Crossette star help

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fredopyrox
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Joined: Sun Feb 18, 2018 11:38 pm

Crossette star help

Post by fredopyrox »

Hello , when I remove the crossette star from the pump it breaks at the crossette hole , it is c6 composition with 10% water , it is 3/4 inch crossette pump from pyro gear man , what do you think? Thanks...
davidg
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Location: Manchester

Re: Crossette star help

Post by davidg »

I use a mould release spray on the crossette tip and that seems to help
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Lloyd
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Re: Crossette star help

Post by Lloyd »

Fred, I've pressed (actually) hundreds of thousands of square-hole crossettes in silver, gold glitter, white glitter, and strobe comps.

We would apply a small amount of silicone release agent to the pins, about every five to six pressings. The 'release' was perfect. (eh... usually! <grin>)

FWIW, if the tip isn't properly tapered, it will break out. But the other cause may be using insufficient moisture or pressure (or both).

Lloyd
"Pyro for Fun and Profit for More Than Sixty Years"
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Pyro-Gear
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Re: Crossette star help

Post by Pyro-Gear »

press the star then place the pump on a smooth wooden surface give a small amount of taps with a wooden mallet then eject the star through the base plate, pretty simple, if that doesn’t work your composition is to wet.
tooling is fine ya just need to know how to use it.
Dave F
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Re: Crossette star help

Post by Dave F »

Just out of curiosity, what do you folks think about applying the pressure from the other direction, so the comp around the tip gets the least force on it, rather than the most?
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Lloyd
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Re: Crossette star help

Post by Lloyd »

Because of the friction around the cavity-former, we've found it's most-effective to press 'tips down' into a full load of composition. Surprisingly, with the added friction of the composition around the cavity-former, we found the 'surround' of the tip tended to be under-pressed rather than over-pressed.

Our molds were built so that they could be adjusted in 'fill height', so we could get the same height of pressing, regardless of variations in consistency, moisture, etc. (although we had a VERY tight tolerance for screen size of the materials and moisture content). Still, if we found 'environmental' issues that caused one batch to be a little shorter or longer than that specified, we could adjust the fill height by means of screw stops on the filling position.

My daughter and I pressed hundreds of thousands of small (3/4" o.d.) crossettes this way over about 15 years of production.

Since you're having problems with this, I must ask if you have any taper on your tips. It's essential to have a degree-or-two of taper to make them extract properly.

Lloyd
"Pyro for Fun and Profit for More Than Sixty Years"
fredopyrox
Posts: 53
Joined: Sun Feb 18, 2018 11:38 pm

Re: Crossette star help

Post by fredopyrox »

Hello thank you for your help!!! I have spray silicone releases and I have again this problème,i pump with bottle jack 4 tons ,the tip is up when I pump . The water is 8-10% at composition c6 .
davidg
Posts: 280
Joined: Mon Jul 29, 2013 2:07 pm
Location: Manchester

Re: Crossette star help

Post by davidg »

As PG said a few taps with a wooden mallet will do. No need for the bottle jack.
Too much force will distort the shaft of the crossette pump.

Keep the tool clean as well. Previous composition can cause issues. Treat the crossette gently while removing
It and do not apply anny rotational force ( don't twist)

Practice and patience are both needed.
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richardh08
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Re: Crossette star help

Post by richardh08 »

I don't really have experience with pressing crossettes, but it sounds to me as though the binder (which I assume is dextrin) might not be working as well as it should.

One thing that might help is covering the wetted mix (to prevent evaporation) and letting it rest for a few hours (or overnight) before pressing it.
Even when I'm wrong, I'm convincing.
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Pyro-Gear
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Re: Crossette star help

Post by Pyro-Gear »

Fred a bottle jack! as Dave said there is no need for that, the tip of the tool has a 2 degree taper to aid release, I would suspect that your composition is a little too wet walk away from it and allow it to dry a little then try again without the bottle jack, I have not tried C6 personally but have pumped many other compositions with success.
Mixer
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Re: Crossette star help

Post by Mixer »

Your problem is easily dealt with - simply by using strictly 8% 75/25 water alcohol then reducing the pressing pressure until they release cleanly. You will be surprised at how low you can go with reduced pressure, and still have them hold up and break nicely.
fredopyrox
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Re: Crossette star help

Post by fredopyrox »

Hello , thank you for your help, i will try your tips...
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