Model Engine Maker

Engines => From Kits/Castings => Topic started by: RayW on April 15, 2019, 08:19:04 PM

Title: Alyn Foundry Sphinx
Post by: RayW 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.
Title: Re: Alyn Foundry Sphinx
Post by: Jo 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
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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.

(https://oimg.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/1-3rd%20Ruston%20Hornsby%20BPR/DSC01524_zpshprrj0cv.jpg)

(https://oimg.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/1-3rd%20Galloway/IMAG1667_zps15b8e1eb.jpg)

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

(https://oimg.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/1-3rd%20Galloway/IMAG1672_zpsa598252f.jpg)
Title: Re: Alyn Foundry Sphinx
Post by: RayW 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.
Title: Re: Alyn Foundry Sphinx
Post by: Jo 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
Title: Re: Alyn Foundry Sphinx
Post by: RayW on April 15, 2019, 08:58:44 PM
Thanks Jo. I will have a look to see if that would be possible.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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.

(https://oimg.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Half%20Scale%20Gade/HPIM1390_zpsocmrsox7.jpg)

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.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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.

(https://oimg.photobucket.com/albums/v156/jasonballamy/Engineering/DSC03582_zpswblxudca.jpg)

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

(https://oimg.photobucket.com/albums/v156/jasonballamy/Engineering/DSC03583_zps4zs9i5ea.jpg)

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

(https://oimg.photobucket.com/albums/v156/jasonballamy/Engineering/DSC03584_zpsy9misq8x.jpg)

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. :)

(https://oimg.photobucket.com/albums/v156/jasonballamy/Engineering/DSC03585_zpsieywabc0.jpg)
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry 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.

0pxNlFMT24I
Title: Re: Alyn Foundry Sphinx
Post by: RayW 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!!


Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry 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....

vx7HvnAfjTQ
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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.
Title: Re: Alyn Foundry Sphinx
Post by: Roger B on April 16, 2019, 07:35:04 PM
Interesting stuff  :ThumbsUp:  :ThumbsUp:  :) Those serrated clamping wedges seem to support your casting nicely Jason  :)  :wine1:
Title: Re: Alyn Foundry Sphinx
Post by: RayW 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.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on April 17, 2019, 01:24:19 PM
Hi Ray.

Hmmm, must be getting old.... I'd completely forgotten about the Brass ring and seal assembly!

I wouldn't Loctite the open end as the liner will expand as the engine warms up. And as a footnote I've always preferred to use Acetate cure clear Silicon for all gaskets on my engines. If your mating faces are good a light smear and a tightened bolt will seal even exhaust fittings.

Regarding your PM, sadly I don't have a replacement " Starwheel " casting. May I suggest making one from some mild Steel round bar?

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on April 17, 2019, 01:41:15 PM
Damn.

The gas bottle man arrived just as I was finishing.... Totally missed the jacket question.

Having just measured that rough new one and another from 30 years ago they both are 4 and 5/16" long so it seems Ray you're the first to point out that the drawing is in error!! I think it should read 4 and 1/16" long as machined.

The cylinder liner casting is a MK 2 version and was made a little longer than the original so that it protrudes through the base a little more than previously.

Jason.

I chose Brass for a reason. Theoretically it shouldn't corrode onto the Iron liner making disassembly impossible in the future.

However, a thick bead of Acetate cure Silicon to fill the gap is a very cheap but suitable alternative and these days I'd probably just do that! As I'm getting lazy.... The thin " O " ring at the front is a good idea.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on April 17, 2019, 01:52:04 PM
Thanks again Graham and Jason for your thoughts. One thought I had is to machine a recess for a ring at the end of the jacket where the four lugs are and Loctite that in. The lugs are plenty long enough to allow this.This would provide a larger surface area for the cylinder flange to seal against - particularly necessary if reducing the diameter of the flange to recess in the cylinder head.
As regards the open end, as far as I can see, the o-ring seal as shown on the plans would only work if the cylinder was a snug fit into the hole in the front of the main body casting, otherwise the o-ring would tend to deform and be squeezed into any gap when the barrel retaining bolts were tightened.
Perhaps an o-ring groove on the inner face of the brass ring would provide a better seal?
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on April 17, 2019, 02:47:53 PM
Ray, if you need to file up a new star wheel this drawing has the radii and ctrs of the arcs that I think will give the right sort of shape. I think I would cut the flat faces with a thin slitting saw then rough hack saw the curves before filing to shape.

I'm not sure if I can use my casting but it would give me an excuse to play with the CNC. I think a 4mm cutter would be as small as I would want to go so the corners would need clearing up but may give it a go.

Title: Re: Alyn Foundry Sphinx
Post by: RayW on April 17, 2019, 06:48:14 PM
Many thanks Jason, that will be very helpful. I did 3D model the wheel in Fusion 360 and created the radii by eye. I am going to see if the casting is usable, but looks as if I may need to make one manually.
Title: Re: Alyn Foundry Sphinx
Post by: crueby on April 17, 2019, 09:29:00 PM
Thats a very interesting shape on the star wheel - if I follow the video correctly it holds the arm up away from pushing the rod every other time around. Clever stuff!

 :popcorn:
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on April 18, 2019, 06:43:56 PM
I decided to CNC a Star wheel from scratch just to get some more practice with the KX-3, more details in the "going over to the dark side thread"

http://www.modelenginemaker.com/index.php/topic,8882.msg199296.html#msg199296

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829232.jpg)

Title: Re: Alyn Foundry Sphinx
Post by: RayW on April 18, 2019, 06:57:43 PM
That looks really good Jason.A perfect demonstration of the benefits of CNC. Just one observation.- I think the central recess should be on the other side so that the teeth are facing to the right.
Would you be willing to make a star wheel for me please? I would, of course, be happy to pay you for your trouble.
Regards
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on April 18, 2019, 07:25:09 PM
Yes that is the back of the wheel, I photographed it that way as all the machining shots were from the same side. Buy cutting it that way up I could get the nut lower down which meant less of the 4mm dia cutter sticking out of the collet to avoid crashes.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on April 19, 2019, 12:23:38 PM
Hi Both.

The recess in the back of the Starwheel is to accommodate a " double flat Grover washer " more commonly known as a spring washer these days.

