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91mm SAK mod 'Mountain Tinker' 1014

No Life Club Posts: 4,235
91mm SAK mod 'Mountain Tinker'
« on: July 13, 2019, 04:45:50 PM »
Hi, all.


Backspring "Corkscrew vs Phillips" is an endless debate for all 91mm SAK enthusiasts, how about having both at the same time? :D


Mountain Tinker



This is the very first mod I made after my initial post "Gathering thoughts/tools/materials for first mod" and I'd like to share with you what I've learnt as a newbie.  My special thanks to D_T and Vidar, for your patience and sharing of all things machining/modding, this mod is dedicated to you two! :cheers:   And also a big thank you for hiraethus, for sourcing the brass rods, it won't be possible without all of you! :hatsoff:




Executive Summary: To replace the Victorinox 91mm Mountaineer's backside awl/hook with a 91mm Tinker backside Phillips driver.


Materials needed: 1 SAK 91mm Mountaineer, 1 91mm Tinker, few 0.3mm-0.4mm thick 2.5mm(inner hole diameter) spacer.





I used a used 91mm SAK Mountaineer as my base for this mod, which is one of my all time favorites for EDC.  First off, I used steel wool to clean up the old metal file before the mod.



Getting the scale off is easy.  I soaked the entire SAK into a glass of boiling(really) hot water for 3 min(not in the pot on fire/stove, where the bottom will be more than 100C, but in a glass), lift it up by the lanyard ring, then quickly insert a very small flathead into the toothpick to lift up the scale and proceed to peel the entire scale off with a small SAK blade as fast as I can.  The trick here is don't hesitate and act fast, or else the scale may cool down and it might be wrapped.  I placed heavy box on top of the scales once off, to keep them straight during the cool down.(Thanks to Jaya for the details, good points!)



If there is anything I learnt in this mod, is that having all the right tools is half the battle won.  You don't need everything, but some essential tools and patience are must for a good perfect mod.(I will list out what I think are essential/nice to have to a newbie in the end)



I center-punch each of the rivets with a manual punch.  I tried auto center punch, maybe what I get is a crappy one or I'm no good at it, the slack inside the punch/little skidding just when you are pressing down on the auto punch will make the dent completely off center.  The manual punch, on the other hand, is rather accurate and reliable.  This process is important, because you may damage the rivet bushing otherwise, and you will need that if you are going to put scales back on. :o



A drill press is absolutely awesome, so far I had practiced peening and disassembly a few times, and the drill press makes the whole process very consistent and prevent any damage to the rivet bushing.  I've used 2.5mm and 2mm cobalt drill bits for drilling out the rivets on 91mm SAK.




Once I made the initial hole at the rivet, I proceed to using dremel to thin out whatever left of the rivet inside the bushing.  Then I carefully lift off the bushing with a flush cut pliers.  (Thanks to Jaya for reminding me, another way is to drill enough of the material out, then use the punch to punch it thru)



Next I used a 1.5mm and 2mm punch to punch out the rivet/pivot.  This is where a wood jig comes in very handy.  The jig is the first thing I build even before dissembling the first SAK.  The four holes on the wood doesn't have to be perfect, but need to be large enough to house the rivets and bushing and keep the SAK flat for drilling/punching.  So as I punch out the pivots, the bushing/pivot/rivet will fall thru into the jig underneath.  Notice the tape around the SAK, this really helps prevent the tools explode out when the pivots are being punched out.




91mm Mountaineer "exploded view".  It is up to you how you'd like to punch out pivots, I recommend layer by layer, so you get a chance to resemble the layer and take photograph as you go.
Now is a good time to make measurements of all the tool layers and take notes.



Onto the main feature of this post, there are probably a few ways to fit in a back spring phillips simultaneously with corkscrew.  AimlessWanderer's Mega84 dual blade layers or Syph's thinned out phillips are both good in this post, also there are more discussion in this thread here.


My way is try to replace the Awl/Hook on a 91mm with the back spring phillips.  I first fit in the backside phillips driver instead of the awl into the "openers" layer(no mod required on the phillips).  The reason of replacing the awl, instead of the hook, is because the strong similarity of their tangs.  However, the backspring phillips is thicker, so I put in 0.3mm spacers onto other three pivots to fill the gap and avoid side play. 


