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Old 10-15-2013, 10:00 AM
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dubby dubby is offline
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Default Heating elements and control systems

In our plastic lure making setups, we commonly use a pot manufactured by Presto for kitchen use. It's basically just a fry-daddy with a selectable temp control. Users heat their raw plastic in it, add colorant, and then draw the plastic out with an injector to shoot into their molds. Requirements are pretty basic...get to temp, hold temp, and keep cycling as needed. Temps vary between 290-370° depending on type, but it stays about 320° normally.

Another product we have, is a heated block that draws from a tapped hole in the bottom of the pot. It has a built in mechanism that acts as a valve to start/stop plastic flow into the injectors. It uses the 1/4" cartridge heaters and a controller. I have only seen pictures of it, never used one of these, as it's made by an outside fella and I really have no need to spend the money (even at cost) to have one in my shop here. Video here.

The weak link in the system is the actual injector itself. I've been making the standard hand injectors, and I've taken a couple of the ones like in the video in for tuning to fix little issues the customers have had. The biggest problem with the ones that are being made now is that no two are ever alike. The machinist making them builds them to work, but when they break, the whole thing has to be sent in for repair/replacement because you can't just send out a part. You just don't know if it'll fit or not.

I understand all the mechanical parts of it, that's really simple. What I don't know about are the electrical parts. What type of heaters to use? What type of controller? What else do I need, or how could I make it better?
I've always had more time than money.

Wade's Custom Kydex
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Old 10-15-2013, 05:36 PM
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Scotts Scotts is offline
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you will need the heaters, look for voltage and wattage size you want. you will need a controller and contactor. as the heater will probably pull more amps then the relay in the temp controller will handle. You will need a thermocouple to measure the temp of your media, for those temps a type J should do you fine.

You are talking about the little silver box on the left side of the left pot in the video?

That has all that in it. Controller, thermocouple and contactor.

Go here and look around, you can get the $300 temp controllers for $100 bucks or so from Here, also look for the contactors from factorymation as well.

IMS has fairly good prices on heaters. usually cartridge heaters have all the info on them stamped on the outside. If you know someone with the setup you can get them to pull or ohm out a heater and find out what they have.

We should be able to get you up and going without too much pain and suffering.

You may be able to get some of this stuff down at the salvage yard.

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Old 10-15-2013, 08:18 PM
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GWIZ GWIZ is offline
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From inside this link.

Found this,
You will have to match the type of probe to the controller this link shows type K

I don't have a clue on heaters because my soldering irons range 25 watts to 600 watts or so, more then likely will have something to do with the amount of surface area you want to heat and time to get up to temp.

Maybe a cheap way is to use a HF router speed controller and mark the knob with a temp range.
For safety mount a 400 deg over temperature switch with relay to kill the power.
The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment. ~Warren G. Bennis
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Old 10-15-2013, 08:49 PM
BukitCase BukitCase is offline
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If you were closer to the gulf I'd try to steer you AWAY from a type J thermocouple - all tc's are created by welding two dissimilar metals together - as the temp changes at that junction, they generate a varying millivolt signal across the junction, which is used as an input to a controller or indicator, or both.

The two metals used in a type J are Iron and "Constantan" alloy - the iron doesn't do well in high humidity, connections tend to rust up pretty quickly unless they are hermetically sealed.

Type K's use "Chromel" (NiChrome wire) and "Alumel", another alloy. Neither side of a type K is prone to rust/corrosion - they will typically stay good for 10 to 50 times as long as a type J, especially in high humidity conditions.

Instrumentation in this century is plenty accurate at lower temps with a type K - Old fossil-type instruments not so much, which is why the "Lore" still says use a type J for lower temps.

K's these days, with fairly new instruments, can handle anything from your refrigerator to your forge - makes it simpler to rig up something like you're wanting to do... Steve
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Old 10-15-2013, 09:46 PM
coleasterling coleasterling is offline
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Location: Post and College Station, Tx
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I've never used either of these, but for the price they seem worth messing with.®-K-Type...ure+controller

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