Kershaw Piston Thumb Stud Deployment Issue

[Cardnyl]

Using information gleaned from searches on this forum I've recently updated my EDC folders of many years (spine lock Imperial and Schrade folder) to a Kershaw Piston. For xmas I ordered one for myself (a factory blem) and one for a friend (NIB). It's rather embarassing to make this my first post here on Bladeforums but I am having difficulty deploying both the NIB and blem using only the thumb studs.

I sat down for about an hour trying to deploy both knives using the thumb studs with rather dismal results. The knurling on the thumbstuds has turned my thumbs raw to the point of pain. On my dominant hand, I managed to split the skin where my thumb nail meets my thumb from pushing on the thumbstud. Typically what happens is I push the blade past the cam-over point where the AO kicks in but the torsion bar doesn't have enough force to open the blade till lock-up occurs. Occasionally this results in another type of injury where the skin on the tip of my thumb makes contact with the blade just beyond the flipper. Another few hours of practicing over the course of a few days and the knicks became deep enough to bleed me. When I handed over my friends Piston I told him it was bathed in human blood (mine) to please the Incan gods. He seemed pleased by this much to my dismay :grumpy:.

Both blades open with a crisp gratifying click using the flipper which leads me to believe that my issue isnt the knife and is the user. I don't think it's the internals so I haven't tried to open/clean/lube anything on the blade and at this point I can't (I don't have a good set of Torx and read here that the screws can be stripped with poor drivers). I can continue to practice provided I wrap my thumbs in some form of tape.

I tried searching the net/forums a bit but I'm comming up empty handed. Is there some technique to this blade I'm unaware of? If there isn't are there any options at my disposal to make this a bit easier (e.g different lube or pivot screw adjustment)?

Any feedback/help is appreciated

Thanks

 

[GrinderMcgee]

I push straight up instead of out.

I had to modify the flipper on mine because it was uncomfortable on my index but never had issue with the Blur type studs.

 

[Scurvy092]

Push in the direction of the steps not across them. They are angled to guide you in the right direction not to wreck your thumbs.

 

[grownstar]

Push in the direction of the steps not across them. They are angled to guide you in the right direction not to wreck your thumbs.

Solid advice. I don't own a Piston but I love my Blur and the angled thumbstuds are some of the most useful I've ever used. It shouldn't be giving you that much of a problem. As with anything, practice makes perfect. Worse comes to worse, just keep using the flipper.

 

[celtic11]

I agree with the others. I just got a piston for Christmas and love it. Kicked my Blur out of my pocket. My piston hung up a little when it was broken in but the fact that yours flips nicely with the flipper tells me its more a technique issue. The direction you push will be about a 45 degree angle. If you're doing it right it shouldn't hurt your thumb at all.

 

[gooeytek]

Maybe it's just me, but if I do something and it causes me pain and bleeding, I'll stop and find some other way to do it.

Regarding the angled thumbstuds in the Blur, it's strange how many people hate the same exact thumbstuds on the Speedform yet love them on the Blur. Even stranger, is how people will also hate them on the Blur, but rave about how they are perfection on a custom Estrella.

 

[annasoH323]

I've had a USA Zing and a Blur and when they were new, I had the exact same problems with the raw thumbs (didn't help that I had just cut my nails pretty far). They eventually smoothed out (and my thumbs healed). Sometimes, it just has to break in a little bit. I would say use the flipper until then and try the studs periodically.

 

[RevDevil]

Maybe it's just me, but if I do something and it causes me pain and bleeding, I'll stop and find some other way to do it.

Regarding the angled thumbstuds in the Blur, it's strange how many people hate the same exact thumbstuds on the Speedform yet love them on the Blur. Even stranger, is how people will also hate them on the Blur, but rave about how they are perfection on a custom Estrella.

Chicken....

Yet sometimes a bit of callus on the thumbs is all you need. Not everyone has the same hand strength and manual dexterity either. Working in a job where you use hand tools daily and pulling/splicing cables for 8-10 hours a day I can say that I have stronger hands than most folks and the thumb studs on these knives have never really been an issue for me.

 

[G. Scott H.]

Push in the direction of the steps not across them. They are angled to guide you in the right direction not to wreck your thumbs.

^This. My new ZT0700 has the same studs (my first knife with this style), and with a firm push on them the blade pops open like an assisted opener, though it isn't. :thumbup:

 

[HappyDaddy]

I had precisely the same issue with my Blur, and posted about it here. The answer is, as said above, learn to push in the direction the studs are guiding you to push - much more forward than out. Once you do it properly once or twice you'll know you've got it.

 

[flarp]

Push in the direction of the steps not across them. They are angled to guide you in the right direction not to wreck your thumbs.

^^^^ This. Push in this direction like so:

And when it gets to about this point, the Speedsafe torsion bar should kick the blade open the rest of the way:

 

[dkb45]

The issue you are having is that the thumb studs are called thumb slicers for a reason. I do not understand what monster at Kershaw thinks those studs are good. Sure, you get good traction on them, and if you happen to be Colossus then there is no issue, but for us non-mutants we have the issue of fleshy thumb skin. I used those studs on Speedform 2 for about 2 days before I angrily hammered them out.

For every person that likes those studs, there is another person with a mutilated thumb that hates them for a reason.

 

[Scurvy092]

For every 100 people that likes those studs, there is one person with a mutilated thumb that hates them for a reason.

Ftfy.

 

[celtic11]

The issue you are having is that the thumb studs are called thumb slicers for a reason. I do not understand what monster at Kershaw thinks those studs are good. Sure, you get good traction on them, and if you happen to be Colossus then there is no issue, but for us non-mutants we have the issue of fleshy thumb skin. I used those studs on Speedform 2 for about 2 days before I angrily hammered them out.

For every person that likes those studs, there is another person with a mutilated thumb that hates them for a reason.

I just don't understand the issue. I have a zing, two blurs, and now a piston with those studs and when used right they don't hurt my thumb at all. And based on my time on this forum I would day it's more like for every 10 people that like the studs there is one person who can't figure out how to use them.

 

[Cardnyl]

Push in the direction of the steps not across them. They are angled to guide you in the right direction not to wreck your thumbs.

^^^^ This. Push in this direction like so:

And when it gets to about this point, the Speedsafe torsion bar should kick the blade open the rest of the way:

I've had a USA Zing and a Blur and when they were new, I had the exact same problems with the raw thumbs (didn't help that I had just cut my nails pretty far). They eventually smoothed out (and my thumbs healed). Sometimes, it just has to break in a little bit. I would say use the flipper until then and try the studs periodically.

Sounds good, I will give this a whirl. Its possible I did the most damage to my thumbs trying to open it by pushing 45 degrees to other side of how they are angled (based on the orientation in the pictures, straight up and straight left).

Maybe it's just me, but if I do something and it causes me pain and bleeding, I'll stop and find some other way to do it.

Well it wasnt instant pain/death/blood letting; it took a bit of time over the course of a few days to mangle my thumbs enough for me to seek assistance. I didn't want to waste time with a post until after I'd exhausted ideas, search terms, and my thumbs

Chicken....

Yet sometimes a bit of callus on the thumbs is all you need. Not everyone has the same hand strength and manual dexterity either. Working in a job where you use hand tools daily and pulling/splicing cables for 8-10 hours a day I can say that I have stronger hands than most folks and the thumb studs on these knives have never really been an issue for me.

Unfortunately for me I work on a keyboard for my daily grind so hand strength and callusing are foreign to these hands.

The issue you are having is that the thumb studs are called thumb slicers for a reason. I do not understand what monster at Kershaw thinks those studs are good. Sure, you get good traction on them, and if you happen to be Colossus then there is no issue, but for us non-mutants we have the issue of fleshy thumb skin. I used those studs on Speedform 2 for about 2 days before I angrily hammered them out.

For every person that likes those studs, there is another person with a mutilated thumb that hates them for a reason.

That is too funny. I suppose if all else fails I could grind/file them down. I'd probably end up doing something like that as a last resort. For as much as my thumbs hurt I can definitely appreciate the knurling/jimping depending on the situation. If your hands were wet/greasy/gloved I'm sure the traction would come in handy.

Just wanted to say thanks to all who took time out to post; I appreciate it.

 

[dkb45]

I've noticed a similar issue with the thumb studs and axis bar on most of the Benchmades I have had. I'm sure like above it helps for people with very calloused hands, or when the extra traction is needed, but for every other time all it does it try to rip your fingers up. All they need is just a little bit of smoothing, but every time I have tried the smooth sharp thumb studs all I do is somehow make them sharper.