The idea is to reduce the possibility of the wheel being dragged as the pawl retracts. I noticed on the picture that Jo posted earlier the builder had fitted a neat vertical flat spring to keep the Starwheel from going backwards.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on April 19, 2019, 02:18:15 PM
Oops!
My apologies to Jason for thinking that he had put the recess on the wrong side of the wheel! I had mistakenly thought from the drawing that the spring washer was located between the bolt and the wheel, not between the wheel and the main body. It was only when I looked at the exploded view that I realised my error.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on April 19, 2019, 05:03:20 PM
Don't worry Ray, I have a second one cut this afternoon which has the recess on the outside that may suit your way of thinking :Doh:

I got distracted while doing some alterations to the CAM and forgot to flip the part over, never mind I'll make use of this one as I had been thinking of putting a recess on the visible face that could be painted to look like a casting so you won't have any filing to do on yours.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on April 19, 2019, 05:27:48 PM
Thanks Jason. I have just realised that, by putting the spring washer between the head of the bolt and the wheel, I will need to put a short spacer between the wheel and the engine body to stop it rubbing, which would not be a problem with the washer on the inside. I'm sure either will work fine.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on April 19, 2019, 06:06:16 PM
Thanks Jason. I have just realised that, by putting the spring washer between the head of the bolt and the wheel, I will need to put a short spacer between the wheel and the engine body to stop it rubbing, which would not be a problem with the washer on the inside. I'm sure either will work fine.

Hi Ray.

Just make sure it's made of Brass !  ;)

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on April 19, 2019, 07:51:20 PM
The modified cutting sequence included some 2.0mm holes at the root of each internal corner that made it easier to file out the waste that the 6mm milling cutter could not get to. I have also enlarged the incorrect recess on mine with a round nose tool and will paint the recess.

(https://oimg.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/20190419_185827_zpsnjjbrvtz.jpg)

(https://oimg.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/20190419_192428_zpsrgthoqk1.jpg)

Title: Re: Alyn Foundry Sphinx
Post by: RayW 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.


Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry 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.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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.
Title: Re: Alyn Foundry Sphinx
Post by: RayW 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.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry 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.

Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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
Title: Re: Alyn Foundry Sphinx
Post by: RayW 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.
Title: Re: Alyn Foundry Sphinx
Post by: RayW 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?
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry 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.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb 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.

Title: Re: Alyn Foundry Sphinx
Post by: RayW 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?
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on April 25, 2019, 05:04:26 PM
I can't see a problem with that.
Title: Re: Alyn Foundry Sphinx
Post by: RayW 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.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on May 01, 2019, 08:40:47 PM
Ray, did you put the inlet stud holes in at the drawn 13/32" or at 21/32" (13/32 + Recess depth) ? ditto the inlet hole at 1/2" or 3/4"
Title: Re: Alyn Foundry Sphinx
Post by: RayW on May 01, 2019, 09:37:23 PM
Hi Jason,
I stuck to the dimensions as per the drawing and it looks ok. The cylinder flange just shows in the inlet port, so I may just round off that part with a Dremel to provide a smooth gas flow in and out.
Have you noticed, by the way, that there are no dimensions for the central cylinder head bore? Also, the holes for the manifold studs intersect two of the four vertical holes





Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on May 02, 2019, 07:18:46 AM
Hi Jason,
I stuck to the dimensions as per the drawing and it looks ok. The cylinder flange just shows in the inlet port, so I may just round off that part with a Dremel to provide a smooth gas flow in and out.
Have you noticed, by the way, that there are no dimensions for the central cylinder head bore? Also, the holes for the manifold studs intersect two of the four vertical holes

I expect it will run fine with those dimensions but you may need to shorten something in the exhaust valve/eccentric as the valve block will be closer to the crankshaft by 1/4"

Yes even at 2BA they still clash so could be drilled shallower as the studs won't go in past the head bolts. The shallower depth won't be such an issue with the smaller diameter as you will get more than one diameter depth thread engagement.

I took the recess as 5/8"



Title: Re: Alyn Foundry Sphinx
Post by: RayW on May 02, 2019, 10:06:45 AM
Yes, I had already thought of that. Shouldn't be a problem to shorten the pushrod to compensate. I made the central bore 9/16".
Title: Re: Alyn Foundry Sphinx
Post by: RayW on May 02, 2019, 10:40:26 AM
This is my cylinder head on Fusion 360, with dimensions as per drawing, ie. no adjustment to compensate for the 1/4" recess.


Title: Re: Alyn Foundry Sphinx
Post by: RayW on May 07, 2019, 04:53:34 PM
Finished honing the cylinder. After I had bored out the casting, there were about 8 or 10 blow holes, ranging from pinprick size up to about 2 or 3mm. Fortunately, none of the larger ones were at what I would call the business end of the cylinder. Filled them all with JB Weld before final honing, and have ended up with a really nice finish to the bore. With the cylinder held vertically against a flat surface, a heavy brass plug slides down quite slowly, and, if pushed down, there is quite good compression.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on June 10, 2019, 03:16:13 PM
 After an enjoyable 3 week break in Scotland, I am back in the workshop and making swarf (or cast iron dust) again. After several abortive attempts using different methods to bore the large hole in the front face of the main casting, I finally came up with a solution - a hole saw, as seen in the attached photo. Definitely not the quickest way, but it did the job in the end. Bearing in mind that this does not need to be a precision fit hole, I am satisfied with the result.

 
Title: Re: Alyn Foundry Sphinx
Post by: Roger B on June 10, 2019, 05:08:38 PM
Hole saws are good  :ThumbsUp: I have used them to start cylinder bores, they are slow but probably quicker than boring and you end up with a usable blank rather than swarf.

This was a 22mm hole in a 50mm diameter 80mm long piece of cast iron cut from both ends.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on June 13, 2019, 08:58:42 PM
Hi Roger,
Unfortunately, before using the hole saw, I had already drilled a central hole, so the plug I have left will only be useful for making washers!

Drilled and tapped the holes for the bearing cap studs today, and the holes for the cylinder head studs. The brass rings at both ends of the water jacket have now been Loctited in position. Once they are fully set, there is just a small amount to skim off the one at the cylinder head end. I have ordered some stainless rod for making the various studs and a selection of stainless BSW nuts (from China!).
As shown in the attached photo, I roughly assembled the main body, cylinder and water Jacket, and cylinder head to ensure that everything lined up. 
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on June 13, 2019, 09:12:42 PM
Hi Ray.

