Dipping tubes from a presto pot

[TightLine]

Last year was my first year dipping my own tubes. I managed to get by using mason jars and a microwave but want to improve the process.

I just picked up a presto pot thinking I might be able to submerse the mason jars in plastic in the pot and be able to heat and dip several colors at one time. Four mason jars will fit in the pot.

I just gave it a shot but it would appear the presto pot would not heat that amount of plastic evenly enough to make it work. I found the pot about 50F hotter on the bottom than at the top (about 4-5" deep). This caused the plastic at the bottom of the pot burn while the top was still too thick. With the mason jars in there, it's difficult to stir the plastic to try to even out the heat.

Does anyone heat this much plastic without stirring? Any suggestions for an alternate media for around the jars that might transfer heat faster/more evenly? I thought about oil but don't want to even think about the reaction that might occur if I dripped plastic into 340F cooking oil. Aluminum shavings or something might do the trick but I can't think of a source.

Any other suggestions how I might make this work?

Thanks,

Ray

[kelly]

sand?

[Richard Prager]

This thread might help or give you an idea.

http://www.tackleunderground.com/forum/showthread.php?t=11472

[Delw]

The preston pot heats from the bottom, you will have to mix the plastic no matter what you use or do.

Your best bet is sand from what everyone tells me that has used it.

anything that you put in there for a media will need to be a very fine grain like sand. alum brass metal of any sort will not pack right getting air into the media allowing it to cool faster and not keep a constant tempature.

it will act as a big giant heat sink drawing heat away from what you need to heat.

DONT use mason jars they are not a tempered glass and will/ could explode.

in all honesty get a few pots and have a mixer for each one, that will be your best bet.

[TightLine]

sand?

I actually tried sand in a cast iron kettle but it takes far too long to heat the sand up and you end up with the same problem -- burnt bottom and cold top. I suppose I should have known that since I've bury my feet in the sand when it's uncomfortably hot. The sand just below the surface was often much cooler. That's why I was thinking about aluminum scrap or something that conducts better.

I actually foiund a partial solution with the aluminum deep fry basket that comes with the presto. It sits on 3 feet, just off the bottom and just inside the wall of the presto. That seemed to help distribute the heat but I didn't have enough time to see if the entire pot would come up to temp. It got to about 300 when set at 350 after about 2 hours. That's a little longer than I want to wait but a step in the right direction.

152nd Street Baits, thanks for the link! I might give something similar a try. I've heated pop molds in a microwave to warm them to make pouring easier so a big 'ole pop mold preheated for the jars might just be the ticket. If ghostbaits is listening, thanks for sharing that. Definitely have some more head scratching to do...

- Ray

[Richard Prager]

Keep us posted on what you come up with.

[Delw]

Tightline

the sand in the pot is more for keeping the plastic hot evenly. Cooking plastic would take a long time.

the center of the plastic would be cooler and it should be stired to distibute the heat.

The way I understand it is that people cook the plastic then pour it in the sand surrounded container. some have gas burners on the bottom and 1" of sand between the bottom and the container this heats up much faster.

sand being cold when you dig under the surface is due to the overall average temp. like wise if you had 118º degree days and cool nights and dug a hole the sand would be warmer.

your heating from the bottom unlike the sun which heats from the top.

The reason sand is use is due to it can be packed tightly with little air pockets, anything with air pockets would release the heat instead of keeping it contained to were you want it.

[squigster]

I have 4 aluminum dipping cups made with 3/8" walls. They are about 4" o.d. and 3 1/4" i.d. x 9" deep. I use 4 of them on two hot plates for mutlicolor tubes and swimbaits. They take a little while to heat up but they stay hotter than anything I have used. I dont really get the problem as much as the top plastic cooling way down. You still have to stir them because the plastic in the bottom will burn but you have to do that with anything except maybe the riteheat pots. I also wrapped them in Kaowool Fiber (Used for insulating industrial furnaces) and put big hose clamps on them to keep the insulation in place. It works well for me. I was using Martini mixers and they do work but they wouldnt retain the heat because of the small wall thickness. When I tried to compensate by turing up the temp, the plastic would burn.

