Swimbait V-joint Experiment

[blazt*]

Have you considered using wood of a different density for the head only, using relatively lighter wood for the rest? Further still, what about dovetailing lighter wood to the top third or so of the rear sections to reduce roll? My thinking - and this is pure conjecture - is that adjusting ballast to kill the roll and shake may be self - defeating, because it strengthens the center of gravity. Visualize one of those bowling pin looking toys that pop right back up again when knocked over. Of course I've never built a swimbait; the thought just hit me.

[Vodkaman]

A piano hinge joint will get rid of the head shake and also get rid of your slight rolling provided you ballast is correctly. Some may scorn you for using this type of joint b/c it appearently belongs to someone lol. They are difficult to build but once youve done it once you get pretty good at it. Also with this style hinge you lose hardware weight and gain bouyancy from the added material that makes the hinge since it is lighter than the S.S. harware you would use in an eye-pin set up.

Awesome videos by the way! I know your saving someone out there goooooobs of time. I think i may build myself one of those tanks too!

Nitro98, I don't want to get into piano hinges, but if it is true, there is something to learn here. Do you have a link to a video of a piano hinged bait swimming? I think the main difference is the much reduced play with the piano hinge, yet the play in the double pin hinge is massive. In fact, out of water and hanging from your fingers, it looks positively ugly. Here is a pic of what I mean:

You mentioned the roll and you are right, the reduced play of the piano hinge would reduce the roll and probably increase the amplitude/movement. I will have a think about tightening up the hinges, reducing the play.

When you are ready to start work on the tank, pm me and I will share some ideas and experiences to help you.

Thanks for the solid input Nitro.

Have you considered using wood of a different density for the head only, using relatively lighter wood for the rest? Further still, what about dovetailing lighter wood to the top third or so of the rear sections to reduce roll? My thinking - and this is pure conjecture - is that adjusting ballast to kill the roll and shake may be self - defeating, because it strengthens the center of gravity. Visualize one of those bowling pin looking toys that pop right back up again when knocked over. Of course I've never built a swimbait; the thought just hit me.

Blatz, first of all, you don't need to be a builder to have an idea. I have designed aircraft for a living and never been near a pilots seat.

The dense wood for the first section is a great idea and I will be trying that one out. Your argument against your second idea is a strong one. I don't fancy the extra work, but it maybe something that I will try further down the road.

Notice in the videos how the roll leads from the bottom. This indicates where the water is pushing on the body. The water curls over the top of the head, pulling at the head. It then continues to curl over and pushes at the bottom. If this is true, then raising the CoG of the rear sections would only make the roll worse. Other than tightening up the hinges, I do not see a solution for the roll.

Good input, thanks.

Dave

[Vodkaman]

Three more experiments carried out today:

1 – I tried Blatz’ suggestion, of a dense wood head (V7) attached to a light body (V4). The intention being to prove that wood density makes a difference with head shake. The result was no difference, still lots of head shake.

2 – I attached the V7 dense head to the body of V3, the double pin hinged lure. For a successful test, this needed to fail and show head shake. The result was head shake.

This proves that the head shake solution is in the double pin hinge. It could either be the rounding of the head section (no V shape) or the mechanics of the double pin hinge itself. Rather than make or modify another head, to test the rounded head idea, I decided to test the hinge itself on lure V3.

3 – I immobilized the hinge in the head of V3 (double pin hinge) with rolled up paper. The result was head shake. I then removed the rolls of paper and the head shake was gone.

Explanation – referring to the two PDF files attached, diagrams 1 to 4 describe the pin – eye hinge and diagrams 5 – 8 describe the double pin hinge.

DP theory_Sheet_1.pdf

DP theory_Sheet_2.pdf

The water flows across the head and starts a vortex. The flow turns back and pushes the second section along its length, causing the side movement.

Diagrams 1 and 2 show the effect of the water pushing on the end of section 2, resulting in the swing of section 2, just like pushing a door open.

