Small Batch run of MagnaCut Frame Locks

Had a productive weekend working on these framelocks. Due to my day job, most progress will be made on weekends and there will be a huge photo dump/post on Monday!

First step this weekend was to get the lockside of the handle scales cut out. Love the Swag table with my portaband, makes it a lot easier! I'll explain why later that I don't cut out both sides at the same time. Again, just got them roughed out and will grind to shape on the belt sander. I don't go right to my lines, that'll be for later.

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Next, I again use the optical center punch to mark the center of my pivot, through holes for the stand-off screws, detent ball, and the upper corners of my lockbar. If the upper corner of the lock bar holes aren't drilled, it would be very difficult to get the cut to stop in just the right place since I use a dremel type disc in my mini mill. I will also mark the pivot on the show side scale as well.

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I don't mark the stop pin hole right now, that'll be done using the DRO on my mini mill in order to get the stop pin in the exact location that I need it to be.

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Next, I drill the holes in my lock side scale. I use the spotting drill to mark the pivot hole, follow that up with the #15 bit, and finish up with a 3/16" chucking reamer. The through holes for the stand-offs will be drill with a #44 dill bit. I use a 5/64" bit to drill the corners of the lock bar. I don't drill the detent hole at this point. I could, just don't yet.

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Next, I have to center my rotary table to my spindle using a coaxial indicator. Once the table is centered, I need to center the 1/4" aluminum plate that I mount to the top of the rotary table. To do this, I place a precision ground ground 3/16" rod into my spindle and place it into the 3/16" reamed hole that I have in the center of the aluminum plate. You can see the hold down bar that I have in order to keep the blade stabalized while milling the stop pin track. Once the aluminum plate is centered, I will lock down the X-axis and move the Y-axis .3060 which is the distance from the pivot to the stop pin hole according to my CAD software. Once I have the blade in place, I will mark the location of the stop pin with the spotting drill bit. Once marked, I will drill the stop pin hole with a #44 drill bit. I do this so that I can counterbore that hole for the head of the stop pin screw.

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Once I have the #44 hole in the stop pin location of the lock side liner, it's time to get the show side scale going. I dykem to back of the show side scale piece. I then place to pivot through the lock side and into the show side. I then clamp them together with a Kant Twist clamp and scribe the outline of the lock side scale onto the show side. Before separating them, I use the lock side as a template and transfer the stop pin hole and the two through holes for the stand off. Then it's time to cut out the show side. I find that this is the best method (for me) to make sure that all my holes line up on both sets of scales since we are dealing with thousandths of an inch!

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Now it's time to countersink the stop pin and through holes for the stand-offs. The height of the screw head is around .046" since I'll be contouring these scales, I'll go a bit deep and countersink these to .060" deep. I use a carbide counterbore with a built in pilot from USAKM. Using the DRO on my mini mill, I get the counterbore hole as close to .060" as possible.

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Now that the stand-off and stop pin holes are counterbored, I have to shorten the screws for the stand-offs and the stop pin. As they sit, they are too long and the ends of the screws would hit each other inside of the stand-offs and the stop pin, preventing them from tightening down properly. For this task, I drilled and tapped a scrap piece of 1/8" metal and screw the screws all the way in. Then using the belt sander, remove the threaded portion of the screw that sticks out of the back.

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Once the screws are shortened, I can use some sacrificial screws and stand-offs to assemble the handle scales. Because I'll be using caged bearings for the build, I'll recess the inside of the pivot area of both scales and leave a .020" clearance between the blade and handle scales. To simulate this clearance, I use a couple of .020" PH washers sandwiched around a piece of 1/8" scrap steel that has a reamed 3/16" pivot hole. My stand-offs are .165" which accounts for my .125" blade and the two .020" clearance gaps on either side. Now I can profile both scales at the same time to get my final dimensions. I grind these up to 120 grit for now.

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Now that the handle scales are to their final dimensions, I need to open up the stop pin hole to its final 1/8" diameter. In order to do this, I place the scales with the outsides facing each other so that I see the #44 hole and not the counterbored #44 hole. I hop that makes sense. I place a pivot through both pivot holes and use 3 #44 drill bits in the stop pin hole and the two through holes for the stand-offs so that I am as aligned as I can get all the holes. I then clamp them together and remove the drill bits and pivot. Finally I use a #33 drill bit to open up the stop pin hole and ream to size with a .125" chucking reamer.

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Now that my stop pin hole is to it's final diameter, I can set the open and close positions of the stop pin track on my blade. To do this, I place a pivot through the lock side scale and the blade. I get the blade to the position that I want it to be in when opened. I clap the scale and blade together and drill through the stop pin hole with a 1/8" drill bit. I then clamp the blade in the closed position that I want and clamp them and drill through the stop pin hole again. Now I have the ends of my stop pin track set.

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Now it's time to mill the stop pin track. Since the mill is already setup to drill the stop pin hole, it is ready to go for the stop pin track. I place a 1/8" drill bit the chuck and clamp down my blade. I rotate the table until the drill bit fits securely into the pre-drilled hole in the blade. I check the rotary table and mark that number down. I then rotate the table and do the same for the other hole in the blade. Now I have my two stop locations for the rotary table. After that it is just rotating from one number to the next until the track is milled out. I use a 9/64" carbide end mill to make the cuts. Using the DRO, I go down about .010" at a time until the track is done. Do some check on open and stop locations, and looks like we are good to go!

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Finally a quick soak in acetone removes the templates. A quick hit on the disc grinder to remove the burred edges and we are good to go!

Next up I need to set the detent hole in the blade and do some spine jimping and these are ready for heat treating!!

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Last night I drill the liner and the blade for the detent. First step was to drill all the lock side liners with a #54 drill bit. I need the hole in the blade to be a #54, so I have to use that bit to drill the lock side liner detent hole so I can transfer it to the blade. I will go back later and open up the lock side liner detent hole to a #53 so I can press in the 1/16" ceramic detent ball.

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Once the #54 hole is in the lock side liner, I assemble the knife with the sacrificial hardware. I close the blade fully against the stop pin and set it on a 1-2-3 block. I set it on the block so that my clamp doesn't stick out below the scale, that way it will sit flat on the 1-2-3 blocks while drilling the detent hole in my blade. Using a Kant Twist clamp, I force the blade further into the closed position by just a bit. This will give the blade the opportunity to load against the detent while in the closed position so that we get that "snappy" action when opening the knife.

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I then drill into the blade for a few seconds, just to put a divot for the detent ball. While the blade is assembled, I take the chance to do some profiling and get my blade and liners to be even and symmetrical in a few key spots to get those nice smooth transitions.

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Great stuff JRB! Dare I say good solid down to earth Old School build showing some planning and execution of said plan in clear detail.
Looking forward to more.
 
This was an enjoyable read. Thank you for taking the time to write this out and sharing!
 
ice-pic said:
Great stuff JRB! Dare I say good solid down to earth Old School build showing some planning and execution of said plan in clear detail.
Looking forward to more.
Click to expand...

Thank you! It has taken a while to get a good process down, lot's of mistakes and wasted material on the way. If I can save somebody even one day of frustration or one piece of material, it was worth it.
 
So the last step before sending these out for heat treating is to do some jimping on the spine. I use a 1/8" chainsaw file to do this. First step is to Dykem the spine and use my digital calipers to evenly (as best as I can) space the jimping. I mark the location with my carbide scribe and go to work with the chainsaw file. Since I am using an 1/8" chainsaw file and I want 1/8" between each of the marks, I set my calipers to 1/4" and mark them out.

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Sending them out to heat treat today! Now to get these handle scales ready!
 
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