Author Topic: Alyn Foundry Sphinx  (Read 5465 times)

Offline RayW

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Alyn Foundry Sphinx
« on: April 15, 2019, 08:19:04 PM »
Just returned a couple of days ago from a very enjoyable short break in Wales and a visit to Graham to collect a set of Sphinx castings. Graham and his son made my wife and I very welcome and ran a couple of their little CHUK flame ignition engines for us to see.

Most of the castings were made by a small one man concern and are of rougher external texture than Graham's normal ones, but where they have been cut, they appear to be of good quality with no evidence of flaws. A bit of fettling with a sanding disc should soon smooth them out a bit. Graham managed to find an older barrel casting for me as well as a Robinson piston and these are of much smoother finish.

First task will be to mill the bottom of the main casting, then the mating face onto which the barrel locates. Next job will be to bore the 1.75" hole in the mating face, through which the cylinder protrudes. This presents something of a problem as my milling machine is not tall enough to take the casting in a vertical position and I really do not relish the idea of swinging a 10 inch long, 9.7 kg lump of cast iron in the lathe. I can probably use my drill press, but how to hold the very heavy and irregular casting in an appropriate position will need a bit of thought.
Ray

Offline Jo

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Re: Alyn Foundry Sphinx
« Reply #1 on: April 15, 2019, 08:29:18 PM »
Another Sphinx, nice one Ray  8)

Have you thought of clamping the base casting to your cross slide and holding a boring head in the spindle of the lathe?

Jo
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Online Jasonb

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Re: Alyn Foundry Sphinx
« Reply #2 on: April 15, 2019, 08:36:21 PM »
As Jo says mount it on the cross slide, depending on what height you have above the surface you may just be able to mount on packing or if not enough then use angle plates, I have done several engines this way though I prefer a between centres boring bar. You can flycut the back face of teh casting for the cylinder flange at the same setting so it is true.





You can then swing it round to do the main bearings so they are at the same height.


Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #3 on: April 15, 2019, 08:50:40 PM »
Thanks Jo and Jason,

That would be the ideal solution, but unfortunately my lathe has no facilities for mounting anything on the cross slide.
Ray

Offline Jo

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Re: Alyn Foundry Sphinx
« Reply #4 on: April 15, 2019, 08:55:14 PM »
Have you considered taking off the Lathe tool post and using its mounting studs to mount an angle plate onto which the base casting could be clamped?

Jo
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Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #5 on: April 15, 2019, 08:58:44 PM »
Thanks Jo. I will have a look to see if that would be possible.
Ray

Online Jasonb

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Re: Alyn Foundry Sphinx
« Reply #6 on: April 16, 2019, 07:23:00 AM »
I'll need to go and look at my casting but it may be possible to bore the bole with the bearings uppermost and pass the head down between them which would mean you need less head room, if the mounting face were machined first with the casting sitting flat on the mill table you could them use this surface to clamp it down which should get the bore square to the hole.

The other thought is how tight a fit does the liner really need to be, could be that you could just mount it on end to mill the face and drill the holes ( drill bit in MT collet if needed) then file or otherwise bring the hole to a size that the liner will fit through. I have done a couple of engines where the cylinder is just supported on two sides and not in a hole.



Final thought, you don't need to use a boring head which takes up head room. A simple piece of bar to fit your largest MT collet with a reduced shank if needed (or a small flycutter) drilled for a HSS tool can be used with the tool being manually advanced. Even if the hole were +/- 0.010" it would not be a problem provided the liner were made to fit.

Online Jasonb

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Re: Alyn Foundry Sphinx
« Reply #7 on: April 16, 2019, 09:23:52 AM »
Had a quick play with my casting and tooling. Pics to illustrate my post above.

1. Boring with 2" head between the bearings, also if you let the foot of the casting overhang the table that will gain you another 2" or so in height.



2. Using a holder with HSS tool or small flycutter to plunge down tool will be advanced manually.



3. If you don't go with an accurate hole the four mounting holes can be drilled with minimal height and the surface can be milled at same setting



The far eastern machines may be quite small but they do generally have reasonable Z height for their size, as you can see my X3 has plenty to spare. :)


Online Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #8 on: April 16, 2019, 02:53:00 PM »
Hi Ray.

It was great to meet you both again and I'm glad to read you enjoyed your stay near Rhyg Capel.

The Sphinx was only my second engine design, a bit of a greenhorn! Conceived late 1983. I made it very " chunky " as cast Iron wasn't very expensive back then. It's at this point I have a confession to make....
I didn't ever machine the bed casting once myself.... I made several Sphinxes over the years for customers but always used the services of AWR for the very same reason as you're finding now. However at that time my entire workshop consisted of a bench pillar drill and a tiny Tyzak 3" lathe. I hope I can be forgiven?

The main reason for a " gearless " 2:1 reduction was, A. Zero gear cutting knowledge/equipment and B. Geoff Challinor had recently sent me photocopies of Robinson's 1890 patent Oblique engine, I was amazed at its simplicity.

At this time Vincent Salter who'd already made the patterns for my first design, the " Penultimate gas engine " was well underway with his " Retlas " and I thought " well if he can make patterns then so can I " !!   As work progressed the bed pattern shape reminded me of the famous Egyptian statue, the engine got its name.

Several months later Vincent's Retlas debuted at the very first 1000 engine rally held at Tatton park in June 1985. This 1000 engine rally shouldn't be confused with the two previous rallies that had been tried in 1979 and 1981 by the founder and editor of " The stationary engine " magazine, David Edgington. I'm proud to say that I attended the second event with my massive 1919 Lister type " P " who's magneto died almost immediately after its first start on the Saturday morning.

