Vodkaman

Drying Wheel Speeds

49 posts in this topic

The question of drying wheel rotation comes up fairly often: how big, how fast etc. So I did some research and found some calculations and here is what I discovered:

Their are three variables that all affect centrifugal force, speed of rotation, distance from axle to lure and the mass of the lure.

Speed and distance are fairly easy to understand, the faster the spin, the more outward force (centrifugal force) exists. The larger the wheel radius, the faster the lure is traveling, thus the outward force increases.

Try a simple experiment: tie a length of thread to a weight. Hold the string short and see what speed you have to rotate it (vertically, like the drying wheel) to get it to spin. Now lengthen the string and repeat.

When you increase the length of the string, you do not need to spin the weight as fast as you do with a short string.

When the weight is just able to spin, the outward force (centrifugal force) is equal to the mass of the weight, so the weight essentially becomes weightless at the top of the cycle, but at the bottom of the cycle, the downward force is doubled (outward centrifugal force plus gravity effect on the weight). At this speed, at the bottom of the cycle, the epoxy would be pushed downwards to the back of the lure (back facing out). At the top of the cycle, the epoxy would be weightless and remain on the back of the lure. Clearly not a good situation, as with each rotation, the epoxy would gather to the back of the lure.

The ideal wheel speed for even distribution would be next to zero with no centrifugal forces, but of course, the epoxy would fall and harden before it had a chance to distribute. So what is the ideal wheel speed? Well, you need as many rotations in the epoxies fluid state as possible, to aid leveling, with the least force applied centrifugally, in other words, the solution is going to be a compromise.

But we do not need to get involved in words and numbers like centrifugal forces. In fact, we don’t even have to know the weight of the lure or more relevant, the weight of the wet epoxy. We could let the above condition be 100% and decide what percentage of the above ‘spin’ example would be acceptable. One percent seems like a reasonable place to start. This means that the forces on the epoxy would be 1% heavy at the bottom of the rotation and 1% light at the top of the rotation.

I did some calculations based on the 1% scenario. What this means is that each of these conditions should produce the same epoxy distribution results.

Wheel radius/rpm combinations for 1% centrifugal force condition:

1” radius = 18.8 rpm / 2” radius = 13.3 rpm / 3” radius = 10.8 rpm / 4” radius = 9.4 rpm / 5” radius = 8.4 rpm

6” radius = 7.7 rpm / 7” radius = 7.1 rpm / 8” radius = 6.6 rpm / 9” radius = 6.3 rpm / 10” radius = 5.9 rpm

15” radius = 4.8 rpm / 20” radius = 4.2 rpm / 30” radius = 3.4rpm

Conclusions, it seems that the years of trials and experience of the TU members, are borne out by the calculations, wheels upto 6rpm are good up to 10” radius. What we do not know is at what percentage does the epoxy distribution become unacceptable, a future experiment with a variable speed motor.

For those interested, for more details on the calcs and spreadsheets, PM me your e-mail address. It has been a while since I posted a technical thread, I just had to get it out of my system, I feel better now.

Dave

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Wheel radius/rpm combinations for 1% centrifugal force condition:

1” radius = 18.8 rpm / 2” radius = 13.3 rpm / 3” radius = 10.8 rpm / 4” radius = 9.4 rpm / 5” radius = 8.4 rpm

6” radius = 7.7 rpm / 7” radius = 7.1 rpm / 8” radius = 6.6 rpm / 9” radius = 6.3 rpm / 10” radius = 5.9 rpm

15” radius = 4.8 rpm / 20” radius = 4.2 rpm / 30” radius = 3.4rpm

Conclusions, it seems that the years of trials and experience of the TU members, are borne out by the calculations, wheels upto 6rpm are good up to 10” radius. What we do not know is at what percentage does the epoxy distribution become unacceptable, a future experiment with a variable speed motor.

For those interested, for more details on the calcs and spreadsheets, PM me your e-mail address. It has been a while since I posted a technical thread, I just had to get it out of my system, I feel better now.

Dave

Excellent Work!!

It explains my posts last year when I went from a single bait turning at 10 RPM on it's own axis and why I could not turn a 6" diameter wheel for multiple baits without going to a slower motor. My conclusion was that you may turn as slow as possible with good results, but you cannot turn too fast with good results.

Edited by DUCBOS

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My wheel runs 6 rpm and has a 6" radius. One minor advantage - this is about as fast as you want one to run if you like to keep it running and just clip the lures on there as you epoxy them.

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Good work Dave.

Now, for the numerically challenged, like me, slow is better seems to be the bottom line.

