Custom Baits - Forum
Soft Plastic Bait Making => Soft Plastic and Plastic Baits - How To??? => Topic started by: Thembonez on 01/06/19 12:33 UTC
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Any clues as to why all my attempts at dual injection ends up calico or swirled?, I’ve tried fast slow, kept my temps close. I’ve shot hot, I’ve shot cold.
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Thembonez
I recall having a similar issue with one of my molds
Have you tried preheating the mold and blending block before you pour
as it solved my issue
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Thembonez
I recall having a similar issue with one of my molds
Have you tried preheating the mold and blending block before you pour
as it solved my issue
Yes sir everything is brought up to temp before shooting
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Baits that have straight bodies laminate far better than baits that don't. A ribbon tail worm or a Senko will generally laminate better than a swimbait with a big belly. One thing I do to mitigate this and achieve even cooler colors is to hand pour the belly of the bait and then use my dual injector to inject two more colors. I've also hand poured the back of the bait and then injected two more colors.
The only mold I have done this with so far is my jerkbait mold and since it isn't a Do-It mold I can't post the pics here, but...they were awesome! ;)
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Straight bodies havent been any different for me.
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Interesting, maybe try this. Start making a log of every shot you make (I did this with the Senko molds I'm selling), I kept track of temps, time of the pressure hold and how long before I open it. This way I could go back and see what I've tried and what I didn't try. I hope this helps.
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Making sure the temps of the colors are close is important but more important to me is to make sure the two colors are the same viscosity. Unfortunately that's something hard to quantify, its more of a feel thing. White can be a real dog to make lams with as it always wants to take over the other color. If I'm using white I let it cool more than the second color.
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Be certain the injectors are clean and moving smoothly. If there's any "catching" taking place you'll get weird injection results. Check and be sure your injectors are moving equally and the same time [timed] thru the whole injection too. If one starts before the other expect weird results.
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I know this doesn't help, but I kinda like the looks of those Thembonez.
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Any time the plastic coming from a twin injector has to turn a corner it will likely not inject a cleanly defined split in colors. On the swim baits with the ball at the front of the bait, I'm guessing that the ball chamber messes up the dynamics of the flowing plastic and handing you the issue. If it was a clean, straight shot into the cavity you'd get the best baits.
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Baits that have straight bodies laminate far better than baits that don't. A ribbon tail worm or a Senko will generally laminate better than a swimbait with a big belly. One thing I do to mitigate this and achieve even cooler colors is to hand pour the belly of the bait and then use my dual injector to inject two more colors. I've also hand poured the back of the bait and then injected two more colors.
The only mold I have done this with so far is my jerkbait mold and since it isn't a Do-It mold I can't post the pics here, but...they were awesome! ;)
I have seen photos of lots of baits on this site that were not from do-it molds. a pic or two might help, and besides we like lookin at what folks are doing.
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Any time the plastic coming from a twin injector has to turn a corner it will likely not inject a cleanly defined split in colors. On the swim baits with the ball at the front of the bait, I'm guessing that the ball chamber messes up the dynamics of the flowing plastic and handing you the issue. If it was a clean, straight shot into the cavity you'd get the best baits.
I was wondering about the “ball” chamber effecting the shot. But on the 90° turn spru I’ve seen the ripper Cnc molds shoot some good dual injections. What’s everyone preference on temps. Hotter side of temps or cooler?
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Less viscous(hotter) will tend to mix more. Also take your time in the shoot. Don’t shoot too fast. This will tend to spray your colors together.
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Slightly cooler plastic will probably give you better twin injections if you're doing the 90 degree thing. By the way, you can get some pretty nice baits doing the 90 degree injections but straight in injections will give the best color separation. Straight lines will have to be done with a plate. Personally I like two color baits with some blending at the color merger....they look far more natural.
That ball chamber would bother me if it were my mold, but I'm about ready to spring on a mold that it cut just like that one you have. A friend and I want a certain bait and can get the mold but it too has that round cut-out ahead of the bait and after the runner. We want this mold for two color baits, but we're looking at tail color, not a split color so that chamber should not matter. But I'd bet a buck that the plastics are swirling in that round spot and is why you're getting fudged bait coloring.
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I wonder what the purpose of that cutout is? Pretty sure it’s a standard injection port. If its important to lam this bait and your sure that the cutout/restriction is causing your problem, it can probably be removed. Clamp the two halves together with c clamps and with a 5/8 inch bit on a drill press looks like you could cut it out. Not sure why it’s there? Maybe it was the designers way of creating extra plastic to draw from as the bait cooled. Unnecessary in my opinion. Just a longer straight runner will do the same.
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I am looking at your pics....Your problem here does not have anything to do with your mold gates.... This is a viscosity issue. Hopefully you are using accurate thermometers. (probe style, not point and shoot style).
Colorant will act the same as softener which will speed(thin) the viscosity. So when shooting lams, if you have exactly the same amount of colorant in each color, the viscosity will be the same, so shooting within about 10 degrees of each other will produce a 50/50 lam. If one color has more colorant, the viscosity will be thinner(faster) in that color, so the thicker(slower) viscosity color will need to be hotter than the other to get a perfect lam because it will flow slower. This is not a perfect science, as there are many variables. i.e....If you use a lot of powder in one color and not the other it will slow the viscosity too.
I would bet you have more colorant in the darker color here. Try it again with the darker color hotter than the lighter color.
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I am looking at your pics....Your problem here does not have anything to do with your mold gates.... This is a viscosity issue. Hopefully you are using accurate thermometers. (probe style, not point and shoot style).
Colorant will act the same as softener which will speed(thin) the viscosity. So when shooting lams, if you have exactly the same amount of colorant in each color, the viscosity will be the same, so shooting within about 10 degrees of each other will produce a 50/50 lam. If one color has more colorant, the viscosity will be thinner(faster) in that color, so the thicker(slower) viscosity color will need to be hotter than the other to get a perfect lam because it will flow slower. This is not a perfect science, as there are many variables. i.e....If you use a lot of powder in one color and not the other it will slow the viscosity too.
I would bet you have more colorant in the darker color here. Try it again with the darker color hotter than the lighter color.
I’ll say this, and it has been stated here already. If this is the case white will be a bear to do laminates with! That white colorant really thickens up the plastisol(in my opinion) going forward I’m about done with my second presto pot and stirer (both PID heat controlled) so I’ll be able to dial in a temp and hold it. That’ll make my life a lot easier then, I should hope!
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I wonder what the purpose of that cutout is? Pretty sure it’s a standard injection port. If its important to lam this bait and your sure that the cutout/restriction is causing your problem, it can probably be removed. Clamp the two halves together with c clamps and with a 5/8 inch bit on a drill press looks like you could cut it out. Not sure why it’s there? Maybe it was the designers way of creating extra plastic to draw from as the bait cooled. Unnecessary in my opinion. Just a longer straight runner will do the same.
Not sure the reasoning behind the “ball” chamber, but it makes shooting core shots a breeze on a few other molds. Open pour that chamber and shoot. It’s almost as if it’s pre measured for this method. Haven’t tried it on these select molds yet.