Dimples

[tboxfish]

I've had a problem shooting my 3.5" Super Fry mold. 1/3 to 1/2 of them have deep dimples in the sides of the baits. I've tried holding slight pressure on the injector after the shoot, but it doesn't help.
Any suggestions would be greatly appreciated!

[jl3140]

I sometimes get the same thing on my mold. Try shooting at lower temperatures and then hold pressure for 20 seconds or so and they should go away.

[tboxfish]

Thanks jl
I am doing that now, we'll see how it works. Normally heat up to 345-350, will shoot cooler, maybe like 335 or so.

[ctom]

Shoot down to 320 even.

[bassinfool]

Most of the dimpling/denting issues come from the plastic being too hot like others have suggested.  I don't have this specific mold, but I know several of mine will still pop out good baits down to nearly 300 degrees.

[Justin9j]

Heat the mold some and cool
The plastic some.

[BareKnuckleJigs]

The runner may be too small on that mold to feed the cavities when the cavities cool/shrink.  An insufficient runner willl cool/set before the cavities do, starving the cavities because the cavities try to pull more plastic after the runner has set.  My Super Stinger mold has that problem, so I opened up the runner on 1 mold-half (Dremel) and the dents have greatly decreased.  Once I hit the other half of the runner with the Dremel, I'll be Makin' Minnow Bacon.  My SuSt runner was maybe 1/4"-5/16" diameter, but needs to be like the 3" Glider runner or even the 3.5" Regular Carrot runner.  The runner has to be the last plastic to set.

[ctom]

People need to be pretty careful about routing out the runner. Lots of these molds have very marginal room between the runner and the front of the bait [gate]. Mess with that enough and the baits will be messed up. The best answer isn't always the Dremel tool.

[BareKnuckleJigs]

The best answer is Do-It making the adjustment to cut the bigger runner, but I have to settle for 2nd Best.  I've shot that mold every way but no plastic, and I still get dents.  Me, I KNOW what the problem is, I don't need another opinion.  I know the facts about what's needed.  Read my last post because that's where the problem is.

[andrewlamberson]

Dimples are caused by the dense core cooling slower than the skin and thus "sucking in" the skin. It is called Differential Shrinking and is a problem with any plastic part that has a section that is thick.

As many have suggested you need to shoot the bait as cool as possible (that still allows enough flow to fill out all the areas of the mold).

Make sure you still heat up your plastic on the first heat to 350 degrees so that it fully changes state or you will get cloudy or sticky baits. After the first heat you can heat/cool the plastic to any temperature that will inject properly. Holding some "back pressure" (keeping light pressure on your injector) for a 20 count might help.

Make sure you have a good thermometer! 

Andy

[ctom]

I have the mold and I seldom see a dent, but I shoot it with cooler plastic [320-325 degrees, even as low as 310]. I don't have short fills nor do I have much in the order of dents or dimples. I do keep the pressure on the injector after it stops for perhaps 10-12 seconds....this forces liquid plastic into the runner when the plastic want to suck in. When I open the mold and handle the plastic inside it is not at all unusual to have liquid plastic ooze out of the runner. I stand on the opinion that its a plastic temperature issue, not one of insufficient runner volume.

[BareKnuckleJigs]

I have THICK baits that have runners that are overkill.  I don't even have to hold pressure on these...and the Gates (narrow cut from Runner to Cavity) are tiny.  Deep-bellied baits have denting issues when the Runner won't feed cavities plastic when they need it.  Our material is ThermoPlastic, it expands when it heats, contracts when it cools.  For the part to retain the shape of the Cavity-to-Copy, that part must be fed material as it cools.  An insufficient Runner sets before the part so the part starves...it can't receive the material it needs to retain its shape as it cools.  The "skin" cools first but the core stays liquid longer, then as the core cools it shrinks so it needs more material, but an Insufficient Runner will set before the thickest Core Section of the Part, so the ThermoPlastic cools/shrinks in on itself, starved for the extra liquid material it needs, so it dents.  These are the FACTS that are the cause.  Not temperature.  Jerry, keep my store account active but please delete my forum account.

[ctom]

I can see this is your way or no way. So be it. I'm just happy that mine turn out.

[Lamar]

All that over a Dimple. Seriously ?

[bassinfool]

So much butt hurt, so little time.