Diagrams 3 and 4 show the effect of the water pushing close to the pivot hinge of section 2. There is no leverage to move section 2 alone, so the force rotates both sections 1 and 2 around the centre of gravity of section 1, resulting in head shake.

Diagrams 5 and 6 show the effect of the water pushing on the end of section 2, resulting in the swing of section 2, just like pushing a door open (same as diagrams 1 and 2).

Diagrams 7 and 8 show the effect of the water pushing close to the pivot hinge of section 2. The extra pivot in section 1 allows section 2 to move without dragging section 1 with it, resulting in no head shake.

This is all my theory/opinion and may or may not be true, but it does fit.

Conclusions – This suite of experiments has convinced me that wood density and ballast placement has very little effect on how a swimbait performs. If the ballast is placed too high, instability will result. This is just as well, as the opportunities for varying ballast location is very limited. If a swimbait does not swim, moving the ballast or changing the material is not going to fix it in my opinion.

Flat head or rounded head made very little difference.

If head shake is a problem for you, then you need to reconsider the hinge type.

These experiments are only valid for the low nose geometry body. Whether things will be different for other shaped bodies, I don’t know, but I suspect not.

This concludes this set of experiments. Should I decide to do more, I will start a new thread.

Dave

DP theory_Sheet_2.pdf

DP theory_Sheet_1.pdf

DP theory_Sheet_2.pdf

DP theory_Sheet_1.pdf

DP theory_Sheet_2.pdf

DP theory_Sheet_1.pdf

DP theory_Sheet_2.pdf

DP theory_Sheet_1.pdf

DP theory_Sheet_2.pdf

DP theory_Sheet_1.pdf

DP theory_Sheet_2.pdf

DP theory_Sheet_1.pdf

DP theory_Sheet_2.pdf

DP theory_Sheet_1.pdf

DP theory_Sheet_2.pdf

DP theory_Sheet_1.pdf

[mark poulson]

Dave,

Thanks for all the hard work, thought, and analysis. It's very generous of you to share this with the rest of us.

I never considered how the force of the water would act differently on each part of each section.

That makes perfect sense, and makes the double pin hinge a great solution, and you diagrams and explanations make it understandable for me.

Thanks again.

Mark

[SmokeyJ]

Nitro98, I don't want to get into piano hinges, but if it is true, there is something to learn here. Do you have a link to a video of a piano hinged bait swimming?

I have no idea if the piano hinge is why it swims without the roll (or if this is even what you mean by piano hinge), but this baby swims beautifully.

[Anglinarcher]

Video No3:

Four lures have now been tested.

Video 1 - proved that rear facing joints have a stronger action than front facing V joints.

Video 2 - proved only that it was possible to minimize head movement, but with too many variables changed to identify the controlling factor.

Video 3 - proved that forward/rear placement of the ballast does not control head movement.

The variables introduced in video 2 are: density and joint flex.

Joint flex - I attempted to explore the joint flex idea, by increasing the flex of lure V2 (2^nd lure from first video) and also lure V4 (forward ballast location). Neither test reduced the head movement. I addition, closer examination of the videos, shows that the head is moving before the segments. This virtually eliminates the joint flex argument. This could be confirmed by building a double pin hinged lure of light density. I intend to test the density angle first, as I don’t relish the idea of building a swimbait that is destined to fail.

Density – there is a reasonably strong argument for density causing the head movement. As the water flows over the head, it is pulling or dragging the head. An increase on body density would increase the inertia, resisting this tendency. I intend to test this idea next, by fitting 30% of the front section ballast in the top/rear of the body, using low density wood. This will increase the inertia, simulating a high density wood.

Nose design – The shape that I chose for these tests was a low nose location, below the centerline. I am now inclined to think that a high nose location would eliminate the head movement, as the water will be pulling on the throat rather than the head. After the inertia and joint flex tests, this will be the next test.

I am tempted to build another double pin hinged lure, using light material, all other features identical to V3 (DP hinge). This would be a direct comparison for density as the head shaking factor. But again, this feels like a wasted build, when I could be testing the inertia theory.

