Author Topic: Alyn Foundry Sphinx  (Read 7644 times)

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #30 on: April 23, 2019, 03:30:37 PM »
I have been working on the cylinder and jacket today, and pondering how it is possible to recess the cylinder flange into the head if you stick to the dimensions as drawn for both items.
The head and the flange are both 2 1/2" diameter. The four 3/16" studs are on a 2 1/16" PCD, giving an outside dimension across the studs of 2 1/4". To leave at least 1/16" of metal around the outside diameter, the minimum diameter that the flange could be reduced to is 2 3/8".
To recess that size of flange into the head would only leave a mere 1/16" of metal around the outside of the head. I just wonder how others have resolved this - possibly by reducing the PCD of the studs perhaps?

Personally, I quite like the look of the engine with the flange showing, as per number 103, so will probably go with that anyway.


Ray

Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #31 on: April 23, 2019, 06:19:02 PM »
I don't think there is a need for the flange to be larger than the outside dimension across the studs, I have made many engines where the flange is only 1/16" all round bigger than the OD of the liner which puts it completely withing the studs. However that was with the liner making contact all the way around it's side at the end of the jacket, here we only have contact against the four lugs unless the top of the cylinder is bored out for say 1//4" deep and a solid ring inserted and loctited into place.

If the depth of the recess were left a few thou shallower than the projection of the liner flange then all would be pulled up tight when the head was bolted on.

J

Offline Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #32 on: April 23, 2019, 06:59:22 PM »
Hi All.

Let's not get into a " tizzy " 'Twas just an observation, each to their own....

You could, however pre drill the holes on the correct PCD in both the cylinder head and liner, then machine the flange OD halfway through the holes. When ready the head could be then counterbored with the opposite halves of the holes to match.

I've just located the Sphinx " Daybook " it would seem that you, Ray have got engine number 129, Jo 130 and Jason 131.

Cheers Graham.

Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #33 on: April 23, 2019, 07:21:17 PM »
I've just has a bit of a measure up of my castings and this is what I think I will do and is along similar lines to the sketch I posted earlier. I have shown O rings at each end but that would be optional and a smear of liquid silicon gasket would do the job and that is what I tend to use on all flat face to face joints anyway.

Head end of cylinder bored out to 2.25" for a depth of 1/4". Into this recess a ring 1/4" thick and 1.75" ID will be retained with Loctite. Once set the four stud holes can be drilled and tapped, holes are shown at full 3/16" dia see first image which includes a nominal 1/16" o ring sitting in a 1/16" x 1/16" recess.

The liner will be made with the flange at 2.25" OD, I have gained 1/16" on the cylinder length now 4.125" long so reduced flange thickness to 3/16" which retains same overall length and means the recess in the head only need be say 0.190"  2nd image. Four 5mm dia clearance holes in flange.

Last image shows a section through the parts together with a similar ring at the opposite end.

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #34 on: April 23, 2019, 08:19:32 PM »
That looks like a neat solution. I had already considered recessing a ring into the head end of the jacket to give a bigger mating surface with the cylinder flange,  but not thought about screwing the studs into that instead of the cylinder flange. It seems far more logical to bolt the head to the jacket rather than to the liner.
For a total belt and braces job , you could always put a couple of small screws through the jacket wall into the recessed ring to stop any possibility of it pulling out.
Ray

Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #35 on: April 23, 2019, 08:31:06 PM »
Ray, I think it was always Grahams intention that the head studs pass through the liner's flange and hold into the jacket, the 4 "lugs" inside the end of the jacket give some meat around the stud holes. This is how I read the original drawing before mention was made of recessing the head which will pull all three parts together once the nuts are done up, second image is as it would be with the ring added.

As the thread cuts across the joint that would stop any risk of teh ring pulling out even if you did not carry the threaded holes down into the lugs.

Offline Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #36 on: April 24, 2019, 03:10:43 PM »
Indeed it was Jason!

However, the cylinder liner and head patterns were modified ( lengthened and deepened ) to accept the reverse of what you've drawn.
Rather than recess the water jacket you allow the liner flange to sit flat and recess the head instead.

Cheers Graham.


Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #37 on: April 24, 2019, 03:31:01 PM »
Graham, intent is to still have the liner flange in the same position as you did but sit it on a recessed ring for increased sealing area. Liner flange is then reduced to 2.25" dia so that the head can slip over the top of it with 1/8" wall to the recess.

I'll draw the head up later and post pic of the assembly.

j

PS Ray star wheel has made it as far as a jiffy bag, hope to post tomorrow

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #38 on: April 24, 2019, 03:43:20 PM »
Yes, what Jason says!! I was literally just typing a similar reply when his popped up.

Jason, many thanks again for the star wheel. Do please let me know if I owe you anything.
Ray

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #39 on: April 25, 2019, 11:50:38 AM »
Made some more progress on the water jacket and cylinder today. Bored out the head end of the jacket to accept a brass ring as has recently been discussed, and temporarily fitted the ring to ensure that the cylinder lined up with the brass O-ring retaining ring at the other end.
The head end ring still needs a final skim to bring it flush with the end of the jacket, but I will not do that until it has been Loctited in position, I will then also drill and tap the holes for the cylinder head studs. The cylinder still needs boring and the flange reducing in diameter so that it can be recessed in the head. The O-ring was made from some material that I already had to hand.I am not sure yet if I have made the groove in the brass ring deep enough. I will only be able to tell once I bolt the jacket to the main body and see how much the o-ring compresses.

Graham,
As you know, the water jacket casting I have is one of the older style ones with the inlet and outlets at opposite ends. On the plan, there is a note that the inlet underneath the jacket was moved to the middle. What was the reason for that?
« Last Edit: August 05, 2019, 08:13:55 PM by RayW »
Ray

Offline Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #40 on: April 25, 2019, 12:05:05 PM »
Good morning Ray.

You have quite a " pace " on! Progressing nicely.

The original position was to ensure a full flow of coolant across the entire length of the cylinder liner. The rearmost boss being close to the bed way made coupling a pipe fitting difficult but not insurmountable.

I decided to move the boss to make life easier for the constructor.

Cheers Graham.

Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #41 on: April 25, 2019, 12:36:20 PM »
Looks good Ray, I got a rough head drawn and assembled. I see that the flat face where the valve fits is 1 3/16" front ctr line which means it will be 1/16" at the narrowest when hollowed out. may be worth moving the face out to 1.25" and adjusting the valve block or eccentric etc to take that into account.

Regarding the pipe connections would there be anything to stop you having it the other way up? Which would put the bottom inlet near the head and top outlet nearer the engine body. There is one on Station Road that has the newer casting but with the inlet at the head end in a similar way.

https://www.stationroadsteam.com/sphinx-star-wheel-engine-stock-code-3793/

Star wheel is is posties hands now.


Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #42 on: April 25, 2019, 04:46:24 PM »
Thanks Graham and Jason for your thoughts. Turning the jacket the other way up seems quite a neat solution, rather than moving the boss. Keeping the bosses at opposite ends should help circulation as Graham says.
Thanks for the tip off about the face dimension for the valve block Jason. Given that there is now a solid mating face between the cylinder flange and the inset brass barrel ring would you see any problem in reducing the flange diameter even further, say to 2.125", which would still give a reasonable mating area and leave more meat on the cylinder head?
Ray

Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #43 on: April 25, 2019, 05:04:26 PM »
I can't see a problem with that.

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #44 on: May 01, 2019, 08:06:42 PM »
Completed work on the cylinder head today. Totally forgot about Graham's suggestion about reducing the size of the studs for attaching the manifold, so have drilled and tapped to 5/16" Whitworth as shown on the plans. It would not be a problem to make up some stepped studs to reduce from 5/16 BSW at one end to 2BA at the other.
I ended up reducing the dimensions of the cylinder flange to 2"diameter x 1/4"thick, which still leaves plenty of sealing surface with the brass ring in the water jacket.
I have shown the cylinder assembled with the cylinder head, but you will notice that I have not yet drilled the cylinder flange to fit around the studs.
The cylinder itself has been bored to within a few thou of finished size and will be brought to final size with a brake cylinder honing tool, which will also be used to remove a slight taper from one end to the other.
Ray