The fire door assembly was quickly finished today and I chanced upon a useful tip I will use in the future. There was a need to cut three slots for the door catch to fit into and using the Proxxon mini drill with a cutter disk the first slot was attempted. However the thickness of the slot meant taking several adjacent cuts. However the light bulb in the head moment was why not add more cutting discs to match the required slot thickness? A verry tentative cut was started and it worked fine! Admittedly this was in brass but I suspect that if taken carefully and the cut at 90 degree to the work, then it should work on other metals. I know I shall use it again.

Once the door hinge corners were rounded (using a stainless steel rod button turned to the correct radius) and the slots cut then for the moment this phase of the fire door build was completed.

The next task is to redo a part made very early on in my novice model engineering days. Days that are still here! However I feel I can make a better part now hence this project. After marking out the holes and slot it was over to the milling machine for work to start. A full description can be found on my website http://www.mikes-models.com/largelever.html however I would recommend to other novice model engineers that both the optical centre punch and a height (mine is digital as it lets you work in both imperial and metric and is easier on my eye sight!) gauge. When co-ordinate drilling  with the milling machine the digital readouts lined up exactly with the centre punched marks.

Photo of progress to date below.

Well I managed to get an hour in the workshop today. The fire door itself is ready for assembly and I concentrated on the hinge. The last time I silver soldered the 1/4" dia bar onto 1 edge and today I milled most of it away! Leaving only two small sections at the edge.

Next I filed some of the fire door casting off to ensure a nice fit between the door and hinge. I have searched the internet for a 1.25" 3/32 rivet for the hinge but to no avail. I then tried turning my own copper bar down to size. That was achieved, but trying to round one end over to form the head resulted in failure. I decided I would use a length of 6BA studding until I can source a rivet. If you know where I can get one, please let me know.

Once the hinge and door fitted each other the next task was to mill the hinge to size and to mark out the 2 holes for the bolts to secure it to the boiler. I used the tool below, to centre punch the holes in the correct positions. It works by using a perspex rod, with magnified cross hairs. to place the holder in the correct position.  You then remove the perspex and replace it with the harderned centre punch. Then a sharp tap and its perfect every time! Well worth the money.

All that remains now is to drill the clearance holes in the hinge and drill and tap the boiler to suit. Then it will be a case of getting the door to close, with the baffle plate giving as much protection to the door as possible, from the fire itself. 

For more information please visit the Fowler section on my website www.mikes-models.com