The Sphinx was coming together slowly but wouldn't be seen running until September. We three, Vincent, Martin ( The Great Lorenzo ) and myself actually finished number 103 on the Rally Field at the Malpas event held at Gredington park Hanmer using a Crossley powered generator set that Vincent had " cobbled together " for electric power tools.

It was mid afternoon on the Sunday that she finally sputtered into life amidst applause from both exhibitors and public alike. I felt so many emotions, 'twas amazing.

Being such a novice I had decided to use as many readily available parts as possible, the crankshaft came from a J.A.P. 1A petrol engine and the piston from a Honda C90. The parts that couldn't be machined on a lathe were all hand filed. I really overdid the fasteners, I mean 5/16" BSW for the valve chest, c'mon Graham, what were you thinking?? I'd suggest downsizing a little here Ray.

Three decades plus later the video attached shows number 103 with all the knowledge gained and applied, plus a little adaptation that stopped the occasional breaking of the ratchet pawl !! By extending the exhaust valve stem to be closer to the ratchet wheel centreline it stops the pushrod getting caught underneath if the engine should backfire and run backwards.

I hope you enjoyed my ramble down " memory lane " as much as I did. The Sphinx wasn't very popular probably less than 40 kits produced in as many years!!

Cheers Graham.


Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #9 on: April 16, 2019, 04:31:31 PM »
Thanks Jason and Graham for your helpful suggestions and comments.
As Jason suggests, machining the front face first then mounting the casting bearings upwards on the milling machine is certainly a possibility.
I made a start on machining the underside of the base today but think I need to invest in some carbide tools as my HSS cutters were blunting pretty rapidly, even once I got under the outer skin. This is only my second experience of working with cast iron (the Robinson X type being my first), and this casting seems a lot harder than the Robinson ones.

P.S. Thoroughly enjoyed the "ramblings" Graham.
P.P.S. I always start machining with the bottom of the main casting. It gives me a chance to get a feel for how the material cuts, and is also a great place to hide any blunders!!


Ray

Online Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #10 on: April 16, 2019, 06:56:35 PM »
Continued....

As my workshop grew I managed to afford my first milling machine, a beast of a thing, a Denbigh Universal weighing in at a touch under two tons!! I still use it occasionally as it makes short work of keyways in horizontal mode. However, the vertical head is capable of pushing a 6" diameter Carbide tipped face mill that I used for the very job you're having a spot of bother with at this moment.

As Jason has pointed out the cylinder liner needs to be able to slide through the hole to allow for expansion. With hindsight it might be prudent to have an " O " ring inserted to stop the water from escaping into the bed way.

Another modification came later with regards to the cylinder head/liner flange/outer jacket assembly. A " canny " customer came up with an alteration that hides the cylinder liner flange. This makes it appear that the cylinder head fits directly to the water jacket casting. By reducing the liner flange diameter a little and counterboring the cylinder head the flange disappears. Because of this your head casting is deeper now as I modified the pattern many years ago.

Attached is a video of one of the few Penultimate's that were sold fitted with the Starwheel running flawlessly....


Online Jasonb

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Re: Alyn Foundry Sphinx
« Reply #11 on: April 16, 2019, 07:19:01 PM »
Thanks for the insight into how the Sphinx came about Graham.

The drawings I have do show an O ring seal though I may do mine a little differently when I get round to doing this engine. Will also look into hiding the flange now that you have mentioned it.

Offline Roger B

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Re: Alyn Foundry Sphinx
« Reply #12 on: April 16, 2019, 07:35:04 PM »
Interesting stuff  :ThumbsUp:  :ThumbsUp:  :) Those serrated clamping wedges seem to support your casting nicely Jason  :)  :wine1:
Best regards

Roger

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #13 on: April 17, 2019, 11:53:08 AM »
Hi Graham,

As regards water leakage, as Jason has mentioned, the plans already show an o-ring in the brass sealing ring at the flange end of the water jacket but just a face to face seal between the other end of the jacket and the cylinder flange. I was intending to build as per plan, but to use Loctite as an additional seal at each end to prevent any possibility of leakage.
Incidentally, the earlier jacket casting that you found for me is actually only 4 1/16" long (unmachined) as against the finished length shown on the plans of 4 7/16". Do you think that I will need to shorten the cylinder by a corresponding amount to avoid the con rod fouling it?
I like the idea of recessing the head casting to hide the cylinder flange and will probably adopt that idea.
Ray

Online Jasonb

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Re: Alyn Foundry Sphinx
« Reply #14 on: April 17, 2019, 12:59:28 PM »
I don't think I will make my ring from brass as I can't really see much point in it, iron or even steel would do and the rest of the engine is going to rust if in contact with water so why bother with a non ferrous ring. I will probably put a lip on it so the tightening force is metal to metal rather than risk the locctite bond failing and that means it can also be made thinner.

Depending on what room there is at the head end I'd also like to see if I can get a small section O ring in there to seal as the only contact is the end of the jacket and under the lip of the liner., it only touches the inside of the jacket where the four small lugs are.

Looks like my head will easily accommodate a 1/4" recess to take the lip on the liner and may try for a bit more to keep compression ratio down as it looks like my jacket will only give 4 3/16 after a clean up maybe 4 1/4

Rough sketch of my thoughts