Sciencemadness Discussion Board - DIY Heating Mantle (How To Build It)

DIY Heating Mantle (How To Build It)

Ubya - 17-1-2019 at 16:59

How to Build a Heating Mantle

Materials:
Heating Mantle Sleeve (i bought this one)
Metal pot with lid
Glass wool
Power cord
2 wire connectors
Heat shrink tubing

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Total cost for the matierials 15€

First of all you must choose the Heating element, you could try building one yourself but it's hard and improper building can lead to short circuits or bare wires touching the housing. I chose to buy on ebay a 250W heating element already woven with fiberglass that fits a 500ml RBF.

Once we chose the heating element we need a container, it should be metal, (wood and plastics are not really compatible with high heat) and be big enough to fit the heating element and some insulation. I bought a cheap aluminium pot with a diameter of 20cm and a height of 10cm, you could use an empty paint can or a big tin can. My heating element is 12cm wide and 7cm tall so i can fit 3cm of insulation on the bottom and 4cm on the sides, your countainer should be big enough to fit at least some insulation on the bottom and on the sides, more insulation is better, just don't go overkill.

As insulation i chose glass wool because is cheap and easy to find, i bough a panel 1mx50cm for just 2€ at an hardware store, i cut a strip 10cmx50cm for the sides and a 10cm disc for the bottom, cut what you need depending on the housing you chose.

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Next we need to choose how we are going to connect the heating element to a power cord, i first thought of using a socket with a detachable power cord but i ended up connecting them directly. Soldering nichorme wire to a copper wire is not easy, the easiest way is to just crimp them toghether, i twisted the nichrome wire around the copper core tightly and then secured it with a wire connector screwed tight but not so tight to break the wire, heat shrink tubing is used to cover the live wires.

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Needless to say the heating element is going to get hot, really hot, so it would be wise to use heat resistant wire insulation, but i didn't have any so i improvised putting the wires close to the edge of the container with lots of insulation between them and the heating element.

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Now we cut a hole in the lid as wide as the element and place everything together. The lid can be secured with screws, mine had a lip that i bent in a way that could be crimped around the pot once put on top of it.

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The heating element should not be loose in the container once closed, if it is add more insulation.

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And it's done, just 30 minutes of building time and 1 month of waiting for the element to arrive from china

Remember to never plug the heating mantle directly into a wall socket, always use a variac or a dimmer.

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XeonTheMGPony - 17-1-2019 at 17:12

I used a can, and you need to support the mantle with the lid.

All so may I recommend mineral wool. Vs Fiber glass

Ask your local lumber yard for scrap pieces as you can often get them for free or near free

[Edited on 18-1-2019 by XeonTheMGPony]

Ubya - 17-1-2019 at 17:19

Quote: Originally posted by XeonTheMGPony

you need to support the mantle with the lid.

yes i know, right now the insulation is holding it tight to the lid from below, i'll use some metal wire to "sew" it to to the lid

Sulaiman - 17-1-2019 at 18:34

The fibreglass wool looks similar to some that I tried for my diy mantle,
the yellowness is some chemical treatment that smokes when hot.

I think that the plastic insulation of your cable will melt

Ubya - 18-1-2019 at 02:25

Quote: Originally posted by Sulaiman

The fibreglass wool looks similar to some that I tried for my diy mantle,
the yellowness is some chemical treatment that smokes when hot.

I think that the plastic insulation of your cable will melt

ah damn it, it smokes... if i heat it long enough can i remove all of the chemical? or maybe i should buy rockwool (but what if even it has this binder?)
for the cable insulation, yea probably, i will try to test its limits, in the mean time i'm searching those high temperature insulating sleeves found for example in soldering irons

wg48 - 18-1-2019 at 04:17

Quote: Originally posted by Ubya

Quote: Originally posted by Sulaiman

The fibreglass wool looks similar to some that I tried for my diy mantle,
the yellowness is some chemical treatment that smokes when hot.

I think that the plastic insulation of your cable will melt

The danger is if the "binder" carbonizers it can short circuit your wiring or heating element or make the metal container live but hopfully you did add an earth but from your pics it looks like you did not.

Yes the heat shrink insulation is very likely to overheat and carbonize as well. A common method to reduce the heating/temperature at the connection to the heating wire is to fold the heating wire back on its self at least once and twist it together tightly. That reduces the temperature rise because of its increased surface area and reduced resistance.

Its also common to place the connections in small ventilated box on the outside of the main housing to increases it cooling and reduce heat flow. Unless the power lead is silicon insulated that has to be kept very cool (about <100C). You can purchase ceramics terminal blocks for the connection. Brass and copper will significantly oxidise above 200C (or was it 300C) which will cause the connection to heat up even more and fail even quicker. Special nickel wire is produced to make connection to the heating wire which is spot welded or crimped. Some low current terminal/cheap terminal blocks have the clamps made from steel. Those will not oxidise at the temperatures that copper and brass do. Iron wire for garden purposes is also available which I assume could also be use as a transition connection and much cheaper than nickel. The thicker type iron wire would be best.

Ubya - 18-1-2019 at 05:00

i will test the conductivity of carbonized glass wool as a test.
wg48 nope i didn't add an earth connection because the circuit where my fumehood is connected to doesn't have one, not safe i know but that would require a major upgrade to the electrical system. i will do the connections outside the container and will use fiberglass insulation on the inside

Sulaiman - 18-1-2019 at 06:40

My cake tin enclosure for my mantle is earthed and as WG48 mentioned, it is a good idea, but if not possible then a little extra care is required.

The smoke from the fibreglass binder is acrid and it stained my heating mantle yellow/brown - no harm, just ugly.

