Richard Morrell

I have been asked several times for an illustration of the linked door opening mechanism on my glory hole, so: here it is! The essential components are:
• Pneumatic ram,
• Adjustable link rod,
• Adjustable stop,
• Left actuating arm,
• Right actuating arm

The link rod is constructed from a piece of i.d. tube, with a nut welded on one end. A length of all-thread is screwed into this, and yokes welded on each end. The rest of the mechanism is constructed from bits of old angle iron and steel rod, with welded nuts being used to construct threaded components. Hopefully it is fairly self explanatory. This particular arrangement was constructed during a visit to Keith Rowe’s studio, thus it is a rather typical ‘Roweworld’ creation, being made out of whatever was lying to hand.

The link rod is adjusted to ensure both doors meet nicely when closed, with the adjustable stop set so the doors only just make contact with the front of the glory hole. The pneumatic ram is double acting, 30mm x 200 or similar. The footswitch is a standard 5-port, which can be set up to provide control of opening and closing motions. I prefer a ‘press and release’ switch, but some may prefer a ‘double press’ operation.

The key to good operation is to fit a flow control valve only to the opening side of the ram. This can be adjusted so the doors both open and close smoothly. 1 control valve is better for this than two (when the ram is closing, the valve restricts the air as it exits from the ram) Two valve systems can be very weird to set up! If you have a ram with two valves, leave the valve at one end wide open, and do all the adjustments on the other valve.

This type of door is capable of considerable fuel savings, plus freeing the ‘door opening person’ to do something more useful. I am working on an improved version, which incorporates a switch that turns the flame up and down as the doors open and close. It should be a big fuel saver. For more details, watch this space!!