Quadrant inserts

[schroedinger]

About these i could only find two videos about these getting used in a shell, but not one picture or tutorial how they are constructed.

Does someone has hint on these with picture?

Edited October 29, 2014 by schroedinger

[dagabu]

Passfire did a write up on the quad pump I think.

[Mumbles]

There is a brief description in Hardt, as well as an image that helps to tell the tale. They can be used in 2 different ways.

 

Basically either way4 pumped comets are assembled into a pattern which resembles a circle with a square hole in the center. You can place these on top of a solid comet, add a burst charge to the center, and roll them up with an end disk and paper to essentially form a crossette. This is one way to guarantee they burst into 4 equal segments.

 

There is also a way to make these into inserts. I'm sure you've seen the 2 examples on youtube. Most examples I've seen utilize 2 "layers" of these, so 8 total quadrants. You then roll them up in a few layers of paper to form a casing, add a burst charge, and fuse them.

[schroedinger]

Ok, i think i understand now now they work. Not to much work but much more then a normwl crossette. Basically it's the same construction like TR demonstates for crossete headers in his crossete rocket movie

 

 

Still interesting for making big crossetes without speciall tooling.

[Mumbles]

I've always wanted a set of quad pump tooling. Unfortunately it's trading large specialty crossette tooling for another set of large specialty tooling. In some ways crossette tooling may be easier to make-shift.

[schroedinger]

Can understand that. About the quad pump wolther offered, was it just a gang pump, or did they have a speciall shape?

[Mumbles]

He offered a tool to make both single quadrants and 4 at a time. They do have a special shape. It's probably easiest if you just looked at the image in Hardt. If you don't have it, just imagine the below image with cuts between the corners of the square and the outside of the circle.

 

http://www.mathisfunforum.com/showimage.php?pid=250460&filename=Bourne88.gif&preview=true

 

By the way, there is a much better description of this here: http://newsgroups.derkeiler.com/Archive/Rec/rec.pyrotechnics/2006-12/msg00243.html

[schroedinger]

Well thats easy to understand thank you. Now i will just need to get the right pump for those.

[Mumbles]

Let us know if you figure out an easy way to make it. Wolter told me he stopped making them since they involve a fair amount of mill work for a low demand item. I have a few ideas, but I don't know if they'd actuallywork.

[dagabu]

The biggest problem with the cavity is that if made in one piece, they have to be broach cut, Rich (if my mind remembers correctly) made the cavity from four pieces of aluminum. Perhaps it was only two, I cant find the picture anymore. A molded pump might be easier to make, fiber filled epoxy might do the trick.

[ddewees]

TR's "chicklet" pumps are made from two pieces. You can't even tell when holding it though.

[schroedinger]

Well i was more thinking about making a pump for single parts of the star and pump 4 times. Schould be possible since i now got acces to a cnc mill, but see maybe there is an easy way if i can find some right sized metal profile.

[dagabu]

How about a crossette style pump with the cruciform going all the way to the walls? Depending on the webbing angle and thickness, a single press could make four segments at a time and five or six segments could be used to make a tight fitting circle of them.

[MrB]

Quite a huge crossette type pump, but yeah. But would it really need 5-6 elements for a unit? I'm guessing the wall thickness between the segments is the reason, and it cant be to thin or it would lose it's shape over time, from the pressings?

How about making a "crossette type" but with only 2 (3?) segments being pumped each time, for perfect fitting quadrants? 2 makes more sense for quadrants, since you'd make 4, 8 12, and the intermediates, while 3 makes a couple to many all the way up to 12.

 

Actually... 4, 5 or 6 it doesn't really matter , now does it? The effect is the same, as long as it gives a consistent result it should be fine.

 

But when you say crossette type... Those pumps work since they don't need to have a divider all the way to the bottom.For this to work you'd need to make a pump that makes the "star" to long, and then have a reliable way to cut of the excess down to where the segments actually start. Not impossible by any means. but making a (what, 3-6"? ) pump that you can reliably cut at a given height with a single stroke without disturbing the comp... You need something pretty large to do the cutting with, and it cant flex to much, or it will catch on the cruciform bits n' pieces.

I want one, so if you can figure out how to do it reliably, i'm all for it.

B!

[dagabu]

Quite a huge crossette type pump, but yeah. But would it really need 5-6 elements for a unit? I'm guessing the wall thickness between the segments is the reason, and it cant be to thin or it would lose it's shape over time, from the pressings?

How about making a "crossette type" but with only 2 (3?) segments being pumped each time, for perfect fitting quadrants? 2 makes more sense for quadrants, since you'd make 4, 8 12, and the intermediates, while 3 makes a couple to many all the way up to 12.

