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First time Mod

Jerm · 55 · 7891

nz Offline Jerm

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First time Mod
on: June 11, 2014, 08:27:47 AM
Hi Guys,

First time poster here, I've gained a lot of info from browsing this forum so I thought I'd share my first knife mod with you guys.

To cut a long story short, I ordered an Alox Cadet from Amazon and it arrived with a manufacturing defect, as seen in the photos below. Due to complications (location, freight forwarding service I had used) the good people at Amazon deemed it prohibitively expensive for me to return the knife and offered me a refund and let me keep the knife.

As you can see below, there is a small washer out of place on the knife, which caused one of the scales to bow outwards slightly.




I decided to try and fix it.....

After discovering Syph007's GREAT thread http://forum.multitool.org/index.php/topic,34772.0.html , I was inspired to have a go at creating some custom scales and use the pivot method of assembling the knife.

I sketched up some concepts.


CAD modelled my final design.


Luckily I am employed at a company as an engineer with access to great prototyping facilities and workshops!

SLA 3D print, to check the design.


I then designed and machined an aluminium injection mold tool. Below is a picture of the tool and freshly molded parts. The material is a carbon fibre filled nylon, which is extremely stiff, allowing me to keep the scales very thin. I have also bead blasted the cavities in the tool to give the finished part a nice texture.



And here's the finished product.




What do you guys think?!

One of the most challenging things was cutting down the screws and pivots which I ordered (as specified on page 1 of Syph007's thread). I ended up completing this task using a Dremel fitted with a cut-off wheen and I'm not sure if I've done a very good job.

Not all is completely finished though, the scales came out just as I liked them, but I've had some issues assembling the knife. It's quite a fiddly job and I can't seem to get all the tools to function perfectly, as a factory standard Alox Cadet does.

I'm not sure what the problem is but, depending on how tightly I have the screws the main blade isn't sitting perfectly right and the tip is sometimes caught when closing the flat screwdriver tool. Obviously when I tighten the screws a lot, the tools become quite stiff to open also, which is expected.

As you know these are quite small devices and the tolerances must be quite tight, there are a few things that I think may be the cause:

  • I was careless and haven't got perfect centre on one of the holes when drilling out all the components to 1/8".
  • I have cut the pivots too short and this is causing some kind of issue?
  • One other thing that has been bugging me is that when modelling the scales I did not include the slightly (0.06mm) thicker sections which surround the pivot holes on the inside of the factory Alox scales. I didn't think it was necessary but I am wondering if this is my problem? I could modify my mold tool to add these features in and mold some more scales if I need to.

I'm hoping someone on here with a bit of experience in Alox mods can help me?!

Cheers
J
« Last Edit: June 11, 2014, 08:56:48 AM by Jerm »


de Offline lowtech

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Re: First time Mod
Reply #1 on: June 11, 2014, 08:45:16 AM
First, let me welcome you to MTO.
This is an impressive first post.

I am sure one of the ALOX Guys will chime in shortly, but I can imagine teh following:
- the missing standoffs on the inside or the material itself cause too much friction on teh tools to let tehm cloxe properly, could maybe be solved by using thin washers at teh pivots
- the scales allow more flex tahn teh aluminium ones, thus letting teh knife warp when opening/closing tools.

Anyhow, I guess the issues can be solved and I think you might be able to get rid of one or another sets of those scales here...  ;)
Nice to have you here, let us know if you make progress.


fr Offline Michel M.

