Author Topic: Another Westbury Wyvern build  (Read 7022 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

Online 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

Online 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

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #70 on: June 22, 2019, 10:09:04 AM »
The Wyvern camshaft is simply a length of 1/4" silver steel running in two bronze brackets and driven by 1:2 skew gears from the crankshaft.With the help of some small calipers I more-or-less just eyeballed and centre-popped the centers of the bosses on the two brackets:



then fixed them in the 4-jaw and lined up the centres with a needle:



then faced off, drilled and reamed 1/4":



With both brackets at this stage they were super-glued to a bit of 1/4" rod and held in a pair of V-blocks in the milling vice to machine off the bolting faces. I'd used a straight edge to measure the difference in height between bolting pads on the cylinder head and bearing stand on the engine and the hope here was that this difference could be reproduced precisely with the DRO:



The stub of 1/4" and super-glue were also used to hold the parts in a collet to clean up the other faces:



The 8 tooth driver and 16 tooth driven skew gears were supplied with the kit of bits from Hemingway and just needed drilling, reaming and finish turning:



The alignment wasn't exact and a very thin shim at the head end was needed to get the camshaft to run freely but the shaft is now in place:




Progress has been slow due to two weeks a way, three weeks with the flu and another month trying to get rid of a bacterial infection - just love getting older in winter, don't we?

David

Offline RayW

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Re: Another Westbury Wyvern build
« Reply #71 on: June 22, 2019, 10:46:43 AM »
You are making great progress David. It's really beginning to look like an engine now! Watching your thread with interest as a fellow Wyvern man.
Ray

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #72 on: June 22, 2019, 12:02:42 PM »
Thanks Ray, I'm pleased you are following along.

Regards, David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #73 on: July 10, 2019, 12:15:27 PM »
Having the flywheels fitted would make turning the engine over while setting up the valve gear much easier so these came next. The two iron castings had been poured with the two halves well out of line so there was a lot of filing work to (mostly) smooth off the parting line on the inside of the rim and the sides of the spokes. Coarse emery tape took down a lot of the rest of the surface roughness, hopefully to the point where a little primer/surfacer and a couple of coats of primer will give an appropriate finish. The castings were still irregular and it wasn't obvious how to hold them to machine the rims. I fiddled around for over an hour with first the 4-jaw and then on the faceplate, without being convinced I could make them secure enough to machine. Drilling and tapping some extra holes in the faceplate and fitting some packing to lift the rims clear of the surface looked like the best option until I remembered seeing pictures of using a wood sub-surface for the faceplate when you can then put in wood screws wherever they are needed. A bit of hardwood was dug out of the piling system, roughly sawn to size, bolted to the faceplate and given a light skim to true it up. Once it has been kiln dried Aussie hardwood (commonly Mountain Ash or Messmate around here I think) is very hard and stable and machines quite well if with a lot of dust:



A sacrificial layer of 1cm ply stood the castings away from the face and gave enough thickness for some existing brass screws to be used for clamping. I chose to have the inside of the rim running as true as possible as the slippage between the two halves was very pronounced on the outer edge:



As you can see in the picture the QC tool post had to be turned around to get a tool far enough out to turn the rim faces and edge:



The clamps over the spokes were replaced one by one so the hub was clear for facing and drilling:



and the 5* taper bored with an inverted tool at the back of the hole:



This arrangement, which allows the taper collets to be turned the conventional way was easier, I think, than the other way around. The flywheel was then reversed, trued off the turned rim and the other faces turned. With all the holes for the clamping screws already there and the procedures worked out then the second casting went quickly. More proof, I think, that it is always worthwhile pausing to make jigs or fixtures to help with holding work.

The taper collets were simple turning jobs from FCMS:



then slit in the mill and parted off:



The project really is now starting to look like an engine :



Lots of little fiddly bits left in the valve gear and carbie but the end is getting much closer. Painting will have to wait until the weather warms up a bit as I don't have any heated space where spray painting is possible, then the really hard decision - should the rims be painted or not?

David

Offline crueby

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Re: Another Westbury Wyvern build
« Reply #74 on: July 10, 2019, 02:30:14 PM »
Great setup for doing the flywheel!   :ThumbsUp: