Vodkaman

Another thought; note the 'nose down' angle of the completed lure. Now, at the leveling stage, balance to a 'nose up' angle of the same value. On completion, the angles will cancel out. Dave

Yes, please do post your results, it will be helpful for me at least. I could take my CAD experiment further, but I will hold on it for now. Fingers crossed for a good result Dave

There is always a way to 'wing it'. What I would try, is to take the correctly balanced assembled lure without top coat, and balance it over a knife edge, say the body of a pencil, and mark the balance point. Measure the distance from the tow eye. Complete the topcoat and repeat, find the position of the new balance position. The difference between the two measurements is the correction distance for the next lure, this may only be a few millimeters (keep notes). On the next build, after balancing level, mark the pencil balance point. Now, either add lead to the rear or drill lead from the front, enough to move the balance point the correction distance. Do the float test again and make a note of the nose up angle for next time. Complete the top coat, re-test to check for level. Hopefully the next build will be close if not perfect. Subsequent builds you can make small adjustments accordingly. On future builds, instead of balancing level, you will aim to balance nose up at the same angle that you noted down. If you have read any of my posts, you will understand that I take the scientific approach. I am sure other builders will offer up more user friendly ideas Dave

I must admit that I struggled to get my head around this problem. I understood that it was to do with the body shape and the addition of a heavy topcoat which shifts the COG. I assumed an Etex density of 1.2g/cm³ which I figured would move the COG forward due to the thicker part of the body. I was just about to post the idea, but decided to find the density of Etex Lite. The density is 0.97g/cm³ which actually makes it slightly lighter than water. This changed everything. My argument would actually prove that the lure would go nose up, so further investigation had to be done. I modeled a shaped body and constructed the Center of floatation, the upward force of the wood. You would then fit the hardware and arrange your ballast so that the COG was directly below the COF, this would give a horizontal attitude, you achieved this by trial and error which is fine. I then modeled the Etex coating at 0.5mm thick and constructed its COG, which was actually aft of the lure COG by 7.5mm. So, the minimal float effect of the Etex aft of the COG causes the nose to dip. Obviously the solution is to drill out a little of one of the forward weights and repair the hole. Unfortunately, I cannot give you an exact number for the lead to be removed as this is totally dependent on the lure size and shape, so you are stuck with trial and error. I suggest drill a small amount, seal with CA glue (superglue) and test, repeat until you get your desired float, then repair your hole. Another solution might be to make the first coat just on the front third of the body, but this would have no guarantees of getting a level float. Incidentally, if you had used D2T which is heavier than water, you would have had a nose up problem. This was an interesting exercise. Not much help I am afraid, but at least you know the reason why. Dave

I have read that brake fluid works. Do a TU search for articles. Not recommended for plastic lures. Dave

As WoodieB8 correctly pointed out, the pressure at 150ft is 65psi. This is not that great a number, in fact your shop compressor is easily capable of generating such a pressure. If you placed your lure in a steel box and cranked the pressure to 65psi, would you expect it to fall apart, I don't think so. Air compression under pressure - 14.7 / 65 *100 = 22.6% Air in a balloon will compress to 22.6% of its original volume. Yes, this is huge. Wooden body - the outer skin is supported by the wooden structure, and so the air within the wood is NOT compressed. Solid resin body - zero compression. Hollow plastic body - this is the only situation under question. Can you deform a hollow body between finger and thumb? How much pressure can you apply with finger and thumb? What area are you applying that pressure over? Let's look at this from an engineering point: Looking at my finger and thumb compression area, I make it roughly 1cm2, approximately 1/6th of a square inch. In other words, if you an apply 10.8Lbs force with no deflection of the body wall then you are good for 65psi. Put 5Ltr of water in a bucket minus the weight of the bucket and pick it up with the tip of your finger. This is the force of 65psi. It is a bit of a struggle, but you can certainly more than achieve this pressure with a body pinch. I would say that 150ft depth is no problem for any lure. Dave

I would love to jump in on this post, but everything I want to say has already been said. Dave

Your lure body is fairly high in the back and shallow bottom. You obviously understand the mechanics of COG and ballast, it is just something to be taken into account at the artist stage. Personally, I draw the hardware and then draw the lure around it. Sure it is nice to have the eye on the tip of the nose, like it was meant to be and not an after thought. But the only way to achieve this is to draw the nose where it needs to be rather than accurately reproducing a bait fish. A slightly flatter back and slightly deeper belly would achieve a good compromise. Dave

