Texas Toothpick Slipjoint WIP/Tutorial

I have been asked a few times to put a tutorial together so here we go.This tutorial is also posted on my web site.http://www.medawebs.com/knives/tutorials/Slipjoint/Slipjoint_Introduction.htm

The most difficult part of making a slipjoint is getting the geometries of the tang and spring to work in harmony. Many custom makers are designing their slipjoints so the backspring is flush with the back of the knife when it is opened, closed and at the half stop. The illustration below shows how the dimensions of the tang works in conjunction with the backspring. For illustration purposes, the dotted lines are for reference only. The distances from lines A, B and C to the center of the pivot must all be the same in order to obtain a flush backspring in all 3 positions.Dimension “A” should be approximately 10% longer than dimension “B”. This is to keep the blade from extending beyond the end of the backspring when the blade is rotated.


So now you have to decide, which pattern knife will I make? Well, that's totally up to you. For purposes of this tutorial, we are going to make a Texas Toothpick. To get you started, I have made available a full size drawing in PDF.
format. http://www.medawebs.com/knives/tutorials/slipjoint/toothpick.pdf


If I am going to make more than one of any style knife, I make a pattern out of steel which I can use repeatedly. This pattern is a fully functioning slipjoint. You can use the drawing I have supplied either to make a pattern or just use it to make a knife. First thing I do is to trace the outline of my pattern onto steel that I have marked with red Dykem. For some reason, I like the red better than the blue. You can also use a sharpie to darken the steel for tracing.

Cut the blade and spring out as close as you can to the line. Drill your pivot hole in the blade and the center hole in the backspring. Once the parts are cut out, you can profile them just to the line. You want to make sure you leave a bit on there for making the small adjustments. At this point, I grind the inside of the backspring right to the line and finish to 600 grit. The end of the backspring is left a little long and unfinished at this point. We will finish the end later on.


Using bushing in slipjoint is a personal preference. Slipjoint knives have been made for decades without them. I like to use them for two reasons. Firstly, I think they add a bit of smoothness to the action. Secondly, the make peening the pivot pin a bit easier. When you use bushings, the final goal is to have the blade rotate around the bushing. The bushing does not rotate around the pivot pin.
The only place I have found bushings to date is at K& G Knife Supply http://www.knifeandgun.com/ProductDetails.asp?ProductCode=B2
. They are 3/16 outside, 3/32 inside and 1/8 thick. Please measure these bushings as they are not made with very close tolerances.
Drill and ream out your pivot hole to accept the 3/16 bushing. I start with a #14 Drill (.182) and ream to size. I then use a barrel lap and polish the inside of the pivot with Clover 1000 grit polishing compound.

The tool shown below is simply a piece of 3/16ths rod threaded with a 1-72 screw. This allows me to chuck the bushing in the drill press and polish the outside to 1500 grit.

In order to have the blade rotate on the bushing and not the pivot, the bushing needs to be thicker than the blade. I try to hone the bushing so it is .001 thicker than the blade. When peening the pivot pin, the liners will be resting against the bushing and not the blade which will allow for a smooth action. The tool below is a block of hardened 01 Tool Steel with a 3/16ths hole. This is used to hone the bushing to the exact needed thickness while keeping it square.

Nice job Bill. I look forward to seeing the knife completed.

Carey

nice wip one question when you drilled the spring do you not create a set by moving the back of the spring up 20 thou or so? just wondering I have made several slip joints (still learning) just curious. thanks
Ted

I set my spring by manually bending it prior to heat treat.

thanks Bill, makes perfect sense, how many thousands do you bend the spring? Glad I ask I was getting ready to make another spring for a barlow I was working on I didnt get enough set, so now i just need to bend it a little, thanks again

I'll bend the spring about the same distance as the thickness of the spring. Seems to work fine for me.

Very cool Bill! I'll try a slipjoint one of these days, and when I do, you can bet I'll be reviewing this one. Can't wait to see it finished!

Continued.................

Here is the critical part of making a slipjoint. Getting all the parts to fit together. For this part, I use a rise and fall indicator as shown below. This improves the accuracy of the fit and will allow you to make more accurate adjustment. I made this rise and fall indicator from aluminum plate. The purpose of the rise and fall indicator is to measure the position of the backspring as the blade is rotated from the open to the half stop to the closed positions. Ideally, you want each of these positions to be exactly the same. You can also perform this step by mounting the blade and spring on a piece of wood and drawing a line on the outside of the spring. The following illustration show the various parts of the tang.

