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Member postings for Bob Stevenson

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

Thread: Darwin's long-lost microscope
17/12/2021 22:57:03

About 40 years back someone passed to me a list of 'model engineering' drawings which, If i recall accurately, were published by MAP.......I had no interest in model steam engines at th time and still don't, but there among the pages of drawings for meaningless (to me) bits was 'a research microscope' which did catch my eye...........

When I was in junior school we briefly had a fantastic lady teacher who gave us an incredible afternoon disecting some flowers from the school garden called 'flags'.......she showed us the various parts and what they did and the whole class was totally absorbed, and so were various parents who came to find out why their kids had not come home!

The next week she melted glass stirring rod on her desk using a bunsen and stretched the glass before our amazed eyes!.....then she snapped of the thin filament and melted the end into a blob........this became a very servieable microscope lens! She made one for everybody and we got busy gluing the lenses between two small bits of carboard. The we really got to look at the bits of flags!

I kept my homemade microscope until quite recently..........

Thread: Looking for telescopic box section steel
12/12/2021 20:52:19

I have some bits of hollow steel beam which were off-cuts from a house extension nearby a few years ago....I don't know the exact internal dimensions and I'm not going down the workshop on a night like this,...however I do know the wall thickness is 6mm and that there is/was a steel section to fit inside this, although to what accuracy I don't know. The corners of the tubes are rounded and the tube was used to support the extra staircase to a roof apartment

..........Go to a good architectural steel supplier and ask there!

Thread: Any Old Gun Experts out there?
09/12/2021 16:22:33

The TZ type rear sight looks complete to me...was a standard target shooting item, maybe still is...The last 'double clamp' thing is what used to be called a 'foresight sett' and basically bends the foresight blade according to the pressure of the threads.

see here for TZ.

Thread: Warco DM180 DRO
03/12/2021 21:56:02

Grizzly 0768 is a larger lathe than WM180.......the manual lists 8 1/4 inches by 15 3/4 inches between cntres and WM180 is a 7x12 machine. Also see two comtrol knobs on headstock casing....

Thread: Perfect Stainless
02/12/2021 14:26:09

No, the use of 'union flag' only became known in 1902 officially and the Admiralty and Royal Navy insisit both names can be used equally......

02/12/2021 12:13:42

Some (the?) first stainless cuttlery was branded "Firth Staybrite" and is completely non magnetic. A few years bag it had a very high scrap value and I was told that it was used for non-mag hand tools and prosthetic limb joints.

SS was discovered by accident in 1913 at Woolwich Arsenal when experimental rifling that had poor results was left in the rain and did not rust.

The first maker was Herberts and in 2013 the centenary was celebrated by the Swedish owner of Herbert's business who made some ingots of SS with the union jack pattern thru the bar when it was cut.

Thread: Filing Technique
28/11/2021 13:01:21

second ratchet aside;.......I enjoy filing and find it quite theraputic, not to say cathartic. However, over the lock-down I filed up the ratchet for my latest clock by hand...16 teeth and not too much accuracy required. One eye was on the nearby TV and then 'Montalbano' came on....I continued filing and reading the sub-titles while following the plot. Towards the end of the episode I was also nearing the completion of all the teeth, but then found that I had 12 teeth pointing in one direction and the remainder pointing in the other direction.........

.........Always pays to have the brain properly engaged!

28/11/2021 09:23:26

In my view there is only one way to file effectively and productively......

I have noticed that many of the people who have alot to say about filing methods being unimportant, don't actually need to file much and have never done so. However, once there is a real need to remove lots of metal accuately then there is usually a quick change to 'the right way'

In my clock club (EFHC) there are people who will do almost anything and use extreme mental excercise to NOT have to file....the easiest filing job involves sometimes two different milling machines and even CNC and filing is now trully a 'lost art' for the vast population of western countries along with many other forms of hand/eye/tool dexterity.

It has been my lot to hve to impart the secrets of accurate filing to at least seven other people and I have been amused by the way they glaze over when you get to the fine details....NONE of those people took up my guidance initially and EVERY SINGLE ONE eventually came to the right way of filing once the real need became vital.

Once you get into making clocks from scratch by hand files suddenly become a vital set of tools as they were in antiquity and people start asking to look at the said clocks using magnifying glasses......But most people who make things don't need to file nowadays and most don't even own a file worthy of the name. Like most things in life it's "horses for courses".

Thread: Metrotropolitan Vicker Single phase motor
27/11/2021 17:56:09

I have a Met Vickers single phase motor that I understand was surplus from WWI......when I last tried it about 25 years back it worked well......and ran a small lathe very effectively. It was part of an obvious conversion of my 'RSB' treadle lathe which is also WWI vintage and apparently quite rare.

Thread: Wonky threads using die
22/11/2021 11:31:19

You don't actually need a tailstock die can use an ordinary die stock and use the tailstock barrel to steady it and keep it accurate......I've been cutting threads in the lathe for many years but, as yet, I don't own a tailstock die holder although I do use one in the club workshop sometimes and i can't truthfully say that one is better than the other but of the two, I tend to prefer the ordinary 'manual' die holder steadied against the tailstock.

20/11/2021 11:46:43

Cut the threads while the piece is still in the lathe chuck.....put the die holder against the end of the tailstock barrel and turn the chuck by hand while gently advancing the tailstock crank......

Thread: How do you stop brass tarnishing
18/11/2021 18:26:53

Rod Jenkins et al,......I do believe you are correct about Renaisance Wax being parafin based,..a slip of the fingers on my part!

