sawn off knives, methods?

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FNQ Simmo

Joined
May 26, 2026
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4
Hi guys,
I've got a couple of cheap knives I want to shorten the blade lengths of for legal and practical reasons.
I'm thinking of using a battery angle grinder with a cut off blade and using a garden hose as a cooling water stream ?-

ones a nothing Milwaukee work knife that I want to take 3/4 inch off and the other is a way too long chopper / bush knife. some may call it a machete but it's not ( because Australia )

Is there a better way to do this - as in keeping the blade cool? whats the standard practice on this?

cheers
 
FNQ Simmo said:
Hi guys,
I've got a couple of cheap knives I want to shorten the blade lengths of for legal and practical reasons.
I'm thinking of using a battery angle grinder with a cut off blade and using a garden hose as a cooling water stream ?-

ones a nothing Milwaukee work knife that I want to take 3/4 inch off and the other is a way too long chopper / bush knife. some may call it a machete but it's not ( because Australia )

Is there a better way to do this - as in keeping the blade cool? whats the standard practice on this?

cheers
Click to expand...
Sell the knives and buy knives in the size you want. Cutting the blade will damage the knife and would still leave you with an oversized handle.

N2s
 
not2sharp said:
Sell the knives and buy knives in the size you want. Cutting the blade will damage the knife and would still leave you with an oversized handle.

N2s
Click to expand...
A big handle and small blade works for me in the work knife, It's a $10 knife - but in all honesty it's almost the perfect knife for what I use it for and how I carry it. (work use)

Disposable box cutters are getting phased out (I won't miss them either) basically I want to turn the $10 milwaukee into a foldable box cutter - aka wharncliffe with a 1.5 inch blade, I need a full handle with a short blade that fits in a pocket.
 
I think most people just dunk in a bucket after each cut, so a continuous stream of water would work better. Assuming you can keep the water out of the grinder.
 
Water and electricity can be a thrilling & expensive combination.
If I were to attempt this I’d use a wet towel to cool the blade and have more control of the water.
The also makes heat sink paste (that I have no experience with).

Speaking for myself, I would not bother.
It’s akin to getting in and out of your car through the sunroof. Yes you can do it, but why?
Which leads me to……

This is bladeforums man!
BUY ANOTHER KNIFE!!!!

;) :D
 
I don’t suggest a hose and a handheld grinder.

I’ve done a lot of blade modifications over the years. You could use a vertical sander and a bucket of water. However, if you think “oo, that blade is getting hot,” it’s too far or close to too far.
 
I've cut knives off with a cutoff wheel before. I left 1/4" or so beyond what I wanted to keep and cleaned it up with a belt grinder. I would make a pass with the cutoff wheel then pour water on to cool it. You'll end up needing to sand or grind to thin the blade down where you cut it off as well.

It's a perfectly doable project, just make sure to keep it cool.
 
FNQ Simmo said:
Hi guys,
I've got a couple of cheap knives I want to shorten the blade lengths of for legal and practical reasons.
I'm thinking of using a battery angle grinder with a cut off blade and using a garden hose as a cooling water stream ?-

ones a nothing Milwaukee work knife that I want to take 3/4 inch off and the other is a way too long chopper / bush knife. some may call it a machete but it's not ( because Australia )

Is there a better way to do this - as in keeping the blade cool? whats the standard practice on this?

cheers
Click to expand...
Well I'll probably get in all kinds of trouble for this , from the mods here , but if you go to the Spyderco Forums and look up the thread called :

Obsession With M4 Blade Alloy And The Gayle Bradley & Tenacious

you will see some images of the tools I use and some suggestions about how to use them .
I cannot post an actual link to it . That would put in motion an air strike on me . . . on my couch . . . but maybe . . . just this once . . . they might be merciful and allow the above description .

PS : In my defence I posted over there that I would highly recommend that they coming over here to Blade Forums and read and watch Charlie Mike Videos on similar work . (Shaping brand new knives ) .
 
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dfarm said:
I've cut knives off with a cutoff wheel before. I left 1/4" or so beyond what I wanted to keep and cleaned it up with a belt grinder. I would make a pass with the cutoff wheel then pour water on to cool it. You'll end up needing to sand or grind to thin the blade down where you cut it off as well.

It's a perfectly doable project, just make sure to keep it cool.
Click to expand...
This. Draw your line, then cut back from it a little ways using light passes, never staying in one spot for long. This helps keep the blade relatively cool and the heat affected zone a good distance from where the new edge will be. Once cut, you can then grind back to the line.
 
After modding / shortening probably 30 knives with steel from Case basic SS and CV to 3V , SPY 27 , lots of 14C28N , a good bit of XHP , M4 and most recently Cruwear and I don't know what all else before that . . .
using the VERY THIN , < 1mm , Dremel cutoff wheels pictured in my "other post" . . . I find it is extremely easy to limit heat input into a knife blade . I make light passes , spending less time in the thin portion of the blade at or near the edge and much more time in the thick portion of the blade . With a few drops of water sitting on the blade from your last chill you can watch it and when the drop starts to shrink in diameter the blade is getting warm .

