Turner S50

[Michael FodenParticipant @michaelfoden39595]

Hi, I'm just returning to metalwork after a 20yr. absence, although during this time I've used My ML10 for Ornamental Turning, & wodturning. I also have a Coronet woodturning lathe, & a small bench drill. I built the V10 some years ago, but think I will need assistance with the S50.

There appears to be a lot of casting sand on the C.I. parts, & although I have had success with the flywheel rim & edge, I am unsure how to tackle inside the cylinder to remove ingrained sand prior to boring. S.T. are ignoring my emails. Also , I have commenced the tedious task of transferring the drawings into metric. Why do they insist on imperial – AND, expressed as fractions.?

Are there any digital calipers out there that show fractions- I think not. Maybe I'm supposed to measure with a ruler !

Any assistance would be appreciated.

Many thanks

Mike.

[Michael FodenParticipant @michaelfoden39595]

[WolfieParticipant @wolfie]

I've just built an S50 more or less from scratch, although I did buy the cylinder and flywheel castings. I don't recall any problems boring the cylinder, just trued it up as much as possible with a DTI and faced and turned one end, then turned it round and repeated.

I have a copy of metric plans for the S50 that someone on here sent me although I built mine in Imperial in the end. Email me, truckmodeller@talktalk.net and I'll pass you on a copy.

Funnily enough I've just bought a digital height gauge which does have a fractions option, so they are out there. But its not difficult to work out…

1/4 = .250" (250 thou)

1/8 = .125" (125 thou)

1/16 = .0625" (62.5 thou)

1/32 = .03125" (31 thou)

1/64 = .015625" (15.5 thou)

So for say 5/32 simply multiply .03125 by 5 = 0.15625 0r 156 thou

[David LittlewoodParticipant @davidlittlewood51847]

Mike,

I believe you can get calipers which show fractions, but quite honestly I think it is a barking mad idea, you have little or no idea how close you are to spot on. I don't think any of us have any difficulty down to eighths, maybe sixteenths for those who use imperial all the time, but there can't be many people who can mentally convert 29/64 ths into decimal on the fly. My solution has always been to have a Zeus data booklet next to the machinery, the table at the front gives me all the dimensional assistence I need, and the laminated finish means they are virtually indestructible. Just take the ISO metric tapping drill sizes with a large dose of salt though.

The other approach would be to sit down before you start and pencil in the decimal equivalent of all the dimensions on the plans.

David

[JasonBModerator @jasonb]

As for removing any remaining sand then a stiff wire brush and a bent old scriber should shift most of whats there. Also worth getting some thin wire down the cast in passages as these often have sand in them.

As David says there are a number of digital callipers that will also read in fractions never found the need myself, you soon get used to what the common fractions are in decimal and its easy enough to look up or punch the others into a calculator.

It also works the other way, if they put on the drawings drill a 0.453 hole what drill bit would you reach for? far easier if they say drill a 29/64" drill. or tap 0.281"x40 when its a 9/32" tap.

You will find 90% of ME drawings are still in imperial and the majority of those fractional.

J

PS David the fractiuonal callipers also disply the decimal at the same time so you know where you are as can be seen here

Edited By JasonB on 15/08/2012 13:27:56

[Michael FodenParticipant @michaelfoden39595]

Thanks everyone for the replies.

I have found a metric conversion chart on Google, so although it is time consuming, I'll just do a little at a time. Being involved in woodturning for many years, I find that metalwork is done at a much slower pace – so I'll have to adapt !

Just one thing that puzzles me so far, is the S50 con. rod. The kit supplies a rectangular piece of steel, 1/4" x 3/8" x 3.5", & the finished drawing shows that it is tapered 1/4" to 3/16", with rounded ends.

I can't figure out how to tackle it. Do I set over the tailstock & knock off the corners ? On the plan drawing, it is illustrated on its side with one length tapered, & one side flat – as if only one side has been tapered.

Can someone please sort me out on this one ?

Many thanks

Mike.

[The Merry MillerParticipant @themerrymiller]

Michael,

When I started my S50, (I'm more than halfway through at the moment) I discovered a brilliant article by Tubal Cain on the build of the S50. It's in the form of a 28 page PDF which I discovered on Google.

It's a fantastic article and was originally published in the "Model Engineer" starting on 21 August 1992.

I suggest you download this article and then all or most of your troubles will be answered.

Avoid the American " Tubal Cain" for this article.

