Stan Bray's Slim Sam

Hi Guys,

Has anybody out there built a Slim Sam from Stan Bray's book "Making Simple Model Steam Engines"? I only ask because a friend tried and failed. I tried and, once redesigned, succeeded. So I would welcome your views on this "..a perfect introduction to model engineeriong for the uninitiated and ideal relaxation for the more experienced engineer."

chriStephens

What problems did your friend have?

What did you redesign?

Did you post the errors found (if any) to the errors section of this or any other website?

I built one for a young relative using the published plan as a guide, but to be honest I didn't pay much attention to the plans, and ad-libbed much of it to suit available materials.

JD

Edited By Jeff Dayman on 03/09/2012 13:29:33

I built an Opus Proximum table engine from a design by Stan Bray that was published in ME some years ago.>>

There were several errors in the drawing and the engine would not go together as drawn so I wrote a polite letter to ME in the hope that my findings would help others. The letter was not published but I got an irate letter direct from Stan along the lines of 'who was I to criticise his design and drawing'! >>

I still have the engine but it has never run. Whenever I look at drawings or articles by Stan Bray I still tend to cast a more critical eye over them than those from other authors, never the less I am greatful for his prolific articles.

Hi Guys,

Jeff, first off the crank disc radius was greater than the space between the bearing and the base, easily over come by reducing to an appropriate dimension. Second, the ports in the upright are uncovered because the cylinder base is too narrow, corrected by making it wider. Another fault that i corrected was to make the piston longer, this reduced the tendency for it to rock in the bore and try to lift the cylinder off the upright. I also added a bush in the upright for the crankshaft which was clearly shown in the photos but not in the plans. Your method is, I am afraid, the correct one as the engine cannot be built according to the plans. I have not raised the issue anywhere save for the original question two month ago, I was wondering how many other folks were also disappointed in what I had thought to be a competent author and designer. Clearly i was mistaken.

John, I think the appropriate answer to his question is "someone who can at least read a caliper" or perhaps, "someone who has the ability to do simple arithmetic and knows that you can't get a quart in a pint pot" or maybe just "someone who is disappointed in how the mighty have fallen"

I have to say that for a book to be aimed at beginners, as I said it "...is a perfect introduction to model engineering or the uninitiated..." I am somewhat appalled that this book was not sufficiently proof read by the author before publication or that no errata (plural because there are more than one errors) sheet was added. From my experience I have found that beginners will try to follow plans exactly because they don't, yet, have the confidence or experience to "wing it". A book from such a prestigious author as Mr. Bray should, in my opinion, be above reproach which regrettably cannot be said of this volume.

Clearly the models can be built, there are after all photos to prove it, but why could not accurate drawings have been produced? I will say however that I derived great (or should that read some) pleasure from building this motor, but most of that was from overcoming the faults, I always enjoy an engineering puzzle you know.

I might also say that if this book had been written by an amateur that i would have had more compassion for the author, but someone who has the attitude that this author seems to have, from the above comments, deserves none. If, however, the author was trying to do the old Meccano trick of deliberately putting faults in the plans to inspire thought in his readers then I might review my opinions.

I do not know the chap and have had no dealings with him but model engineering does owe him a certain amount of appreciation for his past work, but "how the mighty have fallen" does seem fitting. So much so that there was a discussion, albeit somewhat frivolous, about "Sale of goods" and "fit for purpose"!

So if any of you folks want to write a book, please make sure that you check what the publishers have done with your work, because of course you sent them perfection, didn't you? If you do do a "Meccano" please put a note to that fact in your preface or introduction and perhaps offer a prize, maybe a fistfull of old swarf, to the first to point the error out.

Rant over, normal service will be resumed shortly.

chriStephens

This build blog warns against mixing imperial and metric dimensions, but also concludes that teh engine as drawn won't work:

**LINK**

Joey

Chris quote-"Jeff, first off the crank disc radius was greater than the space between the bearing and the base, easily over come by reducing to an appropriate dimension. Second, the ports in the upright are uncovered because the cylinder base is too narrow, corrected by making it wider. Another fault that i corrected was to make the piston longer, this reduced the tendency for it to rock in the bore and try to lift the cylinder off the upright. I also added a bush in the upright for the crankshaft which was clearly shown in the photos but not in the plans. "

I visited my young relative yesterday and had a look at the engine I made for him. Looks like I dodged a few bullets when I made it via freelancing. My flywheel was 7/8" dia, rather than 1" as in the plans, so I didn't see the interference to base that you had. The upright was made from a 3/4 x 3/4" bar scrap, as was the cylinder base so the ports are not uncovered as they would be per the plan at 1/2", and the wide stock did not require a bushing for the shaft. Not sure how long I made the piston but I remember sizing it by checking it in place in the bore at TDC and BDC and marking the crankpin hole and skirt length directly off the engine, so it would have the longest possible piston and still clear at TDC.

Just out of curiosity I went back to the plans and checked the ports layout. The horizontal spacing of 1/4" is OK but there are two vertical dimensions noted for the ports, 11/16" from the cylinder pivot, and in a side note, 17.5 mm radius! Both are wrong though if the 11/16" port to pivot dim on the cylinder is used. The correct radius pivot to port on the cylinder for perfect port alignment from my CAD layout is .701" or 17.8 mm, if the upright ports are made to plans at 11/16" vertically from pivot and 1/4" between ports horizontally. I'll forward these notes to Alan Stepney for inclusion in the errors section of his website.

Mr. Bray certainly missed the mark on these plans.

JD

Hi Jeff,

When I knew that the plans were all to c*ck, my philosphy was to use the stand as drawn and modify the bits that did not fit. I did use a bit of 2"X2"x!1/4" brass angle(machined to size) instead of sticking two seperate bits of brass together. I do not use CAD, but I did some simple Trig to make sure that the ports were correctly drawn, so i knew I would have to make the cylinder face wider. I also cheated and made the head and cylinder as one but put a line to simulate a separate head, just my little tease to fool people.

Generally speaking, I much prefer to repair things rather than make new and i suppose making this engine work is more akin to a repair than a new build. Must have a go at one of his more complicated engines, one day, for the mental exercise involved in making it work. It would be nice if a redesign were not needed to copy a certain person's plans

chriStephens