You're over the hardest part now, with the cylinder liner hole made and faced.

I hope from your photograph, that with a little imagination, you can see where the engine got its name from?

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on June 14, 2019, 07:08:15 AM
I think that Sphinx has got it's head stuck in a tin of cat food :LittleDevil:

Looking good Ray, on the subject of nuts for those that like a nice looking BSF or Whit nut that is single chamfer and fully machined rather than the presses out offerings these people have some nice ones though at a price.

https://historicthreads.co.uk/
Title: Re: Alyn Foundry Sphinx
Post by: RayW on June 14, 2019, 08:00:30 AM
Hi Graham and Jason.
I can definitely  see what you mean about the Egyptian look (and the cat food tin!). The nuts from Historic Threads look good, but, as you say, pretty expensive. I will see what my Chinese cheapies are like when they arrive before I decide if they look OK.
Title: Re: Alyn Foundry Sphinx
Post by: Jo on June 14, 2019, 09:15:30 AM
Well done Ray  :)

You're over the hardest part now, with the cylinder liner hole made and faced.

Does that mean I will have no problem getting mine to run? Jason will be so disappointed  ::)

Jo
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on June 14, 2019, 10:32:47 AM
Well it would probably be your first 4-stroke that runs if it did, though you have got to finish it first :LittleDevil:
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on June 14, 2019, 11:38:10 AM
Cat food tin??

Where?

I'm a champion for the cause of recycling/repurposing items you know!   :)

In answer to Jo, of the few kits sold there are many videos showing a successful running engine on YouTube. She's a simple design with no fiddlely gears, get the air/gas ratio correct, voila!!

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on June 20, 2019, 11:03:55 AM
Made a start boring out the valve chest casting and things did not go well! The valve stem is 0.25" diameter, so, having marked the approximate centre at each end, I decided that I would bore a 6mm pilot hole right through the casting, starting from the inlet valve (bracket) end.
The casting is quite an awkward shape to hold and despite thinking that I had it mounted absolutely vertically in the milling machine vise, I clearly didn't as the hole was way off centre at the exhaust valve end.
The only way I can see to rectify this is to enlarge the valve stem hole, fill with a cast iron plug fitted with JB Weld, then re-drill.

Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on June 20, 2019, 11:41:30 AM
Could just fettle the outside of the casting so it looks more central and make the two mounting holes a good clearance so you can mount it with the valve hole horizontal.

For something like that I would have slipped a couple of pins into the bolt holes and set then on the vice jaw or parallels to the hole was at right angles to them. Alternatively with the mounting face and bolt holes done screw it to a true block and use that to hold it by for the other ops so easy to line it up in all 3 axis.

Any decision on the strap material yet?
Title: Re: Alyn Foundry Sphinx
Post by: RayW on June 20, 2019, 12:27:28 PM
The valve hole is horizontal but angled in towards the body of the engine, so I suppose I could get it parallel by slightly angling the mounting surface but I am not really happy doing it that way. The real problem is that I started boring out the other end after adjusting the casting in the vice to correct the vertical position, as a result of which the valve hole is not parallel to the larger bore meaning that the valve would not sit squarely on its seat. I still think that the best solution would be to bore and plug the valve hole then re-drill. The other consideration is that the extension tube to support the longer exhaust valve also needs to be bored perfectly in line with the valve chest.

Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on June 20, 2019, 01:13:30 PM
In that case I would open it up right the way through to 3/8" BSP tapping size which could be done in the 4, jaw with a boring bar so you don't get any wandering. Or you could go that size most of the way through but then reduce down to say 0.518" dia which would give a shoulder for the sleeve to sit against and end of sleeve can be threaded 1/4" BSP for the extension

Then turn up an insert, reamed 1/4" and with the valve seat turned at the same setting with the top slide angled which will keep those two concentric. Finally reverse it round and machine the smaller dia and thread end
Title: Re: Alyn Foundry Sphinx
Post by: RayW on June 20, 2019, 03:44:25 PM
Thanks Jason, That's definitely a possibility, but given the difficult shape of the casting, I'm not sure how you could set it up in the 4 jaw to run true so that the centre points at each end were exactly aligned with each other.

The tapered nipple on the end of the casting was quite mis-shapen so I have removed it. Measuring up on the cross section drawing, the distance between the exhaust port hole and the end of the casting is only about 0.6". I reckon if I just drill and plug that short section, once I have bored out the 3/8 BSP part and the 0.375" section, I can then make up a drilling guide to fit in there to drill the 0.25" section. I would extend the plug beyond the end of the casting and thread 1/4 BSP for the extension.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on June 20, 2019, 04:27:49 PM
Hi Ray.

Now you know why Jo spends so much " fondling " time....  :)

Never mind, perhaps as you're  going to add the extension you could just bore through at 1/4" BSP tapping and put the 1/4" valve stem hole concentric with the new threaded insert.

As it's on the LP side Loctite would be more than adequate as a retainer.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on June 20, 2019, 04:58:29 PM
Quote
Thanks Jason, That's definitely a possibility, but given the difficult shape of the casting, I'm not sure how you could set it up in the 4 jaw to run true so that the centre points at each end were exactly aligned with each other.

You could always clamp it lightly  to an angle plate on the faceplate and pop a dead ctr in the spindle, line one end up with that and the other with the tailstock ctr before tightening the clamps.

Too late for the trick of using a drill bit in the lathe spindle and applying pressure with a tailstock ctr at the other end to get the two punch marks to line up.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on June 22, 2019, 02:04:08 PM
Further to what I said in the last post, flange machined flat and both ends of casting marked out at the same setting with a point in the mill and height gauge, casting having been adjusted in the vice to get best positions before milling flange

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Sphinx/20190621_174706_zpsii4hkgor.jpg)

Fixed loosely to an angle plate then held between ctrs in punch marks, 1-2-3 blocks used to set angle plate parallel to faceplate, tighten casting to angle plate.

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Sphinx/20190622_120917_zps4e5iquew.jpg)

Now set the casting to run true knowing the back end will also be running true.

