Edison thread tap

I have searched the internet extensively, but have found no firm selling a tap for threading material for an Edison E10 lamp thread. Does anyone know where to buy one? It does not have to cut the thread; to form the thread would be better.

Ha! I just went back to Tracy Tools and looked through all of the taps. My search for 'Edison' had not revealed 'Eddison'! I have sent an inquiry.

Thank you.

Never thought about it before but would there have ever been any taps made? The only Edison screw threads I've ever seen are the ones, both male & female, that are formed in thin brass tubes for the bulb cap and holder.

I have a chaser for producing Edison threads but sadly not for an E10. Threads needed to be produced to make the tooling to make the pressings.

When the local Dormer factory closed down, all the master tooling went into the skip, except that a friend who worked there asked if he could take it and he gave it to me. I've only ever found a use for a couple of tools but I live in hope!

Brian

Thanks for the replies thus far.

I received a reply from my inquiry to Tracy Tools: ... I only have a couple of dies available from stock and to have a tap manufactured the cost would be £250 net and 3 weeks to make ...

Looks like I will be making my own tap.

The thread is 10mm OD, 14 tpi with a crest and valley radius 0.533mm. Because I only need a tap to make formed threads (not cut) in aluminium, my thoughts are to grind a cutting tool with the correct radius to cut the valleys in the steel tap and then file the radius on the crest. Also, incorporate a taper along the way.

Cheers.

can you screw cut it on the lathe or is the part too big to turn?

At least it is a slack thread form so should be quite forgiving

.

I'm intrigued, Phillip ... can you tell us what you are making ?

If the female will be in aluminium, it's presumably not an electrical connection.

MichaelG.

Jason, I might as well screw cut the tap, thus giving a male thread which allows me to shape the crest, rather than trying to grind a cutting tool with both convex and concave curves. Besides, I want to 'form' the thread rather than cut it. The length of the formed thread is only about 8mm. And yes, while I can swing the object (for the centre hole but maybe not the peripheral holes), moving the object on a lathe faceplate 20 times has no appeal.

Michael, I want to make an array of small lights. Are you telling me that Al will not be suitable for running a low voltage current? I know it is used in HT power cables. I can swap over to Cu instead, no big deal except cost.

Thanks,

Phillip

I obviously don't know exactly what you're doing or the standard and appearance you want the holders to be, but Edison screw lamp fittings can be very simple and still work very well as an ES10 holder I removed from an old radio shows.

Sandgrounder, I see where you are coming from. Drill a hole, light countersink on both sides to remove square edge, file a small notch and put a slight twist on the hole, down on one side of the notch and up on the other. A few experiments and I believe I have a solution. Thanks very much.

.

Yes, Phillip ... I'm afraid that is what I am telling you

The first thing that fresh Aluminium does [within seconds] when exposed to the Air is cover itself with a layer of Aluminium Oxide ... Which is not only very hard, but also a very good insulator.

If you intend using the Edison fitting in the normal manner, then I would strongly advise against using Aluminium.

The good news is ... If you are prepared to use Copper [or anything more precious], you could probably electroform the sockets; then fix them into holes in a plate.

MichaelG.

PosrScript:

If something like Sandgrounder illustated is adequate for your purpose then I think there is another way that might be tidy:

1. Drill a plain hole in the plate, clearance diameter for the Edison screw
2. Drill a small cross-hole, to meet it
3. Insert a pin [screwed or spring-loaded] with a rounded end.

MichaelG.

Thats all it is, very simple and if you do have a go at something similar I've just measured it and the material is 0.6mm thick and a bit springy, so something perhaps like nickel silver sheet would be best but I've never worked with it so can't advise, but it is used a lot in electrical contacts etc or some grade of brass sheet?

Interesting views on the use of aluminium, my electronic edge finder's body is an aluminium alloy and after 12 years of use it still happily passes a low voltage electrical current. Never had to clean any oxide or anything else off it for that matter.

Phillip, with the number you have then screwcutting may not be the best option.

.

So be it, Jason

I do know that a thin, transparent oxide layer forms on freshly exposed Aluminium ... which is why it is tricky to bond with some adhesives.

MichaelG.

.

Edit: This may, or may not, be relevant :

https://ieeexplore.ieee.org/document/113051

Edited By Michael Gilligan on 31/07/2019 16:12:14

That would seem to confirm my findings, the typical HE30 or 6082 contains both magnesium and silicon in excess of the percentages suggested in your link and that would make "aluminium joints as stable as those of copper"

Forget tungsten bulbs, use big LEDs and glue them in

.

That's fine, Jason ... and yes, it probably explains the success of your edge finder

But, would those alloys be suitable for forming an Edison screw thread in a [presumably thin-wall] tube ?

... or would one need to use something more closely resembling Aluminium ?

[Straight question ... I don't know the answer]

MichaelG.

Copper or aluminium?

By way of complementing the points made above, I seem to recall that the Renault Dauphine's battery lived in the (front) boot and that the relatively long cable run was in aluminium.

.

Years ahead of its time, the Dauphine

But this may be of interest: **LINK**

https://www.sews-e.com/product/aluminium-cables/

" The development of new aluminum alloys suited for automotive wiring harnesses has allowed us to overcome a number of technical problems. ... "

MichaelG.