Member postings for loco man

I believe that Mike Poole made a very accurate comment re the huge size of the original Whitworth size heads. After those standards were set it - and possibly late 1939 - early 1940? - it seems as though there was a re-think and sizes were dropped - for instance the hex size of a 5/16 BSW bolt hexagon dropped down to the size of a 1/4" head size. Along with the introduction of BSF - ie British Standard Fine threads. Maybe this was why the dual marking of some spanners was introduced - for instance - 3/16"BSW / 1/4"BSF.

Some of the older fitters that I worked with used to refer to the down-sizing of hexagon dimensions as 'war standards' -- maybe a way of conserving / making better use of steel supplies??

Maybe someone else has some more accurate information over the change - I await with interest.

Ian

From a 'Holo-Krome Ltd Metric Series Socket Screw Selector' , the following sizes are listed --

M1,4 - clearance hole 1,6 dia, counterbore for head 2,8 dia.

M1,6 - clearance hole 1,8 dia, counterbore for head 3,3 dia

M2 - clearance hole 2,4 dia, counterbore for head 4,3 dia

M2,5 - clearance hole 2,9 dia, counterbore for head 5 dia.

M3 - clearance hole 3,4 dia, counterbore for head 6 dia

M4 - clearance hole 4,5 dia, counterbore for head 8 dia

M5 - clearance hole 5,5 dia, counterbore for head 10 dia

M6 - clearance hole 6,6 dia, counterbore for head 11 dia

M8 - clearance hole 9 dia, counterbore for head 15 dia

As these sizes are the manufacturer's recommendations, can it be assumed that they allow for any under-head fillet radii? In general, both in model engineering and 'full-size - on steelworks and mining machinery' I have found that metric fasteners both socket head and hexagon to be over-sized (across-flat in particular) and clumsy compared to their near-equivalent imperial sizes. Please, why??

Ian

Again, draughtsman for over 40 years. Drawing board at first then, from 1978, primarily CAD. Including Computervision, Radan Radraft, Tektronix, and Microstation. Initial design sketches with pen on sqared paper then CAD (at home), with A4 prints to take into the workshop. Trained to draw to the (old) BS308 and still much prefer and use it as black lines rather than 'colour coding'

The question has been raised as to whether En1A is lead bearing.

From a copy of 'Macready's Standard stock range of quality steels and specifications' dated October 1975 it would appear that there were a number of 'sub-sets' of En1A. Quoting their descriptions and trade names, 'Usaspeed' classed as 'super freecutting bright steel' was listed as " BS970:1955:En1A" replaced by BS970:Part 1:1972:220M07, colour coded Green. The same catalogue refers to 'Usalead' lead bearing freecutting bright steel. Same BS description but colour coded Magenta.

In the same catalogue there is reference to 'Usatel' - 'Tellurium bearing freecutting bright steel' colour coded gold' and noted as being one of the fastest machining of all steels. However I cannot find any trace of a BS970 'En number'

The lead-containing En1A I knew in my time in the 'shops' as 'Leadloy' (sic) and was used widely for the production of such items as hydraulic fittings - where the very good surface finish straight from the tool (NO emery cloth!) was a help in sealing against up to 4000 lb/sq.in. oil.

Unfortunately - as a direct result of having lost my job last year after 19 years in the drawing office when the steelworks at Redcar closed down - I can only refer to such catalogues {especially the afore-mentioned 'Macready's) etc. that I have managed to retain. So it is quite likely that there are others who have more up-to-date information and I look forward to their knowledge / input / information

I am following this thread with interest. I would stress that I have, and have not, had any connection whatsoever with Macreadys -- other than referring regularly to their (by now long-outdated) catalogue

Ian

For general machining details - and providing that no arc-welding is involved- I would much prefer En1A Pb. With sharp tools and plenty of cutting fluid it can give a surface finish approaching that available from cylindrical grinding. As I remember from my time 'on the tools' in the late '60's / early 70's the lead content of En1A could cause porosity in welds.

No problem, though with either silver soldering or 'sifbronzing' .

En8 is the next - readily available - higher tensile steel. After that, En16T - but possibly an 'over-kill' for the Shay.

Ian

Although having two milling machines (both, 'warco', Super Major, and WM12) I still find that my little Corbett 7" stroke shaper of much use. When I was serving my apprenticeship in the mid 60's there was a general feeling that to set up in a shaper took five minutes and to machine the job took an hour. The reverse was the case with the milling machine. One area that I feel that the shaper has over the milling machine is the ease of tooling/tool grinding. In some cases a suitable lathe tool goes straIght into the shaper toolholder (aka clapper box?) Much easier to regrind by hand than a slot drill/end mill. My considered feelings are that both milling machines and shapers have their own places/homes in the workshop and I would hate to be with out either.

Ian

Three lathes - a Warco WM180, great for small bar work such as pins, bushes and studs. Limited travel on slides, no tee-slotted cross-slide, and, initially, no leadscrew handle / handwheel. Thanks, though, to some brilliant service from the Warco spares departmenf that was soon rectified.

Warco GH1232 - again a very nice lathe, especially with the digital readouts on saddle and cross-slide. Let down only by the relatively high bottom speed of 70 rpm. A bit high for roughing out 9" and 12" diameter cast-iron loco driving wheels? Even with carbide tips? And for screwcutting coarse threads? Some time ago I discussed this matter on another site - I am not at all keen on variable-frequency drives and intend now to machine new pulleys to half the speeds.

'Zyto' - despite its age and the flat-belt drive possibly the most versatile in the workshop. As currently arranged with an ovehead countershaft, screwcutting up to a shoulder is easy -- pull the belt over and stop. Tee-slotted cross-slide allows readily for rear toolpost and other attachments. Only one complaint - 3/8" bore / 1MT mandrel and yet a 2MT tailstock quill?

I would query that for an 8" outside diameter x 4mm thick boiler the working pressure would have to be 'very low' A quick check, assuming a working pressure of 120psi, gives a hoop stress in the barrel of only 1,31 tons per square inch (hoop stress = pressure x inside diameter / twice thickness).

Even if a relatively low grade of stainless was to be used, say of an ultimate tensile of 28 tons per square inch, this would give a factor of safety of 21.4:1 based on ultimate.

There are other factors to consider though, such as the widespread opposition in the UK to stainless steel boilers whereas on the continent boilers tig welded from 316L stainless seem to be commonly accepted - even preferred.

Sorry - but before anyone else spots the mistake- I meant 2-10-2

An earlier post suggested that coupling rods cannot be inside the wheels. Not so. Chapelon in his 2-10-0 compounds used inside coupling rods (between the frames and hence 'inside the wheels' ) to couple the H.P. and L.P. cylinders. This arrangement is clearly shewn in the reprint of Chapelon's book "La locomotive a' vapeur" figure 319