time fuse

[MadMat]

I tried something in a pinch that isn't supposed to work well, but it worked fine (for that time). I rolled regular visco with paper to make a time fuse. The paper was firmly rolled and I didn't have any problem with blow-by and pre-ignition. So... what is supposed to be the problem with doing this? I made a "quicky" 2" can shell and it worked just fine.

[lloyd]

The problems are at least three-fold.

 

First, unless the paper wrapping seals perfectly to the entire surface of the visco (which means it must be paste-wetted paper to do so), the likelihood is that the assembly will "quickmatch"... throw fire forward down the paper tube, and drastically shorten the intended burn time.

 

Second, visco is not terribly reliable as to timing. It's good enough to use as 'wick' for lighting Class-C effects, but is not reliable enough foot-to-foot (or even inch-to-inch) to be able to accurately predict how long it will burn per inch.

 

Third, visco presents a VERY small burn geometry. It has a tiny core, and a very minor amount of powder in it... so the amount of fire it can throw is small. This can jeopardize the ignition of shells.

 

I wouldn't use this for regular work, but "In a pinch" is OK. I've done it exactly like you, with the possible exception that I used pasted paper to roll up the visco so that it would seal to the surface well.

 

Hey... you "run what you brung"!

 

Lloyd

[Mumbles]

There are some articles on doing this if you look around. There's one in one of the Best of AFN editions. They used a few turns of Aluminum foil between the fuse and the paper. It really conforms to the shape of the fuse. I've used this with success before. As Lloyd mentioned, the fatter the core the better.

 

This is fine for a one off, but I still think it'd be easier to just make a spolette if you don't have access to real time fuse.

[MadMat]

I didn't plan on doing this again, I was just wondering what the problems were as it worked just fine. I figured the small core would be a problem, so I wetted the ends with nc lacquer and dipped it in mill dust. I got a decent sized ball of bp on the ends this way. I would be willing to bet if I did it, say a half dozen times, I would run into problems.

Edited December 16, 2015 by MadMat

[Ubehage]

I have also done this, although not with Visco - I used Flying Fish Silver, because it was the thinnest I could get.

For small 1"-shells and the likes, I have had no problems. Timing and ignition worked perfectly each time (each time the fuse was lit )

 

But - I always keep in mind that the fuse is homemade, and therefor I do not trust them 100%.

[Stef727]

I used visco rolled in paper with glue for pretty much every shell until now, no flowerpots all good.

 

The only reason I now use real time fuse it's because it's easy to glue it to the shell and also easy to prime.

[schroedinger]

If you use visco for timing Al-tape is the best you can use, since it really easy accomodates to the shape of the visco and fine to use. The chinese do these on small shells too. Only thing to worry about is outside of the fuse not igniting, on the inside you can just leave the fuse extending for 2", that will ignite every bp.

 

But visco isn't as consistent burning as time fuse and doesn't likes to be bend at all.

 

Also there is an alternativ to using visco, wanno does produce 3 and 4.7 mm timefuse. These are thinner then a visco rolled up in tape, better to work with, can be crossmatched and are made from high quality powder witch gives a good spray of sparks. Just tie it into a bucket with some black match and there you go.

[MadMat]

I mainly make spolettes for my shells. This time I had an old friend visit that I hadn't seen in a long time. He was very interested in seeing what my shells looked like so I "whipped" one up and used visco wrapped in paper (it was pasted by the way). To speed things up, I used hot glue and pregummed tape. The shell worked without a hitch (am I that good or did I just get lucky? )

[Peret]

For at least a year after I started making shells, I fused them with visco rolled in masking tape. I didn't move up to time fuse until I bought some hemis that were punched for 1/4 inch. I actually still have a roll of thin visco in the magazine that I timed (3 sec/inch) and marked not to be used for anything else...

 

I had a couple of passfire failures, maybe 1%, but I don't know if they were caused by the visco not lighting, or not having enough spit to fire the break. The former, I suspect. I had more trouble with 1/4 inch time fuse when I bought a roll of cheap chinese white. I recovered a couple of shells where the fuse had burned through and not fired the break. I was able to push visco right through the burned out time fuse core and launch them again

[MadMat]

That's funny cause I got 3 sec/ inch as well with the visco I used for that shell. For my 2" shell 3 seconds is what I wanted for a delay, so it worked out. I used regular printer paper to wrap it with hot glue to paste it. I wrapped it to a dia of 1/4" LOL wasn't going to take any chances of a burn through.

Edited December 21, 2015 by MadMat

[Fulmen]

unless the paper wrapping seals perfectly to the entire surface of the visco..., the likelihood is that the assembly will "quickmatch".

Back in the days I got encouraging results with my homemade visco by wrapping black match in PFTE tape (plumber's tape). I never did anything with it as I got my hands on the real thing, but it is something to explore.

