What is a Lug Sweater?

[GeorgineerParticipant @georgineer]

I've been reading Will Doggett's article Bandsaw Blade Silver Soldering Station in the latest issue of MEW, and it has left me with a puzzle.

He refers to using a "lug sweater" instead of a gas torch for the silver soldering, speaks as though it is a common enough plumbing item, and refers to its being available in DIY shops.

It's a term I have never come across, so I got on the interwebs to find out more and found: precisely nothing. Even combinations of words which I thought might be related brought up nothing.

From the picture in the article I deduce that it is a resistance heater with carbon electrodes, but can get no further.

Can anybody enlighten me?

George B.

[GeorgineerParticipant @georgineer]

A puzzle from MEW 304

[Stuart Smith 5Participant @stuartsmith5]

I think this may be the sort of tool he is talking about:

**LINK**

Though I don’t think it would get hot enough for silver solder.

Stuart

[Jon LawesParticipant @jonlawes51698]

Lug nut being the american term for wheel nuts could he be referring to an inductive heating tool, often used for shifting stuck nuts and bolts as the heat is more localised than gas?

[William ChithamParticipant @williamchitham75949]

Maybe one of these?

**LINK**

[HowiParticipant @howi]

I thought it was something my gran knitted to keep my ears warm in winter……!

[Ex contributorParticipant @mgnbuk]

Sweating is an old term for soft soldering & lugs an old term for cable end terminations, so maybe an electricians tool rather than a plumbers ?

This link to a passage printed in an old "how to" manual describes the process, but doesn't mention any special tool to accomplish it. Given the apparent age of the description, the heat was probably produced by a parafin blowlamp.

Not something that was taught as a skill in the "first year off the job" part of my electrical apprenticeship – such lugs were crimped on by 1977.

Nigel B.

[Martin KyteParticipant @martinkyte99762]

Not an old term at all, certainly still in use. Sweating is descriptive of soft soldering.

See example below.

Cable Lug

regards Martin

[Michael GilliganParticipant @michaelgilligan61133]

I believe the chap in the foreground may be wearing a ‘lug sweater’

**LINK**

https://homersykes.photoshelter.com/image/I0000zpNx95CM9lc

MichaelG.

[Roger BParticipant @rogerb61624]

I think this is what he is talking about:

**LINK**

I borrowed something similar from work many years ago when rebuilding my bathroom. Wonderful, no flames, no smoldering floorboards.

[GeorgineerParticipant @georgineer]

Posted by Roger B on 20/05/2021 12:11:17:

I think this is what he is talking about:

**LINK**

I borrowed something similar from work many years ago when rebuilding my bathroom. Wonderful, no flames, no smoldering floorboards.

Ah, now we're getting somewhere! The TT5 Thermotool looks like the sort of thing. Thanks, Roger.

As for some of the other suggestions, in my schoolteacher days I would have scrawled RTQ!! across them in red ink. Read The Question!! We've had induction heaters, gas torch tips, crimp lugs… I do like Michael G.'s picture, though.

I'm glad I'm not the only one who doesn't (didn't) know what a lug sweater is.

George B.

[Ex contributorParticipant @mgnbuk]

See example below.

Cable Lug

I order those with a different description from a popular industrial source – and crimp them on.

Soldering electrical terminations is so last century – "sweating" possibly the century before that ?

Nigel B.

[Martin KyteParticipant @martinkyte99762]

So do I and call them crimp lugs.

There are now many Hi Tech systems for joining things together. Copper pipes can be joined by crimp connectors instead of soldered fittings which is very usefull when working on old listed buildings. Cambridge colleges insist that plumbers remain on site for at least one hour after using heat and they must obtain written permission before hand to do so. Notthe case with crimp fittings.

Trade names are XPRESS MPRESS etc

**LINK**

I had the chrome pipes in my bathroom towel rail done with stainless crimp fittings and it looks the buissness. The only other way would have been compression fittings which look bulky and out of place.

Most of our lab plumbing is in plastic and the joints are thermally fused. For the life of me I cannot remember what the trade name is but the fittings have terminals and internal resistance elements. The pipe and fittings are assembled and the battery driven power unit is attached. Hit the button and a controlled currrent is delivered for a set time. This thermally bonds the joint.

All these system are expensive in consumables but reliability is better and the avoidance of gas flames very benificial allowing joints in some very awkward places. It gets expensive when you burn buildings down too.

regards Martin

[Will DoggettParticipant @willdoggett95799]

nigel B Is correct they were used as he said they were going to the skip when I got them

regards Will Doggett

[Grindstone CowboyParticipant @grindstonecowboy]

Posted by Stuart Smith 5 on 19/05/2021 21:00:42:

I think this may be the sort of tool he is talking about:

**LINK**

Though I don’t think it would get hot enough for silver solder.

Stuart

I've got one of those – it doesn't even get the pipes hot enough for soft soldering

Might work under ideal conditions, but not in the real world – the heat seems to be conducted away too quickly.

Rob

[Nigel Graham 2Participant @nigelgraham2]

The pipe-jointing system Martin describes, using an internal element, is used in large scales too, in the water and gas grid mains at quite large diameters.

I've not seen crimped plumbing fittings but my home has quite a number of 'Push-Fit' connectors, indeed including some I installed on both copper and plastic pipes. (Different connector types but the same principle, with the PVC pipes needing a thin-walled metal ferule in the end to stop the fitting from compressing them.)

[Dave HalfordParticipant @davehalford22513]

Posted by Martin Kyte on 20/05/2021 14:44:35:

Cambridge colleges insist that plumbers remain on site for at least one hour after using heat and they must obtain written permission before hand to do so. Not the case with crimp fittings.

regards Martin

They aren't the only ones Martin, any 'hot works' is notifiable these days, even heat shrink with a tiny hand held hot air tool.

[StueeeeParticipant @stueeee]

This video (with obtrusive soundtrack) shows resistance soldering (sweating) a cable lug between two carbon blocks. youtube vid.

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