Author Topic: Another Westbury Wyvern build  (Read 9020 times)

Offline Ye-Ole Steam Dude

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Re: Another Westbury Wyvern build
« Reply #75 on: July 10, 2019, 02:30:52 PM »
Hello David,

Nice job on the flywheel and your project is looking good.

Have a great day,
Thomas

Offline Muddy Rutter

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Re: Another Westbury Wyvern build
« Reply #76 on: July 12, 2019, 08:56:49 AM »
Hi David,

That's really looking good and you have made a lot of progress since I last logged in. I really like the colour of the main casting.

We moved about two months ago to Sussex so the machinery is packed away and sprayed in preservative pending the day I can convert a very damp garage into a decent workshop.

Hope you had a good time in Japan.

Must go - I have lots of wallpaper to strip before the plasterer comes!

Best wishes,

Nick

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #77 on: July 13, 2019, 07:57:55 AM »
Chris and Thomas - many thanks for the comments!

Nick, thanks, the rattle can colour is labelled "Indian Red" but in the poor lighting it looks more "chocolate" than anything. Japan is a great place to visit with lovely tool shops! It is July so shouldn't the damp have dried up? :)

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #78 on: August 04, 2019, 02:39:31 AM »
Carrying on with the valve gear the rocker castings came next. The two rockers are supplied as a single casting and the bosses on each side are the same height for both parts so the pair could be milled to thickness together:



and the holes drilled, reamed and threaded:



The two rockers were then sawn apart and I started to think about shaping the ends and outline. This could be done to the drawings but, being cautious, I left them rough until the rocker pivots, cams and cam rollers were made. The rocker pivots have a 0.01" eccentricity (which I guess is for adjusting valve clearance) and this was somewhere where the 4- jaw SC chuck came in handy - a bit of packing between one jaw and the work made setting this up easy:



The cams and cam rollers come next and then the whole lot can be assembled and the rockers finished off.

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #79 on: August 10, 2019, 05:12:30 AM »
The cams themselves started out as short lengths of 3/4" silver steel. Most of the length was reduced to 16 mm to go in the largest collet I have for the Aciera dividing head, the other end was reduced to diameter for the collar on the cam. A groove was turned in the 16 mm portion down to the 1/2" base circle of the cam and the bore drilled letter "D" for later reaming to 1/4":



The cam profiles were formed by machining successive small flats on the 3/4" blank at 3 degree intervals. The inlet cam has an opening angle of120 degrees and the exhaust has 130. As described a few times before on MEM the size of the steps was calculated using a version of the CamCalc program (.xlsx files with the values are attached below). The 3 degree steps result in visible, but small, flats that are easily smoothed out with a fine file:





I chose to use two M2 grub screws at 90 degrees apart in the collar to secure the cams to the shaft and the holes for these were drilled and tapped last. The cams were parted off and then held in a collet by the collar, turned to thickness and reamed 1/4" for the camshaft:



The cam profiles are pretty distinctive but I stamped then anyway before hardening (and leaving hard):



I've been in hurrying lately and failed to take pictures of the cam rollers and a few other simple bits but these all show up in the "family shot":



Now I have something to play with properly and turning the flywheels makes the valves work - great! The clearance in the camshaft drive gears becomes obvious when I do this as there is a click as each cam follower starts down the closing flank of the cam.  With the force from this the shaft slides to take up the clearance. I may have to adjust the meshing of the gears to close up the clearance but this can never be zero so a small movement seems inevitable.

David

Offline tangler

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Re: Another Westbury Wyvern build
« Reply #80 on: August 10, 2019, 10:35:56 AM »
Looking great.  Not too much left to do now.

Rod

Offline Roger B

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Re: Another Westbury Wyvern build
« Reply #81 on: August 10, 2019, 05:34:30 PM »
Excellent, as Rod says not long now  :ThumbsUp:  :ThumbsUp:  :wine1:
Best regards

Roger

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #82 on: August 14, 2019, 05:15:28 AM »
Thank you Roger and Rod! I'm making more progress now that I can see the end ahead (hear the first pops?).

