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Hot knives?


Original Post
David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 122

I've always just cut cordage and burned the ends, but this tends to cause the sheath to separate from the core at the ends which isn't ideal. I did a lot of this for hanging some training gear recently and was annoyed with the process, so I thought of getting a cheap hot knife, i.e. one of these. Has anyone had experience with these? Do they work well for getting clean cuts at rope/cord ends?

Kyle Ruda · · Unknown Hometown · Joined Dec 2016 · Points: 20

Those are nice, I used one for wood engraving but wouldn’t recommend it unless you are just using it for cutting rope as there will be left over residue on the metal point. What I do when I cut cord or rope is heat up the outer sheath enough so when hot you can cover the exposed inner core with the molten outer sheath. It ends up covering up the exposed core and in turn have no more problem of it separating down the road. How this helps!

aikibujin · · Castle Rock, CO · Joined Oct 2014 · Points: 294

I use a really cheap knife over the open flame of my Jetboil until it turns red, and cut whatever cord/rope I need to cut. I then melt the sheath with the knife to create a bit of a taper. This basically ruins the knife, so I just have one knife dedicated to this purpose.

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,535
aikibujin wrote:

I use a really cheap knife over the open flame of my Jetboil until it turns red, and cut whatever cord/rope I need to cut. I then melt the sheath with the knife to create a bit of a taper. This basically ruins the knife, so I just have one knife dedicated to this purpose.

This is what I did for years as well and what I'd recommend. 

Nick · · Unknown Hometown · Joined Jan 2016 · Points: 0

cheap box cutter from dollar store and torch/stove

simplyput . · · Unknown Hometown · Joined Nov 2013 · Points: 60

Wrapping the area in tape before cutting with a sharp knife allows you to melt a very clean, flat surface.

mpech · · Unknown Hometown · Joined Sep 2013 · Points: 2

you can heat up a box cutter, as other people have mentioned. 

you can also use an open flame to melt the ends, if you use the right technique-- the key is to melt in a way that melts the sheath and core together. 

that guy named seb · · Britland · Joined Oct 2015 · Points: 205

Go for a bladless heat knife a actual cutting edge is the last thing you want if you are cutting up rope. 

Brad Johnson · · Charlotte, NC · Joined Jul 2017 · Points: 0

I've always just used a butter knife and heat it until red hot.  Slices right through no problems.  I have one butter knife dedicated to this. 

Brocky · · Unknown Hometown · Joined Jun 2016 · Points: 0

This works very good, you could probably find a used one pretty cheap
David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 122

Using a dull hot thing to cut makes sense to me, as it guarantees that the ends melt. I think I'll try the butter knife over the stove idea, since I already have that.

Brad Johnson · · Charlotte, NC · Joined Jul 2017 · Points: 0
David Kerkeslager wrote:

Using a dull hot thing to cut makes sense to me, as it guarantees that the ends melt. I think I'll try the butter knife over the stove idea, since I already have that.

Speaking from experience, the only advice I would give is to make sure to only hold the handle.  One time I put my index finger over top the blade as I pushed down, yeah never made that mistake again. 

David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 122
Brad Johnson wrote:

Speaking from experience, the only advice I would give is to make sure to only hold the handle.  One time I put my index finger over top the blade as I pushed down, yeah never made that mistake again. 

Yeah, I'm gonna use gloves. I've gained enough familiarity with how well metal conducts heat for one lifetime. :)

EDIT: Story time: I took a chemistry class in college, and as part of a lab we had to heat a solution of ethanol which is flammable. To do this safely we heated ceramic cubes over a Bunsen burner with tongs, then dropped the hot cubes into the solution until we got the proper temperature to kick off the reaction. This allowed us to keep a gap of a few feet between the flammable solution and the open flame. I'd held things briefly over the Bunsen burner before so I thought nothing of it, and the lab TA didn't tell us to put on gloves. But it turns out if you hold tongs over an open flame for an extended period of time, the metal conducts the heat from the hot parts of the tongs to the cold parts of the tongs. This happens surprisingly fast.

I don't remember what the lesson of the reaction was, but heat conductivity is a chemistry thing I guess, so I suppose I did learn some chemistry.

Marc801 C · · Sandy, Utah · Joined Feb 2014 · Points: 65
that guy named seb wrote:

Go for a bladless heat knife a actual cutting edge is the last thing you want if you are cutting up rope. 

Huh?

aikibujin · · Castle Rock, CO · Joined Oct 2014 · Points: 294
that guy named seb wrote:

Go for a bladless heat knife a actual cutting edge is the last thing you want if you are cutting up rope. 

You're totally right. A lightsaber is the perfect weapon for this.

simplyput . · · Unknown Hometown · Joined Nov 2013 · Points: 60
Marc801 C wrote:

Huh?

Exactly.

Alan Emery · · Lebanon, NH · Joined Aug 2011 · Points: 251
Tradiban · · Unknown Hometown · Joined Apr 2004 · Points: 11,365

Just cut with a scissors and melt the ends with a regular lighter, while the ends are molten take your fingers and pinch the tubing together while pulling your fingers off the end of the webbing. 

You still have to do this with a hot knife for a proper finish.

Marc801 C · · Sandy, Utah · Joined Feb 2014 · Points: 65
Tradiban wrote:

Just cut with a scissors and melt the ends with a regular lighter, while the ends are molten take your fingers and pinch the tubing together while pulling your fingers off the end of the webbing. 

You still have to do this with a hot knife for a proper finish.

He's asking about cordage, not webbing.

OP: Pretty much any of the suggestions here will work - pick the one you like.

Alan Emery · · Lebanon, NH · Joined Aug 2011 · Points: 251

When choosing, may I suggest you choose a method you can use when climbing where there is no electricity or heavy bulky camp gear.   You will be able to fix your rope with just a sharp knife, your climbing tape and a small torch, all something one could easily carry with them. Keep it simple.  These three peices can be used for many reasons, not just fixing a damaged rope.

kck · · Unknown Hometown · Joined Jul 2015 · Points: 85
simplyput . wrote:

Wrapping the area in tape before cutting with a sharp knife allows you to melt a very clean, flat surface.

This. A friend told me about it and I was skeptical, but it really works. Wrap the cutting area with climbing tape - 2 to 3 wraps. Cut, Then take a lighter and light the end. The tape acts as fuel and the flames keeps going and melts the sheath and core together. When satisfied, blow out the flame and unwrap whatever remaining tape is left. I have done this twice and the end has held up better than the factory finish.

Guideline #1: Don't be a jerk.

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