[TightLine]

Now I see how the sand is being used. Very much like the plaster as an insulator. Sand has a high thermal mass but low conductivity. I'm trying to move in the opposite direction and transfer the heat quickly around the container so I'm looking for high conductivity in the media.

As I see it, one of the main problems with melting plastic is bringing it up to temperature evenly. Since plastic isn't a very good conductor, when you heat it from the bottom, the heat tends to stay there and burn the plastic.

On the other hand, I'd think if you could heat the plastic from all sides, it would melt more evenly with less chance of burning. This is what I'm trying to accomplish. I'd suspect the comercial melting pots accomplish this with an element that is wrapped around the container or the some sort of heat transfer around the entire container.

I did find that insulating the presto helped quite a bit since my ventilation was cooling the sides of the pot pretty dramatically. Air is actually a good insulator if it's not moving - think fiberglass insulation, syrofoam, double paned windows. It's likely I will insulate on top of the aluminum if I can get it working like I want. Perhaps with a layer of plaster.

My next step will be to find an appropriately sized aluminum can for dipping and try packing aluminum foil around the containers inside the presto (rather than using plastic as the media). Sort of like an aluminum mold for the containers within the presto. The hope is that the heat will quickly transfer off the bottom of the pot and surround the containers more evenly.

- Ray

[TightLine]

squigster, those containers are exactly what I'm looking for. Can you tell me where you got them?

Thanks,

Ray

[squigster]

Ray,

My brother is a machinist so I nagged him for a few weeks until he made them for me. I decided that If he did not make them, I was going to go to a metals supplier that sells to the public and buy the bars and cut them to length and bore them out with a lathe or with a carbide tipped forstner bit. You may want to try and buy some bar stock and find a local machine shop near you to bore them out. I dont know what it would cost though.

[Delw]

use candle molds, you can get them as deep as you want them. machine shops will cost an arm and a leg for this.

Candle molds are easy to find locally and on the internet. I posted a link a few years back, just do a search for candle molds

[TightLine]

Thanks Delw, candle molds look like a good solution. Especially after looking at the prices for aluminum stock

[TightLine]

I thought I'd post back on my progress with getting this to work. After a few failed attempts, I'm getting close and actually dipped some tubes yesterday.

The setup is an aluminum pot, about the size of the presto pot with four 3x6" candle molds in it. Between the molds and the pot I poured aluminum oxide (Al2O3) grit - an abrasive used in place of sand for blasting. I also surrounded the pot with fiberglass insulation and packed some in the top inch or so of the pot above the Al2O3. All this sits on a cheap hot plate.

The good news is that it works. The bad news is that it takes about 2 hours to come up to temperature.

My next steps are to insulate the rig better (probably with kaowool) and to find a way to "form" the Al2O3 so I can remove and insert the candle molds. If I remove them now, the Al2O3 will collapse and I wont be able to stick a new mold in. I'd like to be able to remove the molds to change colors, pour out plastic remenants as well as only heat the plastic I need.

I'm thining I might mix the Al2O3 with enough plaster to bind it together but haven't figured out how to free the molds once the plaster hardens (I think it will shrink around the molds and hold them tight). If I figure that out, I might also insulate the top inch or so with plaster mixed with perlite.

EDIT: BTW: I couldn't get the presto pot past about 310F with this setup and that's why I switched to the hot plate.

- Ray

[bdomina]

i had an idea i have not tried yet. there are many different kinds of thermoses out there some will pretty much evenly heat liquid for several hours. i found one that you would put a styrofoam coffe cup in that looks like it would work. i use a griddle to keep stuff hot and put a towel or something on top of it. i think with the right bottom insulation you could even put it on the griddle. the thing i would say to look for is one that could take some heat from the bottom and one that is easy to clean

[joshimoto son]

I did the speed read on this subject, so if I missed anything I apologise, but I used cooking oil to keep my candle molds hot and just kept the plastic stirred. I also JB welded a handle on the candle mold to keep from having to grab the hot cylinders.

I found the oil kept a more even temp because of it's viscosity and natural convection.

Just like anything, be careful and take into consideration the volume of oil the candle molds will displace.

Josh

[TightLine]

joshimoto son,

I'd be interested in hearing more details of your setup. How do you keep the candle molds in position? Have you dripped plastic in the hot oil, what's the result?

