Mortar Fusing

[whitefox77]

I've read several posts about people putting small wholes in the side of their mortar near the bottom for fuse. This seems a much easier way to fuse a mortar to me, yet every book or tutorial I read includes quick-match going up to the mouth of the mortar.

 

Personally I'm the type that tends to question the status quo. "Because it's always been done that way." is the worlds best reason not to do it that way.

 

So, what do you prefer/do and why?

 

Do you find that side fuse works better for some things, and QM from the mouth better for others?

[tentacles]

I prefer to dump lift in the tube and side fuse as it saves QM and fuse, plus I don't have to make lift cups (but you still can if you are clever).

[Mumbles]

From a reloading standpoint, lift cups and quickmatch make it easier. If you only have a few small shells or mines, fusing the side won't hurt at all. I wouldn't do it with anything larger than 2" though.

 

You have to think about the logistics a bit. Larger shell and mine mortars are usually burried to prevent damage from accidental flowerpot/explosion/etc. This makes side fusing near impossible as the fuse would be a a foot or more beneath sand/earth.

 

Obviously, the larger the shell, the larger the lift force. I would be worried about the hole serving as a a weak point in the bottom of the mortar, a very critical point in the mortar.

 

It seems that you make reasonably small shells and devices (3" or less), so the above concerns probably arn't as applicable. I will admit, side fusing makes timing cakes and such much easier.

[whitefox77]

I have a single 1 7/8 inch mortar. Just enough to learn with.

 

Wouldn't bottom fusing it also allow for the use of less lift, as you can make your comets/shells fit the mortar much tighter?

[TheSidewinder]

EDIT: Wow, there were NO responses when I started writing this, lol.

 

Each application has its uses.

 

Bottom-fusing and lighting from a hole in the side of the mortar removes the risk of having a top-fused shell's timefuse lighting successfully, but then failing to transfer fire to the lift charge through the quickmatch passfire.

 

A slightly modified method is used for almost all Class C shells. Bottom-fusing, but uses quick-burning visco down the mouth of the mortar very much like commercials shells that use quickmatch. The difference is that these bottom-fused shells have the visco go directly into the lift cup, igniting the lift and the timefuse at the same time. If one goes, the other almost certainly will. It works very well for small shells.

 

Commercial and most hobby shells have quickmatch to the timefuse on top of the shell, and another length of it going from the timefuse to the lift charge. If the timefuse lights, but the passfire fails to light the lift, you get a flowerpot when the timefuse lights the burst charge.

 

But bottom-fusing of shells above a certain size is said to be a problem. The timefuse or spolette can get blown UP into the shell by the higher lift pressures of larger shells, creating a flowerpot. Or so I've read. I believe it.

 

I have a little experience with both.

 

For my very first shells, I made a small 4-tube rack of 2" mortars (actual 2" ID too, not 1-7/8" ID), specifically sized to fit a Skylighter plastic can shell that was bottom-fused. Drilled visco-sized (slightly over) holes in the sides about 1/4 above the bottom plugs and treated the holes with waterglass. It made a very simple, but reliable combination. Hot glue your pre-punched timefuse in the hole in the cap of the can, cross-match with that paper "side-by-side" 2-strand firecracker fuse which has been seperated into 2 single strands, one in each hole of the timefuse, and prime both ends heavily. Pour loose stars and burst in shell, snap cap into place and seal with MEK. This fits so snugly in the mortar that you do NOT spike it at all. In my case, I used only a 1/2-teaspoon of 2Fg and it lifted just fine. The snug fit made all the difference. Anyway, pour in lift, drop shell in mortar (FUSE DOWN). Insert length of visco in the side-hole of the mortar, light and retire. Plain yet colorful. The only downside is that it is time-consuming to set up and fire more than a few shells. And you have to make DAMN sure there's no live sparks in the mortar when you reload. Remember you're pouring loose powder in there when you reload and that can cause a nasty burn if it ignites.

 

But, once I started making my own paper cans in 3" and 4" sizes, I switched to the top-fusing method with quickmatch passfire to the lift charge. For cross-matching I use genuine Thermalite (prepared carefully as in the tutorial I made) and top-fuse all of them. Wrap the main length of quickmatch and the passfire around the timefuse at the Thermalite crossmatch, wrap the Thermalite around the strands of bare match, and wrap it all up in the final paper covering putting the lift charge inside the folds at the bottom of the shell. I may jinx myself by saying so, but I'm batting 1000 on my lift and burst. It's the aesthetic results of the contents I have to work on.

 

Hope that helped you. As you can see, both types of fusing work but each has its pluses and minuses. My bottom-fused plastic cans were quick to make, but slow to fire if I had more than a few because of the side-fuse method with no lift cup. My top-fused shells take a long time to make, but can be fired a lot more quickly.

[Frozentech]

I've read several posts about people putting small wholes in the side of their mortar near the bottom for fuse.  This seems a much easier way to fuse a mortar to me, yet every book or tutorial I read includes quick-match going up to the mouth of the mortar.

 

Personally I'm the type that tends to question the status quo.  "Because it's always been done that way." is the worlds best reason not to do it that way.

 

So, what do you prefer/do and why?

 

Do you find that side fuse works better for some things, and QM from the mouth better for others?

Well, if you use pricey fiberglass or HDPE mortars, you won't be drilling holes in them. I do exclusively piped match top fusing.

 

Side-fused is generally for one-shot devices, and top fused for reloadables. It may also just be a factor of shell size too, I couldn't imagine a 4" mine or shell from a side fused tube for instance, but cake shot tubes are all side fused.

 

Also, if you make cylindrical shells with top mounted spolette, the piped match is an integral part of the function of the shell, for the passfire from spolette to lift charge.

