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Member postings for Don Cox

Here is a list of all the postings Don Cox has made in our forums. Click on a thread name to jump to the thread.

Thread: strange power socket
15/08/2019 09:08:48

My father ran his own electrical contracting business following the second world war and was able to have the opportunity to buy a house on a small development, on the outskirts of Bath, where he was installing the electrics. As I understood it in later years (I was three when we moved in) ring mains were a new innovation then, everything previously had been spur wired and sockets were usually a maximum of 15A. As domestic electrical appliances became more common more sockets were needed (I have seen electric irons run off of lamp holders) which created cupboards full of switch fuses to control each socket, some of these were double pole fused which made for even more ironwork. He opted to use the Wylex plug and socket system and I remember our house being unusually well provide with socket outlets, all neatly terminated to a single consumer unit. Meanwhile the MK system was starting to appear and I think the British Standard was written around this. In the end he was forced to accept the change and MK pattern became the order of the day in his house. Some while back a 16A plug design was talked about but never adopted.

Thread: Meter Probe
13/08/2019 09:42:35

Over the 33 years I worked for PO/BT I had pretty much daily contact with their multi-meters, both as an exchange maintainer and as a linesman. Over that time the test gear was updated and the test leads too. One of the more annoying "improvements" was to the test leads which joined the probes, pictured above in the original posting, to the meter. Later ones of these had spring loaded insulating shrouds which covered the bare metal lead ends if they weren't plugged in. These had the very annoying effect of forcing the probes off of the end of the meter leads at the crucial moment. The need to get the probe onto a soldered tag deep inside a switch was difficult enough without the thing coming away in your hand just as you were going to look at the meter.

The latest standard test leads are next to useless in those type of circumstances, so the message must be look after any of this kit you still have, there ain't going to be anymore.


12/08/2019 19:21:14

I'm pretty sure those were the ones which came with most B.T. test gear when I last worked for them, now 23 years ago. In all that time I've never been able to track down a source of supply for replacements and I too have had to buy sub standard flimsy stuff. I'll be interested to see what else comes up.


Thread: Myford ML7 - Size of Mandrel Through Drilling?
12/08/2019 14:25:08

I have an ML 7 of (I think) 1949 vintage, no. K3475, it has a through bore of 0.58" although I reckon there may be some bits of swarf jammed in there which might have reduced it a bit.

I also have an S7 mk2 of (also, I think) 1963 vintage, no. SK62224 which has a through bore of 0.63"


Thread: "I'm calling about your accident" - how does this scam work?
30/07/2019 09:07:20

For quite a while now, BT has changed the policy on who controls the call. Originally it was always the incoming caller who could hold your line even after you, the called party, had "hung up" (it used to be for up to two metering periods when I worked for them). This was used to good effect by scammers who told you to call the security number on your bank card to verify what they had just told you about your account being raided was true.

Because of this, the system was changed to enable what is known in the trade as first party clearing, ie the called party can clear the call by hanging up and the line is freed. Since this facility has been available I have taken delight in explaining it to nuisance callers, with the parting shot of "I will now demonstrate this to you."

I don't know if other providers have this facility, it might be worth trying it out on the next incoming friendly call you have.

Thread: Pendulum enquiry
24/07/2019 08:01:47

I maintained a number of small/medium telephone exchanges until the digital revolution swept away all of the interesting stuff back in the '80s. Some had clocks 36, as mentioned in the link by Brian Oldford above, which provided timing to detect faults on the electro-mechanical equipment and a host of other functions. The stepper wheels at the top of the clock gave 1,6 and 30 second pulses (from memory) and the latter were used to drive slave clocks within the larger Post Office buildings and exchanges.

The basic principle used a Hipp contact to energise an electro magnet to restore the pendulum swing when it got below a pre-determined point, I seem to remember this happened every 6 swings. I inherited the task of changing the complete clock when I took over one of my rural exchanges, a bit like trying to nail a coffin to a wall, it took quite a while just to get the pendulum to hang directly over the pointer fitted at the bottom of the cabinet. After that I gave it a daily tweak to get the swing right, it took about 3 weeks to completely settle down. One of my ex colleagues has one working in his workshop.

Thread: Drip feed oiler plans
08/06/2019 19:36:47

This might be a good starting point:

Thread: Quicksilver
06/06/2019 09:31:46

My father used to tell the story that his father was given a mercury filled Fortin type barometer from a house he was working on. Having carried it, tucked horizontally under his arm, whilst walking from one side of Bath to the other, he was disappointed to find that the mercury had all run out! This was sometime pre second world war, imagine the hazard suited clean up campaign that would provoke today.

Dad ran his own electrical business and a couple of his customers were dentists, actually brothers, and he reckoned they were both mad as hatters (hatters, another part of the mercury story) The NHS still uses mercury amalgam for its bog standard fillings, my wife pays privately to have fillings in colour matched polymer which seems to have quite a long life. I did ask our dentist why they persisted in using what is generally regarded as a dangerous substance, his answer was that the biggest concern related to emissions from cremations, I told him that when it came to my turn I would try to keep my mouth shut.

