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.

The first job tackled today was marking out the latch blank and drilling the hole for the phosphur bronze pivot pin. Then the radius around the hole was shaped. To get the shape of the latch handle a 1/4" brass bar was secured in the vice trapping the latch. Careful 'tapping' with a copper headed hammer soon had it to shape. Pleased, it was taken to the door only to find it was the wrong way! Doh! So after straightening it was then tapped over the right way.

The next task was to mill out a recess in the fire door casting to allow the latch to be set flush with the back of the fire door. My method was to use a rotary table to machine the recess. I decided that it didn't require my 6" rotary table and as I have a small table as well, that was secured to the milling table. This is the first time I have used this little rotary table and when looking for a method of securing the fire door, I realised I didn't have any nuts for the small 'T' slots!

So I had to machine some up and this took a little while. The rotary table was raised off the mill table by setting it on some machine blocks (their first use as well). This raised the rotary table up clear of the handle and the fire door was then secured with some aluminum to protect the front face of the door as it was only the raised letters that would be in contact with the surface it sat on. Therefore very light cuts were made with the digital readouts used to maintain the accuracy of the recess.

Once checked that the angle of clearance seemed to be correct, the fire door was removed and placed against the boiler to make sure the latch would be able to be raised high enough to come out of the catch plate.

And that was enough for me today so the hinge plate and catch plate will be left to the next session (or sessions!).