7 equi-spaced holes on a pcd - why?

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You must be older than you look

MichaelG.

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... I know, don't bother explaining.

Edited By Michael Gilligan on 04/02/2018 21:38:25

So was i and lived in Handsworth to 1969 when there was a Lotus garage, quite posh then. Soho main drag to Hockley flyover.

Though have moved, lived, worked in and out the true Black Country, Brum and Wolvo were never in it. Black Country Museum has examples of products made in surrounding areas, ie Sunbeam, AJS, Clyno and many others see my album just created.
Weird i have a piccy of a van in BCM with Soho Foundry on the side in for renovation. http://www.model-engineer.co.uk/sites/7/images/member_albums/75533/788366.jpg

Thanks to all and particular to JasonB for the inclusion of the part section drawing.

I have a copy of the single Westbury drawing from Reeves which does not show the position of the cylinder drain hole which justifies the unusual flange hole distribution.

The drawing raises a larger point - how will we get the younger generation of engineers to follow in our hobby if these very poor imperial dimensioned drawings are the only design source material? I have spent my life involved with gearing and engines and have built a few models but even to me this drawing of the Double Tangye is more of an initiative test than an aid. I haven't located a copy of the articles that originally aided the construction. My interest in the engine was raised by seeing a unit at the Broomy Hill Engine site in Hereford - I'll go back on the next 'steaming day' and count the bolts.

Tony

Tony, looking at Jasons' pic, 8 holes/studs may fit in really well, and simpler to divide (for those not into CNC).

That's before coffee has kicked in, so draw it out yourself, and see if 8 would do better in your workshop.

John.

Just don”t forget what I mentioned about getting to the standard to fit the cylinders with extra studs.

When John Bertinat did his compound version using many of the same castings he managed to use 8 fixings. To do so the minimum of metal was taken off the cylinder mounting flanges thereby increasing it's diameter, fixing size reduced from 6BA down to 7BA whichcombined allowed the PCD to be increased by 1/8" so the fixings had more clearance to the trunk guide.

Going back to Ian Hewson's two photos posted 03/02/18, what a lovely looking engine, beautifully finished, a credit to you Ian.

Chris

Thanks for the praise, Emgee and Chris, much appreciated although that was not what I posted for. Engine was 95% complete when pics were taken, see through oilers and drain cocks fitted since.

Just wanted to say that the clearance is limited between the cylinders and standards, was a pain to fit the nuts to the studs with the room available, took a lot of work to provide clearance with the Dremmel.

The Black Country Living Museum are very strict about the territory. The Perkins Heritage Group have a 1923 Autocrat car, (one of only two left). We offered it to BCM. It was declined since it was manufactured in Balsall Heath which isn't in the Black Country!

It was terrible to see machine tools left in a field, already rusty, from being without any protection, not even a sheet or tarpaulin.

Probably, the last of the Tangye ("We launched the Great Eastern. The Great Eastern launched us" family was the late Derek Tangye, a charming man, who moved, with his wife, to a remote part of Cornwall to write books, grow tomatoes and daffodils. The books were the more lucrative crop!.  Tangyes went on to manufacture large compression ignition engines (There is one at The WaterWorks Museum in Hereford, which until relatively recently ran under its own power.  Since a crack was found in a crank web, it has been rotated by an electric motor)

Howard

Edited By Howard Lewis on 06/02/2018 11:00:42