 

Actually... 4, 5 or 6 it doesn't really matter , now does it? The effect is the same, as long as it gives a consistent result it should be fine.

 

But when you say crossette type... Those pumps work since they don't need to have a divider all the way to the bottom.For this to work you'd need to make a pump that makes the "star" to long, and then have a reliable way to cut of the excess down to where the segments actually start. Not impossible by any means. but making a (what, 3-6"? ) pump that you can reliably cut at a given height with a single stroke without disturbing the comp... You need something pretty large to do the cutting with, and it cant flex to much, or it will catch on the cruciform bits n' pieces.

I want one, so if you can figure out how to do it reliably, i'm all for it.

B!

 

Lots of stuff there to chew on there B. Ill start with the 4 segments from the pump to 5 or 6 used in a shell round:

 

The outer ring made by a cruciform pump with walls (webbing) thick enough to resist bending under load will not have enough segments to complete a tight fitting circle. If 5 segments are used, a complete and tight fitting circle can be made with the segments.

 

On to the length of the star:

 

As with all crossettes pumped with Wolter tooling, the pump is loaded and compressed, the star is ejected to the 'trim' line and then trimmed with a knife. The star is then ejected the rest of the way out. I honestly have nothing nice to say about Wolter pumps when it comes to the trim line, the rammer has to be turned inline to the slot in the pump and breaks the crossette at the cruciform causing lots of damage to the finished crossestte and has to be presses a second time to re-bond the comp. That all said, its a matter of trimming the star off at the trim line and ejecting the finished segments.

 

And finally, the size:

 

Crossette pumps can be made any size, the tooling is only limited by the materials and end mill bits. It would be easier to plan and make a 3" segmented pump than a 0.75" one by far. It would take longer as there is a lot of material to remove but would be much more forgiving.

[MrB]

The outer ring made by a cruciform pump with walls (webbing) thick enough to resist bending under load will not have enough segments to complete a tight fitting circle. If 5 segments are used, a complete and tight fitting circle can be made with the segments.

But does the wall really have to have thickness to them? I mean, they need some, of course, but, shouldn't the bending be resisted by the simple fact that there will be the same load exerted on both sides of the wall? That is, in a perfect wall, where there is exactly identical amounts of composition on both sides, it shouldn't need to be more then a hair's thickness. Were never getting to that point, but how thin could one actually get away with?

 

 

As with all crossettes pumped with Wolter tooling, the pump is loaded and compressed, the star is ejected to the 'trim' line and then trimmed with a knife. The star is then ejected the rest of the way out. I honestly have nothing nice to say about Wolter pumps when it comes to the trim line, the rammer has to be turned inline to the slot in the pump and breaks the crossette at the cruciform causing lots of damage to the finished crossestte and has to be presses a second time to re-bond the comp. That all said, its a matter of trimming the star off at the trim line and ejecting the finished segments.

I'm more thinking about the fact that what ever your using to trim with, it's going to 'dip in to' a 3" cavity, and need to climb back out when it hits the cruciform shaped bits, or simply get stuck on them, a lot to do with the angle it hits an edge with. It's pretty easy to just say "trim it" but the tools used for trimming tend to have a little flex in them, seeing as they tend to be thin metal things from a painters supply, used for applying stuff to walls. What i'm getting at, you might need to look at a tool for doing the cutting as well. And with the size of these, a ejection-sleeve and spacer that lets you do both the trimming, and removing of the unit.

 

 

 

Crossette pumps can be made any size, the tooling is only limited by the materials and end mill bits. It would be easier to plan and make a 3" segmented pump than a 0.75" one by far. It would take longer as there is a lot of material to remove but would be much more forgiving.

This sort of effects doesn't really come in to it's own until it's a significant size anyway, making 1" quad pumps, at least to me, seems silly.

 

Anyway, you make it, and i'll sit here and moan about the price of it, and the price of shipping.

B!

[dagabu]

But does the wall really have to have thickness to them? I mean, they need some, of course, but, shouldn't the bending be resisted by the simple fact that there will be the same load exerted on both sides of the wall? That is, in a perfect wall, where there is exactly identical amounts of composition on both sides, it shouldn't need to be more then a hair's thickness. Were never getting to that point, but how thin could one actually get away with?

 

Sadly, yes. The wall has to be much more robust then you would think. Because we are using a powdered comp, there is no way to keep the pressure the same all around the circumference without pressing it down to a comet first, then the load would be on the end and fold them like paper. Could we do this? Sure, it's no harder than the dozen cruciform pumps I have made already, just a smaller end mill and some match to determine the plunge cuts. I have a collet type index for my lathe that I could use to index the four quadrants rather easily.