Could the phillips replace the hook in the scissors layer?  Maybe, but there is a fair chance it can't stand straight since there is not enough material to push against the scissors backspring. :facepalm:




One of the two things needed modding is the openers liner.  Here I use a dremel and 'stock removal' method to cut an opening to fit in the phillips.  Notice, this opening is NOT the same opening as the blade/corkscrew liner.  The backspring of the scissors is slanted, so beware how much you cut or it might not be as 'pretty'.




This is the patient part, use dremel/file/sandpaper to give just the space necessary for the phillips to rest at the back.



The second part needs modding is the hook.  Just cut it off to give space to the phillips, its a no brainer.  But it needs to be there otherwise there is no support to the scissors backspring.



After putting on other layers, finally put on the bushings.  Do be very careful, there are four pivots in a 91mm SAK, only 3 needs bushing(2 2.5mm ones, and the floating pin 2.25mm).  And do be careful, the two 2.5mm pivots needs the bigger rivet bushing, and the remaining 2.25mm pivot needs the smaller rivet bushing.  I left only 0.5-0.7mm material on each side of the bushings, and it peens perfectly.



Giving the mod translucent scale, here I use sponge vise cover or leather to protect scales from marring.




Different close up and photo for reference, notice the 0.3mm spacers at the openers layer to avoid side play.



One last look at the back side, in comparison to the awl/hook.  The phillips won't be completely flat against the chassis, but the slight slanted angle is just perfect for fitting my finger in to lift it up.  In fact, it's less noticeable than the corkscrew.




What I think is essential tools for making this mod:
Drill
2 and 2.5mm drill bits
Center Punch
Jig(debatable, but it just make life so so much easier, can't imagine without it)
Tape
File
Saw(to mod the liner)
Sand paper



Nice to have tools:
Drill press
Dremel + diamond cutoff disk(for quick liner/hook modding)
Dental pick(or something similar to pull the springs back to install the layers)






Thank you for reading!  I will be making more mods based on the SAK 91mm Mountaineer in the near future, please stay tuned!  :popcorn:
« Last Edit: July 13, 2019, 06:32:24 PM by comis »

No Life Club Posts: 4,235
No Life Club Posts: 2,424
Re: 91mm SAK mod "Mountain Tinker"
« Reply #2 on: July 13, 2019, 05:02:17 PM »
Excellent mod and write up! Cool pics too

[It's not failure if you learn something from it]

No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #3 on: July 13, 2019, 05:05:06 PM »
Excellent mod and write up! Cool pics too

[It's not failure if you learn something from it]



 :cheers: :D
Global Moderator Absolutely No Life Club Posts: 8,454
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #4 on: July 13, 2019, 05:57:59 PM »
Nice mod and detailed steps comis... :tu:

If I may add (for future mods), warm or hot water will do the scale removal trick... boiling water is way to riskier for the SAK and the person doing the mod. After drilling, the punch can be used to push the pins through the bushings and layers... if it’s hard to punch the pins, drill a little bit more... learned this trick based from experience and from other modders... good thing about this, less damage to the bushing... :cheers:
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #5 on: July 13, 2019, 06:20:18 PM »
Nice mod and detailed steps comis... :tu:

If I may add (for future mods), warm or hot water will do the scale removal trick... boiling water is way to riskier for the SAK and the person doing the mod. After drilling, the punch can be used to push the pins through the bushings and layers... if it’s hard to punch the pins, drill a little bit more... learned this trick based from experience and from other modders... good thing about this, less damage to the bushing... :cheers:

Good points! :cheers:   I gonna experiment/research more to see what's the minimum hot water temperature to get the job done, and thank you for the reminder on the punch out trick, I too actually use sometimes after some dremeling.  Original post edited to reflect these good pointers!  :D
Global Moderator Absolutely No Life Club Posts: 8,454
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #6 on: July 13, 2019, 06:27:44 PM »
My pleasure comis... just keeping the MTO spirit alive... All the things I learned about modding SAKs I got here in MTO... only appropriate to pass it along to others as well...
No Life Club Posts: 1,201
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #7 on: July 13, 2019, 07:22:20 PM »
Thanks for sharing your experience.
No Life Club Posts: 1,953
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #8 on: July 13, 2019, 08:27:35 PM »
Very nice indeed and very professional!