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Nice work Dave. And you didn't even have to use the "pie r square and cornbread r round" theory. :P

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Phew ;) Dave I just went from 12 to 6 Rpm, like you have said that seems to be the consensus- I got some really good results @ 12, but the blood de-clotter motor died!!! Thats all on about 6" rad.

Thanks for the head work, good to see you posting again.

Pete

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Thanks for all the nice comments guys. I nearly didn't post this one, thought it might have been a bit too heavy.

Pete, 12rpm @ 6" rad, gives a centrifugal force percentage CFP = 2.45%, but like I said, we have to establish the limit at some point. I have the experiment method worked out, just need the motor now.

Bobs 6rpm @ 6" rad, gives CFP = 0.61

Ducbos 10rpm @ 6" rad, gives CFP = 1.7, for the record, what was the problem? Just trying to gather intel' on other peoples experience.

Dave

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Thanks for all the nice comments guys. I nearly didn't post this one, thought it might have been a bit too heavy.

Pete, 12rpm @ 6" rad, gives a centrifugal force percentage CFP = 2.45%, but like I said, we have to establish the limit at some point. I have the experiment method worked out, just need the motor now.

Bobs 6rpm @ 6" rad, gives CFP = 0.61

Ducbos 10rpm @ 6" rad, gives CFP = 1.7, for the record, what was the problem? Just trying to gather intel' on other peoples experience.

Dave

Dude, that's alot of info to digest! LOL

I've been using a rotissarie motor for a couple of years and it does well for me. It turns at 2rpm with a 14" wheel. I can load 8 large muskie cranks on it at once. I'd like to get a dc motor set up with a rheostat (spelling?) so that I can adjust the speed. I'm also building a drying box this weekend with a light on a dimmer to control temp.

jeremy

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Thanks Dave for initiating this discussion.

I've been using a 1 rpm dryer, lures placed about 10 inches from rotational axis, since slightly after the invention of the rotisserie. I've dried many lures on it without a problem, but 1 rpm is often criticized as being too slow if one uses too much epoxy.

I do get some argument from time to time, but I stand by my logic of not using excessive amounts of epoxy, versus rebuilding my wheel with a higher rpm motor.

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Vman, this is a very interesting post, and I agree with what you say. I cannot understand your calculations, but I am sure they are right.

What you are telling us here seems to confirm what I have been guessing about how to make a drying wheel as close to the ideal one as possible. In my opinion, the ideal rotator should have only one lure to rotate, and the lure should be situated on the very rotation axis. The centrifugal force would be minimum in this case, allowing the topcoat to level out in the best possible way. The rotation speed could go up to about 20 - 25 rpm in such a case, without any fear for a badly topcoated lure.

My first rotator had a speed of 15 rpm, but the disc was very small in diameter (a CD). Never saw a problem in the topcoat. After that motor died, I replaced it by a microwave motor with a 5 rpm speed. The results are perfect too, as far as I can notice.

The radius of a CD is about 59 mm, and the radius to the lure is about 47 mm (1.85"). Enough space in the disc to put on 4 lures at a time. More than enough for me. When I need to attach a new lure, I stop the motor for 3-4 seconds.

So my opinion is that instead of using a large diameter wheel, which can hold many lures (some even use 2 rows of lures on the same wheel), one should better have several pairs of small wheels on the same axis, if the number of lures is an issue.

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Rofish,

I'm no math whiz, so I can't do Dave's math, either, but a 1 rpm motor and 14" wheels gives you a lot of room to maneuver.

I've coated with D2T, Etex, and Nu Lustre 55 on it.

I have one row of hangers out at 14", and another at 7", and the epoxy is the same on both of them. Plus, for whatever reason, my rotisserie motor reverses itself if I shut it off and restart it, so I do that every 15 minutes for the first hour.

I'll bet the actual speed of the lure face as it turns that far out is probably not that much at either diameter.

All this is assuming you don't overload the lures with too much epoxy at one time.

Of course, it's too fast to fix problems while it's turning, but it's slow enough to inspect the epoxy for dry spots as it turns.

As for how fast is too fast, I don't want to find out. Epoxy is a bear to clean off anything.

Edited by mark poulson

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Mark,

I didn't know that a rotisserie motor can reverse its direction of rotation. But I do the same with my microwave motor. Shut it off and restart it to change direction of rotation. Need to do several trials until the motor understands what I want from it.

Now just imagine the epoxy would be much thinner that it actually is. How could it level out smoothly on the lure, if you had a big wheel ? You would need to increase the rotation speed, to prevent the epoxy from dripping off the lure. But in such a case you could have the surprise to do a nice work on the ceiling with epoxy. Contrary, if the lure would be situated on the rotation axis, you could increase the rotation speed so as not to lose epoxy by dripping, and at the same time you won't fear that epoxy could escape from the lure as a result of centrifugal forces.