 

 

I'm more thinking about the fact that what ever your using to trim with, it's going to 'dip in to' a 3" cavity, and need to climb back out when it hits the cruciform shaped bits, or simply get stuck on them, a lot to do with the angle it hits an edge with. It's pretty easy to just say "trim it" but the tools used for trimming tend to have a little flex in them, seeing as they tend to be thin metal things from a painters supply, used for applying stuff to walls. What i'm getting at, you might need to look at a tool for doing the cutting as well. And with the size of these, a ejection-sleeve and spacer that lets you do both the trimming, and removing of the unit.

 

Naw, I'm thinking that the knife dipping thing isnt' really a problem, I have three or four rigid blades capable of a non-dipping trim in my garage alone. A good stiff and flat edge kitchen knife will not flex across 3" either. A stiff putty knife has less than 0.0001 deflection when laid nearly flat across a 3" EMT pipe end. Thin wall mudding knives are designed to deflect to feather the compound so that is not surprising.

 

Yes, trimming ring and ejection sleeve would be necessary just as you say.

 

 

This sort of effects doesn't really come in to it's own until it's a significant size anyway, making 1" quad pumps, at least to me, seems silly.

 

Anyway, you make it, and i'll sit here and moan about the price of it, and the price of shipping.

 

$300.00 US or more plus the shipping, it would be quite the expense for sure!

 

B!

[Mumbles]

Just so everyone is on the same page, I make a couple quick figures. The form would be held together with bolts or screws. This is basically what the figure in Hardt shows and is basically what Wolter used to make. His quad pump would make 4 inserts at once. It's the same basic idea only the mold was 3 pieces instead of 2. The center had 4 trapezoids machined into it, and the two outer pieces each had a semi-circle. Maybe it was the otherway around, but same basic idea. Then the rammer was basically just 4 individual ones secured into a plate.

 

http://amateurpyro.com/Mumbles/Components.jpg

I've always envisioned the tool to be something a little different, mostly because I don't have the expertise, skills, or tools to work with most metals and actually make them as above. My ideas are mostly based on wood and workable plastics.

 

The "standard" tooling would emulate what is above. The curved plate could be made from some plastic, probably HDPE or Acetal or something. You could make the groove with a router and suitable bit or by drilling down on the edge with an appropriately sized drill bit. I'd be worried that the flex of the plastic or any sway from a drill bit would not leave a clean groove. I'd imagine you could secure the plastic to a piece of scrap board and drill out the 1/4 of a circle needed, or even bore a hole through a solid piece of plastic and slice off the two useable ends with a bandsaw. The trapezoid end could again be made with a router (if the correct bit was available), or by forming a square groove and utilizing two right angle pieces of plastic to make the appropriate edges.

 

For the rammer, I'd probably just sacrifice a full round bar of the material. An "X" could be cut, and 3 of the 4 pieces would be cut off. The flat could be made by similarly cutting the slice vertically, and then ultimately slicing it all off. This would leave (ideally) a correct shaped rammer, which could be mounted to something for convenience. If you had the means, you could put flat edges on the 3 sacraficed quarter circle pieces. With plastic, clamps may be best to reinforce and hold together the mold, or just use metal backing to sandwich and reinforce with traditional screws.

 

 

 

My other idea is similar to what you guys were coming up with. Instead of having the fins on the plunger, I was imagining sort of a modified star plate with 4 openings in it. Basically a stout comet pump with an X of metal fins inside. I figured around 1/16" thick or so would be fine. The center could be an insert that is inserted over the metal fins, and essentially holds them roughly in place while also forming the cavity. This could be done equally well with a square or round piece of stock.

 

http://www.amateurpyro.com/Mumbles/quadpumpround.jpg

 

For the purpose of making the plunger, I feel a round central cavity would be easiest though. A lathe would still be needed to bore the hole, but the cavities for the fins could be cut with a saw. One caveat to this method is that you have to account for the thickness of the fins. So for a 1.75" insert, the whole thing may need to be made in a 1.875" or 2" form. The pieces may not form a perfectly round insert, but assuming the fins are thin relative to the diameter it'll be close enough. Something like this might even be able to be done by modifying existing comet pumps as an advantage.

 

Like Dave pointed out, there is little need to make tiny versions of this. Making perfect 4 segment crossettes is basically the only small diameter use for these things. Small crossette tooling is already cheap, and would be incredibly laborious. They're basically made in common comet and insert diameters to make life easier. 1.75" would be as small as I'd go. And to be honest, I probably wouldn't go larger than 2.5". A few sets of these would make all the pseudo-crossettes and inserts you want.