"It is better to lose health like a spendthrift than to waste it like a miser." - Robert Louis Stevenson
Hero Member Posts: 753
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #9 on: July 13, 2019, 10:29:30 PM »
Nice work! It looks great!!
:like: :tu:

Sent from my Redmi Note 5

No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #10 on: July 14, 2019, 07:15:59 AM »
My pleasure comis... just keeping the MTO spirit alive... All the things I learned about modding SAKs I got here in MTO... only appropriate to pass it along to others as well...
:like: I'd read some of your posts in the past, and thank you for sharing too!  It is essentially what makes MTO great.




Thanks for sharing your experience.
Thanks for reading! :cheers:
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #11 on: July 14, 2019, 07:18:15 AM »
Very nice indeed and very professional!
Thank you!  I am probably no where near the pro level of stuff, but I'd take my time and enjoy every steps of the way! :D


Nice work! It looks great!!
 :like: :tu:

Sent from my Redmi Note 5


 :cheers:
Newbie Posts: 47
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #12 on: July 14, 2019, 06:22:52 PM »
Very nice tutorial, Comis.  Thanks for your contributions!  This is a very cool mod. :cheers:
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #13 on: July 15, 2019, 03:03:56 AM »
Very nice tutorial, Comis.  Thanks for your contributions!  This is a very cool mod. :cheers:

Thanks, jph!  :cheers:
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #14 on: July 15, 2019, 03:55:17 AM »
I just realized I've forgotten to put in hammer as essential tools! :facepalm:


I used a few hammers to peen and punch out the pivots. 


The heavier 500g/17oz hammer is only used to punch out the pivot with a center punch, layer by layer, and I carefully monitored the shape of the pivot as I was punching them out.  Any deformation of the pivot may marr the liner holes or get stuck and warp the liner, so I would try to file away any debris/deformation before punching them.


I got a 3.5oz(100g) and 5oz(150g) hammer, and I used them changeably for peening the 91mm.  I practiced a few times on beater 91 and 93mm before attempting this mod, just to get a feel on how to peen.  I know some folks here have some mad peening skill, but my newbie two cents worth are:


1) For smooth, flat installation of 91mm scales, we will probably need the rivet be completely flat and smooth on top of the bushing(pls see your bushings and take pictures before taking them apart).  But no worries, 91mm peening is much, much easier than 93mm peening.


2) Ball peen hammer will 'move' the material, sort of expand the surface material, and give the appearance of 'dome' shape of the rivet.  We don't really need that in 91mm per se since we need the rivet to be totally smooth within the bushing, but I do use ball peen anyway to 'fill up' the top of the bushings.


3) Flatter the ball peen/hammer face, smoother the hit on the rivet, and vice versa.  If you use a small ball peen hammer with a really round ball peen, that obviously will leave a very visible 'dent' on the face of the rivet(part of the reason why ball peen will 'expand' the material).  So for 91mm, you could basically get away with even using a flat face hammer.


4) With my 93mm peening practice, I know there is this balance/sweet spot we want to get to--On one hand, I would want to use flatter ball peen/flat face hammer to smooth the appearance, but that won't give the dome shape and flat face may hurt the aluminum scale easier.  On the other hand, there is a tendency to try to use a really small round ball peen to avoid hitting the scale, but that would expend the surface quickly, and the edge of the dome may become too thin, and as you hammer the pivot down into the rivet, and eventually get so thin that it may even start to 'crack' at the edge as it touches the scale. 

That's probably one of the reason why 93mm peening is difficult, how much length left for the optimal shape/function, what technique, etc.  I am still too new and not successfully enough to make any real contribution here, but that's another story for another time.  If anyone whom have done it in the past, please do feel free to chime in!
:hatsoff:


5) I know some modder like to use a punch at the end of the process to ensure the material fit up the rivet bushing nicely.  That is subjective, but if you felt there is not enough material inside the bushing to form a effective rivet, then I guess this is a good way to help.


Thanks for reading again! :tu:
No Life Club Posts: 1,585
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #15 on: August 01, 2019, 10:28:38 PM »
comis, I liked your mod so much I modded one for myself. I did not add the file to mine so I guess mine is a Climber/Super Tinker.
Thank you for the great mod!




Sent from my iPhone using Tapatalk

I think Alcohol, Tabacco and Firearms should be a convenience store, not a government agency. 