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Sphinx/20190622_121621_zpscxo7sefa.jpg)

Face and start off with a sharp stub drill, at this point F1 Qualifying stopped play

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Sphinx/20190622_123721_zps0pajlrfb.jpg)

Also my strap ended up at 1.720" so just put the eccentric into the soft jaws and reduced flanges to 1.75"

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Sphinx/DSC03694_zpsplmgtyw6.jpg)
Title: Re: Alyn Foundry Sphinx
Post by: RayW on June 23, 2019, 05:37:39 PM
I decided to rectify my error with the exhaust valve, by boring out the valve chest casting to accept a steel bush which will act as the valve seat and guide. The main hole was bored to 19/32" (3/8 BSP tapping size), with the hole for the bush 17/32". I also made up a 2" long extension to support the long exhaust valve stem. The extension is bored out to accommodate the valve spring and collet.
I will not Loctite the bush in position until I have drilled the 20 degree sloping hole from the mounting face so that I can check exactly where it comes out in the larger bore, to ensure that the exhaust valve bush is deep enough.

Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on June 23, 2019, 06:15:08 PM
Hi Ray.

An admirable recovery, well done!

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on July 05, 2019, 05:06:44 PM
Not much done in the workshop lately due to painting and decorating taking priority during the current heatwave.
Finally got back in there today and re-made the inlet manifold, after having to scrap the first attempt when the 1/32" drill bit for the gas inlet snapped in the hole and totally defied all efforts to remove it. I just need to make the inlet valve now, then sort out inlet and exhaust springs, then that will be the valve chest assembly complete.
The inlet valve spring is supposed to be tapered. Has anyone any tips on how to make a tapered spring?
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on July 05, 2019, 05:47:52 PM
Wind it around a tapered mandrel

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/1-3rd%20Galloway/IMAG1988_zps07b9eece.jpg)

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/1-3rd%20Galloway/IMAG1984_zps1078f853.jpg)

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/1-3rd%20Galloway/IMAG1986_zps0a4dccf8.jpg)

I took a different route and used a smaller dia spring as per Grahams engine in his video, also did not like the holes breaking out of the tapered section

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Sphinx/20190630_082950_zpswnksp0wm.jpg)
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on July 06, 2019, 06:35:25 PM
Hey Guys.

Nice work!

I've been besides myself for the last several days my relief came yesterday with a visit to the Dentist.

Ray, I'll be popping into the Post office next week, sorry for the delay.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on July 06, 2019, 08:47:38 PM
Sorry to hear you have been suffering more dental problems Graham. No rush with the casting. Post it when you are feeling fitter. As I said earlier, there are plenty of other bits for me to be getting on with in the meantime.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on July 24, 2019, 03:23:26 PM
I have now completed the crank webs and just received some silver steel to assemble the crankshaft. While waiting for the steel to arrive, I decided to start machining the piston. When I got the casting from Graham, he told me that it was actually a Robinson one, a fact borne out by RO cast on the side. We both thought that it would be fine for use on the Sphinx, but what Graham had forgotten, and what I did not realise at the time, was that the Robinson piston is something like an inch shorter than the Sphinx one.
I had already started to make the connecting rod, based on the between centres dimension of 6.25" as per the drawing. As can be seen from the attached photos the shortness of the piston meant that the top would be nowhere near the end of the cylinder when at TDC which would dramatically affect compression.
Having discussed possible solutions with Graham, it came down to three possibilities:
1) Extend the length of the connecting rod
2) Extend the piston casting
3 Make a completely new piston from scratch

I decided to go with option 2, having found a suitable offcut of cast iron bar of ideal dimensions.I machined down the existing spigot on the top of the piston to 0.5" diameter by 0.25" long, then bored out the extension piece to match. I also bored 0.25" through the centre of the piston and drilled and tapped a blind hole in the centre of the extension piece. I then inserted a 1/4 BSF dome-headed socket screw through the piston and into the extension piece and screwed the two together tightly, with a thin layer of JB Weld between the parts and around the head of the screw inside the piston.
I will now wait for everything to set hard before turning down to final size and cutting the piston ring grooves.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on July 24, 2019, 04:50:42 PM
Have you made the balance weights bigger to compensate for all that extra weight of the solid extension compared with the hollow piston shown on the drawings?

May have been better to have a larger diameter spigot say 33mm and hollowed out the extension to 3mm wall and crown.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on July 24, 2019, 05:13:52 PM
No, I have made the cranks webs exactly as per drawing. I figured that with such a heavy flywheel, the extra weight of the piston wouldn't be a problem.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on July 26, 2019, 12:40:55 PM
After pondering further on Jason's comments about the piston weight, I managed to dismantle the two parts by chipping away the JB Weld from around the screw head, then applying heat with a gas torch to soften the thin film between the two parts.
Once they were separated, I hollowed out as much as possible from the extension piece before re-assembling. I also used thread locking compound on the screw rather than JB Weld around the head.
I propose using three Viton O rings as piston rings as they have proved excellent on other engines that I have built. I have just ordered them and will delay cutting the ring grooves in the piston until they arrive.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on July 26, 2019, 12:56:42 PM
The Vitron does seem to work well, you may be able to leave a groove or two empty as I only fitted one to the Allman and did not put the iron rings into the other two grooves, less drag too.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on July 28, 2019, 03:57:47 PM
More progress yesterday and today with completion of the crankshaft. Just needs a final polish up, but I will leave that until I am ready to assemble the engine.
The joints are all silver soldered and pinned with 5mm steel pins Loctited in position. The completed crankshaft is quite a solid lump, weighing in at just on 0.9kg, and it took a surprising amount of heating with the propane torch to reach soldering temperature.
Next job will be to complete the connecting rod which needs the little end block and bush added. The piston also needs turning to size and the ring grooves added, once the O rings that I ordered have been received.

P.S.  OK, did anyone spot my deliberate mistake? Since typing this post saying that the crank was finished,I have just realised that it is lacking two vital things - the keyways! Another job for tomorrow.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on August 03, 2019, 04:42:20 PM
Been working on the eccentric mechanism for the exhaust valve today and pleased to say, Graham, that my concerns about the undersize casting for the eccentric strap were unfounded as I managed to bore out to the necessary size without a problem. I also reduced the diameter of the outside flanges to 1.75" to match the OD of the casting. The ring that is left may be a bit thinner than the drawing, but should be plenty strong enough. I still have to make and fit the pushrod which operates the star wheel and opens the exhaust valve.
As can be seen from the photos, the exhaust valve and extension guide tube are currently quite a bit too long, but I will leave adjusting them until I have made the pushrod assembly, then I can see exactly how much to shorten them by.