Sorry if this read has been complicated, but this is what prototyping is all about. I welcome any other thoughts or ideas on the head shaking phenomenon.

Dave

I was just reviewing the videos again and I noticed that Version 3 revised differed from versions 1, 2, & 4 in rotational flexibility about the longitudinal axis. Version 3 R had a fair amount of roll from the second segment back while the head remained stable.

Is it possible that the loose hinges allowed the excess energy to be absorbed by the enhanced rotation of the rear segments?

[Vodkaman]

I was just reviewing the videos again and I noticed that Version 3 revised differed from versions 1, 2, & 4 in rotational flexibility about the longitudinal axis. Version 3 R had a fair amount of roll from the second segment back while the head remained stable.

Is it possible that the loose hinges allowed the excess energy to be absorbed by the enhanced rotation of the rear segments?

Good observation and you are correct, the over generous play in the hinges allows the segments to roll more.

Since this thread died, I have continued testing. I have built ten swimbaits and tested numerous variations/combinations and nine hinge variations. I have even designed a new hinge. Still, the goal of building a swimbait with zero head shake and zero roll eludes me, but I am getting close.

The single jointed rear segment does give a false representation of the amount of roll, but the roll forces are there, otherwise it wouldn't flop from side to side. I have since changed the body design to incorporate two hinges in the rear joint. This reduced the appearance of the roll, but it is still there.

I have more ideas that I want to test, but to be honest, I got tired of having to carve the bodies. It takes 90 minutes to prepare and carve each body and this became tiresome, knowing that it is only going to swim up and down my test tank about 20 times and then retire.

It is doubly frustrating having a duplicator machine next to were I work, but it was only designed for small cranks upto 5" length. So I have shelved the swimbait testing while I design and build a new duplicator machine, this time with a 15" length capacity and a half depth capacity of 2.6", this should cover all my future swimbait needs. Once this is built, I will be much happier to turn out a new body for an insignificant or low possibility test.

My personal goal remains to build zero roll and zero head shake. I am starting to think it may not be 100% possible, but I will get as close as I can.

Dave

[Anglinarcher]

Good observation and you are correct, the over generous play in the hinges allows the segments to roll more.

Since this thread died, I have continued testing. I have built ten swimbaits and tested numerous variations/combinations and nine hinge variations. I have even designed a new hinge. Still, the goal of building a swimbait with zero head shake and zero roll eludes me, but I am getting close.

The single jointed rear segment does give a false representation of the amount of roll, but the roll forces are there, otherwise it wouldn't flop from side to side. I have since changed the body design to incorporate two hinges in the rear joint. This reduced the appearance of the roll, but it is still there.

I have more ideas that I want to test, but to be honest, I got tired of having to carve the bodies. It takes 90 minutes to prepare and carve each body and this became tiresome, knowing that it is only going to swim up and down my test tank about 20 times and then retire.

It is doubly frustrating having a duplicator machine next to were I work, but it was only designed for small cranks upto 5" length. So I have shelved the swimbait testing while I design and build a new duplicator machine, this time with a 15" length capacity and a half depth capacity of 2.6", this should cover all my future swimbait needs. Once this is built, I will be much happier to turn out a new body for an insignificant or low possibility test.

My personal goal remains to build zero roll and zero head shake. I am starting to think it may not be 100% possible, but I will get as close as I can.

Dave

Dave,

Have you considered, now that the body shape is set and hinges are your only variable, making the swimbaits out of urathane, using silicone molds? You can make up body sections in about 10 minutes and you can drill, sand, cut, etc., just like wood. Using microballons or metal powder as an addative, you can adjust your specific gravity to match any wood, and be more consistent.

Just an idea, I'm too lazy to use wood anymore. LOL

[Vodkaman]

Dave,

Have you considered, now that the body shape is set and hinges are your only variable, making the swimbaits out of urathane, using silicone molds? You can make up body sections in about 10 minutes and you can drill, sand, cut, etc., just like wood. Using microballons or metal powder as an addative, you can adjust your specific gravity to match any wood, and be more consistent.

