Floating Resin For Hard Baits

[CNC Molds N Stuff]

The recent thread on sealing wood got me thinking.  I really would like to make a nice floating wake bait with the action of a Kicktail Lure, but I don't have the skills or the patiences to seal and paint wood.  On the other hand if I could find a slightly buoyant resin (just enough to touch the surface with hooks and hardware) I am sure I could design and cut my own mold for a bait to fit that niche.  

 

So what is there that will pour or cast, that is strong, and floats?  

 

 

[JimP]

Bob:

AlumiFoam sounds like what you are looking for. (Click here for a link)  This makes a 20 pound per cubic foot foam.  You will still need to add blast to reach your target buoyancy.

Be forewarned some have problems with this resin, sealing and painting.  Make sure you read the details about cure time, its very quick.

[Vodkaman]

The foam may be a bit light for what you want. 20 Lb/cuft is a specific gravity (SG) of 0.32 (water SG=1).

 

Smooth-on feather lite is 41.3 cu in/Lb which is an SG = 0.66

 

I think the feather lite will be better suited for this application.

 

Dave

[token12]

The foam may be a bit light for what you want. 20 Lb/cuft is a specific gravity (SG) of 0.32 (water SG=1).

 

Smooth-on feather lite is 41.3 cu in/Lb which is an SG = 0.66

 

I think the feather lite will be better suited for this application.

 

Dave

x2

[Jdeee]

X3 Vodkaman has it exactly right.

[Vodkaman]

Bob - I think one day we are going to have to collaborate, design and manufacture a lipless swimbait mold, incorporating the double pin hinge. The ballast and hardware will be molded in. The hinges will be fitted into the pre-molded holes after painting and top coating.

The mold will also include lead pouring, so that the correct size lead slugs will be made for the desired lure. The mold will provide for three options; a floater, suspender and sinker, depending on which lead slugs are fitted.

If a standard part cannot be found for the figure 8 hinge wires, inserts could be included to aid the manual forming of the hinge wires.

The mold would be designed for a specific resin, like the above mentioned feather lite, a particular hook size and split ring size and hinge pins. This would enable me to determine the amount of ballast and the exact positioning so that the lure was as close to perfect and consistent with each pour.

A five section shad or crappie in a 2:1:1:1:1 ratio with fins and tail molded in. Gills, eye sockets and even scales molded in.

It is a monster job from my side of the fence, probably a couple hundred hours and obviously a high risk from yours, given that the lure might not work first time or even second. But, I think we could make something special.

This would have to be an on-going project, as I am snowed under with car design work at the moment.

Let me know what you think.

In the mean time, I would be glad to help you out with some CAD work for your project.

Dave

[CNC Molds N Stuff]

I was thinking of a mold with a pin through it for the hinges.  You pull the pin, then open the mold.  Not knowing how tough the resin is I was thinking the eyelet could be a piece of stainless wire that goes back and forms a loop inside the plastic hinge to act as re-bar.  Once the dynamics of that is figured out I thought a fixed pin bending jig might allow for rapid shaping of wire forms.  Then only slight tweaks of the wire form would be needed to set it properly in the mold.  

[Vodkaman]

Yes, you've got it pretty well figured out.

 

I am not sure if the small eyelets used on the plastic commercials would hold in resin, someone with experience will have to advise on that. The rebar idea with a longer wire will certainly do the job.

 

Dave

[woodieb8]

if your going with 16lb foam the insert pins wont cut it on a foamy. wire thru would be the option and lead inserts weve been doing urethane mold/foam. good stuff but gass-off can be an issue if not prepared corrsectly. plastic injection,costly but the best alternative from what I see.. doing a segmented mold,hope your planning production to absorb cost over time. just my thoughts.

[CNC Molds N Stuff]

Well, obviously I would cut the mold/molds myself between other jobs, so the biggest cost is time not spent doing paying work.  

Edited March 31, 2015 by Bob La Londe

[CNC Molds N Stuff]

The foam may be a bit light for what you want. 20 Lb/cuft is a specific gravity (SG) of 0.32 (water SG=1).

