Member postings for Martin 100

The point I was making is you can very easily achieve isolation using injection moulded plastics with separate primary and secondary sections on an E-I core, whereas with the toroid isolation is only achieved through the use of very specitic deliberate actions and materials during the very complex winding process.

With a toroid the means of isolation are always without exception buried within the construction and are not suitable to later non destructive visual inspection, the exact opposite of a transformer with separated bobbin E-I construction.

The claim that a pair of toroid windings will somehow achieve better isolation than an E-I core is one I cannot agree with.

With proper levels of design the type of core used is immaterial. An E-I design is inherently more tolerant of assembly issues than a toroid, there is really nothing to stop the former being assembled with nothing other than wire windings on each half of the bobbin and it fully meeting isolation requirements, whilst the latter must have a multi layer taping separating the windings to achieve any reasonable level of isolation.

I've one of those screwdrivers somewhere and while I have used it I prefer magnetism or a blob of blutak or grease.

I was surprised he made no mention of the Post Office standard issue screwdrivers he used at one stage.

**LINK**

Phone dismantling articles here

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and here

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Apparently this is 'slow TV' BBC Four have shown many bits of 'slow TV' over the years, all of which have been excellent,  'Handmade' being the most recent

**LINK** (no episodes there but a few clips)

In my view just about every bit of telly and writing May has done over the years has been interesting. Can't see this been any different. It's a pity he's been lost to the BBC after this (or so I hear)

Edited By Martin 100 on 29/03/2016 16:02:29

On the Boxford TCL 160 (and maybe the 125?) it's more than one pulse per rev (32 minus one missing) and yes it is a processor on that board, a Z80 (or equivalent), can't recall if it's the lathe, the Boxford mill or even both that also have another processor on smaller board with an 8051 (or equivalent) for the turret changer on the lathe or the Z axis on the mill.

Boxford TCL 160 head assembly showing encoder disc.

Edited By Martin 100 on 28/03/2016 13:43:26

1902

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I'm a professional engineer for mumble mumble decades in a totally unrelated field, but have had a workshop at my parents house and then at home for as long as I can remember (no, despite the alzheimers I don't mean 2 minutes ago)

I used to regularly read ME through most of the 1980's, MEW and EIM too. But 100 hours weeks, often working overseas, and lots of other distractions brought all magazine reading to an end in the early to mid 1990's after subscription copies were just piling up at home a few feet high still in their wraps. Many went in the bin or off to the local doctors surgery.

I still grab the odd copy of ME or MEW now and again, but it's not a regular purchase, most of my recent reads have been hand me down second hand ones a few months after publication.

I've produced monthly / quarterly newsletters in the past on another hobby, not much more than half a dozen pages and even with modern technology it's a mammoth task, even worse if you have to originate the content yourself. The idea of having to produce a magazine every two weeks, even with content provided by others fills me with dread.

Many thanks for those. 1st link despite being a 'co.uk' is actually based in Austria! with a choice of 270 or 290mm, 2nd one based in the UK but with 300mm the shortest belt on offer.

With postage it's working out at around 8 quid a belt when buying five. I'm almost convinced a belt from a Dyson would be the right size, I have one somewhere!

Boxford don't seem to list these on their website and being down to my last one that is more than a bit perished I wondered if anyone knew of a source for them (length 280mm, 10mm wide, maybe 1mm thick.

First thoughts were vacuum cleaner belts

It may vary (I've personally not used IMO drives) but OMRON inverters drives for example have a parameter n036, Motor Rated Current, 0.0 to 999.9 "Set to the rated current from the nameplate." which in conjunction with parameter n037 and n038 is used for motor thermal overload protection.

Users Manual Here
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This difference in the thread form is what made a shedload of direct nose fitting ER32 chucks unusable. Despite being unfit for purpose that didn't stop someone who shall remain nameless selling them to UK customers for many many months.

Fortunately ER32 chucks from the likes of arceuro are easily fitted to a boxford backplate, a bit bulkier but not really a problem.

There is also the possibility that the hardware could be totally identical to one with a larger output capability, but knobbled to a lower level by the firmware. It's often far easier to run one larger volume production line with the exact same bill of materials and just apply a different label and level of firmware before it exits the factory gates. Such an approach has become quite common in recent years with test equipment such as oscilloscopes.

From the listing of his publications at https://en.wikipedia.org/wiki/Tom_Walshaw I'd guess I'd have the 1st or 2nd edition Model Engineers Handbook from 1981 or 1986, most likely the latter.

Nearly 30 years on one thing I recall is opening the parcel and not only receiving the book but also a huge number of die cut sticky corrections, possibly extending to two or three sheets of A5 that were sized to overlay dozens of printing errors.

I've certainly broken BA taps in the past, but I can't blame Tubal Cain as I usually used books & tables from Moore & Wright, Dormer, Presto or Starrett.