[lloyd]

Fulmen,

Have you tried gluing anything to PTFE? <G>

 

Lloyd

[Fulmen]

Point well taken, but it did do wonders on the black match. I can't remember what I used on top of the teflon, perhaps heat shrink? Nevertheless, I managed to get black match to burn quite consistently this way. PFTE tape is extremely flexible and quite heat resistant, allowing it to coat the fuse and seal against flash-overs.

[lloyd]

"Flooded" or "meltable core" heat shrink will do it, too!

 

Lloyd

[jrin0630]

I've been using visco exclusively for time fuse for a few years now and have never had an issue. The one or two times I tried

regular time fuse I must have screwed up the cross match or something because both were duds. I use the American 3/32 green

visco that burns at about 21sec/ft. I cut it to length (2" for a 3" shell)and wrap it in 4-5 turns of masking tape. I leave a little less than 1/8" exposed on the side that goes in the shell and about 1/4" exposed on the lift side. When I mount the fuse, I put liberal amounts of hot glue on both ends inside and outside the hemi. For the lift end of the fuse, I make sure to put enough hot glue to go past the tape on to the fuse so it creates a solid seal.

After the shell is pasted, I apply a liberal amount of BP slurry to the end of the exposed fuse. I make sure the slurry has sharp edges which aids in ignition. With this method I have never had an issue.

[lloyd]

You will have issues. Please take the time to learn how to use time fuse.

 

One sure way to cross-match 1/4" fuse is to slit the ends, drop cross-match in the slot, and tie it shut again.

 

This tuto shows how (among other things): http://www.pyrobin.com/files/shell%20class%20handout.pdf

 

Lloyd

[pyroman2498]

Lloyd, I found that putting a slit into the timefuse to be a pain. I prefer a sharp time fuse punch for crossmatching. Much easier for my unsteady hands.

 

Stay safe and stay green

 

~Steven

[OldMarine]

I think I'm going to try spollettes before even messing with time fuse. From what I've read they're more consistent for timing and are pretty easy to manufacture. I've got rolling the tubes pretty well down. I'll make me a pound or so of powder just for them so I'll have consistent timing (I hope)

[lloyd]

Steven,

I've done both for five decades. Depending upon the fuse, punching can smear tar across the punching hole, resulting in a dud.

 

Slitting never can cause that. I will admit it takes 30 seconds longer to slit and tie than it does to punch. But I've found it 100% reliable. Not one has ever failed, either for me or my beginner students in the shell class. And I can truly say that I've had at least one PGI Grand Master switch to that method after I demonstrated it to him.

 

Let's face it: Spending an extra minute on a shell that's taken you hours to build isn't much of an investment to guarantee it ignites without fail.

 

Lloyd

[Nessalco]

I've moved to slitting time fuse recently, and like it very much. I have two different punches, and both require setup and cleaning. Any time I have a razor knife I can slit time fuse, even on the field.

 

I cut the fuse much less than you show, Lloyd, maybe 3/8" total. I cut from the end using a razor knife with a fresh blade, and find it very easy to cut the fuse accurately without disturbing the core. I use cotton crochet thread to bind the fuse closed.

 

Works like a charm.

 

Kevin

[lloyd]

Kevin,

 

Yeah, I also cut it less than I showed for that "never seen inside a shell before" class! That loooong cut was to give them the chance that if they screwed it up at the start, they could correct their cut and still keep good core at the base of the slit.

 

LLoyd

[pyroman2498]

My problem isnt time it takes , my problem is I can't keep the razor going straight down. And I never end up with a nice core intact.

[lloyd]

How do you slice it? I do not recommend trying to lay the fuse flat and cutting lengthwise, but rather plunging the blade into the end and working it down as you adjust it's position to keep it dead-center.

 

Lloyd

[schroedinger]

Pyroman do you use a fresh blade and what knife? I had the same problem when starting with slitting. The blade walked anywhere it wanted. Sometimes ig worked, sometimes it even left the fuse to early. For those i used razorblades. First two or three cuts where troublesome, but most ti es ok. After that the fail rate increased drastic, due to the fact that the knife got dull. A razorblade just isn't made for such an abuse. Well i comp, tly switched to punching untill i laid my punch somewhere (ok right in front of me and it was gone) and thought well then just cut it. Couldn't find a razorblade but still had a new utility knife (trapeziode blade) on hand. Worked like a charm. These knives give a lot of controll, cut good if new (if it doesn't cut tf anymore use it for for everythjng else) and the thicker blade is sturdy enough. You can make at least 50 cuts with one side before feeling any difference (longest time i ever got before i abused the tf knive for something else).

[pyroman2498]

as i only build at my club , i dont have any pictures of me cutting the time fuse but everyone else seems to make it look easy, maybe its due to my tremors or something.When i go back and build in the spring i will bring some new blades with me and give it another shot...

 

Stay Safe and Stay Green

 

~Steven