4.5 Swim Shad Troubleshooting Dents

[BassDetective]

Hey There-

I am having trouble with denting on the left side of the bait.  The dent is the same every time.  I have been able to produce some baits without dents but certainly more with than without.  I can't seem to figure out the step I am missing.  Here are some details:

Plastic:  CC Soft
Mold:  CC 4.5 Swim Shad
Plastic Temp:  Around 350
Color:  None, Pearl, Green Pumpkin
Glitter:  Silver, Red or Black Flake
Injector:  CC 4 oz
Heating Method:  Microwave
Injecting steps:  Draw plastic, "burp the injector to get out the air, insert injector to mold, hold for 3 secs, inject slowly, hold for 5 secs after feeling back pressure, continue to fill the sprue as it draws down
Clamps:  3 600 lb Irwin front middle and rear
Problem area:  left side (looking from front to back) - upper side as it sits in the mold - the dent is on the body just behind the nose but not affecting the tail - no major air bubbles to speak of

[pjmcla]

I do not own this mold; but I can produce dents.  This is a fairly large bait and mold for volume.  I can somewhat compare it to the 3.5" Carrot.  You have provided good information.   
Here are my thoughts.  At 350 degrees there will be a fair bit of shrinkage in that big of a bait.  You might try hold a fair bit longer after back pressure is felt.  Not a ton of pressure, but a fair bit.  When I inject the 3.5" carrot it is the only mold I inject with that injector full.  I "hug" the mold a good ten to twelve seconds;  several seconds after any indication the mold has drawn any plastic.  A little cooler plastic may help here, especially after the mold has heated up some.  I have found topping the sprue after a fairly long hug is not required as it never draws down any more plastic.  If you are having to top off a draw down after holding pressure you are not "hugging" long enough or possibly not quite enough pressure.  The thicker bodied baits need a longer "hug" while the plastic cools.     
Now Jason; or Ghostbaits; or Microspoons; or Frank can post what you really need to do to solve your problem.           

[ghostbaits]

I will agree with Paul, your plastic temp might be a little high. Try shooting around 325-330.

I get the dents on the left side (Upper side in the mold) with the 3.5" version if I have my plastic to hot...

Everything else looks spot on!!!!

Jim

[BassDetective]

Photos _ I will try to shoot it a little cooler and see what happens.

[MicroSpoons]

I will agree with Paul, your plastic temp might be a little high. Try shooting around 325-330.

I get the dents on the left side (Upper side in the mold) with the 3.5" version if I have my plastic to hot...

Everything else looks spot on!!!!

Jim
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[Jason]

Everyone is correct - it is plastic temp, and it is shrinking in on itself.

Here is more detailed information:

Let's start with the plastic:  The softer it is, the thinner it gets when heated, it also shrinks more when cooling (less mass / PVC).  I personally pour the swim shad in regular.  The tail action is what I'm looking for, and the durability of the bait is better.

Now the mold: The spru is the part you put your injector in, the runner is the part the plastic travels through, the gate is where the runner gets smaller before entering the mold cavity. 

In cases where a bait dents like this the reason is it's being starved of plastic because the plastic at the gate has hardened (it's smaller) than the body of the bait (thicker / takes longer to cool).  There are a couple ways this can be addressed:

1) Make the gate bigger.  Allows the plastic to stay fluid longer and be pulled into the cavity if needed.  The good with this is it lets you shoot the mold hotter without dents.  The bad is your bait has a big flat nose and requires cutting off the runner vs. pulling off.  So there is a balance we try to achieve between the bait and ease of use.

2) Shoot the mold cooler.

3) Holding pressure can also help with this, but it's really easier just to shoot it cooler.

Hopefully this helps with not just this mold, but understanding what's going on inside any mold.

Jason