I am hopeful that the engine will have excellent compression once everything is tightened up and sealed. To test the fit of the piston in the cylinder, I held the cylinder vertically with the bottom sealed against a sheet of rubber, then put the piston in to see how far it would drop. The answer was hardly at all. In fact, if you tried to force the piston down it would actually bounce, so it appears there is no significant leakage past it. As soon as the bottom seal was broken, the piston  immediately dropped to the bottom. If it is that good now, it should be even better with one or two Viton o-rings as piston rings.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on August 06, 2019, 08:03:06 PM
Hi Ray.

Your Sphinx is looking great, well done.

I think the best position for the end of the exhaust valve stem will be the centre of the " Starwheel " pivot, or just a bit before.

As I mentioned previously in this thread I had many an accident in the early days with the pushrod getting stuck under the stem in a reverse rotation scenario. Tube ignition being notorious for this condition!
I think you'll be the first customer to implement this design change.

Obviously the valve timing will be next on the list. With care, " textbook timing " can be achieved with the valve commencing at BDC and closing at TDC. You can however commence a little before but definitely not after.

Your piston to bore fit sounds perfect, a single ring would be my recommendation. ;)

Looking forward to seeing further progress.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on August 09, 2019, 05:52:58 PM
Hi Graham,

Been playing around with the star wheel and eccentric mechanism and think I have managed to get the timing just about right.
For those not familiar with the star wheel arrangement, I thought that the two attached photos might help explain how it works.
In picture 1, the push rod is held in the "miss" position, above the exhaust valve stem, by the higher part of the star wheel. In picture 2, the pecker arm has dropped in to the deeper part of the star wheel, bringing the push rod into line with the exhaust valve stem.
A tension spring pulls the eccentric arm down, ensuring that it remains firmly in contact with the star wheel. A spring washer behind the star wheel prevents it from being dragged backwards by the pecker arm as it returns.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on August 13, 2019, 03:26:27 PM
It became clear from turning the engine over with an electric drill, that I was losing compression through various leaking joints and through both valves, so I have spent the last couple of days making gaskets and re-grinding both valves. Things are now much improved and, from past experience, I know that compression will increase significantly when the valves have bedded in once the engine is running.

I have been working on the last major component today - the flywheel. The machining is now finished apart from cutting the keyway which I will have to do on the lathe as I don't own any broaches. There is also a lot of flashing that will require filing or grinding off to get an acceptable finish for painting. I don't usually use filler on my engines, but the main body casting in particular is very rough and will need quite a bit of grinding and filling to achieve an acceptable surface.


Title: Re: Alyn Foundry Sphinx
Post by: crueby on August 13, 2019, 04:06:58 PM
Looking great - thanks especially for the explanation on the star wheel, that is a clever setup.
 :popcorn: :popcorn: :popcorn:
Title: Re: Alyn Foundry Sphinx
Post by: Roger B on August 20, 2019, 06:31:57 PM
Looking good  :praise2:  :praise2: Your piston fit should be no problem, possibly even without an O ring.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on August 27, 2019, 04:58:57 PM
Thanks guys for your comments. Just been in my sweltering workshop this morning finishing off the drip oiler (34 degrees C outside).
All the major components are now finished, apart from the ignition system which I am still thinking about. I will probably use a trembler (buzz) coil as I have a nice Ford one sitting on my desk as I type this.
Compression seems good with one Viton O ring on the piston, but I still seem to be getting some leakage past the inlet valve on the compression stroke. I do not understand how this is happening as I have tested it by immersing the whole inlet valve assembly (made of brass and stainless) in water and blowing through a tube attached to the gas inlet. There is no leakage from around the valve head itself, although there is very slight leakage from the air inlet holes, indicating that the valve is not shutting all of the holes off fully, allowing some of the air from the gas inlet hole to find its way to one or more of the air holes. I will be using a demand valve in the gas line, therefore gas will only be supplied on the suction stroke, so, in practice, there will be no leakage of gas from the air inlet holes.
On the compression stroke, the pressure should be forcing the valve onto its seat, but it appears that air is somehow escaping past the valve head and out through the air holes. I will have to try further lapping of the valve, but need to be careful to avoid blocking the 1/32" gas inlet hole with lapping compound.
 
Off on holiday in our motorhome (RV) next week so looking forward to a relaxing break away from the workshop.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on August 28, 2019, 11:37:15 AM
Good morning Ray.

It's nice to see your Sphinx nearing completion, well done. I particularly like the " hidden " cylinder liner!!

Your leakage is probably due to the use of dissimilar metals with different hardness. I recall my own problems. I remember having to " fine " polish using automotive rubbing compound or similar metal polish.

I'd suggest a couple of coats of primer before you start playing, just to protect the Iron from oil penetration.

Enjoy your holiday, cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on August 29, 2019, 08:00:23 PM
Thanks  Graham for the advice. I will definitely try lapping in the inlet valve more when I get back from hols. I have already given the flywheel several coats of primer as you can see. There is already a bit of oil on the main casting where I have been running in the engine, but it seems to only be on the surface and should clean  off OK with white spirit.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on October 16, 2019, 05:38:38 PM
The inlet valve is still being a problem to seal. I re-made the valve and lapped in thoroughly with various grades of lapping compounds and achieved what seemed to be a good seal but air is still escaping through the air inlet holes on the compression stroke.
I checked the seating of the valve by painting the valve seat with engineer's blue, then rotating the valve. This left a clear ring showing that the valve is seating correctly so I am baffled how air is getting past the valve head to escape through the air holes. I have even tried fitting a very strong spring to hold the valve firmly on its seat, but still getting air escaping.
I know that there is really good compression, so the pressure should hold the valve firmly on its seat. At the moment, I am a bit of a loss as to what to try next.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on October 16, 2019, 06:47:40 PM
Hi Ray.

Hmmm, this rings a bell!