 

Smooth-on feather lite is 41.3 cu in/Lb which is an SG = 0.66

 

I think the feather lite will be better suited for this application.

 

Dave

 

That is the lightest resin on that page as near as I can tell, but its extremely weak.  No compression strength to speak of and very low tensile strength.  It would require some form of hard shell finish, or the first fish that bit down hard I think would crush it flat.  

[Vodkaman]

That leaves a problem then, because pure resin is too heavy and so you will have to measure out and mix your own microballoons. After resins and foams, I don't know where to go next!

 

I have crammed MB's into resin and one thing I can say is that no fish is going to crush that material. I have never used feather lite, so you will have to take advice from someone who uses it.

 

After the crush factor, the next quality is brittleness, how will it stand up to the rocks. Finally, burst out strength for the hinges. A wall thickness of 5mm over the length of the hinge is more than enough I reckon.

 

Dave

[token12]

I currently use feather-lite resin.  Easy to use and mix with a 1:1 ratio.  I caught one last weekend about 2 1/2 pounds on a glide bait i have designed.  I have also caught a striper on a flat sided crank bait i made with feather-lite.  As far as the crushing of the bait, i've haven't had it happen to me yet.  The maker of the bull shad swimbait  also uses a resin to make his swim baits.  Best advice I can give is this, try it and experiment.  The feather-lite for me, after curing, is hard as a rock. Not to mention I just epoxy in the line tie and the hook hangers into the resin lures and haven't had any problems yet.  
 

[Jdeee]

I have used feather lite on musky baits, never had a complaint yet. I coat them with Etex. Even if it gets destroyed, they only cost a couple of bucks to make. Guys buy bulldawgs and such for $25.00 and they get destroyed after one fish sometimes. No loss no gain.

Edited March 31, 2015 by Jdeee

[SLT785]

If you go to the Smooth-On website, they profile a lure maker that uses two of there products to get the buoyancy he desires.

[CNC Molds N Stuff]

v-man,  I just emailed you some pictures.  I don't want to do a knock-off of course, but it might give us some inspiration or insight into good solid hydro dynamics that work.  

[Vodkaman]

Got it, thanks - email sent.

 

Dave

[CNC Molds N Stuff]

For anybody who might be interested Dave and I have been going back and forth on this design and we have come to a standstill.  In a size small enough for a good shad profile its hard to get enough buoyancy and have reasonably strong hardware.  Even bumping it out to 4.25 inches gives us a sinker with the size wire, pins, hook, etc I want to use when going with the Featherlite resin.  I'm still not convinced that resin is strong enough for the application.  Maybe for a single piece hard shell finish, but the hinges are a huge weak point.  I wanted to do wire reinforced, stainless pinned hinges, but Dave is convinced the resin would be two thin and would break.  I think it will break if its not reinforced.  

 

We are still playing with it, but I doubt we will have anything positive for a long long time.  

 

FYI:  This is a personal project.  Not something I intend to sell.  

 

Sometime in the next few weeks I am going to order some samples of thinner stainless wire in spring temper (full hard) and see if we can shave some weight that way.  I am just afraid if we use wire that is too thin for the tie and hook loops bass will fatigue it and break it with their head shake, and that light hinge pins might jerk out.  I'm thinking a spring temper stainless might resist both of those issues a little longer allowing us to go thinner and lighter.  

 

So far its not looking like we can make a better mousetrap easily.  

[Vodkaman]

It is a very pretty design though

 

Dave

[mark poulson]

Maybe you guys could look at the Spro Baby BBZ as a guide.  Their baits are hollow, so they have air for buoyancy.

 

http://www.tacklewarehouse.com/Spro_BBZ-1_Baby_Shad/descpage-SBBZ1BS.html

[CNC Molds N Stuff]

A hollow bait is certainly one way to go.  Air is the most buoyant material we can work with somewhat easily.  There are several ways to get there.  A closed cell foam is probably simplest for the home shop bait maker, but its even weaker than the featherlite.  Blow molding is probably the cheapest and easiest for large scale production, but its not really practical for the DIY builder.  Clam shell is possible to do.  There are two approaches that might work in the garage.  Some form of paint in resin to make the two halves and glue them together just like they make bass boats.  A little more involved, but not requiring so much secondary work might be to use something like a Gingery injection machine and two molds to make the two halves of a clamshell.  

