Heat Treatment continued, the build starts.

Finding time for such projects is always problematical, we have customer jobs to get out, both gun work and shiny stuff. It is also the game season so I am out a couple days a month as a minimum and we have the two pups to train, plus the old Labrador who is out working, in fact he is out 4 out of 7 days this week so finding time for my HT is difficult so today I am going to work on the frame plus machine some strikers for a couple of shotguns, one of which needs a good service.

Anyway, this is where I am with the project right now, the design has been updated slightly and will now have a removable top so I can re-build it and/or replace the element if needed. The angle iron for the frame is in the workshop ready to be cut and the aluminium in-fill plates to protect the bricks have been cut to size and are ready to go. This is my first oven build so I really hope the insulation properties of the oven bricks are such that the external surfaces do not get too hot.

The bricks are remarkably easy to cut, however the dust is incredibly hazardous so I am taking care to keep dust to a minimum and a face mask and vacuum cleaner keep things reasonably safe (Fingers crossed)

I am gluing the bricks together with a thin bond of refractory mortar which makes assembly and cutting a bit easier as I can form the four sides and them move them as individual sections. The element slots still need to be cut however I have not yet cut the element so that is something for an evening next week.

I sat down and designed the electrical circuit during the week. There are many examples on the internet however they are not ideal for my purposes so I developed my own control circuit for the PID controller which is housed in the control cabinet to the right hand side of the oven.

More to follow on this…

Heat Treatment

I have been meaning to design and build myself a dedicated heat treatment oven for small items for ages and recently kicked the project off by ordering a PID controller and cabinet and a couple of other electrical parts. Today I ordered the insulating fire bricks and mortar which will be used for the construction. The physical capacity of the oven is small at 154 x154x228mm or 6″x6″x9″ however that is more than enough for a handful of strikers (Firing pins) or replacement hammers or for hardening dies and similar.

The image shows the HT Oven concept with the open door, I have omitted the liner plates and frame as this image was the original I used to determine the physical size of the internal space and the layout of the insulating bricks.

The box on the right hand side houses the controls and I have also omitted the screw catch that holds the door closed and the hinge system.

Frame construction will probably be 25,0mm angle iron and the infill will be either stainless of aluminium sheet depending on what I can source locally.

Maximum operating temperature is a theoretical 1050 Celsius which is  1922 Fahrenheit, or more than I will ever need for most applications.

The addition of the HT Oven is something we have recognised a need for as it means I can more accurately control the temperatures for both hardening and annealing of materials in house instead of resorting to a gas torch with the lights out, or shipping things off and waiting days for them to be returned.

The bar at the top is to enable it to be picked up and moved and will probably be shifted towards the right to bring the balance to a central point.

I will use stainless foil sheet to wrap items prior to heat treatment to minimise scaling as it works surprisingly well if you flatten the envelope you have formed to hold the part to be treated. I guess some pictures at some point would better explain this.

More to follow on this project.