is .109 thickness.

The knife was too hard to open. By cutting out a scallop from the inside we thin the spring to make it more flexible.

 

[John Wilson]

I don’t like that the tip of the blade is so close to the opening. I can’t snag the tip of the blade with my fingertip, but I believe the liner in a person’s pocket would. No bueno. Let’s get that tip down in the handle a little deeper.

Remember when we were making the blade? We left some meat on the “kick”. The kick is that protrusion at the ricasso. The kick rests against the inside of the backspring in the closed position. By taking a few thousandths off the kick, we allow the blade to rotate more into the handle.

BE CAREFUL. It only takes a tiny bit to make a big adjustment.

That looks right.

 

[John Wilson]

Since the blade is not yet hand sanded, we don’t have to feel guilty about using it for a handle when we start shaping our handle on the grinder.

I use a 120 grit to get the basic shape and to clean up the bolsters which are still at 60 grit.

Then a 320 grit belt and a change to the 10” contact wheel. The contact wheel helps me blend the transition between the scales and the bolters. Then as usual we shift primarily to slack belt grinding.