 

While I was typing this I came up with another idea.  Use a very light weight insert to displace resin in the top of the bait.  

Styrofoam Foam?  Earplug?  Balsa?  Balloon?  I've done similar things with soft plastics.  It could work.  

 

While high end production methods already exist I am focusing on low tech solutions that any of us could do.  

 

 

 

 

 

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[mark poulson]

Jeez, Bob, I just love it when you talk dirty!  Hahaha

[Vodkaman]

Had this been an 8" Musky bait then we could get away with some of those ideas, but at the end of the day this lure is tiny.

Clam shell hollow bait - there is enough room in the first two sections for some air, 3 minimal, 4 & 5 zero. Molding both halves of the clam shell doubles the machined area of the mold and therefore doubles the cost.

Materials - I think it would come down to a resin again for strength and hardness. A resin without the lightening fillers would be nice, but we will have to wait for the numbers. The bait becoming tail heavy may be an issue, requiring front end ballast to balance, which of course needs more air to generate and less room to generate it in.

I think this idea has to be explored fully and I will add an extra design session and come back with some numbers. We can then discuss wall thicknesses; I will want thinner and you will want thicker, but design is always a compromise.

Foams - We have both given foam a lot of consideration. It comes down to lesser strength and the lack of material around the hinges. There are other disadvantages such as inconsistency and the fear of gluing two halves of an expensive mold together. Buoyancy wise, this would solve all the problems, even using the heaviest of the foams would actually create ballasting space issues, at this point in the design, a problem that I would welcome.

Fillers - I have been down this road before; they have to be manufactured, they weaken the structure and have to be controlled. The lightest filler is air, the most efficient, consistent and easiest to control is micro-balloons, the rest are just a headache waiting to happen. There is no design change for micro-balloons, just a change of numbers in the calculations.

For consistency and ease of use, featherlite is resin pre-filled with micro-balloons (I think). We could add more, as we are already committed to injection, in order to fill all five sections and all the tiny cavities in one hit. But, your doubts as to the strength of featherlite should be compounded by adding more filler.

The paint in filler idea; the hinges are the main problem, also inconsistency.

The ideal solution would be a thin walled hot injection of a hard plastic. If we come up with anything half decent, we won't have to wait long to see that! Had this been anything more than a personal itch being scratched by both Bob and myself, mass production by hot injection would have been the direction after proving the prototypes.

Where are we now - We have a nice, realistic shape generated from a shad image. A robust hinge design, aesthetically pleasing with minimal gaps. However, the idealistic shape design is leaving problems of space around the rear two hinges and a lack of volume to support the real world hardware.

It is time for design to compromise. I have to give up the thin shad tail section and increase the depth to grab more material around the hinge. More thickness in the tail will transfer forward to the front end, giving that extra vital volume that will generate the extra buoyancy to carry the hardware.

While I am here, could someone help me out with some measurements for a size 2 treble, make does not matter, I just need something to look at and numbers for the calculations. See attached image of what I am looking for.

Dave

[mark poulson]

I don't know your actual design, but one thing I find that helps with smaller jointed lures is to only put the treble in the front section.

[Vodkaman]

I have modified the overall dimensions for the proposed compromise.

The hinges at the back look a lot more substantial and the profile still looks very reasonable, although more chunky at the back.

The new numbers for shad V9:

total volume up to 14.755cm3

resin volume14.608 cm3

hardware weight 4.921 g

resin density 0.672 g/cm3

You can use these numbers to calculate that we are 0.017 g in credit, in other words we have neutral buoyancy. BUT, this is with a size 4 treble and no top coat, so I think we are still in trouble.

For the above, I have used D1/16" steel hinge pins.

We need lighter resin or lighter pins.

Mark - I would like to show you a pic to go with this information, but that is up to Bob. Yes, single treble in front section. #4 looks OK, but really a tad small.

Dave