Gallenhamp Heat Treatment Furnace

[awemawson]

My poor old Gallenhamp heat treatment furnace has sat on a shelf, lying on it's side. for the past six years, since I put it there when we moved. The other week I needed it to normalise some cold rolled plate before machining so out it came onto the welding bench.

Sad to say the curved glass had come loose on the pyrometer / controller, and the toggle switch toggle had broken off on the on/off switch. I was able to use it by judicious poking of the switch and balancing the glass where it didn't interfere with the set point and measured value pointers.

But today, when I was about to put it back on it's shelf I decided to also put it right.

[awemawson]

The curved glass was an absolute PIG to sort. The controller is analogue and basically a large meter movement with adjustable set points all held in by four virtually impossible to get at screws and nuts. Much ingenuity later and holding nut runners with long nosed pliers out it came a few inches from the chassis so that I could undo the equally impossible to handle or see screws holding the bezel on.  Then just a simple scrape off the old (possibly pitch based) glass retainer, apply some silicone and re-assemble.

[awemawson]

Then to attack the toggle switch. Nothing special, just a single pole single throw 'Bulgin' toggle switch with a bust toggle. On no, it is actually a special - as the front panel is very thick (about 1/2") the threaded mounting  of the switch is extended.     By one of those very lucky co-incidences I remembered buying a bag of used toggle switches at a SMEE auction decades ago - where is it - is there a special long one ? YES 

In fact this one was even longer but there's plenty of room for the extra length. All put back together and tested.

But it occurred to me that the modern Health and Safety Police would have an absolute field day with this box of tricks. 

Firstly the entire box is made of bolted together asbestos cement heat resistant board

Then there is the main current relay - a mercury tilt switch

Then, were you to tip the box backwards all the live gubbins are there for you to touch - it's massively heavy but it can be done.

Though it might not surprise you to hear I'm going to keep on using it 

[BenH]

Interesting piece of kit, what sort power requirements do they need?

[awemawson]

10 amps off a 240v socket so 2.5 kW - I run it off a standard 13a ring main socket.