Try removing the cage and putting an " O " ring to act as a seal between the faces of the Brass and cast Iron body. I'm pretty sure I had the same problem when tightening the two together, slight distortion occurred causing the valve to leak.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on October 17, 2019, 02:25:17 PM
Thanks for the suggestion Graham. Definitely worth a try, but the thread on the valve cage is quite free fitting in the manifold casting, so I don't think the cage is distorting when I tighten it. I have lapped the valve in some more today, but then discovered that air was leaking past one of the cylinder head studs, so I took the head off and sealed with silicone gasket sealant. Once that has dried fully, I can carry on fiddling with the inlet valve. What I really need is some sort of dye to see exactly where air is getting past the valve head.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on October 19, 2019, 02:57:02 PM
Having successfully sorted out the air leak past one of the cylinder head studs, I became aware of another one between the cylinder head and the main water jacket casting. In theory, it should be impossible for air to get into this gap, however large, as the gasket which sits in the cylinder head recess should completely seal the combustion chamber (apart from the inlet/exhaust port) once the cylinder head is tightly bolted down.
After much trial and error with various gaskets, sealant, etc to no avail, I finally discovered the cause of the problem.
When I machined the recess in the head for the cylinder liner flange, I just broke into the outer part of the port, as a result of which there was nothing to support the gasket in that area. The port opening also extended a little way up the side of the recess. The result of this was to expose a small gap above the gaskets, allowing air to escape between the recess wall and the outer rim of the cylinder liner.
I am now modifying the shape of the port with JB Weld to block the gap, and will probably fit a very thin aluminium ring in the recess to provide support for the gasket(s). I did consider reducing the depth of the recess by inserting a tight fitting ring of sufficient thickness to cover the gap, but that would involve making new, longer head studs to compensate, so I will try the JB Weld solution first and see how that works..
Title: Re: Alyn Foundry Sphinx
Post by: Admiral_dk on October 19, 2019, 07:19:19 PM
If it was me, I think I would have hard-soldered a hard plug into the hole and drilled it again  :thinking:
That way you should not get any temperature issues + you haven't got any epoxy etc. polluting the area if you need to solder it later ....

That said - others have had success with using JB Weld in hot areas - so it's probably just me being a bit paranoid here.

Best wishes

Per
Title: Re: Alyn Foundry Sphinx.
Post by: Alyn Foundry on October 20, 2019, 11:42:01 AM
Hi Ray.

Damn, that's unfortunate!

I'm not sure if it's too late but I'd suggest either hard solder like Per has suggested or even an interference fitting plug. You'd have to be sure that it didn't crack the casting however.

Cheers Graham.

PS. I'm unfamiliar with the capabilities of JB weld as I've never used it.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on October 20, 2019, 05:25:17 PM
Hi Per and Graham.
I have used JB  Weld in similar situations before with no problem. I have built up the port slightly and made up a thin aluminium ring to sit in the head recess. I have sandwiched it between two thin paper type gaskets and stuck them all together with silicone sealant. These modifications have pushed the cylinder head out slightly leaving a gap between the cylinder head and the water jacket which I have filled with a suitable o-ring.
The result of all this is that I now have such good compression that it takes some effort  to turn the flywheel past compression and there is quite strong bounce back.
Title: Re: Alyn Foundry Sphinx
Post by: Admiral_dk on October 20, 2019, 08:01:15 PM
Nice to hear that your fix, worked out as planned  :cheers:
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on October 20, 2019, 09:01:05 PM
 :)
Title: Re: Alyn Foundry Sphinx
Post by: RayW on October 27, 2019, 02:21:01 PM
I have been playing around with the ignition system today and thought I had come up with a really neat solution. I made a Tufnol disc with a brass insert as per drawing and a contact unit, again of Tufnol and brass as per the attached photos.
I hooked up a Model T Ford trembler (buzz) coil and a 12 volt battery and that is where the fun began. With the contacts touching each other, all was well, with the coil buzzing strongly and a good spark at the plug.
As soon as I moved the contacts apart however, I got massive arcing from the contact unit to any available point on the engine body, causing the coil to continue buzzing as the arcs maintained the circuit. Arcs were jumping more than 1/4" from the brass hex nuts, and from the contact tip to the nearby main bearing cap, resulting in a burnt track across the surface of the Tufnol.
I know that these coils will run on anything from 6 to 12 volts, so would I cure the arcing problem by reducing to 6 volts, or do I need a resistor or something somewhere in the circuit?
Also, does it matter whether it is the live or neutral lead that goes to the contacts? Both work, although the spark is weaker one way than the other. I am sure all of you electronics wizards out there will be able to offer words of wisdom.
Photo 1 shows some of the arcing.
 
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on October 27, 2019, 02:33:50 PM
Positive to the isolated contact and negative to the engine frame. have you got a capacitor (condensor) in there anywhere? 6V will do, the small sealed rechargables are OK.

Don't really use the old style stuff these days just a simple contact to switch the low current CDI and ether a single spark or buzz unit.

Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on October 27, 2019, 03:16:01 PM
Hi Ray.

You're getting closer now!

I'd be inclined to use 6 Volts personally, as I've explained several times that the Trembler box was never intended to be run from a Direct current source originally. ( Model T application )

Try a solid, via on off switch, Positive to the trembler box and place the Negative ( and also the ground side of the HT )  of  the trembler box to the engine frame. Take the negative from the battery to your insulated terminal adjacent to the bearing cap. I think this will cure the HT arcing problem for you.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on October 27, 2019, 04:11:38 PM
This is how I have wired them in the past
Title: Re: Alyn Foundry Sphinx
Post by: RayW on October 27, 2019, 04:56:39 PM
Thanks Jason and Graham. I did try a 9 volt battery, but with same arcing problem as 12 volts. I will get a 6 volt rechargeable one and try that.
Not sure what you mean, Graham, by "Try a solid, via on off switch, Positive to the trembler box". Could you explain please. Thanks
I must admit that the old trembler coil is a bit too bulky really, so I may well end up getting something smaller. Do you have any recommendations?
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on October 27, 2019, 05:24:21 PM
Engineer's Emporium sell just the trembler points which you can make your own buzz box from with the addition of a small ATV coil and a lawnmower condenser. This will fit into a box about 3" x 3" x 4" with room for a small 6V battery too.

Here is one I made earlier

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Half%20scale%20Domestic%20Stovepipe/IMAG1000_zpsqzfrps0b.jpg)

Plug with red & black wires if for charging

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Half%20scale%20Domestic%20Stovepipe/buzz%20circuit_zpsltynilnh.jpg)

mtte8UXowUo
Alternative is one from S/S which can either be tripped by a hall sensor or two simple contacts which is what I mostly use. look at the "multi spark buzz coil CDI"

http://www.cncengines.com/ic.html
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on October 27, 2019, 05:49:26 PM
Hi Ray.

Well, thanks to Jason you have your answer, the drawing.