The only thing left to try on this body is to move the eye position. I assume the tow eye is in the nose. Try various positions, I would try between the eyes. Lifting the eye position effectively raises the rotation axis and will make the ballast function more effective. You don't have to drill for testing, you could whip an eye on the lure with cotton thread. You must milk the prototype for every last piece of knowledge. Dave

I may have mixed glider with jerk baits in my comment above (post 2). LHL (post 12) makes a lot of sense, horizontal = longer glide. But, something has to create a vortex in order to generate the side movement. With jerk baits and glider baits it is a single vortex which changes the direction for the rest of that cycle. It strikes me that if the glider is aligned with the direction of the tug then no vortex is generated. The taking up of the slack line before starting the jerk retrieve is possibly aligning the lure with the pull direction, in which case the first jerk should be off to one side. I think I am out of my depth here due to lack of experience, so I apologize if I gave out bad information. Dave

Papa - we all did it Dave

Another tip when testing prototypes, it doesn't apply here but is worth remembering. 'Only change one thing at a time'. Sometimes after a swim test we think 'this needs doing, that needs adjusting'. But, if you do all the changes in one go you will never know what worked and what didn't, or the effect that each change actually made. Also, ALWAYS test with the hooks fitted. Dave

It is because the lure sits level. The lure must be 'nose up'. I suggest a test on a lure you have already built. Wrap some solder or attach weight to the rear hook so that the lure sinks significantly 'nose up', say 30 degrees, then test it again. In fact, try several angles and note the results. Dave

I only did a few minutes searching the casing alloy, and the figure of 1027C came up. It will obviously need a more detailed search. Yes, some kind of kiln, but this too will need research. With today's internet this should not be a problem. I expect that you could find a 'how to' video on the subject. Certainly I know there are such videos for aluminium. The jig molds would have to be steel. Dave

The main issue is that Copper-brass alloys (red brass) have a melting point of 1027C, considerably higher than aluminium which melts at 660C. The next issue is that a specialized furnace would have to be designed and built in order to reach such temperatures. In the past, I have looked into smelting aluminium for another project, and that is right on the limit for normal crucible melting. Dave

What you want is for the lure to float the same as the commercial lure that you are copying. In technical terms; you want to match the density of the lure as a whole, including hooks and all hardware. There are two ways to achieve this; a none-technical method and a technical method. None tech – Float the commercial lure in a pan of water. Observe how much of the lure sticks out of the water. Also, you need to match the angle that the commercial sits, this also is required to be duplicated. Tape lead to the body until the same float is observed. Move the lead around until the angle is duplicated. Tech – As mentioned above by Eastman03, the Archimedes dunk test will enable you to get a very accurate fix on the density and how much weight you will need to add. This requires the use of a gram scale. You will still need to do the float test to determine the angle of float. Most builders will settle for the float test, plenty good enough for this job. Dave

Shepherd 1 - This is very old and famous puzzle, I have come across it before. 2 - The answer is easy but the explanation of the logic is complex. 3 - The puzzle can be found with Google. If I answered, then you would have to figure out if I was telling the truth! Dave

Yes it would, but very slight and not noticeable. The science is all tied together with Reynold's number, which includes many variables like temperature, density, viscosity and more. Vortex shedding (the lure's X-ing motor) is a very mechanical thing. But as you know, an increase in temperature makes the water slightly thinner, so a neutral lure will slow sink. The vortices will form faster and so the X-ing will speed up. Good question Dave

I am tempted to write a technical post on Strouhal number, a simple formula that can predict the cycles per second of the lure. But, I have settled just to sum the subject up in a few simple facts. 1 - If you double the retrieval speed then the cycles per second doubles. 2 - If you double the lip width then the the cycles per second halves. 3 - Most importantly, there is a minimum speed for the function of a lure's action. If you intend to retrieve as slow as possible, you will need to give a brief tug to start the X-ing and then slow down to your desired speed. The minimum speed is best predetermined at the water's edge before fishing commences. There is no minimum width of the lip, the speed becomes so fast and the width of the lure movement becomes so narrow that the wiggle cannot be seen. Note - a complete cycle comprises a left AND right movement. Good luck in counting them Dave

X-motion is wholly controlled by the width of the lip. Simply make the lip narrower, the length can stay the same. Dave

I am retired now, but unfortunately I spent my money on wine, women and squandered the rest. I once approached a large lure business with my ideas but did not even receive a reply, their loss not mine. I have worked hours as a contractor that would make your toes curl, but was paid well. Unfortunately my investment in my local beer establishment did not pay off. I have designs, but no money to develop. Investors welcome Dave

I feel you mate. I am retired, but I have done the hours in my time Dave

It is not that difficult mate. Persevere, it only has to be learned once Dave

You must upload to YouTube, then paste the link into TU. Dave