Edited By Martin 100 on 06/03/2016 13:48:27

I've had "The Complete Handbook of Sand Casting" for many years and there are a couple in the 'workshop practice series' The Backyard Foundry and Foundrywork for the Amateur.

http://www.boxford-software.com/spares/3656GearBoxEng.html

£54 from Boxford not sure about VAT or postage

Sorry I can't recall the dismantle process, last time mine was touched was about 5 years ago but it was relatively straightforward. A good degrease and wipe might reveal taper pins or grub screws. There is nothing silly like left hand threads etc and nothing more required than spanners, pin punches and a copper/hide mallet

I seem to recall a taper pin on the leadscrew but outside the confines of the box, but I could be wrong

A QC box is way better than changewheels for altering feed rates!

Edited By Martin 100 on 28/02/2016 20:13:43

Mains halogens (GU10's) are very sensitive to failure with overvoltage. MTBF remains a matter of a few weeks regardless of supplier.

I know of four halogens in a bathroom that are 12v MR16 fed though an 'electronic' transformer aka switch mode power supply that are at least 15 years old and are still on the original lamps.

I've had a BC compact fluorescent that lasted maybe 40 ms before it went bang.

Sounds like lack of lubrication or gummed up old oil on the gears top right hand side in the boxford drawing, or on the gears on the levers. The shaft 303 is held in place by a taper pin visible on the gearbox outer casing boss

It's significantly easier to work on than a bike or car gearbox, worst bit is refitting to the assembly to the lathe bed when two pairs of hands make it so much easier

Boxford parts drawing

Photo here showing the taper pin location http://modelengineeringnorge.weebly.com/uploads/2/2/8/6/22864734/8407460_orig.jpg

Edited By Martin 100 on 28/02/2016 14:47:29

For flatness presumably with the use of these

https://en.wikipedia.org/wiki/Optical_flat

I find slip gauges useful but only for checking calibration or as big feeler gauges and never for packing purposes.

Edited By Martin 100 on 27/02/2016 08:19:49

Edited By Martin 100 on 27/02/2016 08:21:36

"Myford Super 7 (with gearbox and power cross feed), a Harrison M250/M300 or later at the right price and an equivalent Colchester."

A huge range there and no obvious reason why. If you have the space for anything bigger than a Myford then why wouldn't you choose it.

Many decades ago I was denigrated by a workmate for us choosing a Boxford rather than a Myford. At the time neither my father nor I could afford anything else. But the work that lathe took on over the years was way ahead of anything I could have ever ever handled on a Myford. A bigger lathe or a gapped bed that could have handled brake disc skimming would have been nice in the past but I can easily cope without.

After messing with changewheels for years I now find the gearbox I retrofitted essential, not for screwcutting but for quickly adjusting feedrates. Power longitudinal and cross feed is also a must have for me. Far better this doesn't have the potential to cause leadscrew wear as some implementations do (yes you Myford)

Another essential is a quick change toolpost (arc euro etc) . The 4 way toolpost that cost me a fortune back in the 1980's is really only fit for the bin. Horrible things designed by a masochist. The age of shimming tools long consigned to history. Same with the vertical milling attachment, for the Boxford it cost a lot of money, and it was used quite a bit for small jobs but it's never ever a substitute for a proper genuinely rigid milling machine.

So unless I was limited to a very tiny shed and model making a Myford in any form would never be on my list, the likes of the M250/300 would always be on the list.

Edited By Martin 100 on 18/02/2016 22:23:00

Edited By Martin 100 on 18/02/2016 22:27:06

Booked ahead (max of 12 weeks) it's just £17 single by train from London Kings Cross to Doncaster, 1 hour 30 mins for the fastest service, nearer 2 hours for the slowest. Then maybe £5 for the taxi to the Racecourse where the show is, just a mile and a half from the station or use online mapping / interrogate a local (who should be friendly!) and walk there. If you can follow the finger signs to the Mansion House (and it's on your right) just keep walking south until you get to a big roundabout, turn left and in a couple of hundred yards is the racecourse on your right hand side.

Doncaster to York for the National Railway Museum is less than 25 mins by train (£7 advance fare single)

Steam Train to Scarbrough on the coast is then another possibility

Or Coastliner 840 Bus from York to Pickering (£9 on the day single) for the southern terminus of the North York Moors railway to Whitby

For booking main line trains use virgineastcoast.com because it will be cheaper than other options. Tickets can be picked up by using your credit card in a ticket machine with the reservation number at Kings Cross.

Buying your train ticket on the day will cost about £70 single London - Doncaster

Edited By Martin 100 on 15/02/2016 01:00:24

Edited By Martin 100 on 15/02/2016 01:00:57

ACF50 (google it, it's available on ebay) sprayed everywhere in a thin film, or if you are hell bent on a shiny look, grey ultrafine scotchbrite and a very thin oil.