I started out thinking about using oil but had too many safety concerns.

[dkooser]

I'm about ready to bite the bullet and start dipping my own swimbaits. Here is what I plan on doing. Take a tall alumimum can (RedBull or Monster), find one just slightly larger that the first one will fit into. Melt some tire weights (free from your local tire store) and pour the melted lead into the space between the two cans. You will need to hold the inside can in place as it cools or it will rise out of the lead. Make sure to leave a space between the two cans (toss a nail or rock - make sure they are dry) between them before you pour the lead.

Just my design, have not done it yet, still in the planning stages.

Before dippin' put the can into the oven and bring it up to 300 or so. Then put the can on the pot. Since lead melts at 627 it will not get soft. The issue is breathing in the molten lead but I always melt lead outside anyway.

Give me your thoughts, again I am just in the mind design stage...have not even bough my plastic from Del yet. I do have my two trout size hand carved swimbaits ready though.

[joshimoto son]

Tightline,

My initial idea was to just put the candle mold on the hotplate. Once the handle was put on, it looked like a skinny beer stein.

The hotplate alone was not enough, so I took a pan and put about 2" of vegetable oil in it. Then set the candle mold in and had much better luck.

When a drop of plastic would fall in the oil, it simple fell to the bottom and eventually durned black, no spattering or explosions.

It worked... good, but the plastic up toward the top still wanted to cool on the sides. My plastic did not burn, but I kept it stirred while holding onto the handle.

I think the addition of oil can lead to more hazzards, it's just one more thing you need to be consious of.

The candle mold I bought is only a little over 2" in diameter. I only got about six 4.5" swimbaits out of it before I had to refill.

I have since made my own stainless tube in a 4" diameter and put it directly on my hot plate. I get more swimbaits and don't have to deal with the oil.

Let me know if you have any more questions, I'm always happy to help.

Josh

[joshimoto son]

I'm about ready to bite the bullet and start dipping my own swimbaits. Here is what I plan on doing. Take a tall alumimum can (RedBull or Monster), find one just slightly larger that the first one will fit into. Melt some tire weights (free from your local tire store) and pour the melted lead into the space between the two cans. You will need to hold the inside can in place as it cools or it will rise out of the lead. Make sure to leave a space between the two cans (toss a nail or rock - make sure they are dry) between them before you pour the lead.

Just my design, have not done it yet, still in the planning stages.

dkooser,

I was at Target the other day and found a wine bottle chiller for $7.00

It's made out of stainless and is basically made like a thermos. It appeared to be 3/8" an inch thick but was made with two thin pieces of stainless and is hollow inside. I thought about buying one and drilling a hole (at the top) and filling it with oil, but not all the way to allow for the expansion.

Ever since I started pouring I always thought it was a little pecular that a lot of people were using aluminum. I like stainless because it holds heat better and typically has a smoother surface allowing for easier clean up.

With my background in heating and cooling, it's always been easier to maintain constant temperature with a bigger heat sink or mass so to speak.

The trick it to bring the pot up to temp with out overshooting.

I burn less plastic, due to some nights with too many beers, and have more consistant colors from the beginning of a pour to the end. My plate also does not cycle as much too.

Just something to think about... and hopefully I didn't ruffle any feathers.

joshimoto son

[dkooser]

joshimoto son No feathers ruffled here. Like I said the only dipping I have done is in my mind so you guys are the experts. A question/clarification though. If the space betweent the two cans (filled with lead) is 1/4 to 3/8 inch and the whole rig is preheated in an oven, do you think there will be a big temp difference in the plastic at the top and bottom? My longest trout swimbait is about 9 inches.

[Smallie]

Tightline,

[snip]

I have since made my own stainless tube in a 4" diameter and put it directly on my hot plate. I get more swimbaits and don't have to deal with the oil.

[snip]

Let me know if you have any more questions, I'm always happy to help.

Josh

Josh - can you tell us more about the stainless tube?

[joshimoto son]

Dkooser,

I think there will be a temp. difference, but how much? I don't know.

The good thing is that it won't cost much to find out. The drink cans are cheap and you can always remelt your lead.

I think it would be worth a try for sure. The only set back I see is the preheating in the oven. Once your plastic is cooled down too much, I think it would take a while to reheat.