But we have luck. The viscosity of the epoxy leaves us many alternatives as to the ratio between the radius to the lure and the rotation speed.

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Rofish,

In the case of a rotisserie motor, I think the automatic reverse might be to protect the motor in case it's not loaded evenly. But that's just a guess.

As for faster speed being better, you've made me take out my calculator.

A 14" wheel, traveling at 1rpm, spins at 44" per minute. At the 7" diameter of the inner ring, it spins at 22" per minute.

At either location, the lure turns over 360 degrees each revolution.

By my actual experience, the only time there is sagging at those speeds is if the epoxy is put on in too thick a coat.

I never vary from the 1/1 ratio by volume that the manuf. recommends when I'm coating a lure, and I measure it with syringes.

I made my wheel big so I could turn many baits at once, so the thought of a center axis turner never crossed my mind.

I think having the lure rotate at the center of the axis, suspended between the two points of rotation, would work. But it might have to be rotated at more than 1rpm, since the actual speed that the lure faces are traveling would be so slow.

A lure that's 1 1/2" tall would only rotate at 1 3/4" per minute at it's tallest point, and the nose and tail, where it's attached, would be moving really slowly.

I haven't tried that type of turner, so I can't really comment on how well it would work.

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Dave

When I ran at 10 rpm the D2T would seem to lump or clump up in areas and not cure consistently.

When I slowed down it all went away.

Thanks again for your work

Edited by DUCBOS

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Mark,

It seems to me that you had good marks at maths in school, after all :)

I am afraid I could not have explained too well my idea, so I am trying to correct this.

I never said one should actually make a lure turner for just one bait, situated on the rotation axis, because this would not be practical at all. But I did say that this would be the ideal rotator, and it would be suited for practically any type of clearcoat, because this rotator depends the least on the viscosity of the topcoat and the forces the topcoat are subject to. For practical reasons, I made a drying wheel in which I can put on 4 lures at a time, which can be easily attached or detached (the lureholder’s short handle is pushed into a hole made in a rubber material) . I also said that one should avoid a very big wheel. If you need to turn many baits at once, I think it is better to have several small wheels (or pairs of wheels, depending on the attaching system) on the rotation axis.

The same traveling speed of the lure could be achieved by varying the ratio between the rpm and the radius to the lure. But the leveling out process of the topcoat does not depend on the traveling speed only. It also depends on gravity and centrifugal force.

A liquid has some forces in it, that keep part of the liquid on the surface of the container the liquid is kept in. That force has a specific name that I do not remember now. If you pour out the water from a glass, some drops will still remain in the glass.

In the case of an epoxy, that force is much stronger than in the case of water. Still, if you put on too much epoxy on a lure, you will find out that it will sag, meaning that those forces I was talking about, will retain as much epoxy on the surface of the lure as they can, leaving the excess to gravity (and sagging or dripping is a process in time).

When rotating, the epoxy on the lure is subject to gravity and the centrifugal force.

You and others have already found out that if you put on too much epoxy on a lure at a slow rpm and a big wheel, the epoxy might sag (gravity takes its toll, in this case).

Others have found out that a big wheel, at a high rpm, will make the epoxy clump up in areas (and that’s because of that nasty centrifugal force). I think that these findings only confirm what I was talking about.

So both forces (gravity and centrifugal) have a negative impact on the leveling out process of the epoxy. How can you reduce to a minimum the action of those forces?

There is only one way to do it, and this is to reduce the radius to the lure to zero (well, almost, because the radius to the epoxy on the back and belly of the lure, which really matters, cannot be reduced to zero). And in this case you will not be able to, but you will NEED to increase the rotation speed to combat gravity (or more accurately its action on the epoxy). And believe me, epoxy will love a higher rpm, without having to bother about gravity (whose action on the epoxy is practically counteracted by a high rpm) or centrifugal force (which is almost zero).

If not convinced, make an experiment. Put a lure to turn at about 20 – 25 rpm (my guess, never did that, but I would love that someone could confirm my theory :) ), on a system that could suspend the lure on the very axis of rotation – head to tail axis of rotation. Put on deliberately too much epoxy on it, as much as you would be sure that the epoxy will sag, if you had put the lure to rotate on your drying wheel. See the results and post them to TU community.

But I have to repeat myself. The fact that the epoxy does not flow like milk, for instance, is very good for us, because in order to have good results in topcoating, one may chose from many ratios between radius to the lure and rpm.

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Very astute post Rofish, lots of good information and facts. I agree about the adhesion forces and that the centrufugal and gravity forces will mainly only effect the extra epoxy. The adhesion would be linked to the viscosity of the epoxy and I think it is fairly obvious that different radius/speed configurations will apply for different top coats, as D2T is more viscuous than Etex for example.

