Member postings for John Purdy

Here are some photos of my latest completed project, E.T Westbury's Wyvern. I bought the castings from Hemingway in Nov '13 and completed it in Sep '15, a record for me I think. My projects usually take 10-15 years (or more)! It fired the first time I turned it over but only ran for a few revolutions. The mixer was dripping gas (petrol), obviously flooded. I had started with the needle valve open 2 3/4 turns. After some further attempts it runs well with the needle valve open only 3/4 of a turn. But you have to hold it down or it will walk off the bench, not very well balanced, but isn't bad at its slowest speed.

During the build I found 7 errors/problems on the plans. On checking against the original plans in ME for '63, they were there too. I can list them here or in the drawing errors thread which ever is more appropriate.

I made a few changes which someone familiar with the engine might notice.

Geoff

Thanks for that link to the indexes. The ones I have been using up to now are those published by Colin Usher. These others seem easier to use. But still didn't come up the report I remember. It might have been titled under some other name. Or maybe I'm dreaming! The history in the LEEDS publication on Clarksons was very interesting. Thanks

John

Geoff

The link worked fine. The catalogue I have is the '78 version, and the price list is dated Oct '79. I also have the Steam-Paris flyer. I recall an article in ME on Clarkson's business with pictures of his facilities. It had to be in the early '80s but I cant find it in the ME indexes. The only one I can find was a couple of years before my issues start. Mine start in 1980 (actually Oct 1979). I'll have to go through them an see if I can find it. Can only be 3 or4 years, as the company ceased in '83.

John

Looks pretty, but hardly prototypical!!!

A note to the above. My cost for the castings drawing, gears, and shipping to PEI Canada in May '80 was 51.18.

That was the price of the drawings castings and gears plus 40% extra for shipping. The exchange rate at the time was very close to what it is now. Paid for by mail with a postal money order drawn in UK Pounds!

John

Rod and Geoff

When I bought my castings (May '80,35 years ago the base was also an alum. casting), they had just come out with the gunmetal set for 68.33 pound (drawings gears P&P &VAT) I was tempted but on enquireing of the price to Canada it was almost double due to shipping. I also, like you Geoff, didn't like the thought of traditional bright steel parts in gunmetal or being painted. At least polished CI is a close colour to polished steel. My drawings are also of the dye-line process as they hung on the wall of my workshop in Winnipeg for a couple of years and I took them down when I noticed the had faded to about half.

After all these enlightning exchanges I think the explanation for the discrepancies in the drawings of the same date is that my drawings might be he originals and when the first castings were shipped the beam pattern ended up producing a cast beam the was ~1/8" longer overall than the drawing. When discovered the drawings were altered (you drawing Geoff) but mine never got altered.

That could explain why the dims. on your drawings are very close to the ones I came up with by centreing the beam holes in the bosses.

Geoff and Rod

I'll try this again. I posted a reply to you Geoff on Sat morning but it seems to have got lost.

The dates on my plans are GA 18/12/68, the beam 14/12 96. and the links, 18/10/69. The dimensions for the beam holes are listed as 2 31/32 from piston pivot to link pivot, 1 3/8 to the beam pivot, 1 19/32 to the pump pivot and 2 3/4 to the con rod pivot, for a dist. from the beam pivot to each end of 4.34375. By centreing the holes in the bosses, my dimensions come out to be ( in the same order)3.023, 1.375, 1.592, 2.806, for a centre to end measurement of 4.398. It's strange the both our sheets with the drawings of the links bear the same date yet they have different dimensions. I bought my castings in May '80 ,when did you buy yours?

Your comments on the errors on the steeple engine are interesting as I have just finished building Westbury's Weyvern IC engine from castings I bought from Hemingway in Nov '13 and I found 7 errors in the drawings. Most are easily corrected if found before machining takes place, but the rear cam shaft bearing is impossible the way it is drawn. I checked the Heminway plans against the originals in the '63 issues of ME and they appear to be the same, so the errors have been there since day one.

Rod, Thanks for the dimensions,(different again) but seem to confirm what Geoff has come up with from his draughting board exercise as detailed in his last post.

I think I'll go with the following dims. 3.023, 1 3/16, and .75, seems to be the best results so far.

Thanks for all your help.

John

Geoff

Thanks for your reply. Your description of the geometry of the parallel motion confirms what I had come up with from studying the drawings. So that's good! When I laid-out the holes to be drilled and reamed in my beam I found that using the plan dimensions they didn't come in the centre of the bosses (I don't like the look of that) so I adjusted them to be centred in the bosses, keeping the distance from the beam pivot to the hole at each end equal. The new dimension from the piston rod hole to the one for the the parallel motion linkage turned out to be 3.023" vice 2 31/32" so I assumed that the length of the long link would have to match, otherwise we wouldn't have a parallelogram. Your description confirms my assessment, Thanks. I wonder if that comment in ME came about because, the author, when he built the engine centred the holes in the beam bosses but didn't adjust the length of the link to match?

John

Rod

Thanks, that would be great.

John

I also have gone through all the indexes with no luck. I have read through Stan Bray's build, but it is only pictures, no drawings..(copyright?) If I get no other responses I'll try Blackgates. Thanks

I purchased a set of castings (in CI) for the above engine from Clarkson's in 1980 and have been working on them on and off (mostly off!). I'm at the stage of making the links for the parallel motion and I recall reading, I believe in ME letters column (mid 80s?), a comment that the dimensions on the plans were wrong. I have since been unable to find it. Does any one know of it? Has anyone completed the model and can comment on whether there is a problem with the dimensions?

The dimensions on my set of plans are: 2 off each of 2 31/32", 1 3/16", and 5/8".