Thread: Easy way of finding centre to drill a hole in round stock
09/05/2019 08:17:52

A statement of the obvious I suppose, but I use this method to set lathe tool height too.

Thread: Sump Plug
02/05/2019 09:41:12

I watched a salesman demonstrate a "sump sucker" whilst working in my retirement job as a workshop technician at a local FE college. He emptied the sump, via the dipstick hole, on one of our practice cars, a Maestro, the following day I removed the sump plug and drained a further half litre of very dirty oil. It all depends where the dipstick is in relation to the sump lowest point I suppose. Buy a recent Beemer and you won't even get a dipstick now.

Thread: Fillers & Paint ?
25/04/2019 23:19:35

Knifing Putty is not much more than thick paint suitable for filling stone chips and the like, its hardening time is dependant on the thickness applied and much more than a sixteenth of an inch can take days to go off. P38 Isopon hardens all through in about 20 minutes and sands well, if the imperfections are that small filler primer in multiple thin coats is probably the best option.

Thread: Making Holes in Copper Sheet
19/04/2019 10:55:12

A search of eBay "Holesaws" turns up loads of suitable 22mm cutters for about £3, use the clamped ply idea to keep it all flat and try a nice slow speed to start off with.

Thread: Myford colours
10/04/2019 09:25:29

Have you looked at Stationary Engine Parts website? Their Workshop Machinery paint section does all of the likely colours, be sure to order some of their thinners if you want to spray it. Their Myford grey is a good match, against the original colour, for both my ML7 and S7. I also have a Pultra type P lathe in a fetching shade of apple green which I take to be an original colour, I took a piece off of it to my local car paint factors who matched it with one of their colour card sets and produced a perfect match bottle of touch up paint, with brush, for about a fiver.

Thread: Myford Super 7 motor mounting
26/02/2019 23:28:28

Four of these?

Thread: Model gearwheel pump
21/02/2019 20:19:20

Pumps of this type were used in car engines along with a couple of other types and usually driven off of the distributor drive. I suspect that this is very old technology now and most, if not all, current engines have pumps fitted around the crankshaft at the auxiliary drive end are often of the crescent type. Google types of oil pump and have a look at the images to see a load of types.

Thread: Single to 3 phase invertor and smart meters
10/02/2019 08:29:27

Surely the next logical step in this developing saga would be to have heavier consumption appliances made smart so that they can be switched on by the smart meter when the demand is at its lowest, thus helping to even out demand, and possibly to take advantage of increased wind/solar power generation at certain times.

There was a time when it might have been possible to have had a plug top adaptor to do this (like the time switches for washing machines etc, set to come on when the economy 7 rate was cheap), but since dish washers and washing machines are now fitted with "soft" switches these days, any pre-setting is not possible without some fairly heroic appliance re-wiring. I wonder if the appliance and meter manufacturers have any plans for something like this, I'm not holding my breath.

Thread: ML7 questions
06/12/2018 23:27:17

I don't know if this is any use to you, I had access to an original stand when I worked at an FE college and was able to construct my own from a scrap steel cabinet using the measurements made as the diagram.  I didn't have any metal folding kit but managed to use a thin angle grinder disc to mark the panel to make some "trouser crease" folds and subsequent strengthening/joining with a MIG welder.  I now have an S7 on an original stand as well and my effort stands up quite well by comparison.  

Edited By Don Cox on 06/12/2018 23:34:25

Thread: AF socket sets. Are they extinct
10/11/2018 23:14:46

My long departed 1964 "B" was very definitely UNF with a few UNC thrown in, so A/F spanners fitted everything. Some Morris Minor 1000s I have worked on had BSF/BSW chassis fixings with AF engine nuts/bolts, pre BMC chassis versus and BMC engine etc I presume.

I could always visually pick the right spanner from the A/F range to fit whatever nut/bolt I was working on, a skill I have never developed with the metric system.

Thread: ER Chucks
20/10/2018 23:08:57

Have a look at the Myford web site under their "Collet Systems Adaptors and Collets" option. There's a nose piece collet holder to thread onto a Myford. for either ER25 and 32. ER 32 has a bigger holding capacity than ER25. There are lots of collet adaptors to get ER chucks to MT2, R8 and so on available from the usual sources, ARC Euro to the top right for instance.

Thread: Myford Super 7 Belt and change gear cover material
18/10/2018 07:44:22

Mine had a broken hinge on the clutch cover and I was able to solder it back together with "Lumiweld," not the most cosmetically pleasing job I've ever done, but it has remained mechanically strong and a bit of JB weld type filler followed by some grinding off of the excess with a mini-grinder made it look okay. I'd put my guess on it being an aluminium based alloy.

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