The Positive is going directly to the Trembler box. An on/off switch is not absolutely necessary but can be useful in an emergency situation.

You will notice that it's the Negative side that is " making/breaking " the circuit. Because both the HT and LT coil windings are " joined together " internally at the " ground/earthy " side, so when this is directly connected to the engine frame it ensures the high voltage stays across the sparkplug terminals.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on October 28, 2019, 03:24:19 PM
Thanks to Graham and Jason's help, I now have a healthy spark at the plug without the 4th July fireworks.

Having wired everything up as advised, I still couldn't get a spark to start with. When I removed the 4BA brass screw which holds the Tufnol disc onto the crankshaft, I found that there was a small plug of Tufnol between the end of the screw and the shaft. This was obviously interrupting the circuit between the fixed contact and the body of the engine, via the crankshaft, and probably contributed to the arcing as the current found an alternative path to complete the circuit. 

Once the insulating plug was removed, the circuit was complete and everything worked fine. Unfortunately, when I tried to re-tighten the screw, I found that the thread in the Tufnol had stripped, so I ended up making a completely new disc.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on October 28, 2019, 03:56:58 PM
I don't actually see why the disc needs to be Tufnol as the other contact is insulated. A metal disc with a protruding round head screw would work well
Title: Re: Alyn Foundry Sphinx
Post by: RayW on October 28, 2019, 04:37:41 PM
That's certainly an alternative method of doing it and similar to the contact arrangement on my 1/2 HP Stuart where a stud in the face of a gearwheel touches a sprung brass strip.

Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on October 28, 2019, 04:41:27 PM
That's great news Ray.

Tufnol was abundant during my time with the Supply industry, it got used!!

Pops and bangs to follow....  :)

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on November 03, 2019, 02:35:01 PM
Hi Ray.

How's it going? Are we there yet?   :)

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 03, 2019, 03:21:10 PM
Hi Graham,

Nearly there. Just need to make up a temporary base for the test run.
 
Been in the workshop this morning, but mending a bird table and bird bath instead of playing with engines! In those violent winds yesterday, the bird table blew over, smashing its slate roof and breaking the top of our nice old bird bath in half as it fell onto it. Luckily I had some replacement slates so just a matter of cutting them to size and fitting. I am trying to glue the two halves of the concrete bird bath together with Gorilla Weld epoxy, which claims to be suitable for concrete, but I am not optimistic that it will be strong enough, but we shall see.

I will let you know as soon as there are any pops and bangs.
Title: Re: Alyn Foundry Sphinx
Post by: Admiral_dk on November 03, 2019, 09:06:09 PM
Quote
I will let you know as soon as there are any pops and bangs.

OK - careful now Ray ...!!!... There are bangs and there are BANGS - and you really don't want the wrong ones  :old:

Hope to hear about the right kind of noises soon - best wishes

Per
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 04, 2019, 03:13:17 PM
First signs of life today. Engine firing well when spun over with electric drill, but just not quite running on its own yet.
At one point, I seemed to lose compression, but then noticed that the eccentric push rod was opening the exhaust valve on every stroke. After making various adjustments with the length and height of the pecker arm, I spotted the actual problem.
As explained previously, there are deep and shallow teeth on the star wheel. When the pecker drops into a deeper tooth, it lines up with the exhaust valve, and when in a shallower tooth, it is lifted over the top of the exhaust valve stem.
What had happened was that, following the exhaust stroke, the pecker was dragging the starwheel backwards slightly, as a result of which the wheel was not rotating forward sufficiently for the pecker to move to the next, shallow, tooth.
This was simply remedied by tightening the starwheel retaining nut to increase tension on the spring washer behind the wheel.
I don't know the correct timing for the ignition, but I have set it at just before TDC. Does that sound about right Graham?
I have put a short video of the starting attempts on YouTube at the following link chB4gkz_ysQ
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on November 04, 2019, 03:17:21 PM
Try it without the demand regulator, the inlet valve should close off the gas between inlet strokes.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on November 04, 2019, 05:56:40 PM
Hi Ray.

Yes, a few degrees before TDC is good.

As Jason has pointed out perhaps the demand valve isn't letting enough gas in, perhaps try and increase the input pressure a little?

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on November 04, 2019, 06:13:32 PM
I wonder if the demand valve is opening much at all when it is trying to run on it's own.

There is no form of venturi to create a low pressure area like you get with a carb so the diaphragm won't be getting sucked open much. With the arrangement of holes on the inlet the vacuum created by the piston going down will tend to suck in through the many air holes rather than the single small gas hole.

Without the demand regulator as the piston goes down it opens the inlet valve which will suck in air through the air holes and also uncover the gas hole which will allow gas to flow under the pressure in the bottle.

There should be no need for a demand reg on an engine like this as when the inlet valve is closed that should also shut off the flow of gas, you really only need one on an engine that was designed for liquid fuel where there is no shut off at the needle to stop gas flowing under it's own pressure rather than fuel being sucked in by vacuum.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 04, 2019, 07:57:41 PM
Thanks Jason and Graham for the suggestions. I see what you mean about the demand valve.  With the engine spinning quite fast with the electric drill there is probably enough suction but as soon as it slows down, the demand valve is not opening.
I did try various gas pressures, but if the demand valve is not opening, there would still not be enough gas getting through for it to run.
Watch this space for more updates!
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 05, 2019, 01:16:21 PM
The Sphinx awakes!!
As suggested, I removed the demand valve from the gas line and also made a new lighter inlet valve spring. With those changes the engine was on the verge of starting just by spinning the flywheel, but with a little assistance from the drill, it burst into life.
Next job will to be break the engine down for painting and build a suitable trolley.
Thanks to Graham, Jason et al for their help and advice with this project.2DMoEFhVKSU
Title: Re: Alyn Foundry Sphinx
Post by: ShopShoe on November 05, 2019, 01:21:50 PM
Congratulations.

It's always nice to see a new one come to life.

--ShopShoe
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on November 05, 2019, 01:32:50 PM
Good to know it was just something simple that was holding it back, should be able to hand start once it has all bedded in.

What we really need is a video of the "interesting" side of the engine ;)
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 05, 2019, 01:39:13 PM
Yes, I realised afterwards that that was not the most interesting side. Will do another video to show the other side.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on November 05, 2019, 01:46:28 PM
Well done Ray!!

I will wait until you've painted it to see the " business " end in action.