My goal has always been to try and sustain a constant temp and get my business done as quickly as possible.

With the concave bottoms on the cans, I believe it would be hard to use a hotplate and get good heat transmision.Try it and let us know how it works.

This is what we do, try try and try, laugh at our failures and enjoy our victories. You never know, we might be onto something.

Smallie,

The tube I made of stainless was a piece of scrap I took from work.

It's approximately 3.75" in diameter by 10" tall (I think) and is 3/16" thick.

I welded a piece of stainless flat stock to the bottom of it. The flat stock is 4"wide, 10" long and 1/4" thick.

I know I need to get some pics, but I'll try to explain it in the mean time.

I did not center the pipe on the 10" long piece of flat stock. I welded it so that 1" was hanging off one side and 5" was hanging off the other.

I did this so I would have a nice flat surface to work with. Let me explain.

I don't know what everyone else does, but I trim the drip off of my swim baits after every dip with a pair of scissors. If after I trim it and the shape of the head is not how I like it (usually the nose is too flat or blunt). I simply just use the 5" hot surface to mold the head to a "pointier/rounder" shape. Then wipe the surface clean before the plastic burns and prevent any potential discoloring of other baits.

I hope I answered all your questions.

I'll check back in a couple of hours, after that I'm going to go see Rick Clunn, Kevin VanDam and Boyde Duckett speak at a local fishing show up here in Michigan at Kevin's brothers shop. It really pays off to have a brother make it big time and have some of the best guys ever come to your spring sales event.

Take care,

joshimoto son

[TightLine]

I've been trying to look at this from a technical point of view so aluminum seemed to be the appropriate material. I have to say though that thermodynamics isn't one of my strengths so I might be thinking about this wrong -- I probably know just enough to endanger my thought process but here are some random thoughts.

I chose aluminum because it has the advantage of a high heat transfer coefficient which I'd think would allow for a more consistent heat between the bottom and the top. I'd think oil would be even better due to convection.

I don't know the specific heat or heat transfer coefficient of the plastic we use but by observation, I'd say both numbers are pretty low which is why we have to stir a lot and why it burns and cools relatively quickly.

Surrounding the plastic with a big enough heat sink should keep the plastic at temperature longer but as the plastic sucks heat from the sink, we need to be able to replenish it quickly and evenly.

Using oil with enough heat storage should accomplish both of these since it convects. If you can accomplish that, I don't think the choice of the container metal has a big impact.

I've found with the Al2O3 that I can get consistent heat from the top to bottom but have too much of a heat sink (takes too long to come up to temperature). But then again, I'm heating 4 3x6 molds in a presto sized pot so there is a lot of aluminum in there to heat up. If my math is right, that's about 50% Al2O3. I think I'll try another experiment using a smaller outer container (soup can) to hold the mold and Al2O3 to see how it performs. If that comes up to temperature fast enough, I'll scrap the idea of trying to heat 4 molds at a time.

The wine chiller filled with oil sounds like an execellent solution as well. I'm going to keep my eye out for one of those although I don't need quite that large of a container for dipping. An all stainless tall travel mug would be a good alternative but they tend to have plastic built into them (at least the ones I've found).

- Ray

[joshimoto son]

Tightline,

I see your point. Very well thought out.

You said it... "high heat transfer"

I've had 8 years experience in heating and cooling controls, mainly for large building like hospitals, Universities and Pharmacutical companies.

It might just be the way I was trained and my mental "mind set".

For me it's all about temperature control (it's just my thinking, please don't take offense), and using a material with a high heat transfer will generate higher temp. swings. In my field higher temp. swings meant poor control and higher energy usage, which didn't make our customers happy.

Because we don't want to go out and spend a couple hundred dollars on temperature controllers with a PID control loop that anticipates temperature overshoot. We're stuck with the el'cheepo binary hotplates.

Therefore, my thoughts have always been on the safe side, which is slower reacting materials with smaller temp. swings. The benefit being less scortching of the plastic.

The down side is that it takes longer to get to temperature.

We might be onto something though, that is the oil. It just might be the happy medium we're looking for.

If I don't get back with you today, I'll be back Monday.

joshimoto son