Pouring Shads Through The Tail

[robalo01]

I have been starting to make more and more 2-sided shad molds so that they are poured through the tail:

 

http://bassattacker.weebly.com/moldes-de-dos-lados.html

 

The way they are made allows you to pour a belly or tail (or both) in a diferrent color. They are turning out pretty nice.

Edited October 10, 2013 by robalo01

[Kajan]

   Looks Bon', nice job on the molds and design.

[toadfrog]

Finally somebody has there head out of there butt . Sense I was once involved in the extrusion of plastics and other compounds I often woundered why all the plastic molds I see are shot or poured from the thickest end of the bait . Back in the day non tackle molds I worked with were shot thru the finer points because the flow of plastic cooled as it traveled and a larger area filled easier up to the thinner area where the plastic maintained a higher temp . It was seldom that the finer piece had defects unless you ran out of plastic on the fill . Work with this a little Kajan . Might just surprise ya .

[SlowFISH]

Finally somebody has there head out of there butt . Sense I was once involved in the extrusion of plastics and other compounds I often woundered why all the plastic molds I see are shot or poured from the thickest end of the bait . Back in the day non tackle molds I worked with were shot thru the finer points because the flow of plastic cooled as it traveled and a larger area filled easier up to the thinner area where the plastic maintained a higher temp . It was seldom that the finer piece had defects unless you ran out of plastic on the fill . Work with this a little Kajan . Might just surprise ya .

 

Based on the molds I've made I believe the reason/preference to inject "larger end" is to eliminate dents in the baits as they cool.

 

I've found making a fairly large sprue (sprue = the runner from the injector to bait) let's the bait "suck plastic" as it cools - avoiding dents.  On a drop shot minnow I'm working on I have a 1/2" diameter sprue that then fills into the nose of the bait through an extremely short 1/8" runner.  I found the short 1/8" runner cools faster than the belly of the bait and the 1/2" diameter sprue.... this has caused dents in the belly area.  I went back and opened the runner up to 3/16" diameter and this has reduced the issue greatly.

 

My hypothesis is... if you inject through a small area - it would cool first blocking off the ability of the thicker part of the bait to absorb/suck plastic into itself as it cools - and you'd then have dents.  On a hand poured paddle like the OP is showing it's not that big of a deal as the tail is slightly overfilled and as it cools - all is well - plus in general the bait is pretty thick in all areas so it probably cools pretty evenly.

 

In general I try to make the sprue bigger in diameter/volume than the bait.  In doing this my baits cool first - then the sprue... and my dented baits have reduced greatly.  The negative is I have a good amount of plastic to reheat after I remove the baits from the mold.... but I'd rather do that then have dented baits.  It also provides a visual to what's happening in my mold.  I fill the sucker and top off... after a few minutes I can see the thick sprue "suck in" and I know that plastic is being pulled into the bait.

 

Hope this makes sense... and my baits are made in either Pop molds or machined Ren Plastic... so they take more time to cool than aluminum.

 

     j.

Edited October 10, 2013 by SlowFISH

[mark poulson]

SlowFISH,

Maybe, like you said, the material the mold is made from can make a difference, too.  RTV silicone may not cool fast enough to make pouring through the thin end a problem.

[robalo01]

What I was looking for is a hand-.pour solution for a two-sided mold that allowed pouring a colored tail and belly. I wasn't really thinking about avoiding dents.

 

BTW if you make the tail too thin, it does produce dents. I have also found it best to pour the belly, give it a couple minutes and then pour the rest (even if it is the same color) to help avoid dents.

[SlowFISH]

SlowFISH,

Maybe, like you said, the material the mold is made from can make a difference, too.  RTV silicone may not cool fast enough to make pouring through the thin end a problem.

 

I'd agree... pouring through "non-metal" mold should better facilitate the practice of going through the tails or thin sections without a doubt - as most non-metal molds insulate.... but even in those - if part of the bait gets reasonably thin then thicker - I'd think you'd have dents or distorted baits regardless of mold material.  With the OP's design/style bait and hand pouring - he's in real good shape for what he's doing.  The bait shown has a pretty favorable section thru the body for tail pouring and I assume he's topping off a bit on the tail as it cools - thus why he's having good results.  Plus adding one color first - (assuming it cools and shrinks a bit) - then filling with the second actually reduces the belly volume - further reducing any chance of dents.

 

  In my post I was reacting more to the philosophy of filling tail first on something hand injected.... think if you tried tail filling an old "Manns Jelly Worm" or a Zoom shakey type worm tail first.  Granted these are extreme examples but I'd think you could very well inject into those thru the small tails and fill with pop/silicone/plastic - but likely dent the front/head of the worm as once the tail end cools - it shuts off plastic from the sprue and then there isn't any plastic to be sucked down into the thicker section.

 

  BTW... I like the OP's ingenutity.... I really like the ability to touch off on the tail with another color.... smart move that probably couldn't be done the other way!!!

 

  J.

[toadfrog]

Hot dang I knew I'd get something stirred up . LOL But really some of the molds i used shot from thinner veins without getting dents . The problem is I don't remember if there was a plastic resivoir cut in the mold any place to draw from . That was a reeealy long time ago .

[robalo01]

"I assume he's topping off a bit on the tail as it cools - thus why he's having good results."

 

Actually I made the tails pretty thick, and I wait about 1 min before pouring the tail, so when it does suck some plastic down it comes out just about right.

Edited October 11, 2013 by robalo01

[toadfrog]

Ok... just for shits and giggles I'll make a comparison mold and see what happens then. 

 

Maybe something like a Super Hog style mold.  Two cavities side by side.  One injected through the tails and one injected through the body as is the norm.  Should be easy enough to do.  Probably only take a couple hours on the big mill if I keep it simple. 

 

Maybe its one of those things that will turn out to teach us something really interesting like injecting from the bottom to force out air syringe style. 

Thanks  Bob , You usually come up with information and techniques that are not only of interest but  informative and appreciated .

[robalo01]

I agree that to avoid dents the best place to place a sprue is in the thickest area of the bait, so why not inject directly into the stomach or back? It might eve make for some interesting lams (front/back).

[Kajan]

   I think thats the main reason. Many colour lams work with horizontal configurations. Meanings the fish seem to prefer it. But its not to say some might like some colours the other way, just you don't see as many bait fish or such in nature with that type colour shapes.