Thanks for the telephone call yesterday evening, it was nice to reminisce on our former rally days and our little chat about Stuart IC engines. Thanks for the pictures too.

Cheers Graham.

Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 05, 2019, 04:06:56 PM
Specially for Jason, here's the "interesting side"!! Just a short video as things were getting a bit hot, as evidenced by the wisps of smoke from the cylinder head!


7-Y_BEEOM6A
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on November 05, 2019, 04:16:47 PM
That's a nice star wheel you have there and good to see it in action ;)

I suppose the engine can only be throttle governed or did Graham mention that someone fitted a governor?

It's got me wanting to do a bit on mine, I have some cutters to evaluate for a supplier and some "Challenging" castings would be a good test for them :LittleDevil:
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 05, 2019, 04:24:46 PM
Yes, Jason, the star wheel is definitely the best part of the engine. I seem to remember Graham mentioning that someone had fitted some sort of governor but I don't have any details. Perhaps Graham can elaborate.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on November 05, 2019, 07:32:24 PM
Hi Both.

As I recounted in " the partnership that wasn't " ( Facebook group ) story the commissioned Sphinx was to be a twin flywheel engine running on Petrol.

After I had built the engine we tried a run using a similar carburettor to that of the R.L.E. with near disastrous consequences. The engine fired almost immediately then proceeded to accelerate towards destruction speed. I remember we'd sat it on a corner of a trailer, it damn near took off!!

I then spent several days scaling a " hit and miss " system that was fitted to my little American made Bull Pup engine. This worked very well.

By using gas as a fuel the speed is much easier to control and I'm pretty sure that your engine will run much slower once she's bedded in Ray.

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 06, 2019, 11:58:09 AM
Hi Graham,
The speed was quite controllable just by varying the gas pressure, but I will eventually fit a needle valve in the gas line to give me better control. I have a spare valve like the one that I fitted to the Robinson X Type and I will modify the needle in the same way.

Title: Re: Alyn Foundry Sphinx
Post by: Roger B on November 06, 2019, 01:21:36 PM
A very steady runner  :praise2: I do like the starwheel  :ThumbsUp:  :wine1:
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 09, 2019, 03:53:41 PM
I have made a start on stripping down the engine and preparing for painting. As the body casting was such a rough texture, I took off the worst parts with a sanding disc, then used car body filler to get a nice smooth surface before giving it several coats of primer. Normally, I like to retain some of the cast iron texture, but, in this instance, it was just too rough.
In dismantling the cylinder head from the water jacket/cylinder, I had two small mishaps. Firstly, when building the engine, one of the cylinder head nuts did not seem to tighten very well and I had a horrible feeling that the stud might be pulling out of the water jacket. Sure enough, when I took things apart, that was exactly what had happened. Fortunately, I was able to drill out the hole deeper through the brass ring and into the cast iron of the water jacket and make up a longer stud.
The other little problem/mishap was that the cylinder head casting, complete with spark plug, fell off the bench onto the floor and broke the plug insulator in half. Superglue came the the rescue and the plug still seems to be working fine, but I will get a spare just in case.
All I have to do now is decide what colour to paint the engine.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on November 09, 2019, 04:10:52 PM
Egyptian Blue would seem appropriate.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 14, 2019, 04:09:58 PM
I was getting on well with the painting process until last weekend, when a sudden medical crisis in the middle of the night saw me making an emergency visit to my doctor, who immediately referred me to the local hospital from which I have just emerged four days later. Still have to undergo further rather unpleasant investigations, but hoping to get back in the workshop very soon.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on November 14, 2019, 04:12:26 PM
Both Jules and I wish you a speedy recovery Ray.

Look after yourself, Graham.
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 14, 2019, 04:26:26 PM
Thanks Graham
Regards
Ray
Title: Re: Alyn Foundry Sphinx
Post by: Admiral_dk on November 15, 2019, 01:08:24 PM
Get well soon Ray - though Hospitals are great for emergencies - you do really not want to spend too much time there .... Best wishes

Per
Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 15, 2019, 05:44:01 PM
Thank you Per. I am already feeling much better and getting back to normal. Soon be back at the workbench. At least I am doing better than my neighbour. While I was having my problem, he accidentally locked his car keys and his dog in his car while out for a walk. He walked home to get his spare car keys and, on the way back to the car, he fell over breaking several ribs and his cheek bone in two places!

Regards

Ray

Title: Re: Alyn Foundry Sphinx
Post by: RayW on November 28, 2019, 11:51:54 AM
Finally finished painting Sphinx No.129 and feeling really pleased with the results. The colour is mid-bronze green, the same as my 1/2HP Stuart. I debated what colour to paint the background of the brass nameplate and decided on a dullish red which makes it a nice feature.
The nameplate came originally as a flat plate, and on Graham's suggestion, I machined a piece of hardwood to the correct convex radius ( a 2 5/8" hole saw proved ideal), then sandwiched the plate between that and an aluminium block of the same diameter as the water jacket. A few careful hammer blows on the aluminium block easily bent the plate to the required shape to fit the water jacket .
Next job is to make a trolley and source a suitable cylinder for a water tank. One idea I had is to use a piece of stainless steel ducting of the type used for wood burning stoves.
Title: Re: Alyn Foundry Sphinx
Post by: Alyn Foundry on November 28, 2019, 01:21:02 PM
Very nice Ray, very nice indeed.

I like the colour contrast in the badge.

Considering the poor finish of the " as cast " components you've done a remarkable paint job!

Cheers Graham.
Title: Re: Alyn Foundry Sphinx
Post by: Jasonb on November 28, 2019, 01:22:33 PM
Who said you can't polish a turd :LittleDevil:

Looks really good ray.
Title: Re: Alyn Foundry Sphinx
Post by: Jo on November 28, 2019, 01:28:23 PM
That does look nice Ray  :)

Who said you can't polish a turd :LittleDevil:

Someone mentioned to me the other day that he thought you sprayed yours Silver   :noidea:

Jo

P.S. I think he was implying they were the dog's not yours personally  ::) and he also mentioned that it is best to keep dogs away from model engines otherwise they might do things on to them but he hadn't seen that reaction previously :-X
Title: Re: Alyn Foundry Sphinx
Post by: Admiral_dk on November 28, 2019, 09:40:25 PM
It looks really good Ray  :praise2:  and I too like the colours  :ThumbsUp: