Small Batch Run of MagnaCut frame locks

Mister Coffee

Well-Known Member
Thank you, I appreciate the comment. I have always enjoyed a good build thread and have learned so much from them. Figured if this helps one maker with one aspect of making a framelock, then I'm happy!

I can only pretend to understand everything that you're doing here, but even as a dummy first-year student, I really appreciate your posts. Totally cool.

So, how do you get a frame lock to work? Do you bend the lock part?
 

JRB Blades

Well-Known Member
I can only pretend to understand everything that you're doing here, but even as a dummy first-year student, I really appreciate your posts. Totally cool.

So, how do you get a frame lock to work? Do you bend the lock part?

Yeah. I'll go over that in a few steps. You have to mill a relief into the outside of the lock side liner. Once that is done, I'll heat that area and bend the lock bar over so that it engages with the lock face, which I will also grind to around 8 degrees.
 

JRB Blades

Well-Known Member
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 this way the clamp doesn't stick out past the bottom of the scales and I can set them on my 1-2-3 blocks to drill the detent hole into the 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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JRB Blades

Well-Known Member
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 these blades out for heat treating today! Now to get the handle scales ready!
 

JRB Blades

Well-Known Member
Now it's time to cut the lockbar and mill the lock relief. This takes about 30-40 min per blade, so I'll be done this weekend when I get some more shop time. I did two of them already and thought I'd go ahead and include this portion now. I use .025" cutoff discs from McMaster Carr along with their 1/16" wheel arbor.

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I place two drill bits in the holes that I drilled out for the ends of the lock bar. Then I place the handle scale in the vice with a couple of parralells stacked on top of each other. I set the drill bits on top of the handle scales and tighten the vice. Now my handle scale is level and even.

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I run the mill at 2500RPM and take it slow to cut the lock bar relief. If you're careful, the disc won't break although they are pretty fragile.

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Once the lock bar is cut, I use a 5/16" carbide ball nosed end mill to mill the lockbar relief. Running at about 700RPM, I take about .005-.008" cuts using the DRO to make sure I am not taking too much of a bite at once. My little mill can't handle much more than that. We are shooting to get the "webbing" on the lock bar relief around .045" so we have good tension on the lockbar but not so much that it's a bear to unlock.

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When the relief is finally cut, the cut in our lockbar is covered with the effects of milling our lock bar relief. Since the scale is still secured in the vice, I use the cutoff wheel to re-open that lockbar cut. After that I'll take it to the drill press and re-open the hole at the end of the lockbar relief with my 5/64" drill bit.

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Looks like we are pretty close to our .045" target!

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JRB Blades

Well-Known Member
While the scales are still flat on both sides, time to drill and tap the holes for my pocket clip. I set the clip in place and use an automatic center punch to mark the holes. Then I take it to the drill press and use a 5/64" bit to drill the holes. I am using threadform taps, so this is the correct hole for this application. Once the holes are drilled I use my TapMatic to tap the holes. This was the best investment I have made. Can use one tap for literally hundreds of holes. Quick and easy! The screws are too long, so a quick hit on the belt grinder gets them to their proper length.

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JRB Blades

Well-Known Member
Next, I will counterbore the pivot screw and the pocket for the bearings. I am using a .314 carbide counterbore with a 3/16" pilot from USAKM. The head of the screw will be counterbored .030".

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The bearing pocket will be counterbored to a depth of .042" (bearing is .062" thick and I want .020" clearance on each side of the blade). I use a 13/32" carbide tipped counterbore for this.

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JRB Blades

Well-Known Member
Next. I need to relieve the liners in the area of the lockbar to make unlocking the blade easier and to provide some relief from the hard edges while unlocking the knife. I place my grinder in the horizontal position and use one of the contact wheel on the bottom of my platten to do this. Holding it at roughly a 45 degree angle. Just making sure the keep both sides even and symmetrical.

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Now it's time to set the detent. I use my arbor press for this. I have a .020" feeler gauge that I place around the detent ball so I set it with exactly .020" of the ball sticking up from the liner. This is because the clearance between the blade and the frame is .020"

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JRB Blades

Well-Known Member
Now it's time to contour the scales. I start out by putting Dykem on the edges of my scales. Then, using the height gauge, I scribe a line .065" from the outside edge to give me a line to grind to. To do the coutnouring, I use a pair of 1-2-3 blocks and superglue each line to the blocks. Making sure the detent is off the edge of the block and the outside of the scale is the one I'm contouring. I place the grinder in the horizontal position and use a rocking motion against my platen to get the desired shape. I take this up to about 480 grit for now.

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JRB Blades

Well-Known Member
Next up is to trim the pivot and stop pin and get them to their final length. I place the pivot in the knife and assemble it with my scrap piece of 1/8" steel to represent the blade. Then I take my digital calipers and measure how much it is sticking above my handle scale. In this instance it was . 058".

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Since I counterbored the scale for the pivot screw to a depth of .030", that gives me .088" above the counterbore. Since I want the pivot to sit about .020" below the counterbore, I'll take off .108" from my pivot barrel. To do this, I place an end mill upright in my vice and put the pivot barrel in a 3/16" collet. Then using my DRO for the Z-axis, I mill it down to size.

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Once the pivot barrel was at the correct size, I did the same thing with the stop pin and got it down to proper size too.
 
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JRB Blades

Well-Known Member
Then it was time to soften up the edges of the scales so there aren't any sharp 90 degree angles. To do this I use my scotchbrite wheel on my bench grinder and at about a 45 degree angle, I just soften up all the inside and outside edges.

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Then I released the lock bar. I placed the scale upright in my vice and used a square to get the lock bar cut perfectly vertical. Then I used the same cutoff wheel to release the lock bar.

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Once that was done, I applied heat with my MAP torch to the lock bar relief until it was cherry red. Then using pliers, gently bent the lock bar to where the outside edge of the lockbar was just inside my handle scale.

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Then, using the scotchbrite wheel, I chamfer the inside edge of the lock bar where it will contact the lock face of the blade.

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After that, all that is left to do is bead blast the scales and stonewash them. I use 80 grit glass bead to do the blasting and my HF vibratory tumbler to stonewash them.

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Now I am just waiting for the blades to come back from heat treating, probably middle of next week.

Stayed tuned!!!!
 
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