I've tried retracing the link to the article download with no joy but so many people on this forum have made reference to it and have built it no doubt somebody will step forward with help on locating it.

Best of luck.

Len. P.

P.S. The con-rod is tapered throughout, not just on one side, study the drawing again.

Don't move the tailstock, use the topslide for the taper. The rounded ends are normally done with "buttons" as the article explains. Much better than trying to do it by freehand filing.

[David LittlewoodParticipant @davidlittlewood51847]

Mike,

Thinking back to when I made my S50 – about 25 years ago – the con rod is tapered at both ends, fat in the middle, and is made leaving a small parallel section in the middle. Then working on it with a very fine file (6" No 4 Swiss Vallorbe, with handle, soaked in cutting oil) blend the centre section so you get a smooth curve. Very little needs to be taken off to get a lovely flowing curve.

How you do the taper depends on what you have. Best: taper turning attachment – you can use power feed and get the best good finish. Worst: set-over topslide (you can't use power feed, and it may not be long enough) closely followed with set-over tailstock (takes forever to get it back correctly). If you must turn between centres, far better to use a small boring head in the tailstock, with a small centre in place of the boring tool; you can then set it over to your heart's content without worrying about resetting the tailstock. Take light cuts and ensure the boring head does not rotate in the tailstock though.

David

[mickParticipant @mick65121]

Wolfie has got close to your conversion problem, but to convert imperial to metric you must first express the fractions to four decimal places, so1/16th would equal 0.0625 1/32 0.0320 etc. All you do then is multiply the decimal by 25.4 which will give you the metric conversion. To convert metric to imperial divide by 25.4 25.4mm is equal to one inch.

[JasonBModerator @jasonb]

Mick, should 1/32" not be 0.3125?

May not be much of an error on one 32nd but if you keep adding them you will get a comulative error.

J

[Michael FodenParticipant @michaelfoden39595]

Once again , thanks to all for your help.

I've uncovered the M.E. article by Tom W.- only trouble is, that it's in about 5 parts, & requires me to re-insert the PDF number for each part separately, print it, cancel that part & type in next part, print etc.

Ah, well, it will keep me out of mischief !

Mike.

[Michael FodenParticipant @michaelfoden39595]

Did I say 5 parts ? It's in 10 parts averaging 4 pages to each part.

Has anyone got some spare printer cartridges?

[Sub MandrelParticipant @submandrel]

FWIW I made digital displays for the DROs on my mill. I added a fraction facility wich automatically selects down to 64ths (or perhaps 128ths). I made it so an LED lights up to show when you are within 0.003" of spot on the fraction, which should be close enough for any dimension measured in fractions, not thou.

As far as I can tell the commercial ones don't do this.

When i told Dave Fenner about this, he asked why on earth anyone would bother – but there must be a market – and for the sake of a few hours coding.

Neil

[David LittlewoodParticipant @davidlittlewood51847]

Neil,

All just confirms my view that metric is just so much easier! Personally I'd rather spend 10 minutes just converting the dimensions on the drawing before I start.

Len,

The American Tubal Cain – not heard of him, did he also write articles in ME?

David

[Sub MandrelParticipant @submandrel]

David,

Try laying out a slide valve using fractional measurements.

Makes it a synch.

Neil

[The Merry MillerParticipant @themerrymiller]

David, below are some links to the American "tubalcain" (no space between tubal and cain)

Some of his videos are reasonable, and he has a room in his house stuffed with steam engines of all varieties.

Len. P.

**LINK**

**LINK**

[David LittlewoodParticipant @davidlittlewood51847]

Neil,

Not when your tools have graduations in decimals (imperial or metric).

Miller,

Thanks.

David

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Use of inch fractions on drawings comes from the early days of engineering when most setting out was done with a ruler and most machines had no index dials at all . Limits and fits were described in words – press fit , running fit etc .

As time went on accuracy of general work improved and machines acquired index dials . Calibrating an index dial in fractions , whilst not impossible , was obviously clumsy so an early change was made to decimal system . There now followed an unfortunate period where fractions continued to be used for general dimensions supplemented by decimal dimensions for limits and fits . Many drawings have passed through my hands with this hybrid dimensioning system .

It would have been better if decimal inch had been adopted for all purposes in those early days . Some industries did from about the 1950's on but hybrid inch drawings continued in general use until modern times .

[Eric CoxParticipant @ericcox50497]

Wolfie, an even simpler way, instead of looking up 1/32 as a decimal and then multiplying by 5 just divide 5 by 32.

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