 

I don't worry about conserving fuse, I usually make about 100 foot of black match and 10 yards or so of QM at a time. Some pyros make 3X that per session. I do add some visco 'chicken wick' to give enough time to back off for filming or viewing, but I have a good sized tote storage container of that.

 

"Fuse is no place to scrimp."

 

 

[edit] wow... three replies while I was writing this one LOL... Sidewinder, where could I see your thermalite tutorial ? Is this for homebrew Thermalite ala Dan Williams ?

[TheSidewinder]

Frozentech,

 

Well, I *was* going to say it was just a part of my 3" cannister shell tutorial I wrote, intending to post it here. But now I can't find it. I'm not sure I finished it, now that I think about it. Hrmm... Well, I can remember this part of it anyway.

 

No, the tutorial uses genuine Thermalite. When I said "prepared carefully" I meant as I write below. I managed to get my grubby paws on 4 full rolls (woohoo). So I'll have no need of cross-match for the next few dacedes. The Brazilian substitute might work, but you'd have to make sure the pyrogen on it is very well exposed. Some of the knockoffs I've seen have a full plastic coating on them, and I suspect they wouldn't work well, if at all.

 

 

 

Anyway, here's what I wrote.

 

It's been reported by some that real Thermalite can fail to take fire, although it passes fire like nobodys business On the face of it, that's true, although I suspect those folks didn't prep it the way I do. It has a single-layer plastic-strand outer wrapping on it, applied in a manner very much like visco is woven. And that will inhibit it from taking fire unless you use something with a long-duration heat, like a torch. I can see how it might not take fire very well from the short-duration heat of a quickmatch burn, or the burst charge (to ignite the next break in a multibreak).

 

My preparation of it is: first stripping off ALL, and I mean every speck, of that plastic outer wrap I mentioned above, being careful not to disturb any of the underlying wires. Fortunately, they wrap the wires in the opposite direction, so the plastic strips off fairly easily. Then I *carefully* remove two of the wires only. This exposes more of the pyrogen for ignition. When I insert in it the hole I've punched in the timefuse, I take care not to booger up the wires on the end going through the fuse. Once it's inserted, crimping the timefuse very lightly holds it in place just fine. When attaching the QM and passfire onto the timefuse, I form a loop of bare match strands for each one around the fuse and back into the respective sleeve. The main QM loop goes "under" the Thermalite crossmatch, the passfire QM loop goes "over" it. Then I gently wrap the Thermalite around each of them, one loop per side. Be careful not to crack the pyrogen off the Thermalite during this whole process, but once you've put your final wrapper on, it needs no more special care. And I suspect it's actually quite a bit stronger than conventional black match strands as cross-match. The wires I leave on there really seem to hold things tight and make sure the Thermalite takes fire.

 

I've done this since I started top-fusing and lucked out to score the real Thermalite very early in my habit . Fingers crossed (), but as I said I'm batting 1000 on lift and break!

 

Hope that helped. We got a little offtopic though, unless whitefox is interested in this, lol.

[Frozentech]

OK.. got it. I do the exact same thing with blackmatch. When I use the 1/4 timefuse, I crossmatch the outer end with 2 sticks of of BM into a slit, and use one long strand of BM in my quickmatch and passfire pipes, doubled back to give two strands all the way down the pipe and looped the same as yours. Similar with a spolette, except then I tie 2 or 3 sticks of good match across the exposed (roughed up a bit) powder at the top of the spolette with enough bent down and tied to loop the QM and passfire match around. Never had a failure with either method.

 

I sure do wish I had some thermolite though

[mormanman]

Sorry to bump this back up but I've never had success with side fusing. I know why it didn't work on my first cake but the second one is beyond me. They both just made loud noises that scared the shit out of me. It was awesome do hear but very disappointing. I would rather something go as planned and not just blow up and make boom. I think that with the side fusing you need some way of blocking the passfire from each mortar so it won't cause a pre-ignition of the other lifts.

Maybe doing some sort of indirect way like going around the mortar.

I'm planning on making a comet cake for new years since all my friends think my TT comets are like the coolest thing in the whole wide world (not including the .50 cal BMG vs. Propane tank )

[Bonny]

I think that with the side fusing you need some way of blocking the passfire from each mortar so it won't cause a pre-ignition of the other lifts.

Maybe doing some sort of indirect way like going around the mortar.

I'm planning on making a comet cake for new years since all my friends think my TT comets are like the coolest thing in the whole wide world (not including the .50 cal BMG vs. Propane tank )

 

I've never had that problem chain fusing cakes/repeating mines... You can drill the fuse holes about 90 degrees apart. Then the fuse holes are not in a straight line and shouldn't pre-ignite the other lifts. If the delay is too long use faster fuse.

[Richtee]

I think that with the side fusing you need some way of blocking the passfire from each mortar so it won't cause a pre-ignition of the other lifts.

 

If you use fast visco, this would not be a problem... or any coated fuse would help.

[mormanman]

Bonny, thats what I was thinking of but was unsure of how to say it.

Richtee, Not sure of what your talking about.

[TheSidewinder]

WHITEFOX77 - If you read this:

 

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[Mumbles]

What Richtee is saying is to not use blackmatch. I speak from experience when saying this is a bad way to fuse things. Fast visco is a fast burning visco fuse, about 3 or 4 seconds a foot. It's the fuse on all consumer reloadable aerial shells, and in all the cakes and stuff.

[Richtee]

Hey Morm..here's the stuff ya want:

http://www.cannonfuse.com/store/pc/viewPrd...p;idproduct=287

 

Or better quality:

http://www.cannonfuse.com/store/pc/viewPrd...mp;idproduct=81