Dents

[Delw]

Dents are most commonly cause by gas pockets,

152 street baits is caused by gas pockets,10 inch trick worm

stick baits are both gas pockets or the salt haing air pockets in it or both.

Shanes case I believe he is talking about the 2 piece superfluke, that is caused by the top of the mold having a very smooth finish and nothing to hold it when it cools.

I can go on and on about dents but 90% of the time its due to gas/steam rising smoke(smoke is a gas) etc etc

if you use salt in the baits 70% of the its caused by the salt having air pockets in it the rest of the time its due to gas,

then theres the mold too cold and poring hot plastic into it which creates steam causeing a air pocket/dent.

its most noticeable in alum molds. silicon is least and pop is in between

every style of mold is different. it sticks trick worms flukes swimbaits etc etc.

Edited January 8, 2009 by Delw

[Vodkaman]

Jim, you are a gentleman, thanks.

Del,with utmost respect, I have to disagree about your gas theory.

It is all down to a vacuum forming when the neck is plugged as the plastic solidifies. If the pour hole is too small in diameter, this will happen. The vacuum then draws air to fill the vacuum throu the mating face. This is difficult to prevent on a rigid mold, unless the halves are clamped like a cylinder head, evenly all around.

This is the reason why RTV is the best material for avoiding vents, as it is a flexible material. As the vacuum forms, the mold simply distorts inwards. This distortion is so minimal, that it cannot be seen.

Yes, these are theories, but Jims work has now given credibility to the ideas.

Dave

[GB GONE]

If it is the seal that is causing dents, then why don't we see dents in molds other than worms. I only get an occasional dent in one cavity of one mold.

Good question!!! I wonder if that is the inside cavity that produces the dented bait for you Richard?

I am sure that the seal is not the only factor at play. The larger volume of plastic and the heat of the plastic are certainly variables as well as many other issues.

I think if you look closely, you may be able to find the elusive dent in most baits that have either are produced in a large cavity mold or have a significant smooth area within the mold cavity. Many "dents" will be tiny but they are there if you look close.

Del's point about the various mold styles causing issue is credible to me practically as I see a "dent" in the head of the larger frog I pour but never in the small frogs.

Also, roll this around in your head. Make a laminate bait in the mold you get dents in commonly. My observation is that I never have a dent when I make a laminate bait in a 2 piece mold made from any material.

In addition, I did make some fluke baits again in the acrylic molds again last night to further support the seal theory. I sealed around the outside of the mold again with parafilm wax but left a small area un-sealed to observe the results. As expected, the area left unsealed produced a pencil eraser sized dent. I am able to control where the dent will be produced based on where I seal/unseal the mold cavity.

Final thought.... Who cares about a few dents!!!!?? I took out bags of injected plastics last night and could only find a few baits in 100 that were without physical flaw. Deformed baits are one thing but a few minor dents will probably only enhance the baits catch ability!!

Jim

[Delw]

Jim, you are a gentleman, thanks.

Del,with utmost respect, I have to disagree about your gas theory.

It is all down to a vacuum forming when the neck is plugged as the plastic solidifies. If the pour hole is too small in diameter, this will happen. The vacuum then draws air to fill the vacuum throu the mating face. This is difficult to prevent on a rigid mold, unless the halves are clamped like a cylinder head, evenly all around.

This is the reason why RTV is the best material for avoiding vents, as it is a flexible material. As the vacuum forms, the mold simply distorts inwards. This distortion is so minimal, that it cannot be seen.

Yes, these are theories, but Jims work has now given credibility to the ideas.

Dave

Dave,

no problem however now you through something else info the mix. Vacumm forming.

Hand pouring dents will be different than injection dents and so will vacumm dents. just like dents in alum silicon and pop

throwing another varible into something will cause something different.

Injection will get dents via having the fill runner in the wrong spot and you can get dents in different spots via differnt PSI pressures.

vacumm forming dents can be caused by pulling plastic away from a certain area. for example if there is no seal at a certain spot and your using vaccum you would be pulling the plastic away from that spot causeing a dent.

there are way to many varibles in every type of mold to link them all together or call them the same.

I am assuming we were still talking about hand pouring dents, if you were talking about dents in a vaccum type mold then my post was not correct as I thought we were talking about hand pours.