However, my word of caution stands,.....some musical instrument repair specialists will not take bare brass instruments for plating if they have been treated with Renaisance Wax or similar because removal (and thus good plating) is extremely difficult.

18/11/2021 10:57:17

just a few points to add;.....

If you use laqueur be absolutely sure that you prep carefully and fully, so no fingerprints etc.....don't use petrol as final wash....don't use brake cleaner either.....Meths is as good as anything after hot detergent etc.

Remember that the silicone polishes such as 'Renaisance Wax' while they work well as specified can be virutally impossible to remove completely if you later wish to either laq or silver/gold plate and can really muck up the job!

If you use laq don't just get the first one you see on the shelf at around and ALWAYS do a test first on a carefully prepped piece of similar scrap.

Some laq gives excellent results but has some difficult handling features...clockmakers have lists of recipes that go back into the mists of time with weird and wondrful 'pros and cons'..such as the famed 'dragons blood' etc

A very excellent laq that I have found is 'Le Tonkinois' but it has savage cons for the inexperienced....I used this on my first clock and was pleased with the great working characteristics such as superb smooth finish and easy application. However, one week after application the clock developed purple streaks!......I won't describe my anguish! Then I noticed that the parts whxih had been heated to red heat for silver soldering had not streaked.....I now still use this laq but never of parts that I have not annealed/heated.

Thread: Wanted - Brass tube bending
15/11/2021 13:13:55

There are five methods used in the brass musical instrument business;....

1) anneal the tube and then use finger pressure to bend around a plywood profile of the bend if the curve is not too extreme.

2) Fill with soap solution and freeze then bend as above.

3) Fill with molten lead, bend, then melt out the lead.

4) use a spring the closely fill the pipe while bending as does a plumber.

5) use a dry medium such as fine glass granules or sand, as mentioned....stopping the ends can be tricky.

Thread: US Army : Infantry Squad Vehicle
14/11/2021 11:35:14

Well it might suit the bean counters but i don't think the 82nd Airb orne will be too impressed because they have a very wide training might be ok in Florida but temperatures can drop to well below freezing in parts of the US and the roads are long!....anyone thought about a waterproof covering?...anyone thought about what happens in a 'war event'?......anyone thought about IED's.

Since my first post above, I recalled the many stories of failed civvy components in military use during and after WWII....Read up on the British motor industry and it's major battle to get it's head around the unique requirements of designing and building fighting about the Rootes Group and the Valentine tank which was designed around civvy how Churchill famously threatened Rootes to use specific components....

Even the Germans fell foul of third of Panzer divisions in 1939 were using horses for transport and secondary battlefield uses (amazing but true!) ...but were obliged to change to motor power once training became lethal....

14/11/2021 10:32:40

I don't think this IS any sort of "cultural change"......there is a long history of trying to adapt civvy equipement for military use and also quite a long history of failed excercise.... The Moke has already been mentioned and one only has to look at the multifaceted problems of trying to replace such systems as LandRover and the Warrior series to see how the need for specialisation quickly spoils the quest for 'off the peg' cheapness.

The problem(s) with this vehicle is that while it may be useful for third world armies it lacks the required specialisation and versitility for more sophisticatd formations........a serious lack of protection, both intrinsic and military surely limits it's appeal Modern mil vehicle systems need to be adaptable into various transport needs (the strength of Landrover) which this does not seem to offer.

Thread: 7BA Grub Screws with socket (rather than slot)
09/11/2021 09:09:40

Although BA fixings are making a come-back now I don't think you can (as yet) buy BA socket heads so you need to make or contrive.... The two methods I have used successfully are to use a non BA with enough diameter to turn down in the lathe and then recut in BA....this makes for ratehr large head which may not be what you want.

The other method is to turn up the blanks and using a simple jig, forge the socket head using an allen key, then thread BA...this sounds tricky and time consuming but I found this to work well in practice. The jig I used was part of plate from a scrapped machine which had recessed openings for the right sized bolt with sunken heads. You need to turn down the head when made to give a good finish.

Thread: Smart and brown model 'L' lathe- opinions, please?
31/10/2021 08:06:50

The S&B 'L' lathes are a quarter ton, which is 'heavy' considering the small size of the machine itself. The lathe bed is permanently mounted to the cast base which acts as stand, fluid tray, motor housing and storage looks like one single massive casting but is actually a cleverly assembled collection of parts. I have seen 'L' lathes on ebay that have been separated from the base but this is not a task of a Sunday afternoon in the shed adn you should consider the layout design as permanent. The quarter ton mass gives these lathes great accuracy and turning facility.

.........New collets for S&B are avaiable but not for £82 as far as I know....if they are we will be keen to buy some so please let me know where!

27/10/2021 19:07:36

The nose is threaded and any chuck with the corresponding thread can be fitted....At EFHC we have collets, face & drive plates, large 4-jaw, various 3 jaw and also ER32 chucks.

If you are asking if the 'L' models have powered feeds then the answer is 'no'....these are instrument lathes and quite simple machines, but then, in turning as with much else, 'less is (sometimes) more'.

Thread: Lathe Drilling
26/10/2021 23:08:42

In problems like this always look at the absolute basics first......

If DB8 is like it's Warco equivalent then it comes with a centre for the spindle throat and another for the tailstock,.......find these and fit into the respective throats........slide the tailstock up so that both centres are 'point to point'....check exact accuracy using a glass.

..........Make sure that the throats are both clean by shining a light up and having agood look!.......Also make sure no swarf or foreign body is under the tailstock.

If both centres align perfectly, replace tailstock centre with drill chuck holding a centre drill only (nothing else) and repeat alignment test......

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