Just an idea, I'm too lazy to use wood anymore. LOL

The lowest SG that I ever managed using resin and micro balloons was SG=0.7 and then it was not pourable. You certainly cannot match any wood generally used for lure building.

But even at SG 0.7, it would still be usable for making swimbaits and it is a very good solution, used by many of the successful swimbait builders. It would solve the sealing problems, which is the main drawback of wood. You could justify spending a few days carving detail on the master, knowing that it will be faithfully reproduced.

I simply do not have access to the materials required. Believe me, I have tried, but the RTV suppliers etc will not send to Indonesia, the import duty people give too many problems and then there is the corruption. I am still trying to source materials like RTV, micro balloons, polyurethane resin and even decent epoxy locally, but not having much luck. So I design my production around what I do have available.

I started cutting wood for the duplicator today, it is looking good. I have another machine, still in the design stage, that will enable carved detail to be reproduced, also it will cut bibs, fin and tail parts. It is a complex machine and a long way off, but looking promising.

Dave

[Vodkaman]

Duplicate post, please delete.

Edited May 12, 2011 by Vodkaman

[Anglinarcher]

The lowest SG that I ever managed using resin and micro balloons was SG=0.7 and then it was not pourable. You certainly cannot match any wood generally used for lure building.

But even at SG 0.7, it would still be usable for making swimbaits and it is a very good solution, used by many of the successful swimbait builders. It would solve the sealing problems, which is the main drawback of wood. You could justify spending a few days carving detail on the master, knowing that it will be faithfully reproduced.

I simply do not have access to the materials required. Believe me, I have tried, but the RTV suppliers etc will not send to Indonesia, the import duty people give too many problems and then there is the corruption. I am still trying to source materials like RTV, micro balloons, polyurethane resin and even decent epoxy locally, but not having much luck. So I design my production around what I do have available.

I started cutting wood for the duplicator today, it is looking good. I have another machine, still in the design stage, that will enable carved detail to be reproduced, also it will cut bibs, fin and tail parts. It is a complex machine and a long way off, but looking promising.

Dave

You can get lower SG's by slush molding or roto molding, but it adds a little extra time.

Still, with what you are telling be about availability, I would be doing exactly what you are. I feel for you man, I really do.

[Vodkaman]

You can get lower SG's by slush molding or roto molding, but it adds a little extra time.

Still, with what you are telling be about availability, I would be doing exactly what you are. I feel for you man, I really do.

Ah yes, I forgot about the cavity methods in my statement. You are correct, all the densities can be covered. Appologies,

If I ever get my hands on the materials, I will be seriously looking into the double axis roto-casting method, I think it has great possibilities. There was a very good thread on this a few weeks ago. I think I just like designing and building machines

Dave

[nitro98]

Nitro98, I don't want to get into piano hinges, but if it is true, there is something to learn here. Do you have a link to a video of a piano hinged bait swimming? I think the main difference is the much reduced play with the piano hinge, yet the play in the double pin hinge is massive. In fact, out of water and hanging from your fingers, it looks positively ugly. Here is a pic of what I mean:

You mentioned the roll and you are right, the reduced play of the piano hinge would reduce the roll and probably increase the amplitude/movement. I will have a think about tightening up the hinges, reducing the play.

When you are ready to start work on the tank, pm me and I will share some ideas and experiences to help you.

Thanks for the solid input Nitro.

Sorry I havent replied, been busy with life lately and not a ton of time for fishing or making lures. Hows your project going? Here is a link of one im made a little while back. Havent played much more with it but as you can see it has a much different action than you get with the conventional joint set up.

http://www.youtube.com/watch?v=nr2XGIZgTTQ

[Vodkaman]

That lure certainly has a lively action. I am not sure it it is the hinge type, body profile, nose shape or the fifth section.

