Star plate size question

[Swede]

I have decided that I want to make some stars using a plate rather than cutting them from a loaf. The plates will be Aluminum, the pins stainless, and given the labor required to make a nice star plate, I want to make one that is a good all-around size for my own needs.

 

I focus on shells from 2.5" to 4", lots of 3" cannisters. At this point, nothing larger. I'm thinking 3/8"? Or would 1/4" be a better size?

 

I'll take some pics of the process.

 

Thank you, Gentlemen!

Edited March 11, 2010 by Swede

[Mumbles]

If you make more streamers and glitters, I'd say 3/8", but if you make more colors, I'd say 1/4" You can always cut other sizes that you need.

[Plasm7]

I would go with 3/8inch 1/4inch will be pretty small for a 4inch shell

[Bonny]

I'd also recommend going with 3/8"...nice versatile size. As Mumbles said though , if you make a lot of colours (with all that clean perc) go with 1/4" and just cut the other sizes.

[Ventsi]

One tip, make the plate/s with AT LEAST 50 pins, makes using them way more worth the effort.

[dagabu]

Ventsi,

 

Think of the pressure needed to press all 50 pins! That's 18.75 square inches of area! I had mine built to 16 pins so I could use my dead-blow as well as the press, 50 pins will not allow you to use a hammer at all.

 

Dave

Edited March 12, 2010 by dagabu

[qwezxc12]

Ventsi,

 

Think of the pressure needed to press all 50 pins! That's 18.75 square inches of area! I had mine built to 16 pins so I could use my dead-blow as well as the press, 50 pins will not allow you to use a hammer at all.

 

Dave

 

 

Ummm... 18.75 in²?

Unless my math is wrong...

 

A = Pi r ²

D = .375"

 

r = .1875"

 

A = (3.141593)(.1875)(.1875)

 

A= .11045"

 

A x 50 pins = ~5.52in²

 

I can use hand pressure to consolidate comp in my old 27 pin 3/8" plate. My new big plate from Wolter only needs a few whacks from a deadblow.

Edited March 12, 2010 by qwezxc12

[dagabu]

No wonder I flunked math!!

[Swede]

Thanks fellas. I think the deal with applying pressure to star plates is the use of a very stout and heavy cover plate. If you put your system in a press, and have the hydraulic ram press down on the middle, only those pins in the middle will apply full pressure. The other pins will see less because the plate will definitely flex. But if you lay a 1" thick steel plate on top of the star plate sandwich, it should distribute the pressure well to all of the pins.

 

3/8" it's gonna be. If anyone else wants to make a fancy star plate, look to an aluminum material called mic6 jig plate.

Mic6 plate

 

It is dead flat, and much more accurate than typical extruded plate. A real pleasure to work with. Stainless pins next. Those are going to cost. Ouch!

Edited March 12, 2010 by Swede

[gordohigh]

I made a few star plates a couple of months ago, and the 3/8ths ones were too big for a 2" shell, but will probably work fine for larger shells. When I made tiger tail type stars, they burned out before landing, but when I made red and green magnalium stars, some of them hit the ground. Seems like the metal fueled stars burn for a long time. I did however press them in my hydraulic press so they were extremely tight, which I'm sure makes a lot of difference between just using a star pump and cutting or a loaf and cutting.

 

Some things I learned from my first 2 plates, make sure to leave room to mill some finger points to seperate them. What I did was to clamp them together and turn on side or end and run a mill groove between the two for some finger leaverage.

The other thing I did was to drill the female holes out by a 1/64th bigger after the inital drilling because they were difficult to seperate. The bigger the plate, the more you can bind because of trying to seperate them without being perfectly level. I do like the idea of a bigger plate but mine were done from some scrap alu bar stock so mine were longer than they were wide. I think a square would work best, but I haven't tried it yet. I have 2- 3/8ths plates and one 1/4 in and I love em, they beat the heck out of pushing little tubes out and trying to cut them evenly, at least for me. My next 1/4 in plate will probably be around 40-50 or so holes and yes, use a steel plate between the press and plate top to keep an even pressure.

 

I look forward to seeing your progress, judging by some of your other projects I'm sure it will turn out *kick ass*..

[FrankRizzo]

Hi Gordo,

 

Have you used a star plate before? They can be kinda tricky to get precise lengths if you don't have a trim spacer machined to fit between the plate surfaces.

[Swede]

I'm thinking of adding die ejector springs to the device. Die springs, for those unaware, are viciously strong little buggers designed to separate two die plates after injection molding. If the die springs prove worthless, I can always remove them and fill the holes. The presence of the springs might make using the plate difficult.

 

The cost of the stainless pins is painful. 3/8" X 1/2" stainless pins are a buck each from MSC. 3/8" X 3/4" are $1.50. I guess that's really not that bad... a 50 pin plate would cost $50 to $75 for the pins and would last forever. No corrosion. I haven't started on it yet, still trying to source the materials and get over this stupid bug I've got.

 

Have you used a star plate before? They can be kinda tricky to get precise lengths if you don't have a trim spacer machined to fit between the plate surfaces.

 

Frank, are you referring to a mechanism that would limit the amount of "plunge" you get from the male plate? I was thinking about adding 4 adjustable pin stops... each would have a set screw behind it so the plates could mate only so far, and no farther. Heavy pins would contact the female plate, and any downward travel would cease.

