Edison thread tap

[Dod MoleParticipant @georgeclarihew]

Would something like what we used in skool be of use ?

The Interwebnet is full of choice eg. http://catalog.miniscience.com/Catalog/Electricity/Lamp_Holder.html

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 31/07/2019 20:39:03:

If you've ever seen electricity pylons marching across the landscape, the cables are usually aluminium with a steel reinforcing core.

en.wikipedia.org/wiki/Overhead_power_line#Conductors

Neil

.

I'm aware of that, Neil … but thank you

The problem with Aluminium is not its conductivity, but the comparative difficulty of making good terminations.

… By no means insurmountable [and ultimately very worthwhile on long cable-runs], but not to be taken casually.

MichaelG.

[MeunierParticipant @meunier]

I remember being impressed or should that be amazed with the 'slenderness' of the gear-change lever on the Dauphine and its sister the stylish Floride – thin as a pencil, taking economy of materials beyond BL levels.
DaveD

[Michael GilliganParticipant @michaelgilligan61133]

**LINK**

Design Considerations When Terminating Aluminum Wire

[quote]

• Oxides form an insulating layer – Aluminum forms a dense and very hard oxide layer on the wire surface. The contact design and termination process must fracture these oxides to provide an excellent metal-to-metal contact.

[/quote]

[Enough!Participant @enough]

OP, couldn't you just take the guts from an ES lampholder (the screw part) and insert that into whatever you're making?

[Phillip AllenParticipant @phillipallen34597]

(As I probably cannot assume that you are all men and so as to avoid any offence to the ladies, I'll refer to you collectively as 'Members' – for the sake of PC, you understand)

Members,

I am overwhelmed with the responses and ideas. Firstly to suggestions of using a socket, this deviates from the KIS principle (an earthed plate to hold lamps). Sockets require riveting/soldering and the density precludes them.

Michael's idea of electro-forming is interesting. An additive process – juices flowing! – so why not EDM? An EDM machine is on the bucket list (the one by Langlois from HSM), but far into the future.

I like the idea of making a tap and will use it on copper, instead of aluminium. Thank you, everybody.

(BTW, can someone please change the spell-checker to be UK English? – even tho' I'm not)

[Martin King 2Participant @martinking2]

Hi All,

FWIW, on film sets these days, (and for some time) the large diameter cables used for film lighting are all made of aluminium, purely to save weight.

Film sparks are usuaully of large build and still sometimes struggle to carry the larger length cables used on location. How they ever managed with copper I cannot say.

How they manage the terminations when used in alll weathers again I do not know.

Cheers, Martin

[SillyOldDufferModerator @sillyoldduffer]

Posted by Martin King 2 on 01/08/2019 06:39:18:

Hi All,

… the large diameter cables used for film lighting are all made of aluminium, purely to save weight.

…

How they manage the terminations when used in alll weathers again I do not know.

Cheers, Martin

The trick is to make a solid metal-to-metal connection by welding or a proper crimp. Done properly Aluminium is serviceable as a power conductor. I've come across electric motors wound with Aluminium wire. Sometimes done to reduce weight, sometimes to reduce cost. The connections looked welded to me.

Aluminium has been tried for cheap domestic wiring but got withdrawn because of the fire-risk. When connected to ordinary screw terminals in wall-sockets etc, the joint tends to corrode, go high-resistance, get hot, and start fires. Or fall apart. If the electrician tightened the terminals 'just so' the risk is low, but terminating Aluminium is far less forgiving of mistakes than Copper. For the same reason, I think Aluminium is a poor choice for a lamp-socket. Over time the lamp to holder joint will tend to become unreliable.

Hugh's idea of using Copper may be a poor choice for another reason – Copper is hard to machine. It's prone to tear. If the thread is to be cut with a tap or on a lathe rather than moulded, I'd go for Brass. Not such a good conductor as Copper, but mechanically stronger and much easier to cut. Brass to Copper contacts corrode very slowly.

Dave

[HughEParticipant @hughe]

Dave,

Michael's suggestion not mine.

Hugh

[Michael GilliganParticipant @michaelgilligan61133]

Posted by HughE on 01/08/2019 12:03:29:

Dave,

Michael's suggestion not mine.

Hugh

.

Hugh,

Michael's suggestion was to electroform it from copper, not to use a tap.

… and incidentally [both Dave and Hugh] I believe Phillip was talking of thread forming, not cutting.

[hence my question to Jason when we were discussing Aluminium]

MichaelG.

[JasonBModerator @jasonb]

Posted by Michael Gilligan on 01/08/2019 16:21:19:

Best answer then, If you could get it in one of the lower tempers it would form easier than in say T6 but should still be ductile enough to use a thread forming tap.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JasonB on 01/08/2019 16:35:42:

Posted by Michael Gilligan on 01/08/2019 16:21:19:

Best answer then, If you could get it in one of the lower tempers it would form easier than in say T6 but should still be ductile enough to use a thread forming tap.

.

Thanks, Jason

Probably water-under-the-bridge now … but at least we have the answer for future reference.

MichaelG.

[Andrew TinsleyParticipant @andrewtinsley63637]

Quite a few ES holders are actually made from insulating material. There is a leaf spring that contacts the centre pin and a slot in the side of the insulating female portion of the thread. Through which a second leaf spring contacts the side of the ES cap. The mains is simply connected to the two leaf springs.

Andrew.

[Author]

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