Author Topic: Another Westbury Wyvern build  (Read 4029 times)

Offline MJM460

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Re: Another Westbury Wyvern build
« Reply #30 on: February 24, 2019, 08:42:40 AM »
More great progress David, enjoying following along.

What did you make of those interesting chips?

MJM460

The more I learn, the more I find that I still have to learn!

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #31 on: February 24, 2019, 10:24:03 AM »
Hi MJM,
My initial reaction was aesthetic - they made a good B&W picture. I have lots of images of bits of tree bark, moss, paint surfaces etc that I've collected over the years when I saw something that appealed to me.

More technically the chips were in a small range of sizes, many with 2 to 4 turns which suggests that the material is very consistent throughout. Also the big drill still cuts well which is good as I would have to improvise a way to sharpen it (or find someone with gear big enough to do it for me). The chips aren't as brittle as they look, quite springy in fact.

David

Offline sco

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Re: Another Westbury Wyvern build
« Reply #32 on: February 24, 2019, 01:10:22 PM »
Nice work David, enjoying following your progress,

Simon.
Ars longa, vita brevis.

Offline Admiral_dk

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Re: Another Westbury Wyvern build
« Reply #33 on: February 24, 2019, 08:58:13 PM »
Looks like a perfect cylinder / ring finish on parts that aren't "broken in yet" to me :ThumbsUp:

Though I must admit that a photo can fool you when taken close up  :thinking:

Offline Art K

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Re: Another Westbury Wyvern build
« Reply #34 on: February 25, 2019, 12:25:46 AM »
David,
Despite the problems with juggling the base and all that came out well. It looks great with paint. How long is the cylinder liner (no not the drill)? The liners I have made were for an air cooled engines and pressed into the cooling fin portion of the cylinder. I bored it first and turned the OD with a disposable glove stuffed inside to kill the chatter. Great work!
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #35 on: February 25, 2019, 06:39:46 AM »
Admiral - at least I can't see any chatter! I'll try to remember to take another picture after the engine has run for a while.

Art, Some times I don't see the obvious until it's pointed out - next time I'm making a liner I'll bore it first then turn the outside, possibly on an expanding mandrel which should keep everything stiff enough not to chatter. Stuffing a glove (or a rag?) inside the bore was another good idea. The Wyvern liner is 3.75" long and the bore 1.25".

Thanks David

Offline Ramon

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Re: Another Westbury Wyvern build
« Reply #36 on: February 25, 2019, 08:06:39 AM »
Hello David - apologies for being late to the party ::)

Just been through your thread - looks like you have another nice project here  ;) Some very nice machining on the base and a really lovely job on that crank :ThumbsUp:

Re the cylinder I've always found doing the bore first keeping the od as stock (or as cast) is much the better way to get a good bore first and then bringing the outside to it. Expanding mandrels will hold so securely (and rigidly) with little force required to distort anything - something I'm sure you are aware of anyway :D

Looking forwards to the rest of the build and a nice runner at the end

Regards - Tug



"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline john mills

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Re: Another Westbury Wyvern build
« Reply #37 on: February 25, 2019, 08:47:21 AM »
when using the fixed steady try a lesses pressure a light delicate feel is required the difference from too much to not enough is not much and slight adjustment can be needed while machining progresses.if you do the bore first
you can use a pipe centre ,alive centre with a cone big enough to fit the bore.while you turn the OD.Ihave done that with 10" long sleeves 4" dia and 1/8 wall thickness.even 1/16 wall.
looks like your progressing well.
  John

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #38 on: February 26, 2019, 09:57:30 AM »
John, Thanks for the tips on using the fixed steady. I almost certainly pressed too hard on the fingers when I was setting them, didn't want to have the work able to move. I've seen fixed steadies with ball races fitted to the fingers which might make setting easier but I'm not too sure about the effectiveness.

Ramon, it's good to hear from you again - have you had more "distractions"?
Thanks for the comments! The finish on the crank is partly down to Garryflex (your advice lead to buying a bunch of Garryflex blocks) and partly to draw filing. You reinforce the previous advice re boring first then turning the outside for machining thin shells like cylinder liners. This to me is one of those things that is "obvious" once someone else has pointed it out. I'll try to add notes to my drawings with bits of advice like this. Kozo Hiraoka was the master of including advice like this with drawings. On this forum I sometimes feel that I'm serving an apprenticeship with masters spread all around the world! The next project is still sitting in a box on a farm near Huntingdon and I have to make some plans for retrieving these bits later this year - Forncett?

