Monotype pot element replacing

[Ascensius]

We have to replace both elements in a working English caster. Any hints? The pot works fine, but the terminals are so bad that there is no way to keep wire attached to the ends of the elements. We do have, courtesy of Ed R., new elements.

Melt it out, empty most of the lead out and change one at a time with power off?

Scott

[John Cornelisse]

It is needed to clean your pot at least one time each year.
Take all molten lead out, and remove all oxide from the wall
of the pot en the heaters.

While the pot is heated, lead oxide will grow at the heating metals.
 
When this oxide is not removed regularly, the oxide will grow and grow,
and in the end it will damage the heaters, because the oxide will push
the heating elements from the walls into the pot.

When you need to change the heaters, the lead in the pot needs to be removed completely.

Cleaning the heaters regularly will prevent damage for sure.

[Dave Hughes]

It might be worth checking this thread: Cleaning a Monotype Metal Pot for a few hints, although it doesn't go as far as replacing the element.

[John Cornelisse]

When the oxide layer is growing thicker and thicker, it will isolate the elements from the lead in the pot.

Than the elements cannot get rid of all the heat, and the elements will melt or burn in the end.

After one element has been burned it will take a lot more time before the pot is melted completely.

That should give you some indication, that something went wrong.

[Ascensius]

Thanks for the replies. To be clear, the posts on the end of the elements for wire connections in the box were damaged. Too damaged to attach leads to them. That is the reason for replacement, not how long it takes to heat the pot. But . . . I think we will do it anyway. (cleaning)

[Ascensius]

By the by. . . does anyone out there have a pair of heating elements for an English "British Rototherm" Monotype pot? The Rototherm is the name on the outside of the box attached to the pot. Will pay, of course.

[Frank Satt]

We are also in need of new Monotype pot electric elements. Any Idea of where to get new ones, or old stock or, get them made? I found straight elements on the McMaster Carr website, they can be shaped before they get hot. Anyone use these? Immersion Heater

Frank Sattler

[Ascensius]

Those look like they have to be used with specific liquids; not metals

[KPMartin]

Compatibility with type metal depends on the casing material. It is not clear if the reference to "Incoloy" is for the resistive wire itself, or to the casing, although the fact they mention this gives resistance to "harsh chemicals" would imply this is the casing material and would be in contact with the molten metal.

I have some doubts as to whether Incoloy would be suitable in type metal since the latter will slowly dissolve nickel, a major constituent of Incoloy.

Also, they mention that the element should be fully immersed to prevent hot spots and element failure, which is definitely not the case when filling the caster pot, nor for the short section of element between the metal and the connection box. It is of course unclear how much of a problem this is; after all, the elements on an electric stove and in an electric oven regularly glow bright red with no harm coming to them, though admittedly they may use different internal materials.

Mind you, I have never taken apart a dead Monotype heater to see how they solve the problem of the unsubmerged bits near the ends of the element. I suspect the (non-resistive) leads go a few inches into the casing before they are bonded to the actual heater wire.

[KPMartin]

Scott @Ascensius,
Save your old heaters if the only problem is that the leads are too short. If you can somehow get them to me in the fullness of time, I'd like to see if I can do anything to make them usable again.

[KPMartin]

By the way, a Google search for "custom heater element" gave me two good hits close to me, one in Toronto and one in Windsor, so you may be able to find something similar close to you (and not across a border).

So the elements can be made, but we may not like the price!

If anyone chooses to find out, please post the results (and also if/how the price goes down if you want more than one)!

[Ascensius]

wow that tubular elements place looks awesome. I will look into it. Can't be that expensive.

Scott

[Ascensius]

I sent off an email with a photo to one of those similar companies in the US and they said no to making a few.