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Re: First time Mod
Reply #2 on: June 11, 2014, 08:49:02 AM
Great idea and work  :tu:

Welcome to MTO.
Michel


us Offline captain spaulding

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Re: First time Mod
Reply #3 on: June 11, 2014, 09:19:22 AM
Welcome to the forum. I love the scale design and as lowtech said this is a very impressive first post. I cannot help you with the modding, but their are a handful of people around here that will be able to give you the guidance/advice you need to perfect the fit and finish. If you start cranking out those scales in numbers I would love a pair. Again welcome aboard and I hope to see more of your modding in the future.  :tu:
I'm the milk man!


wales Offline hiraethus

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Re: First time Mod
Reply #4 on: June 11, 2014, 09:49:07 AM
Rather involved for a first mod, don't you think?  You could have picked something simple, like cutting the lanyard loop off.  You're making the rest of us look bad. ;)

I've found when drilling out the tools for larger pivots (I use 3mm on mine, not 1/8" because I make my own barrel pins) that you need a good finish inside the hole and that you have to remove the burrs from both ends of the hole.  If you don't, the tools tend to pick up on the pivots and don't move smoothly.  You also need to make sure that the pivots go into the scales for good support.

Instead of remaking the scales, you could try making your own washers from brass shim stock to space them out a bit.  Fiddly job.


au Offline PTRSAK

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Re: First time Mod
Reply #5 on: June 11, 2014, 10:29:26 AM
Outstanding work.
I believe your "snap" problems may be combination of things.

Yes those small raised pads are important, I made some scales from CF sheet and they needed a set of mylar washers to cut down the drag between the blades/tools and the scales.

The slightest change in the relationship between the three holes in the scales and/or the position of the holes in the tangs can make quite a large change to the snap. If using barrels, they really need to be supported in the scale and not just located by the screw.

The material itself may be less rigid than Aluminium and this could have effect by flexing or even just damping the snap so it sounds less.

Just a few ideas, but I'm no expert. What you have done here is WAY beyond anything I could ever come up with.
As others have said, I'm sure you could find a market here for sets of those scales.

And if you want another project...  do something similar on the 91mm platform and people will beat a path to your door.  Imagine a SwissChamp with scales like this.  :ahhh


wales Offline magentus

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Re: First time Mod
Reply #6 on: June 11, 2014, 11:01:46 AM
I'll just echo what others have said - WOW! beautiful work.
'Use the force Harry' - Gandalf


Offline Glofindel

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Re: First time Mod
Reply #7 on: June 11, 2014, 11:30:52 AM
Great job!! I am a fan of 84mm and new to mod squad too. To see others came something cool like this make me excited.

Sent from my HTC One X using Tapatalk



nz Offline Jerm

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Re: First time Mod
Reply #8 on: June 11, 2014, 12:07:16 PM
Haha thanks for the welcome guys.

Yep rigidity could be an issue but the scales seem to be sitting ok...

My scales only have about 0.5mm allowance for the pivots to extend into, and whether they're doing that is hard to tell. As I mentioned, I had trouble and am not sure that my pivot trimming process was accurate.

Unfortunately/fortunately I'm sure it's against company policy to profit from projects completed in their facilities, so I will NOT be selling them! Although I molded a whole bunch so may offload a few at some point, once I know that they work properly.

J


us Offline captain spaulding

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Re: First time Mod
Reply #9 on: June 11, 2014, 12:19:51 PM
Well if you just give me a pair that would be legit under company rules right?  :whistle:
I'm the milk man!


nz Offline Jerm

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Re: First time Mod
Reply #10 on: June 11, 2014, 12:28:46 PM
One more image for good measure..

Closeup of the mold and a freshly molded pair of scales.



wales Offline hiraethus

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Re: First time Mod
Reply #11 on: June 11, 2014, 12:44:35 PM
So many questions!  What's the tool life like - how many parts could you get out of it?  How accurate and stable is the finished part, and what are the mechanical properties?  Did you do the machining (CNC I assume) yourself?


cs Offline MWDP

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Re: First time Mod
Reply #12 on: June 11, 2014, 12:57:23 PM
Wow that is very good looking! Excellent work!
My custom SAK scale thread: http://bit.ly/1bBIzzD

Always on the lookout for smooth alox 84mm advertising Victorinox models - Bantam, Cadet, Cadet II, Voyageur! Message me if you have something


gb Offline daverobson

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Re: First time Mod
Reply #13 on: June 11, 2014, 01:04:39 PM

Unfortunately/fortunately I'm sure it's against company policy to profit from projects completed in their facilities, so I will NOT be selling them!
J

AAAAAHHHHH!  :ahhh :ahhh :ahhh :ahhh :ahhh :ahhh

I'll tell you what WOULD have been on my wants list, 91mm Black Nylon scales!  :tu:


ca Offline Chako

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Re: First time Mod
Reply #14 on: June 11, 2014, 01:23:27 PM
Hmmm...maybe your company might want to expand into the SAK mod market.  :think:
A little Leatherman information.