To insulate the heating wire tails I used this
https://www.ebay.co.uk/itm/Tube-High-Temperature-Fiber-Glass...

Ubya - 18-1-2019 at 07:14

Quote: Originally posted by Sulaiman

To insulate the heating wire tails I used this
https://www.ebay.co.uk/itm/Tube-High-Temperature-Fiber-Glass...

exactly what i was planning to buy

wg48 - 18-1-2019 at 10:36

Quote: Originally posted by Ubya

i will test the conductivity of carbonized glass wool as a test.
wg48 nope i didn't add an earth connection because the circuit where my fumehood is connected to doesn't have one, not safe i know but that would require a major upgrade to the electrical system. i will do the connections outside the container and will use fiberglass insulation on the inside

As heating elements are notorious for faults to the case. In addition if you unknowing spill something conducting into the mantel plus it is DIY job.

Perhaps you should consider installing RDC trip which does not require an earth connection though you would be safer with one that does. They cost about £/$ 10 and you can probably get one that attaches to the power lead or you can in the UK. They are more expensive at about £20.

I found a 240V version for power lead for about £13 on ebay. You probably have something similar in your country.

https://www.ebay.co.uk/itm/J72G-C-POWERBREAKER-SAFETY-RCD-PL...

PS: You may not care but in America the electrical code may obligate the use of an RCD if water is involved with the appliance and to not do so may invalidate your house insurance.

[Edited on 18-1-2019 by wg48]

highpower48 - 18-1-2019 at 11:11

I've built 3 of these now a 100ml, 250ml and a 500ml. Used glass wool on all three. At first it does smoke a bit and produces a yellow film that will discolor the mantle and coat the RBF. It will disappear with useage. Used steel bolts with washers and nuts to connect the nichrome wire to the lead wire covered this with high temp kapton tape. Ran the lead wires to the outside to ceramic block connector with lead wires on one side and connection cable on the otherside. I did uee a standard 120v plug but labled for Variac use only. If plugged directly into mains it will heat a max temp which is the same as full power on the variac.

I would of liked to have used rock wool rather than the pink glass insulation but cost was a big factor. Could only buy in a large amount at a vary high price.

But to end this reply. Building your own heating mantle is a inexpensive and a fun project. My next project will be a 3 test tube heating mantle using plaster and nichrome wire....

Ubya - 18-1-2019 at 13:17

Quote: Originally posted by wg48

Quote: Originally posted by Ubya

i found this while dismantling a big office printer, looks similar to what you linked me

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Ubya - 26-1-2019 at 13:51

outside connection box

XeonTheMGPony - 26-1-2019 at 15:19

get some fiber glass cloth and fill in the hole by wrapping it around the wires, as that is a fraying risk there!

Ubya - 26-1-2019 at 15:39

Quote: Originally posted by XeonTheMGPony

get some fiber glass cloth and fill in the hole by wrapping it around the wires, as that is a fraying risk there!

don't worry, the electrical connection is well insulated, the tiny metal box is there just to hold everything, this way if i pull the electrical wcord i won't snap the fragile nichrome.
tomorrow i'll let it run at the lowest power i can to burn off all the fiberglass organic binder.

XeonTheMGPony - 26-1-2019 at 15:42

I am talking mechanical protection, leaving the hole as it is in the picture is forbidden by all electrical codes!

It is a very ruff and jagged hole, far too much risk in its current state, you are tempting fate with that !

Other wise the rest looks good

Ubya - 26-1-2019 at 16:59

Quote: Originally posted by XeonTheMGPony

I am talking mechanical protection, leaving the hole as it is in the picture is forbidden by all electrical codes!

It is a very ruff and jagged hole, far too much risk in its current state, you are tempting fate with that !

Other wise the rest looks good

i'm going to fill that up.
that aluminium pot has walls as thin as you can get them. i made that hole with a screw driver and enlarged it with scissors, the aluminium is so thin that it ripped instead of bending or getting scraped... how could someone ever use this to cook?

XeonTheMGPony - 27-1-2019 at 06:55

Aluminium there is first mistake! (I hate aluminium cook ware utter garbage for the most part, Cast iron or Stainless!)

DIY Heating Mantle How To Build It

Aspigma - 2-2-2019 at 07:34

In my opinion you are not right. Write to me in PM, we will communicate.

XeonTheMGPony - 2-2-2019 at 11:58

Quote: Originally posted by Aspigma

In my opinion you are not right. Write to me in PM, we will communicate.

An assertion made with out evidence can be discarded with out evidence.

Demonstrate he is wrong here, or you are the one that is wrong.

Ubya - 2-2-2019 at 12:57

Quote: Originally posted by Aspigma

In my opinion you are not right. Write to me in PM, we will communicate.

i'm all ears, write here so everybody can learn from my mistakes, non just me

andy1988 - 2-2-2019 at 14:28

I'm pretty sure it's spam, a variant of the n-gram model generated spam I see here posted sometimes (gibberish spam without links, but has recognizable words/phrases from the context). Just prune it.

I guess a vintage sock knitting machine could be used to make the heating sleeves from whatever fabric, but the costs don't look worth it unless you're making enough for a classroom or something.

[Edited on 2-2-2019 by andy1988]

morganbw - 2-2-2019 at 14:42

@Ubya
You are on the right track to get a fine heating mantle.
It can be done without any bells and whistles as well and work pretty good.

I have done a couple and they are more ghetto style. Safety not as good as you are doing but as an individual, I know the shortcuts I took, I understand the dangers exposed, and as no one other than me will be using it, I am okay with what I have done.

Just not to be misunderstood, your way is better on all levels than my way.
I am just pointing out that it can be pretty shoddy and still work, providing care is taken.