Mike
No Life Club Posts: 1,643
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #16 on: August 02, 2019, 04:17:22 AM »
Nice write-up comis!  :like: This will come in handy should I ever have access to a drill press.
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #17 on: August 02, 2019, 05:27:39 AM »
comis, I liked your mod so much I modded one for myself. I did not add the file to mine so I guess mine is a Climber/Super Tinker.
Thank you for the great mod!

(Image removed from quote.)


Sent from my iPhone using Tapatalk

That's awesome!  :cheers: :D
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #18 on: August 02, 2019, 05:31:53 AM »
Nice write-up comis!  :like: This will come in handy should I ever have access to a drill press.

Actually, a drill press will be really nice to have to do a clean job, but I do agree with most folks that you don't actually need one to do a 91mm mod.  A dremel or hand drill will actually be suffice. :D
« Last Edit: August 02, 2019, 06:45:31 AM by comis »

Admin Team Zombie Apprentice Posts: 18,913 mmmmm SAKrelicious
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #19 on: August 04, 2019, 11:58:00 AM »
 :clap: Lovely mod! Great pics too.  :cheers:

'Use the force Harry' - Gandalf

'Derail a thread and we'll come at you like a block of cheese'. Captain Mags and Sergeant Fuzzbucket of the Anti Derai.... mmmmmmm cheese
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #20 on: August 04, 2019, 02:17:03 PM »
:clap: Lovely mod! Great pics too.  :cheers:

Thanks, Mag!  Just giving back a little to the community, I learnt a lot from all of you! :hatsoff: :D
No Life Club Posts: 1,221
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #21 on: August 04, 2019, 07:26:40 PM »
Beautiful! And thank you for sharing the details  :cheers:
No Life Club Posts: 1,643
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #22 on: August 05, 2019, 12:51:09 AM »
Actually, a drill press will be really nice to have to do a clean job, but I do agree with most folks that you don't actually need one to do a 91mm mod.  A dremel or hand drill will actually be suffice. :D

I know my skills with a hand drill. Unfortunately I could not hold it straight if my life depended on it. I would just damage the bushing  :facepalm: I have a broken SAK laying around, maybe I do a test run on that to see how it would work  :think:
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #23 on: August 05, 2019, 04:10:10 PM »
Beautiful! And thank you for sharing the details  :cheers:

Thanks for reading!  :cheers:




I know my skills with a hand drill. Unfortunately I could not hold it straight if my life depended on it. I would just damage the bushing  :facepalm: I have a broken SAK laying around, maybe I do a test run on that to see how it would work  :think:


 :popcorn: :popcorn: :popcorn:
Global Moderator Abandon All Hope Ye Who Enter Here... Posts: 40,282
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #24 on: August 05, 2019, 04:22:09 PM »
Nice work comis !    :cheers: :salute: :tu:
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #25 on: August 06, 2019, 04:39:43 AM »
Nice work comis !    :cheers: :salute: :tu:

Thanks, Steve! :hatsoff: :cheers:
Zombie Apprentice Posts: 11,424
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #26 on: August 25, 2019, 02:35:31 PM »
This is a great mod. The ideal of having both the corkscrew and the Phillips on the back side is great! Surprised Victorinox had not already done it! Great name for it by the way!  :hatsoff:
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #27 on: August 26, 2019, 08:44:43 PM »
This is a great mod. The ideal of having both the corkscrew and the Phillips on the back side is great! Surprised Victorinox had not already done it! Great name for it by the way!  :hatsoff:

Thank you for the kind words! :cheers:
Zombie Apprentice Posts: 17,010 I'm not a pessimist, I'm an experienced optimist!
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #28 on: August 26, 2019, 11:21:54 PM »
I did something similar quite a while ago, with my Mega84, and it's great having both corkscrew and driver on the back.

Nice work  :tu:



The cantankerous but occasionally useful member, formally known as 50ft-trad
No Life Club Posts: 4,235
Re: 91mm SAK mod 'Mountain Tinker'
« Reply #29 on: August 27, 2019, 05:03:11 PM »
I did something similar quite a while ago, with my Mega84, and it's great having both corkscrew and driver on the back.

Nice work  :tu:

Aw, I remembered seeing that while researching, thanks to you and many others whom have generously contributed, enabling more folks to join this fun hobby! :cheers:

 

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