[Swede]

OK guys, quick eBay search - no 3/8", but I found a guy basically giving away 1/4" stainless pins in a nice length - 3/4"

 

300 pins for $10! He had two lots of 300. I bought one. One lot left. These would make some excellent 1/4" star plates at a fantastic price.

 

Don't snooze!

Stainless pin deal

 

Thought - If you can find a ridiculous bulk deal for 1/2" or 5/8" stainless pins, there's your ball mill media, ready to go. I can never prowl eBay without finding something worthwhile.

[gordohigh]

I saw some 3/8th on there not too long ago so maybe some will show back up. I have been buying alu in varius sizes and flat and round stock, very reasonable with the usps shipping boxes.

 

 

I don't have a shim spacer for my plates and yes, my star size varies a bit. I usually load and hand press once and look at em, then reload and press. If someone can explain how that works I could easily make one as soon as my collets get here as I just bought a set of boring bars so I think it would be easy to line up on the mill using the original female plate.

 

Swede, I think you will be happy with a 1/4 plate even if you still build the 3/8 one. I have actually been making bombettes with 4-5 1/4 stars and some crackling microstars and they work nice. The 1/4 in is almost too big for that but they do just finishing burning before they land. Of coarse Kno3 based charcoal stars burn a lot faster than the magAl colored stars that I usually make. In a 2 0r 3in shell you can get enough of them in there to get a nice spread and I plan to try a pattern or two soon. Look forward to seeing your progress..

 

 

Edit...After thinking about it, I think I kinda have that spacer pictured in my mind, kiinda like a rectangular spacer that fits all around the perimeter between the plates so you can make sure you are just touching all the way around?

Edited March 19, 2010 by gordohigh

[gordohigh]

Swede, here is a ebay link for .375 stainless 4 ft long for 4.99 each and he has 10 of them. http://cgi.ebay.com/303-Stainless-Steel-Round-Rod-375-dia-x-48-long_W0QQitemZ350298899000QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item518f710238

[Swede]

I appreciate that Gordo. But I am going to go the lazy guy method and use dowel pins. I plan on using a full-blown press fit on the male plate by drilling and then reaming each hole 0.374". On the female side, I'll try maybe a 0.378 drill or ream. The ground dowel pins will give me the precision I want for the press fit. No loctite or epoxy needed.

 

I have found good deals like that for 48" stainless shafting in 1/2" OD where the shafts are slightly warped or otherwise imperfect, and that got turned into media. Like you say, it is a matter of patience.

 

I will definitely make a 1/4" plate set too, with this pin bonanza. Before I do it, I really need to learn how one is best used, before I engineer something in that is either stupid or worse, harmful to the process.

[Swede]

The 1/4" pins arrived in 3 days. They are beautiful! What a bargain. Two big sacks full. Again, they reminded me of stainless ball mill media, except a bit small, but they would work in a little mill setup. If anyone finds a guy selling larger stainless dowel pins in bulk, snap them up, they'd be great media.

 

I need to find some mic-6 plate now in my scrap pile.

 

Does anyone have a favorite web site that details the use of a star plate? I have a good idea on it, but I want to be sure that I'm engineering this thing properly. Thanks!

[gordohigh]

I looked and couldn't find much when I was making mine. This website has some good pictures http://www.wolterpyrotools.com/?page=cc_catg&cat=stars

 

 

There is also a tutorial on pyroguide but you are probably already more advanced than those instructions and I believe they used acrylic. If you find any detailed info please post it.

[Mumbles]

Swede, just send a plate up my way and I'll show you how it works

 

There are two ways to use a plate, and they are engineered a bit differently.

 

Type 1: What I call "Shallow fill"

These are normally slightly thicker than the diameter of the hole. Off hand, maybe 1.5x. So your 1/4" plate would be 3/8" thick. There are 2 ways to use it. You can make kind of a putty from your stars (similar to cutting stars), and smear it on, compress, and eject. I'm not really a fan of this method. The other way, which I really like, is to wet your comp to 6-12% or so based on the composition, and granulate it. Loosely fill the holes, and compress. Repeat a few times until it's more or less full. I think 3 times total was usually the magic number for me.

 

Type 2: What I call "deep fill"

This is more or less the same idea as the granulating and compressing method before, only the holes are deep enough that one compression gives the full length. This is more convenient if you are using a hydraulic press where the press time is the slowest step. It's generally used more for comets in my experience. About 3.5x the star diameter is generally about right.

 

You can tune both ways based on how wet you get it, and what mesh you granulate at. Generally a window screen (16) mesh is pretty convenient size.

[FrankRizzo]

The plates that I use are of the "deep fill" variety that Mumbles was referring to. I granulate the comp, loosely fill each hole all the way by running a pile of comp over the female plate with a wiper card, then press. At this point the stars are usually ~1/8-3/16" too long. I then insert a custom made spacer at each end of the plate, and press the pin plate until the spacers are firmly sandwiched between both plates. At this point, the extra length of comp is sticking out the bottom of the female plate. I run a stainless putty knife across the bottom to trim off the excess, then remove the spacers and fully eject the properly sized stars.

[gordohigh]

Frank, thanks for that description, exactly what I was looking for.