Plastic bit on pull cord switches is for insulation/saftey reasons?

[JohnW2]

I looked at a few of these yesterday where I was working and most had the plastic bit so small that the two knots touched together, I would think if they were for a safety purpose then they'd certainly be longer to prevent this and to migitgate againt a path forming on the outside due to condensed droplets. The instructions would contain a warning about not tying the ends together if it breaks (I've never seen this anywhere). ... I firmly believe that this is a story that has formed somehow, and because it sounds somewhat credible it has propogated, I'm more inclined to belive it came about not just for use convieince (in case of a snapped string) but also a manufacturing convienience... the process that produces the switch body probably doesn't want to contend with a mass of string, so this gets attached later on

Quite so. The initial suggestion was that they were introduced as a safety (insulating) measure and, as I have been discussing with SUNRAY, that is clearly nonsense, since they were initially metal. It could be that when it became possible for them to make plastic versions much more easily/cheaply, they 'noted' that the change might also offer some theoretical 'safety' benefit - but there was clearly a perceived need for such connectors (as you say, presumably for user and/or manufacturing 'convenience') before they came to be 'insulators'.

I would imagine the string is atatched inside to a plastic component anyway, so even if the complete string were sodden then there wouldn't actually be a problem

Indeed. As I've said, I've never seen one in which the top end of the string gets anywhere near anything electrical.

Kind Regards, John

 

[SUNRAY]

I looked at a few of these yesterday where I was working and most had the plastic bit so small that the two knots touched together, I would think if they were for a safety purpose then they'd certainly be longer to prevent this and to migitgate againt a path forming on the outside due to condensed droplets. The instructions would contain a warning about not tying the ends together if it breaks (I've never seen this anywhere).

I firmly believe that this is a story that has formed somehow, and because it sounds somewhat credible it has propogated, I'm more inclined to belive it came about not just for use convieince (in case of a snapped string) but also a manufacturing convienience... the process that produces the switch body probably doesn't want to contend with a mass of string, so this gets attached later on

I would imagine the string is atatched inside to a plastic component anyway, so even if the complete string were sodden then there wouldn't actually be a problem

I agree many of them are now very small but I think you'll find there are still 2 compartments.

I'm convinced it would make no difference whatsoever to the manufacturer fixing the long string to the switch or insulator and I'm sure they would much prefer to reduce the number of manufacturing steps and the number of components, both of which would reduce the cost and therefore increase profits.
I see no inconvenience in removing at least 5 steps from a manufacturing process.

 

[JohnW2]

I'm amazed that there only seems to be 2 people who are aware of the history of these things and this is genuinly no wind up.

As we've discussed, "the history of these things" is that there was initially a perceived need for these 'cord connectors' (presumably for user and/or manufacturing convenience) when they were made out of metal, so it's clearly nonsense to suggest that ('historically') they were initially introduced as a means of 'insulation'. It subsequently became easier/cheaper to make them out of plastic, but that's a different matter.

As I said, we're lucky that the LFB are not now insisting that they be made of of bar metal wire, with no ('combustible') covering!

Kind Regards, John

 

[SUNRAY]

I looked at a few of these yesterday where I was working and most had the plastic bit so small that the two knots touched together, I would think if they were for a safety purpose then they'd certainly be longer to prevent this and to migitgate againt a path forming on the outside due to condensed droplets. The instructions would contain a warning about not tying the ends together if it breaks (I've never seen this anywhere).

I firmly believe that this is a story that has formed somehow, and because it sounds somewhat credible it has propogated, I'm more inclined to belive it came about not just for use convieince (in case of a snapped string) but also a manufacturing convienience... the process that produces the switch body probably doesn't want to contend with a mass of string, so this gets attached later on

I would imagine the string is atatched inside to a plastic component anyway, so even if the complete string were sodden then there wouldn't actually be a problem

I agree many of them are now very small but I think you'll find there are still 2 compartments.

I'm convinced it would make no difference whatsoever to the manufacturer fixing the long string to the switch or insulator and I'm sure they would much prefer to reduce the number of manufacturing steps and the number of components, both of which would reduce the cost and therefore increase profits.
I see no inconvenience in removing at least 5 steps from a manufacturing process.

 

[aptsys]

I agree many of them are now very small but I think you'll find there are still 2 compartments.

I'm convinced it would make no difference whatsoever to the manufacturer fixing the long string to the switch or insulator and I'm sure they would much prefer to reduce the number of manufacturing steps and the number of components, both of which would reduce the cost and therefore increase profits.
I see no inconvenience in removing at least 5 steps from a manufacturing process.

The switch manufacturer are not necessarily the same as the parts integrator/assembler. You've always been able to buy replacement cords for pull-switches and they are designed to be replaced at the plastic connector near the top.