There are three dimensions that you have to fit in this step. The tang bottom, the back square and the half stop. The order that I fit them is first the tang bottom, then the back square and lastly the half stop. The first step in this process is to grind the tang bottom to fit the blade to the backspring. The blade in the closed position should sit within the profile of the knife. You need to make sure there is space between the blade and spring. You do not want the blade to close and snap against the inside of the spring. Grind the "Kick" to lower the blade into the correct position. Keep in mind that you need to leave room for the finish. At this point, I finish the tang bottom to 600 Grit. Once the blade is in the desired position, set your indicator to "0".

The next step is to fit the run up so the dial indicator is at "0" to match the tang bottom. As you can see below, I need to grind off approximately .015 to bring the indicator to "0". Remember, keep in mind that you need to leave a bit of room the finish.

The back square has been ground and finished to 600 grit to the point where the indicator is now at "0". It may look like it's a few thousandth's off but it's just the angle of the photo.

Final step is to grind and finish the half stop to once again bring the indicator to "0". Once again, due to the angle of the photo, it looks like it's a few thousandth's off.

At this point, you should be able to rotate your blade into any of the three positions and have the indicator show "0"

Now that you have the blade and spring fit together, it's time to make the liners. For the liners, I am using .040 410 Stainless. Trace your pattern on the liner material and cut the basic shape on the bandsaw.

Until I have all the holes drilled in the liners, I superglue them together to make sure the holes are lined up perfectly.

After the liners are glued securely together, I mark the pivot hole with a punch, drill and ream to size. To help in locating all the holes in the liners, some people use a block of wood to mount everything to make it easier to work with. I bought some aluminum bar from a scrap dealer and use that instead of wood.
Drill a hole the same size as your pivot pin in the aluminum or wood block and mount the liners and blade to it. At this point, there is only one hole for the pivot drilled into the liners. Lay your spring into the correct position and clamp into place. Using a transfer punch, mark the liner for the springs center hole. Drill and ream the hole to size.

Now you have the liners, blade and spring mounted to your block. Once again, position the spring against the blade and drill the back hole on your spring. I usually drill through the spring, liners and the block all at once.

Now you have all your holes drilled and the entire assembly mounted to the block with pins.

If you remove one of the spring pins, you can rotate your blade around and check the fit one more time. You want to remove one of the pins as the spring is not yet heat treated and will simply bend if you keep all the pins in place. (nothing has been heat treated at this point)

Milling a relief area in the liners allows the blade to rotate without scraping the sides of the liners and leaving ugly scratches on the blade tang. The goal here is to mill out a area that will act as a washer, and an area the same size as the tang. You want the milled area to start right at the end of the spring. Mount your liner and spring on your block and put a pin in the center hole of the spring. Position your spring on the liner where it will be for the final assembly. Trace around the spring as shown below.

Now draw a straight line from the top of the spring down to the bottom of the liner. All of the area in the front of this line (hash marks) will be relieved.

Now pin your blade to the block and liner. Rotate your blade to the position it will be in when fully closed. Make a small mark just in front of the end of the"Kick"

Draw a line from the small mark you just made down to the bottom of the liner.

Draw two symmetrical lines around the pivot area to mark out an area that will act as a washer. The area with hash marks will all be relieved.

The reliefs are cut into the liners with a mill. In my case, a mini-mill. I made a simple fixture to hold both liners so they can be milled at the same time. I found this method to be easier and faster with less setup. I don't think that the relief either being round or square around the pivot makes much of a difference. Tony Bose makes a round relief, Gene Shadley uses a square relief. I am in no position to argue the point with either of those guys.

The reliefs are cut with the mill to the lines scribed on the liners. I cut the reliefs around .010. Once the liners are relief cut, sand off all the burrs using your favorite sandpaper mounted on a flat surface such as a piece of glass or a surface plate.


This is a different knife than the WIP knife but it's all the same. The products I use are Stay Brite Solder and Stay Clean paste flux.

Make sure the surfaces you are going to be soldering are clean and scruffed up a bit to help the solder adhere. You can see here that I added a pencil line where I do not want the solder to stick. Apply a thin coat of paste flux to the liner.

I take a small coil of solder and place it on the liner. you will see a small piece of pin stock in this photo. It's 1/8 nickel silver and about 6 inches long. More on the pin stock further on down.

Here is where most people have problems. Applying heat. If you overheat the liner and burn the flux, it will NOT STICK.Place the liner with the coil of solder over the flame. Once the flux begins to bubble, remove it from the heat. The solder will not melt at this point. The tricky part is applying the heat in small increments. Put the liner into the flame for a second or two and remove it again. You may have to do this a few times to get the solder to melt. You must bring the heat up slowly just to the melting point or you will burn it and have to start over again.

This is what you will end up with.