Chill the blade with the wet sock before the drops start to bubble / boil .
You are all good !
I have had a couple of early ones where the area at the edge , a millimeter or less in length turned brown . A palpable sign the heat treat is being changed .
Keep in mind some woodworking blade manufactures keep this golden / tan color on the blade as "proof" that the blade has been "properly" anealed .

BOTTOM LINE :
I have found that NONE of the blades have acted the least bit "soft" from the trauma they have been put through . . . these have been serious WORK KNIVES that I have put through their paces daily at work for months on end . Especially the Vosteed brand knives with the 14C28N and the knives with XHP . Just today I was using my very short SPY 27 and have been for months . Impressive stuff SPY 27.
and so
I feel my methods are sound .
No need to grind back from the cut zone . . . in fact this grinding back would introduce nearly identical heat input if not increased heat input .
Happy grinding !
 
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PS : I just went back to "the other post" to check my facts and found the best way to find it was to cut and paste the title along with Spyderco Forums into Google and not try to search using the forum search .
I often do that here on BladeForums to find something as well .
 
A light hand, wet cloth and patience with a thin Dremel cut off wheel has worked well for me in modding a number of knives.
You may need multiple wheels depending on the size of the blade.
 
Wowbagger said:
PS : I just went back to "the other post" to check my facts and found the best way to find it was to cut and paste the title along with Spyderco Forums into Google and not try to search using the forum search .
I often do that here on BladeForums to find something as well .
Click to expand...
thanks for that, my google skills didn't work with the normal search.
 
not2sharp said:
Sell the knives and buy knives in the size you want. Cutting the blade will damage the knife and would still leave you with an oversized handle.

N2s
Click to expand...
I actually found a knife that is kind of what I'm looking to turn the cheap Milwaukee into, it's a Taiwanese made Cold Steel 'mini tuff lite'
popped up on a you tube video review. I've got one on order.
 
I started off early on in my knife making with using PHB. These are Harder than most commercial knives. Cut better too, but they are "fun" to work with.

As others have said. Cutoff wheels work great.
Sometimes I've scored most of the way on both sides, then Broke the blade off. That is riskier. It might not follow the scored line, but it's faster.
 
Part of the reason for grinding a little way from the line is that your cut line WILL need additional dressing to finish it nicely, and you can more easily get a good, smooth shape from it by grinding. Grinding has no reason to generate more heat than a cutoff wheel. A cutoff wheel is basically just a thin grinding wheel, usually with some reinforcement to prevent breakage. They are both abrasives cutting the steel, and you should be similarly light on the grinder vs. the cutting wheel.
 
FNQ Simmo said:
I actually found a knife that is kind of what I'm looking to turn the cheap Milwaukee into, it's a Taiwanese made Cold Steel 'mini tuff lite'
popped up on a you tube video review. I've got one on order.
Click to expand...
hahaha
sorry for laughing . I am not laughing at you but at Cold Steel .
THAT IS A GREAT KNIFE !
DON'T GET ME WRONG .
I have a few and have given at least one away as a gift .

My point is , and that Mini Tuff Lite was my very first Cold Steel , that the lock release on most everything they make often requires taking the knife apart and relaxing the spring force and OFTEN touching a diamond file or grinder to the Triad lock latching parts so the effort required to release the lock is reasonable .

So . . . not avoiding the do it your self work in the shop . . . just going to take a different form .
YMMV
(I hope)
 
I’ve never had it modify or alter any Tri-ad lock. It will get smoother with use, but all of mine were fine out of the box.
 
SharpBits said:
I’ve never had it modify or alter any Tri-ad lock. It will get smoother with use, but all of mine were fine out of the box.
Click to expand...
Guess I'm just too picky and used to Axis locks .
ooooohhhhhh
wait .
that first one was before I ever had anything , other than a Buck 110 , to compare it to .
I would have to press down on the lock bar with both thumbs one on top of the other to get the lock bar BELOW the surface of the handle to get the lock to pivoted FAR ENOUGH so the hook on the lock bar would clear the blade notch .

Before modding it I finally had developed a "technique" where I pressed the lock bar in with the bony side of my index finger and could just get the lock to release .

Once I modded it I didn't have to FOCUS on unlocking the blade anymore I could just use the knife without thinking about it .

See the difference ?

I've bought probably a hundred Cold Steels over the last decade and a half and most of them have been this way .
Silly rabbits .
My favorite post that I can't help harping on is the : clamp the lock bar in over night and the Spring will get softer !
If that were true cars would get closer to the ground the longer they sat in the driveway .
 
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