The contact breaker bracket is a rather messy and complex casting:



that looked hard to hold. As it turned out it wasn't too bad, after a bit of filing it was held quite firmly in the 4-jaw chuck to turn the handle:



With two bits of thin card to help the grip two faces were machined at the same setting:



which allowed the part to be held properly in the vice, with a bit of sacrificial brass, for drilling the three holes for the moving blade, pin and fixed contact:



and the bosses trimmed smooth to drawing:



An old 0.020" feeler gauge provided the material for the contact spring and the tungsten tips provided in the kit from Hemingway were super-glued to the spring and to a bit of 6BA thread. With electronic ignition the tips should stay plenty cool enough not to soften the glue (I hope...). The cam was simple turning and fixed to the camshaft with two M2 grub screws in holes at 90* as I did for the other cams. The operating pin was turned from PTFE rod and the spring insulators from SRBP:




Now for the lubricators and carbie and then...

David

Offline Roger B

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Re: Another Westbury Wyvern build
« Reply #83 on: August 14, 2019, 11:18:35 AM »
Have you checked that there is an electrical connection between the tungsten tips and the spring/screw? Superglue is an insulator.
Best regards

Roger

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #84 on: August 14, 2019, 12:51:27 PM »
I have now Roger! Thanks for the warning - there is conduction on the moving side but the resistance is much too high. On the fixed contact no connection at all.

It's getting late here but I just quickly tried to tin one of the the tungsten tips using resin flux without success, will I need an acid flux for this?

David

Offline RayW

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Re: Another Westbury Wyvern build
« Reply #85 on: August 14, 2019, 03:57:09 PM »
Hi David,

Your engine is looking really good now and the paint job sets it off nicely.

As far as I can recall on my Wyvern, I silver soldered the tungsten contact to the spring. With such a small tip and thin spring, you won't need too much heat to do the job. I can't remember what flux I used but I favour Tenacity No.5 as a good one for silver soldering.
As Roger says, there needs to be good contact between the tip and the spring.
Ray

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #86 on: August 15, 2019, 01:24:38 PM »
Thanks to Roger for pointing out what should have been the obvious! I can confirm that super-glue is an insulator :facepalm: . Thanks also to Ray for the soldering advice. Because I'd already failed to soft solder the tip to the moving contact there was flux and solder over the end, rather than trying to clean that off I put a dab of SBA245 on the back of the tip and the soft solder stuck to that with no trouble. The fixed contact tip I silver soldered to its 6BA screw. As predicted by Ray, very little heat was needed.

I've made a start on the three lubricators which are turned brass fabrications. On the original drawings the bodies were detailed at 3/4" diameter which made them likely to interfere with the crank webs so these were reduced to 11/16". The base was given a nice curve using one tooth of a radius cutter as a form tool which worked very well, perhaps better than I should have expected:



and the inner surface produced by drilling and boring to a plug gauge, this should allow the lids to be interchangeable. The three bodies didn't take very long at all to make:



The wick holders were turned to 9 mm, a 5 mm thread formed on one end and parted off:



then an 8 mm hex milled:



There is one more operation of these to bring them to diameter, then on to the lids.

David

Offline b.lindsey

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Re: Another Westbury Wyvern build
« Reply #87 on: August 15, 2019, 02:48:44 PM »
Have missed a few updates David but am caught up again now as you get near to the end of the build. What a fine looking engine it is too! Should be a nice runner soon!!

Bill

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #88 on: August 18, 2019, 04:06:58 AM »
Thanks Bill! It won't be long now and the castings for the next project are waiting for me in the UK.

The lubricators were quickly finished off with the cores held in a mandrel threaded M5 in order to take the outside to dimension:



For the caps a length of 3/4" brass was given a fine diamond knurl the inside and outside turned to size:



and each cap parted off in turn.  The cores were soft soldered in place but I didn't get a picture before adding the wicks, fitting the parts to the engine and filling with oil:



Fitted to the main bearing caps the lubricators look the part to me:



David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #89 on: August 18, 2019, 04:29:29 AM »
Here is the drawing that I should have put a the start of the "Lubricators" posts just to make the structure of the things clearer:



DT