My next series of tests will be based on a bunker design, which is similar to the profile that you have used. I will be exploring nose shapes amongst other things, as well as refining my hinge.

Still a few weeks off before I get back to the project. Currently I am trying to figure out the fitting of all the spindles and bars across the span of the duplicator machine, eight in all. For the machine to work, all have to be perfectly aligned, it is a bit of a headache. After that, I have to build the beam, sort out a motor and fix the electronics.

I am interested to see how you did your hinge and would like to see a pic if possible.

Dave

[mark poulson]

Dave,

In my experience, adding additional sections does lead to a more snake-like swimming motion. The most I've done is five sections, and that lure slithered on a slow retrieve.

But every joint is more time, and I'm lazy, so I do three and four piece lures, and call it a day.

[nitro98]

Vodkaman, Check your inbox.

By the way it is a four segment bait made of resin with a fibbet tail. There is a fine line between looseness of joints and action. To loose and you will never get the ballast correct to keep it from rolling. Too tight and you will have to put a brick on it and burn it though the water to get it to swim. To me the eye screw and pin joint at best will give you the action of a triple trout. And that is fine cuz its a damn good bait. But to me the piano hinge allows you to work the bait slow or fast, and has a slicing action on the pause, less of a mechanical look plus no gaps.

I have been working on some other joint ideas but havent gotten around to finishing. Got a little side tracked on manufacturing and materials and other ideas.

[Vodkaman]

Mark - I am happy with the movement of 4 sections, but the extra sway from that fifth section tail is very nice too.

I am planning a 15" snake lure, which will have seven sections. I am going to see if I can get it to swim with the head out of the water, for a touch of realism. I do forsee problems with this design idea, but it has to be tried.

Nitro98 - good points on the hinge gaps. I found that the slightest burr or rough edge can destroy the action completely. It seems that the hinge gap is one of the most important control points on a swimbait. Thanks for the PM.

Dave

[nitro98]

Id say it is 1B, 1A is the understanding of volume of your bait vs the volume it displaces and how it relates to your ballasting.

[mark poulson]

Mark - I am happy with the movement of 4 sections, but the extra sway from that fifth section tail is very nice too.

I am planning a 15" snake lure, which will have seven sections. I am going to see if I can get it to swim with the head out of the water, for a touch of realism. I do forsee problems with this design idea, but it has to be tried.

Nitro98 - good points on the hinge gaps. I found that the slightest burr or rough edge can destroy the action completely. It seems that the hinge gap is one of the most important control points on a swimbait. Thanks for the PM.

Dave

Offhand, I'd think that making the first section of the snake bait long enough to let you shape it like a banana, with the head up, but enough body in the water to support it, would be a way that would work without having to go to some sort of lamination of light wood over heavy.

If you attack it like you do all your other projects, it should be fun and enlightening to follow your progress, and I look forward to reports.

I have a rule of thumb for swimbait jointing, at least for four piece swimbait jointing.

When I'm done, the bait should fold into a U when held head down, and the last joint should be very loose. I get them to swim at a crawl if they have that jointing.

Edited May 16, 2011 by mark poulson

[sambennett]

I've been trying to decide if this thread makes me want to start some jointed swimbait experiments or dissuades me from the endeavor entirely. Either way, it's a good read, so thanks very much for sharing your results. Valuable stuff.

-Sam

[nitro98]

if you make swimabaits you will be doing these experiments one way or another

[DeltaMan]

Hey Vodkaman,

Recently i made a reverse jointed swimbait and it turned out sick..... Just thought i would let you know

[Vodkaman]

Hey Vodkaman,

Recently i made a reverse jointed swimbait and it turned out sick..... Just thought i would let you know

I am not sure what you mean by reverse jointed. Can you post a pic. A vid would be very nice.

Dave

[DeltaMan]

Sorry, a forward facing C joint. I say C because it's not really a V

[Vodkaman]

Sorry, a forward facing C joint. I say C because it's not really a V

Absolutely right, but this type of joint is traditionally called a VEE joint.

Dave