Sciencemadness Discussion Board

Heating Mantle inter sleeve liner and Variac

highpower48 - 25-8-2018 at 06:48

Anyone used the fiberglass Heating Mantle inter sleeves 500ml, 250w 110vac that Deschem sells to make a DIY heating mandle?. I have searched and seen the various and previous posts. But no one has mentioned using a Variac to power it. I have a 1k, 110vac Variac and it seems the perfect choice. Also how are the connections made to the liner? Are the contacts just the ends of the nicichrome wire sticking out of the sleeve.I already have stirring solution so for around $20.00 each or less I can have a range of mantles. Thanks for any help I can get....:)

[Edited on 25-8-2018 by highpower48]

Sulaiman - 25-8-2018 at 10:06

My 500ml heating mantle element has bare nichrome wire connections,
which do not solder so need mechanical crimping or clamping,
I use one of these https://www.ebay.co.uk/itm/1Pcs-16A-2W8H-2-Way-8-Hole-Connec...
a variac will work very well,
but so will a much cheaper dimmer module such as the one that I use https://www.ebay.co.uk/itm/4000W-AC-220V-SCR-Voltage-Regulat...
another member uses a '10kW' version.
(they are so cheap that it is better to get a seriously over-rated dimmer rather than one a few cents cheaper that may permanently apply full power to the mantle due to a short-circuit triac etc.)
keeping your variac for other uses.

RogueRose - 25-8-2018 at 10:29

I'll have to agree with Sulaiman about the second link he posted I've read on a few electronics forums that people have used these types of things for an application such as this and they work well.

One thing you need to take into account is the "chinese" power rating. If it says 4,000 watts, I would guess that it can handle 1-1.5KW safely w/o worry and continuously. It probably can get to 4KW but it is going to get HOT and the unit is going to die much quicker. If you are running higher wattage, you might want to find a larger heat sink for the triac or maybe something like a 40mm^2 video card fan placed on the heat sink, that may be easier than using a different heat sink.

I would also venture a guess that using a harbor freight "router speed controller" unit should probably work for this as well but IDK how fine the control potentiometer is, I know mine doesn't do much of anything from 1-4 and only starts giving useable motion at about 4-10 (10 max) but that could be due to the motor I was using with it, it may work much better with resistance heating. Sulaiman might have a better idea as to whether this would work or not. These are about $20 but you can get them at and Harbor Freight store and they aren't built too badly.

From HF: $20
https://www.harborfreight.com/router-speed-control-43060.htm...

From Walmart - $17
https://www.walmart.com/ip/Yescom-Electronic-Fan-Speed-Contr...

From Amazon - $18
https://www.amazon.com/Yescom-Variable-Controller-Settings-H...


All made in china.....

Sulaiman - 25-8-2018 at 12:43

I would expect those to work well,
but as with all electronics, keep dry and well ventilated.

Although a larger heatsink does offer higher continuous power/current than as-supplied cooling,
it is cheaper to buy an over-rated unit than add a heatsink to a smaller one,
and more importantly,
the triac is at mains voltage so care is needed,
mounting and insulating a heavier 'live' heat sink is something that I would only recommend to those with electrical experience.
I think that adding forced-air (a fan) would be a better option.

highpower48 - 26-8-2018 at 07:57

Quote: Originally posted by Sulaiman  
My 500ml heating mantle element has bare nichrome wire connections,
which do not solder so need mechanical crimping or clamping,
I use one of these https://www.ebay.co.uk/itm/1Pcs-16A-2W8H-2-Way-8-Hole-Connec...
a variac will work very well,
but so will a much cheaper dimmer module such as the one that I use https://www.ebay.co.uk/itm/4000W-AC-220V-SCR-Voltage-Regulat...
another member uses a '10kW' version.
(they are so cheap that it is better to get a seriously over-rated dimmer rather than one a few cents cheaper that may permanently apply full power to the mantle due to a short-circuit triac etc.)
keeping your variac for other uses.

Thank you for the info and device suggesions. I have ordered both items. From the photos and what little could be seen in them, I had thought that it was just bare nichrome wire. The high temp terminal blocks are a great idea. I had in the past ordered one of the cheap scr voltage regulators but had issues with it. When connected to line voltage, and an output (40 wattt light bulb) the device refused to dim the bulb regardless of the pots location. For some reason I left it on for several minutes on the bench, turned around and heard a load bang and lights flicked. The device had blown a trace totally off the board and I mean vaporized. The trace was the one leading from cap to the center pin on the SCR. I don't like main voltage anyway, so this was a interesting development. What it boiled down to was a $1.76 Chinese device that failed. Who would of thunk it, lol. But have ordered two to try again.

Anyway thanks for the info....

Sulaiman - 26-8-2018 at 09:28

I hope all goes well in your project.

I have one small concern:
I pointed to a 220V controller and you are using 110 V,

It is not a safety concern as the controller voltage rating is more than adequate,
and the current the mantle requires is well below nominal,
I am a little concerned that the bottom end of the potentiometer may have no effect, maybe a quarter-turn or more before any significant current flows.
If this does occur (it may not) then reply here or PM me for a simple fix.
I'm re-watching Star Wars VI at the moment so later I'll test one of my modules on 110Vac and report back

highpower48 - 26-8-2018 at 10:23

Quote: Originally posted by Sulaiman  
I hope all goes well in your project.

I have one small concern:
I pointed to a 220V controller and you are using 110 V,

It is not a safety concern as the controller voltage rating is more than adequate,
and the current the mantle requires is well below nominal,
I am a little concerned that the bottom end of the potentiometer may have no effect, maybe a quarter-turn or more before any significant current flows.
If this does occur (it may not) then reply here or PM me for a simple fix.
I'm re-watching Star Wars VI at the moment so later I'll test one of my modules on 110Vac and report back


No worries I ordered the 110 V version.

Sulaiman - 26-8-2018 at 12:16

Before checking for a reply I checked my controller :(
. on 115 Vac there was no output until about 1/2-turn of the potentiometer
. the small pre-set potentiometer can be adjusted for correct operation on 115 Vac
(the pre-set potentiometer is connected in parallel with the main potentiometer)