 

[SUNRAY]

The switch manufacturer are not necessarily the same as the parts integrator/assembler.

Regardles of the heirachy involved it is always cheaper to remove material and steps in a manufacturing process and this will be done unless there is a real reason for putting the insulator in place. I [and I appreciate I seem to be a lone voice] don't think consumer replacement is a real reason, after all one only has to look at the plethora of sealed/unrepairable items on the market to see they would much rather sell a new switch than a piece of string.

You've always been able to buy replacement cords for pull-switches and they are designed to be replaced at the plastic connector near the top.

I'll dispute this too.
The original switches did not have a joint and the chain went directly into the switch, there have been a lot of revisions in the last half century since then.

 

[aptsys]

Honestly if you're doing DfM for parts like this, the last thing you'd want is a 2m length of string to contend with during the assembly of the switch mechanism. These devices aren't made linearly and the pull cord string will be a separate part likely coming in from another supplier for final assembly prior to packaging. A pull cord manufacturer will make the same pull cord for every kind of pull switch for all kinds of brands.

 

[SUNRAY]

Honestly if you're doing DfM for parts like this, the last thing you'd want is a 2m length of string to contend with during the assembly of the switch mechanism. These devices aren't made linearly and the pull cord string will be a separate part likely coming in from another supplier for final assembly prior to packaging. A pull cord manufacturer will make the same pull cord for every kind of pull switch for all kinds of brands.

Having had a fair bit of manufacturing process control within my panel builing/controls work I do have some knowlege, one of the items I worked with was a puppet, as in a puppet hanging on strings and the strings created no problems whatsoever, and it was a fair number greater than one involved.
I'll make the guess that adding a string 200mm long to a switch will be no different to a 2000mm string prebundled with knob and a 200mm tail.
Another item was a pneumatic control valve which had about a dozen 1/8" bsp hose tail adapters fitted as it went along the line and each fitting required a coil of hose, it was found to be easier and more reliable for the production line operators to prefit the hose to the adaptor and crimp the collet, then coil/cable tie the hose before screwing it into the valve block.
I don't know how many thousands of plugs of all descriptions I've terminated onto cables of all descriptions and the length of cable rarely makes a jot of difference.
A bit of string is a walk in the park in comparison, I estimate the hardest part of the job is keeping it clean if the job is being done by hand.

 

[mattylad]

I echo what Sunray says - a wrapped string would not be a hindrance to a little old Chinese lady in her garage assembling these switches.

 

[aptsys]

I echo what Sunray says - a wrapped string would not be a hindrance to a little old Chinese lady in her garage assembling these switches.

You've clearly not had experience of volume manufacture.

 

[aptsys]

Having had a fair bit of manufacturing process control within my panel builing/controls work I do have some knowlege, one of the items I worked with was a puppet, as in a puppet hanging on strings and the strings created no problems whatsoever, and it was a fair number greater than one involved.
I'll make the guess that adding a string 200mm long to a switch will be no different to a 2000mm string prebundled with knob and a 200mm tail.
Another item was a pneumatic control valve which had about a dozen 1/8" bsp hose tail adapters fitted as it went along the line and each fitting required a coil of hose, it was found to be easier and more reliable for the production line operators to prefit the hose to the adaptor and crimp the collet, then coil/cable tie the hose before screwing it into the valve block.
I don't know how many thousands of plugs of all descriptions I've terminated onto cables of all descriptions and the length of cable rarely makes a jot of difference.
A bit of string is a walk in the park in comparison, I estimate the hardest part of the job is keeping it clean if the job is being done by hand.

Volumes for puppets are presumably nothing like for electrical accessories and quite a different process in general. The two are not comparable.

Having consulted at Elektron for cost reduction activities, the process is almost entirely automated with only final assembly performed by hand.

 

[SUNRAY]

Volumes for puppets are presumably nothing like for electrical accessories and quite a different process in general. The two are not comparable.

Having consulted at Elektron for cost reduction activities, the process is almost entirely automated with only final assembly performed by hand.

Ah I was hoping someone would consult... I trust you got all the details?
So the. Sequence of components please?
And of course the all important question?

EDIT:
The puppet production line was mostly fully automated and mostly wooden parts with metal parts to form the joints, the incoming materials started with branches which were de barked, sawn into standard battons, turned and milled to form body parts, drilled, sealed and coloured... should I continue?
I agree nothing like electrical parts but once up and running there was no plans to stop.

 

[securespark]

Yes, or just easily replaced when it becomes dirty.

I liked the old MK ones that screwed on.
Every so often, I would unscrew them and dunk them in a cup of bleach solution - good as new!

 

[eveares]

Wow, still going. Maybe I should write a letter to the IET and ask them for a definitive answer?

 

[SUNRAY]

Wow, still going. Maybe I should write a letter to the IET and ask them for a definitive answer?

Yes please.