Dial lamp covers

[mike hadley]

Some of the lamp covers were missing from my Philharmonic, so I thought that I would share my method of making a similar part,

in the photo below, from left to right we have,

the metal blank, the die, the punch, and below this a small hose clip.

the punch is made from a piece of 9.5mm drill rod, with the working end turned flat,

the die is made from 1 inch square piece of carbon steel 1/4 inch thick,

these parts could be mild steel if you only intend to make a few.

The die has a hole drilled 13/32, with a smooth entry radius, this radius is not critical, it just helps with the forming of the tinplate, but must be polished smooth to avoid the tinplate from tearing.

the hole size of 13/32 is calculated from the die being 9.5mm, this is taken from the lamp envelope diameter, plus the tinplate tube plus the formed end, this is 4 layers in total,

that's 9.5mm + 4 x 0.2mm, this works out to 10.3mm, the nearest drill I have is 13/32 which is a very convenient 10.31mm,

don't allow too much play between the punch and die as this will affect the finished shape.

The source of tinplate I am using is from an empty 1/2 gallon can that was used to keep isopropyl alcohol in, the material thickness is 0.2mm, painted white on one side. I have found this to be the standard thickness of cans today,

you must remember that if you change material thickness then the die will have to be changed to suit.

The lamp cover layout is given below,

Please be aware that the newer bulbs have a larger glass envelope of 10mm, the older style is 9.5mm, so a punch and die will have to be made to suit.

the next photo shows the tinplate rolled around the die with the hose clip slipped over, the hose clip is not tight, just tight enough to hold everything together,

the end flap is then bent over, making sure that the punch is central to the flap,

this is important otherwise the end flap will be lopsided.

The punch is then offered up to the die,

Ideally there should be something to align the jig, but I have found this method to be good enough,

the punch and tinplate are then tapped through the die with a small hammer,

a light oiling of the die helps here, this can be washed off afterwards,

the punch and the tinplate must be driven all the way through the die in order to extract the job, this is why the hose clip is not done up tight, the newly made shield can now be removed from the end of the punch.

The photo below shows several parts made this way, the white ones did not have the top of the circle on the blank clipped,

 

and looking from the back

the cover is tried out for size over a No47 bulb,

Finally the cover installed on the dial lamp of my Philharmonic

This was fun to do, and the covers are easy to make

Mike.

[David C. Poland]

Nice work.

There should be a piece of heavy weight paper as a liner inside the bulb cover. Check some of the original covers.

Mine are also painted black

[Brad Winder]

Wow! Look great!

The bulb covers on my two are also painted black. 

[Scott Seickel]

Excellent craftsmanship Mike, as we have come to expect from you. 

2 things- the slit looks a bit wider than the originals and your covers don't have the paper lining.  I don't think it matters on both counts so don't worry about it and enjoy your radio. 

[mike hadley]

Scott,

Thanks for your comments, I mentioned in the text that modern lamps have a larger diameter envelope, I have been looking for the smaller size lamp but with no luck, maybe  I will try to use some NOS,

so the answer is I will have to remake the punch and die, although they will be larger, the process still works the same,

Mike