What actually happens inside a 500g cake when it fires? Like how do they pack so many shots into that one box?

[Tina Chen]

#6129

I’ve been shooting 500g cakes for years and never really understood the internals. Like I know there are tubes and fuses in there but how do they get 25-30 shots to fire in sequence from one fuse? Is there like a fuse delay between each tube or something else going on? Always wondered about this.

And do different brands use different internal layouts? I’ve noticed some cakes have a faster pace than others even with the same shot count.

[Danny Roth]

#6131

Tina, the way most 500g cakes work internally is actually pretty clever but simple once you see it. They use a main fuse (usually visco or quickmatch) that runs through the cake and branches off to each individual tube with little delay elements between them. The delay is what spaces out the shots – some manufacturers use different delay compositions to control the tempo.

The actual tube layout inside varies a lot between brands. Some use a linear chain, others use a folded/zigzag pattern to fit more tubes in. That’s why you see different firing patterns even at the same shot count. Faster cakes usually mean shorter delay fuse sections between shots, or they’re using quickmatch throughout.

Honestly if you ever get a chance to cut open a spent cake, do it. It’s a good learning experience seeing how they’re built.

[Michael]

#6132

Good question Tina. Danny covered most of it already but I’ll add – the quality of the delay composition makes a huge difference in consistency. Cheaper cakes sometimes have uneven timing because the delay fuse isn’t manufactured precisely. You’ll notice one shot fires after 1 second and the next one takes 3 seconds, stuff like that.

We’ve got a couple videos over in the Fireworks Guide section that show the guts of different cake designs if you’re curious what they look like inside.

[Author]

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