Understanding how an automatic folding knife works – Kershaw Launch 1 Disassembly and Re-Assembly

In the last post, I showed you a bunch of photos of the Kershaw Launch models 1 and 13. In this post, I am going to take the Launch 1 apart so you can see what it looks like inside. So, let’s get into it.

Tools Required

You will need #6 and #8 Torx bits. Something to pry the blade up and tweezers might help. For me, I have a large Strebito tool kit with a ton of precision bits, handles, tweezers and pry bars designed for electronics that has worked amazingly well for me when working on stuff with small fasteners.

Disassembling the Launch 1

Safety brief: Just remember, you are working with a very sharp spring loaded knife blade. It wants to open. Handle it accordingly and play it safe.
All of these screws use a #6 Torx bit. I removed the clip first and then the three screws holding the handle halves together. Note how the axle bolt is held in place by a hex head on the left. You don’t need to do anything from the side with that bolt – I’m just pointing out it is nice and secure. If you look at the screws at the bottom – especially the one to the right, it looks like some medium strength thread locker was on them.
I missed it on first glance – this is the other half of the axle bolt – kind of like a Chicago-screw or post-screw. I saw the decorative half circles and wondered how they removed it and then I noticed the hole in the center and looked more closely with a flashlight – hidden down in there is a #8 Torx screw.
There must be some thread locker on this as it took some torque to break it free. I didn’t need to use a wrench or heat – I just had to turn more firmly and it came loose.
Looking at the white/grey stuff in the threads – there probably was just a bit of threadlocker to keep it from coming lose but I am not certain. I would tend to think there is because you can’t crank that screw down or the pressure will keep the blade from opening.
At this point, all fasteners have been removed. Notice how I have it turned over so the push button is up – you will want to do the same.
So the scale lifts straight up and off. It is a snug fit on the axle bolt so it may take some wiggling to get it off. Now I need to point something out – look how clean the machining is and the finish is consistent. So many tools and knives look like crap inside due to an “out of sight out of mind” mindset that it is refreshing to see how well this is done. Kudos to the folks in the Oregon Kershaw plant!
The top pin to the left of the push button is hand press fit in place. Pull it out first and the blade will want to rotate clockwise and then the big hole will present itself to the push button and the push button will lift out.
Yes, in the photo above I said remove the pin and then the push button. In my case I was taking pictures and wiggling the blade round – the push button came out on its own. At this point the spring tension is being taken up by the pin. It’s not a crazy amount of spring tension the blade open but it is trying to go a bit further so be careful. This photo also lets us see the removed push button assembly. Normally, the fat bottom portion is engaging one of the cut outs in the bade. Either the one at the top that is keep it closed or the one at the bottom that locks it open. When you push the button the fat piece slides out the way and the blade is released to either open or close. Note, the spring is not sitting properly in the base of the push button in this photo.
I would not have needed the little blue pry bar if I knew the stop pin simply pulls out. If I had slightly closed the blade to take the pressure off the pin, I could have easily lifted the pin out, then controlled the few more degrees of rotation the spring had left in it and the blade would have lifted right off.
The torsion spring is what provides the power to flip the blade into position. The act of the user closing the blade rotates the spring’s coils and store the energy waiting for the button to be pushed spring back into the relaxed position. One leg of the torsion spring sits in the channel of the handle and the other sits in the blade. In this photo I have laid the blade 180 degrees opposite of how it normally sits in the handle so you can see how the torsion spring sits in the two parts. It’s elegant. Notice the ample grease – I think it might be silicone grease. Anything that causes the blade to bind will slow or even stop deployment.
Here are the parts and you can see the nicely done flat torsion spring. Again, I should have removed the stop pin, then the push button and the blade would have lifted right off the axle bolt. This is it other than removing the stop pin which plays into re-assembly.

Re-Assembling the Launch 1

Putting it back together is pretty straight forward. In hindsight I would tell you if something seems complicated, you missed something. That was exactly my thoughts as I was trying to the the torsion spring oriented with one leg in the handle and the other in the blade.

I spent about 5-10 minutes trying to get spring in and had my “duh” moment. Given how the spring sits, no tool so going to fit in there. I thought to myself “I wonder if that that stop pin can pull out?” And it did.
Wow!! Removing that stop pin made it sooooo simple. Rotate the blade such that the torsion spring legs are seated and you will feel the spring working. Then put in the push button and its spring followed by the stop pin.
I wish they designed the spring to snap into the button but they didn’t. An old trick that I used here was to fill the cup of the push button with silicone grease. The grease in turn holds the spring while you install the assembly.
Rotate the blade just enough so you can install the push button in that first large semi-circular opening. You can then push the button down and rotate the blade into the next notch which is the normal lock open moment. In this photo the blade is at a funny angle because the stop pin has not been installed yet.
Notice the blade is pushed all the way down on the axle bolt. To install the stop pin, push the button, carefully close the bade and release the push button. It should engage and hold the blade in the closed position. This presents the hole for the stop pin wonderfully as you can see in the photo and you aren’t fighting the spring. Literally, the pin goes right in.
I put a light coat on silicone grease on this side of the blade as I had wiped most of it off fumbling around. I did clear the silicone out of the bolt if you are wondering. You can also see the stop pin is in its hole.
The handle half is reinstalled. I carefully held it in place and tested to make sure the blade still pivoted and the push button worked.
When you reinstall the end of the axle bolt, you will need to see how much to snug down the screw. I found that if I made it too tight that the blade would not fully deploy. After experimenting, you may want to put just a bit of medium thread locker on the screw to keep it from working loose.
Re-installed these too and with that am done.

Summary

Kershaw did an excellent job on this knife. I thought about doing the same with the Launch 13 and it looks to be the same mechanism so I didn’t bother.

If you are looking for an automatic knife, I am very impressed by the Launch 1 and 13. I suspect the whole line has similar workmanship. I’ll post links further below.


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