Author Topic: Another Westbury Wyvern build  (Read 4877 times)

Offline Muddy Rutter

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Re: Another Westbury Wyvern build
« Reply #60 on: March 28, 2019, 06:45:43 AM »
Thank you David for the updated drawings - they are really useful. Hoping to get some pictures up soon of my progress to date and meanwhile I hope you enjoy your trip to Japan, assuming itís a holiday of course. Nick.

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #61 on: March 28, 2019, 10:13:10 AM »
Hi Nick, I and probably the rest of the forum are looking forward to seeing some more Wyvern pictures.

Japan is holiday. While I was working I went there regularly from 2000 to 2015 but didn't have much time for tourism, this time I get to travel for myself. Sue is going for the first time and is apprehensive of the very big differences (e.g. being effectively illiterate). I hope to convince her that it's a great place to visit and not really all that difficult a place to be.

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #62 on: May 19, 2019, 08:24:58 AM »
OK, after two weeks holiday and a three-week "welcome home" dose of 'flu its back to work on the Wyvern. I did do a bit of shopping in Tokyo, places like this tool stall in Akihabara are hard to resist:



The other places worth a visit are a chain of stores called "Tokyu Hands", high quality small tools (a very fine file; replacement tips for soft-jaw pliers; packets of carborundum powder; really sharp, but reasonably cheap, taps and dies all came home with me).

Ah, yes, Wyvern - the next bits are the conrod and bearings. The rod could be carved from the solid but I chose to have a go at fabricating it. The shaft was found inside a part of the hoard:



The shallow taper was turned by offsetting the tailstock - the first time I've tried doing this - and this worked well. The little end and flange for the big end were from odds-and-ends. The brain fog induced by the 'flu had two effects firstly I forgot to take pictures and, more importantly I failed to think about how I was going to hold the finished taper shank for the rest of the machining. Starting again was probably the easy way but instead I tried 3D printing a fixture in ABS and the final version looked like:



Each half of the hole up the middle is tapered to match the measured shaft. The first attempt left a gap between the two halves into which the jaws of the four-jaw SCC slipped (that brain fog again) so when I came to use the fixture I had to pack it with metal strips. Here the big end flange is being cleaned up after silver soldering:



and the other end being scalloped before attaching the little end:



The oil hole drilled (should have left this until the bronze bush had been fitted):



then it was time to dig out the GM casting for the big end:



this was milled to length then thickness:



hacksawed in two (there was a lot of spare metal so this wasn't stressful) and milled to thickness:



The halves were fixed together with superglue and the crankpin hole drilled and reamed. If you look too closely at this picture you can see that I didn't even up the milling and the sides won't clean up to circular - still learning about dealing with castings:



More superglue (with screws for safety) stuck the part to a 1/2" mandrel and the sides cleaned up to width:



The new version of the ABS fixture held the shaft to drill and ream the little end for the bush:



and the flange milled to width:



The final use for the fixture was drilling the stud holes in the flange:



Two made-to-measure 4BA studs, plus a bit of polishing, finished off the job:



The 3D printed fixture did what was asked of it but I wouldn't use the method for any task requiring precision. An improvement would be to use a harder material than ABS (e.g. polycarbonate) as I could feel distortion when clamping up. The superglue worked well as an alternative to soft solder for holding the bearing halves together but I did make a point of leaving it overnight to cure fully.

David




Offline Roger B

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Re: Another Westbury Wyvern build
« Reply #63 on: May 19, 2019, 09:30:36 AM »
That's an interesting take on making a conrod   :ThumbsUp:  :ThumbsUp: Nicely done  :praise2:
Best regards

Roger

Offline Ye-Ole Steam Dude

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Re: Another Westbury Wyvern build
« Reply #64 on: May 19, 2019, 09:41:43 AM »
Hello David,

Coming along nicely :ThumbsUp:

Have a great day,
Thomas

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #65 on: May 19, 2019, 10:03:15 AM »
Thanks, Roger and Thomas - what time is it in Texas??

David

Offline Ye-Ole Steam Dude

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Re: Another Westbury Wyvern build
« Reply #66 on: May 19, 2019, 11:20:15 AM »
Thanks, Roger and Thomas - what time is it in Texas??

David

Hey again David,

I am on Central Daylight Time for the US and it is now 5:19 am Sunday morning.

Have a great day,
Thomas

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #67 on: May 19, 2019, 12:00:33 PM »
Hi Thomas, I thought you must have been up early! Thanks again for looking in on Wyvern.
David

Offline gbritnell

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Re: Another Westbury Wyvern build
« Reply #68 on: May 19, 2019, 12:06:56 PM »
Hi David,
Very nice fabrication log on the connecting rod.
gbritnell
Talent unshared is talent wasted.

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #69 on: May 19, 2019, 12:38:15 PM »
Thanks George,
If this version breaks and I have to make another one then the big end flange will have a collar on the shaft side to increase the surface for the solder. It would look better as well! It should also be possible to build up a part like this using adhesives, maybe I'll give that a try when the engine is running and I feel like tidying it up.

Cheers, David