I actually have a local guy working on a stepper motor circuit for me. Once I get this motor back, I will be able to do the experiments that you mentioned, as I will be able to accurately control the speed upto 120rpm, possibly faster. I have a source for D2T, but when the time comes, members will have to send me samples of other coatings for testing.

Eventually, when this project is completed, we should be able to give a simple graph of radius against RPM and a curve for each top coat, indicating the safe limits. I know a lot of you will think that this is all a bit over the top, but I do actually enjoy this kind of project. Ironically, I am currently designing a new turbo charger with another engineering friend. The turbo project is using the same calculations as the drying wheel, only a bit smaller and faster.

Dave

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Vman,

Thanks, but I would not go that far with the rpm. 120 rpm is rather scary for me. I think Mark had a good reason to mention this:

As for how fast is too fast, I don't want to find out. Epoxy is a bear to clean off anything.

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Vman,

Thanks, but I would not go that far with the rpm. 120 rpm is rather scary for me. I think Mark had a good reason to mention this:

I agree, 120rpm hopefully should be too much, but that is the point of this exercise. All drying wheel discussions to date have been about what works, this discussion and subsequent testing is about finding and being able to predict what does not work, the operative word being to predict rather than guess.

Welcoming all input from experience.

Dave

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Vman,

you have got way too much time on your hands!!! LOL. I do appreciate your explanation and am glad that I seem to be doing it fairly well, albet by accident. Thanks again. Good Fishin'

Tony

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Hi Guys,

It seems that an easy way to spin lures for epoxy would be to spin them on their axis and use a brush during rotation but everyone is avoiding this because they think it will limit drying to one bait. I'm here to remind everyone that you can run plenty enough centre axis drying points with the help of some bearings, small pulleys and rubber bands as drive belts. I paint and clear all my lures before installing the hardware so to mount them on each pulley I drill the tails where each rear hook hanger will go and mount them on some 1mm tig wire pushed into the bait and the pulley, hey presto!, 10 x centre axis drying mounts and the 1mm hole in the lure acts as a pilot hole for the wire at a later date. Just some food for thought from someone who has had to make or source all their gear from scratch.

Cheers,

John.

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Welcome to TU john.

Sounds like an interesting solution. Certainly different than anything that has been done before. You should post a picture or two. Always room for another drying wheel design. You could post it here, but it would be easier to find in the future if you started a new thread with it.

Dave

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VM

I got an old sewing machine motor given to me. It didn't say on the motor how many rpms it was but when I plugged it in I knew it was fast. Too fast for turning a lure with epoxy on it. I come up with the idea of slowing it with a light dimmer. The dimmer worked to slow the motor. I can really only get the motor to slow to about 40-50 rpm. If I try to slow it more the motor doesn't seem to have enough power to turn the drying wheel. I am counting the revolutions of the lure with a watch so the rpms are an approximate. When I first tried to dry a lure with etex on it I had the motor spining to fast. I had epoxy flying off the lure. I am not sure what the rpms where when this happened. I have since turned a lure at 40-50 rpms and the epoxy seemed to be ok. I didn't have epoxy flying off the lure and the finish on the lure seemed to be smooth with no clumping. My lure drying wheels are about 7 inches in diameter and the lures set about 3 inches from the rotating axis. I think I might switch to a lower rpm motor when I come across one but this motor seems to work for now. Thought I would be my experience out there.

CLM

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VM

I got an old sewing machine motor given to me. It didn't say on the motor how many rpms it was but when I plugged it in I knew it was fast. Too fast for turning a lure with epoxy on it. I come up with the idea of slowing it with a light dimmer. The dimmer worked to slow the motor. I can really only get the motor to slow to about 40-50 rpm. If I try to slow it more the motor doesn't seem to have enough power to turn the drying wheel. I am counting the revolutions of the lure with a watch so the rpms are an approximate. When I first tried to dry a lure with etex on it I had the motor spining to fast. I had epoxy flying off the lure. I am not sure what the rpms where when this happened. I have since turned a lure at 40-50 rpms and the epoxy seemed to be ok. I didn't have epoxy flying off the lure and the finish on the lure seemed to be smooth with no clumping. My lure drying wheels are about 7 inches in diameter and the lures set about 3 inches from the rotating axis. I think I might switch to a lower rpm motor when I come across one but this motor seems to work for now. Thought I would be my experience out there.

CLM

Maybe you could reduce the speed with a pulley system, so the motor has a very small pulley, and the dryer wheel has a large one. That way, it would take many motor revolutions to turn the dryer wheel once.

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