While the solder is fluid, take the piece of pin stock (in the 3rd photo) and move the pool of solder around until it covers the entire area. Once the area is fully covered with solder, you can either use the pin stock to wipe away the excess or just flick the solder off the liner with a quick wrist motion. You will end up with a liner looking something like this.

Now that you have the liner tinned, repeat all the steps for the bolster.

Once everything has cooled, it's time to put them together. I use the pivot pin to help align the parts to be joined. Line the bolster into it's correct position on the liner and clamp it down with 2 clamps. Yes...2 Clamps! You want pressure on both sides of the bolster/liner. I make kind of a tripod with another clamp to make this part easier to do. Apply heat SLOWLY to the bolster side only until the solder becomes fluid. Remove heat immediately.

This is what you have. You can see that the solder flowed out from between the liner and bolster. This is a good thing.

Now you can grind and shape your bolsters and say........Look Ma! No seams!!

Once the bolsters are soldered and you are ready to work on the handles, you need to make sure there is no left over solder where the bolster meets the handle material. I have taken a small piece of lathe tooling, sharpened it and stuck it into a file handle. Use the sharpened edge to scrape away ant residual solder. It's comes off quite easily.

For my handle material, I have selected (actually my customer selected) a nice set of blue mammoth ivory scales.

To prepare for pinning the scales, mark off and drill your holes for the pins.

I use 1/16 416 SS pins for the scales

I will cut the scales a bit long before the actual fitting. The back of the scales are sanded down to the correct thickness before final fitting. When sanding mammoth ivory, you must not get it too hot or it will start to move on you. I will usually grind a bit and then press them against an aluminum plate to kind of cool them off. Once the proper thickness has been achieved, I sand the scales to length. A little trick I use for final fitting is to put the end of the scale against the grinder and move the belt by hand. This way, you are able to take of minimal amount of material. If you take off too much, you can never put it back.

Final fitting with holes drilled and ready for pins. In this case, I will glue the scales along with the pins to the liners. I don't know about you but I get a bit edgy when I have to peen pins when using ivory or pearls. The pins will eventually be ground flush with the handle material.


The handles have been roughed out on the grinder.

Another test fit.

The blade and spring have been heat treated and the blade has been hollow ground with a 10" wheel. Here I am adding the nail nick with a grinding stone mounted in my mini mill. The angle on the grinding wheel was cut using an adjustable angle wheel dresser.

Ready for assembly. The handles have all been finished on the slack belt to this point.

The pins I use are 416SS to blend in with the bolsters once finished. The holes in the bolsters have been reamed with a 2degree reamer held in a pin vice. This will allow for the expansion of the pin when peened. The pins are spun on my drill press and polished with sandpaper to get a nice clean finish. They are then cut so that approximately 3/64ths are sticking out on each side. The ends have a slight chamfer to them as well. The trick here is to make sure everything is clean so the pin blends perfectly with the bolsters after peening. To peen the pins, I use a 2oz. ball pein hammer with both faces highly polished.

The knife is now assembled. Everything is cleaned up on the slack belt ready for final finish. For this knife, the mammoth has been highly polished and the bolsters have a 600 grit finish.

All done and ready for customer pick up!!

superb work and detail . Nice . Scott

Thanks Bill for taking the time to put this up. Have a question you said you spun your pins? Could you tell and show us what you mean? Thanks

Mike,

What I am referring to is chucking the pins up in the drill press before installing them on the knife. This allows me to spin them at high speed and clean them up with sandpaper. It removes all the grime, dirt etc so I have a nice clean pin. This lessens the chance that the pin will show when peened. If the pins are not cleaned, you could end up with a small ring of dirt around the pin.

Thanks Bill,

What an excellent tutorial! I've wanted to make a slipjoint for a long time but it seemed too difficult to get the geometry correct. You explained it very well.

I know this is an old thread but I thought it was great. Tutorials like this are invaluable to me. Thanks Bill.

Frank, I hadn't seen this before. Excellent job, my old friend! :35:

So well explained - Thanks for a GREAT WIP!

Ken H>

Hi Guys
sorry to bother you, i am not able to view images anymore on this forum anymore. I have registered, I'm not sure if there is any additional action I need to do to be able to view? I am tryingto view Bill Vinings tutorial on Slip joint design?

LLOYD MOODLEY

Lloyd - nobody can see certain pictures any longer. Any if the pictures that were hosted by photobucket may be gone forever because the original poster had chosen not to pay the new monthly fee. As a suggestion- google bill vining and go to his website.

Does anyone have this saved with pics anywhere?????? It is such a shame that Photobucket destroyed so many wonderful WIPs in the blink of an eye!! Masters at the craft, who were good enough to share their knowledge, seems to have been lost forever!!