David

Offline john mills

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Re: Another Westbury Wyvern build
« Reply #39 on: February 26, 2019, 10:15:22 AM »
I have used fixed steadies with ball races one on a imported lathe has ones with rollers with radius on the rolling surface with only worked like a pipe cutter cut or rolled a lovely groove to get bigger dia in i made bronze tips with i get to work well.I have seen rollers used with worked well too and on big diameters and heavy probably  the best for that work ,such as pulley or rollers 780mm dia 2 meters long or shaft 350mm dia   3 meters long.   

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #40 on: February 26, 2019, 11:09:29 PM »
The cylinder water jacket is a cored casting and this turned out to be close to being square across the ends with the cored hole close to running true in the centre. A bit of work on one end with a file trued it up enough to allow me to mount the casting in the 4-jaw and true the other end:



I bored the cored hole out to diameter without a hint of chatter (I was so focused that I forgot to take a picture) then opened up the water space with a shop made grooving tool. Despite trying different tool heights and two re-grinds this produced probably the worst surface finish I've ever put on a piece of metal but it will serve the purpose:



With a clean bore at each end the piece went on to an expanding mandrel and both ends were given a truing cut and the piece brought to length:



and the bottom flange cleaned up on the surface that will take the nuts:



This probably should have been spot-faced but that needed a tool making and once painted and with nuts and washers in place the appearance will be OK.
Clamped to an angle plate the water inlet and outlet bosses were milled flat and the water holes drilled:



I wanted to get the water jacket and baseplate painted before moving on so the last work on the baseplate was to drill the oiler holes in the bearing caps. The way these work out is that the oil holes hit the bearing bushes on a tangent :



Once the paint dries I can fit some studs and start to assemble something looking like an engine.

David

Offline Chipswitheverything

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Re: Another Westbury Wyvern build
« Reply #41 on: February 27, 2019, 01:10:42 PM »
Somehow had missed this log of the Wyvern, so Just been enjoying looking through the build log from the introduction a couple of months ago: great photos of the machining sequences, fine drawings, and very nice progress on the build itself.   Your Aciera mill is a beauty...       Cheers, Dave

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #42 on: February 27, 2019, 08:40:30 PM »
Thanks Dave! Pleased to have you along for the story.

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #43 on: February 27, 2019, 11:20:22 PM »
Here is a family shot of the progress to date:



I took this in the bright sun to give a better idea of the colour. Summer is nearly over - officially - but we have four more days of high 30s and too warm nights to contend with.

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #44 on: March 07, 2019, 01:05:40 AM »
I've had more workshop time in the last week and finished the piston and most of the cylinder head so it's time to write up some more of the progress. I have also been working on the drawings as I find errors and omissions and I'll post a new set soon.

The piston started as a rough alli casting and fortunately I had Rod's (tangler) experience, and Jason B's advice, to forewarn me of the problems and provide the solutions. In the picture the boring bar is only there as a pointer while I line up the cored inside of the piston casting to run close to true with the mounting stub in the 4-jaw:



the outside was around 2 mm off centre and starting with that would have led to problems with the piston skirt. With that setting I turned the outside true but still well over finished size:



then reversed and held in the 3-jaw to turn the mounting stub true:



so that the part could go into a collet for the rest of the machining. Starting with truing the inside of the skirt up as far as the gudgeon pin bosses and you can see that this failed to clean up properly to drawing diameter, think I'll have to live with that:




The outside was turned to finished size and the piston ring grooves cut in:



I aligned the as-cast slot between the inside bosses with the y axis of the mill using a bit of metal (no picture) and used a long end mill to clean up the gap:



then turned the part round, aligned it using the same method and drilled and reamed the gudgeon pin hole:



and parted off the piston from the stub:



Back in the 3-jaw chuck with some thick paper for protection the piston was finished to drawing length:



I got a bit nervous here about the thickness of the piston crown but this actually worked out close to the drawn 1/16" perhaps more by good luck than anything when you consider the quality of the casting seen at the start. Like the other alli castings in the set this one has a lot of ugly small pores, I'll find out when the engine runs if these weaken the crown enough for it to fail. For anyone else building Wyvern it would be worth thinking about ignoring the casting and making the piston from bar stock, probably simpler and certainly better looking than this one.

David