 

These are basically the ideas I've been playing around with.

[schroedinger]

Wait is it really neccessary to pump the comet?

Just thought why not just use a star frame, press the whole patty quite god, and then just take a normal cookie cutters which can be gotten in the right form (or just use two round ones and cut the x after).

 

After cutting just let the star dry on the table without moving, just remove every material that is going to be recycled.

 

This way tooling would cost about 2 $ and it would be available in many different ammounts of quadrants (e.g. ikea sells nice apple cutters). I will test that.

Edited November 5, 2014 by schroedinger

[MrB]

http://www.amateurpyro.com/Mumbles/quadpumpround.jpg

 

I think the insides should be flat. I'm just thinking here, but wouldn't the inner edges be likely to shatter and detract from the clean break if they are shaped like that?

B!

[Mumbles]

 

I think the insides should be flat. I'm just thinking here, but wouldn't the inner edges be likely to shatter and detract from the clean break if they are shaped like that?

B!

 

Only one way to find out.

 

It might end up being an issue. If I were going to pay for the tooling I'd want flat edges. Since this was #1 just brainstorming and #2 designed to be simple and homemade, it's something I may have to live with. I was hoping that by having the pieces totally detached from one another, that the casing or pasted paper would give way long before the edges start chipping or shattering. There is also the factor of some burn off before the shell breaks Streamer type compositions would hopefully have any minor shattering hidden by the burst. It may be more of an issue with colored compositions. They'd likely have a prime on them anyway, which may mask the shattering yet again.

 

Wait is it really neccessary to pump the comet?

Just thought why not just use a star frame, press the whole patty quite god, and then just take a normal cookie cutters which can be gotten in the right form (or just use two round ones and cut the x after).

 

After cutting just let the star dry on the table without moving, just remove every material that is going to be recycled.

 

This way tooling would cost about 2 $ and it would be available in many different ammounts of quadrants (e.g. ikea sells nice apple cutters). I will test that.

Try it out and let us know. I suspect it very well might work. My main concern would be deformation during cutting or drying interfering with the final fit. The other issue is that you'd generally be dealing with fairly large stars. The stars for a 1.75" insert would be almost 1" tall, and probably 1" thick at the thickest point. Getting the composition wet enough to cut would lead to some long drying times and potentially driven in stars. There is the issue of inexact cuts too if you're doing it by hand.

 

Using something like thin wheat paste can give good wet strength to stars, which may help to keep them as you want them. A sharp knife or tool would also likely help.

 

To be honest, if I wanted an effect that used more than 4 quadrants, I'd just make comets. 4 comets fit too tightly in a shell to get them to burst right, but 5 can be done, and 6 or more is standard practice.

[dagabu]

Isn't collaborative brainstorming fun?

[schroedinger]

 

Try it out and let us know. I suspect it very well might work. My main concern would be deformation during cutting or drying interfering with the final fit. The other issue is that you'd generally be dealing with fairly large stars. The stars for a 1.75" insert would be almost 1" tall, and probably 1" thick at the thickest point. Getting the composition wet enough to cut would lead to some long drying times and potentially driven in stars. There is the issue of inexact cuts too if you're doing it by hand.

 

Using something like thin wheat paste can give good wet strength to stars, which may help to keep them as you want them. A sharp knife or tool would also likely help.

 

To be honest, if I wanted an effect that used more than 4 quadrants, I'd just make comets. 4 comets fit too tightly in a shell to get them to burst right, but 5 can be done, and 6 or more is standard practice.

No worries i will do it, on the other hand I'm getting a new 2" pump in the next couple days i will also try to use that one

[MrB]

$300.00 US or more plus the shipping, it would be quite the expense for sure!

 

Sorry. I missed this line... Yeah, that would fit the "whine about the price & shipping" bill perfectly. I really would want one, but i cant justify a in the region of close to 400 bucks for a specialty tool that will see little and rare use. Especially since i'm always going to want the "other size" that is "any size i don't currently have access to"

I'd still WANT one, but fat lot of good that do anyone.

B!

[dagabu]

 

Sorry. I missed this line... Yeah, that would fit the "whine about the price & shipping" bill perfectly. I really would want one, but i cant justify a in the region of close to 400 bucks for a specialty tool that will see little and rare use. Especially since i'm always going to want the "other size" that is "any size i don't currently have access to"

I'd still WANT one, but fat lot of good that do anyone.

B!

 

Try the cookie cutter idea, that may or may not work but we will never know till somebody tries...