Leatherman series articles


us Offline MadPlumbarian

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Re: First time Mod
Reply #15 on: June 11, 2014, 01:42:19 PM
Wow, first welcome aboard, and second I must say that is a great design, love it! JR
"The-Mad-Plumbarian" The Punisher Of Pipes!!! JR
As I sit on my Crapper Throne in the Reading Room and explode on the Commode, thinking, how my flush beat John’s and Jerry’s pair? Jack’s had to run for the Water Closet yet ended up tripping on a Can bowing and hitting his Head on the Porcelain God! 🚽


hr Offline enki_ck

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Re: First time Mod
Reply #16 on: June 11, 2014, 01:42:56 PM
That's an excellent intro post and very impressive first mod. :hatsoff:

Welcome to the forum. :waving:


de Offline crackout

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Re: First time Mod
Reply #17 on: June 11, 2014, 01:48:19 PM
Wow, nice.

You should change the design however and use button head screws for the 84mm range (thus use almost no countersinking). The reason behind this (as already stated) is to allow the pivots to extend into the scales as much as possible. The holes in the scales define the position and correct alignment of the pivots/pins which directly affects the tension of the springs and thus the snap of the tools.

The tension between the scales is by far the hardest thing to get right. I even think it's easier to get the correct amount when peening instead of using threaded pivots with screws.
« Last Edit: June 11, 2014, 01:50:11 PM by crackout »
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dk Offline Freaver

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Re: First time Mod
Reply #18 on: June 11, 2014, 02:01:23 PM
Beautiful mod, although I would problably have gone for the second-last sketch instead, but that's just me. Nice pictures and walkthrough and nice result. I hope you get the last small parts figured out, so you'll truly be happy with your SAK. :D


ca Offline Syph007

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Re: First time Mod
Reply #19 on: June 11, 2014, 03:02:41 PM
How did I miss this so far? :D  Neat idea!  Someday I want to make skeletonized Ti scales as I think that would be a sweet look.

Thats an interesting factory defect, looks like the washer meant to sit with the blade, ended up on the wrong rivet.  I assume you used a washer with the blade though as that will be a problem if you didnt as the blade is thinner than the backspring.

Generally though it sounds like your issue is frame rigidity, and most of that is going to be reduced by how far the pivots extend into the scales.  For good rigidity  you need the pivots to go in about the whole thickness of standard cadet scales.  This is why countersinking them just doesn't really work on thin scales.  And its why I stopped working on that size of SAK. 

The pioneer thicker alox scales I work with, the pivots extend about 1.5mm into the scale and provides a nice rigid snap.

As others have mentioned if your material flexes that will be an issue too. 

To test my theory of the pivot in the scale distance issue, here is what I would do.  Rebuild the SAK with long rods instead of pivots as a temporary test.  If all the tools work great with rods right through the scales then that is your problem. 

 :salute:
PM me or email sakmodder [at] gmail . com if you are looking for custom SAK work.

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nl Offline Reinier

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Re: First time Mod
Reply #20 on: June 11, 2014, 03:30:31 PM
Wow that looks fantastic! I can't help you with your modding questions but I think you did an exellent job :tu:
Welcome to MTo! :tu:
You should seriously visit vicfan.com. All the hoopy froods are doing it.