[GB GONE]

Del,

I believe Dave was referring to the vacuum that forms when hand pouring and the mold cavity fills.

Perhaps a widening of the sprue on one of these clear molds is needed as it may allow the air to pull from the sprue vs the sides of the mold. May further the insight on this issue as you get a great visual on what is going on in the mold.

Jim

[Delw]

Originally Posted by 152nd Street Baits

If it is the seal that is causing dents, then why don't we see dents in molds other than worms. I only get an occasional dent in one cavity of one mold.

I might be able to answer that.

if you look at a hand poured alum mold you will see that the 2 halves are not perfectly flat so there is really no seal. pouring one worm could be pushing gas/air into the other worm while your pouring it from the side.

They are flat enough so plastic wont ooze out of the side where the 2 molds meet and in fact let air escape from the sides so they pour easier.

in the first 2 years I made molds perfectly flat as I lapped them in, there were more problems with dents and filling and mainly on molds with heavy ribs like the diamond tails and some others.

most dents don't occour were the molds meet the usually occour on one half or the other were there is no seams.

however sometimes dents will occour at the seams on the inside worms and not on the outside worm.

does that dent occour in the same spot on the same cavity every time? if it does drill a very small hole 1/32 in the middle of the spot that has the dent and chances are it will go away.

The diamond tail worm is pretty much a round for each segment , if you hold it straight up like your going to pour you will see that the liquid goes in then out then in each segment ie small big small. if the plastic cools on the small section before the big section(which it normally does) and steam/smoke is still coming from the big section it will produce a bubble.

I know it doesnt make much sence, but if you look at one half long enough it will.

[Delw]

Del,

I believe Dave was referring to the vacuum that forms when hand pouring and the mold cavity fills.

Perhaps a widening of the sprue on one of these clear molds is needed as it may allow the air to pull from the sprue vs the sides of the mold. May further the insight on this issue as you get a great visual on what is going on in the mold.

Jim

I read his post wrong then.

I would love to do clear molds, and we looked into it last year for a customer to pour multicolor pours and to know when the color is at the right height.

the areas you cut wouldn't be clear either due to tool paths( the would look etched) and to make them clear you would have to add 2-4 times as many lines in the program plus some polishing. driving the cost up even more.

oh and then that cutting plastic mess nasty.

[GB GONE]

pouring one worm could be pushing gas/air into the other worm while your pouring it from the side.

My thought was that the vacuum was pulling air from the cavity that was not filled yet. Could be the other as you say Del.

Wonder if you poured the outside baits first (assuming the mold is 3 cavities??) and then the center last. If gas or air is being pushed into the other cavities, one of the outside baits should have a dent on the side facing the inside cavity.

This could end up being a "dog chasing its tail" deal.

Maybe Randy should just stop pouring that dang bait !!!

Jim

[Vodkaman]

I was only thinking about normal hand pours, not considering vacuum or injection.

As well as the sealing of the mating faces, as suggested by Ghost, I still think there is some mileage in experimenting with the pour hole diameter and making sure that the funnel is filled with hot plastic. This will help keep the pour hole plastic fluid for a little longer. As once the pour hole plastic solidifies, the shrinking plastic creates the vacuum.

Obviously, I would not recommend members drilling out pour holes, just to test a theory, but it could be tried on a PoP mold. I just wish I was in a position to test this stuff out for myself.

This is a very interesting thread. Their well may be more to it than we have considered so far.

Dave

Edited January 8, 2009 by Vodkaman

[HJS]

Jim - Good thought, might just work. Most of my molds are 3-5 cavities wide. So I might try pouring the outside cavities first, wait a few minutes then fill the center cavities. We shall see.

[Delw]

My thought was that the vacuum was pulling air from the cavity that was not filled yet. Could be the other as you say Del.

Wonder if you poured the outside baits first (assuming the mold is 3 cavities??) and then the center last. If gas or air is being pushed into the other cavities, one of the outside baits should have a dent on the side facing the inside cavity.

This could end up being a "dog chasing its tail" deal.

Maybe Randy should just stop pouring that dang bait !!!

Jim

one way to find out is change the pouring routine just for test. like if he poured right to left pour from left to right or pour center first.

pouring center first would allow the air to escape form the both sides.

would be nice to know what cavity gets a bad one which way he pours.

also remember once you pour one worm you made a seal on that cavity.

on some pretty big molds I have made just a cut in betwen each cavity in the length of the mold not touching any cavities. this allows it so once you pour one side and its sealed via the plastic the other cavity and the side next to the worm you poured has a place for air to go.

chasing dents is a pain in the butt as it seems there is no constant even with the same molds same plastic just differnet people pouring.

[GB GONE]

I will try pouring center and work outward on some sticks.

I know my routine is to work left to right on the mold cavities. Lefties might work right to left. Doubt many pour the center first. I have never stopped to check which baits were actually dented and where the dents occurred. We may find a pattern with certain cavities always denting and changing the fill order could resolve that.

Might be a simple fix to the stick "dent" problem.

I doubt this is the issue with the flukes as the dent seems to relate to the flat portion of the mold, whether the mold is made from pop, aluminum or acrylic.

Resolving one out of two would be good though!

Jim

Edited January 8, 2009 by ghostbaits

[Delw]

wait wait, we were talking about the diamond tail not stiks huge difference.

Remember he wasnt using salt in the diamond tail, salt will cause a different type of dent.

I guess I should have gave a definition of them as I see them.

A dent will have the form of a the bait but dented in like the org. picture of the stickbait in the guys pop mold.

shanes Sf mold was dents not voids.

what I should have called 152nd streets was a void were its just a missing section.( I have seen it before on some diamond tails) its trapped gas causing the plastic not to be able to flow to the mold surface.

happens on some claws and pinchers of baits as well.

I got some pics I am sure of many different dents voids and other imperfections from over the years. I will look for them tonight and give a definition.

when I hear dent I am thinking of something like the picture in the org post.

bb in a few let me see if I can find some pics.

Delw

[Delw]

this might help the coversation quick search found these pics

this pic is a dent or what I would consider a dent, as the plastic hit the side then was pulled away during the cooling process. this would fall into daves deal about the vaccum

same picture but closer view

this is a void or what I would consider a void, trapped gas cause this.

I get mixed up and takling about them and should be more specific as to voids or dents.

Edited January 8, 2009 by Delw

[GB GONE]

I still cannot recall a dent in a laminate stick bait. Wonder if anyone else remembers any. May be a clue as well. The voids usually are more from technique for me.

Wish I was at the shop as I would go out and put some of this to the test!

Jim

Edited January 8, 2009 by ghostbaits

[Delw]

you know thats cool that you brought up laminates I never seen a dent in one as well makes one wonder doesnt it.

[JSC]

"you know thats cool that you brought up laminates I never seen a dent in one as well makes one wonder doesnt it."

Now we are getting some where .. where ? I'm not all that sure .. but it is getting closer to the "Dents" not "Voids" which is really the big mystery as voids are mostly from pouring fast or to hot as well as a possible movement of the mold during the pour ... (should not have Voids with laminatea either) ...

I had though of changing my pouring routine to check some of these things but have been doing open molds as of late .....

More to come ....

JSC

[BassnRandy]

I wanted to say thanks to everyone and I mean everyone for the input on this problem. I had 6--2 piece molds and played with them all abit to fix it. What helped the most was opening the pour spout up as much as I could with out ruining the nose of the bait. Venting and putting a barrier around the outside made very little to no difference. Another thing of importance: IF the molds got hot from pouring again to soon it was a bigger problem ecspecially on the two molds that were a bit thicker. So my guess is that uneven cooling is causing some of the problem. In the end I can pour 9-11 baits with out dents by widening the spouts and keeping the molds cool.

These were my first 2 piece molds that worked for me as far as making the molds went. Unfortunatly I did only a sos so job of keeping the envirotex even when i sealed them. Lesson learned but at least I know where I am headed now.

Thanks again!

Randy

Hawg Pours

[danrey]

Hi guy's , thanks to you after a year of research on this site i decided to try my hand at plastics . I 'm using one of Del's 5 in. stick molds, Calhoun plastic, no salt ,no softner .I have poured 250- 300 stik worms with no dent or voids . my first pour I couldn't hit center of the hole for nothing but i'm getting better . My guess would be lack of additives ie, salt , softener . i am now using scent in them as well , but still no dents or voids [not that i want them] . if the plastic does'nt stick to my finger in the pour hole i demold them . Just another angle to look at this dent thing. hope this helps in some way .