us Offline chivaceae

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Re: First time Mod
Reply #21 on: June 11, 2014, 05:08:28 PM
Really nice scales and concept. Perhaps you could increase the rigidity of your CF scales adding thin metal liners (like brass, for color contrast) behind them. I believe than an additional benefit is that the cutout will stand out a lot more (sort of like a filigree design).
 :tu:   :gimme:


us Offline sawman

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Re: First time Mod
Reply #22 on: June 11, 2014, 05:09:31 PM
Holy smurf! that's some very impressive work  :ahhh
SAW


gb Offline Sparky415

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Re: First time Mod
Reply #23 on: June 11, 2014, 08:15:54 PM
That's an excellent intro post and very impressive first mod. :hatsoff:

Welcome to the forum. :waving:

+1  :tu:

 :cheers:
Everything’s adjustable


us Offline toolguy

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Re: First time Mod
Reply #24 on: June 11, 2014, 09:09:19 PM
Excellent work.

I personally don't like skeletonized scales as they present many problems but they do look cool.
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00 Offline kirk13

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Re: First time Mod
Reply #25 on: June 11, 2014, 09:10:50 PM
Holy smurf! that's some very impressive work  :ahhh

Damn straight!
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nz Offline Jerm

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Re: First time Mod
Reply #26 on: June 11, 2014, 10:12:29 PM
So many questions!  What's the tool life like - how many parts could you get out of it?  How accurate and stable is the finished part, and what are the mechanical properties?  Did you do the machining (CNC I assume) yourself?

This is quite a basic tool, so I would think I could get 100 shots out of it easily.

The finished part is VERY accurate, I did not in this case but you can take material shrinkage into account by altering the mold, the amount of shrinkage is dependant on the material being molded.

Yep, I did the CAD, CAM and CNC Machining myself. I am not a fitter and turner or dedicated machinist, I have a degree in Mechanical Engineering and work as a "Product Development Engineer" but luckily my employer trains and encourages us to do the practical work as well as design.

When bent by themselves, the scales do flex a bit more than the standard alox scales. The material itself is very stiff, the stiffest I have seen for a polymer/plastic. As an example, the Spru you can see in the last photo I posted (propping up the pair of scales) is un-breakable by hand.
« Last Edit: June 11, 2014, 10:50:10 PM by Jerm »


nz Offline Jerm

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Re: First time Mod
Reply #27 on: June 11, 2014, 10:22:07 PM
Wow, nice.

You should change the design however and use button head screws for the 84mm range (thus use almost no countersinking). The reason behind this (as already stated) is to allow the pivots to extend into the scales as much as possible. The holes in the scales define the position and correct alignment of the pivots/pins which directly affects the tension of the springs and thus the snap of the tools.

The tension between the scales is by far the hardest thing to get right. I even think it's easier to get the correct amount when peening instead of using threaded pivots with screws.

Yeah I'm thinking this is my main issue. I like the countersunk screw heads, the head is slightly larger than the the pivots so I could easily drill out the scales to allow the pivot to extend further into them, and I think there would still be enough contact with the head to hold it all together.

Current hole geometry.


I just need to figure out a clean and accurate method to cut the pivots down. Any suggestions?! The lathes we have are all too large, and the jaws will not grip such a small object. I may try and make a jig to clamp them in the manual mill.
« Last Edit: June 11, 2014, 10:23:50 PM by Jerm »


nz Offline Jerm

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Re: First time Mod
Reply #28 on: June 11, 2014, 10:53:31 PM
Excellent work.

I personally don't like skeletonized scales as they present many problems but they do look cool.

Thanks.

Problems due to stiffness? In their current state I'm not convinced that this is the issue in my case. Also, if I make these scales slightly thicker, they will be just as stiff as the standard Alox scales. That may be something I look into down the track!


wales Offline hiraethus

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Re: First time Mod
Reply #29 on: June 12, 2014, 12:33:29 PM
Thanks jerm.  Loving your work. :tu:

I just need to figure out a clean and accurate method to cut the pivots down. Any suggestions?! The lathes we have are all too large, and the jaws will not grip such a small object. I may try and make a jig to clamp them in the manual mill.

I use a collet chuck on the lathe we have here to hole the bar stock when making the pins - do you have one for any of your tools?  Other option would be to hold the pin in the jaws of a drill press or mill and bring it down onto a file to remove the end.


 

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