High Pressure Steam Table Engine

[crueby]

A real adventure to do that exhaust passage! That must have been an interesting bit of coring on the mould for a full size engine like that. Does look more interesting than a big pipe wrapped around the side though.
 

[Jasonb]

Others are following, just not sure I should comment

Funny enough the question of cores for a cylinder like this came up on my Unreal thread elsewhere, it's a fairly simple sand ring supported at one end by a core print that is an extension of the central port and at the opposite side but a print that forms the hole in the exhaust pipe stub.

[crueby]

Neat, thanks for the diagram!

[Jo]

Thank you Chris 

While looking at the top cover I have just found another drawing FEATURE    The drawing shows a double step under the cover, if you do it to this drawing you will find that the steam passages on the outside will break though beyond the 35mm surface and "vent" to fresh air  The easy answer is it needs the Cylinder register to be 1.6mm long rather than the 0.8mm shown on the drawing and to ignore the 35mm diameter.


I know why it was drawn this way: The original etching shows a gap round the underside of the cover and you can see the studs. But on that one the steam ports enter the cylinder further down. We have to drill the long holes  down from the top and the distance means it will have to go in vertically as shown. I could possibly plug them and then go in with a tee slot cutter  Na, much easier I'll add a slightly wider diameter boss at 42mm but keep the main register that little bit longer. Which will mean it still looks like the engraving 


Jo

[ettingtonliam]

If the castings you are using, plus the ones you just acquired are original Clarkson castings, they must have been rotten patternmakers and founders! Not too good as draughtsmen either. I hope Blackgates have sorted things out for their.current production.

[scc]

I'm following too Jo, enjoying every bit, but relieved to be working on something else at present.          Excellent standard as usual          Terry

[Jo]

Thank you Terry, I hope this helps (You might want to delay drilling the three holes to screw on the two side frame until later than I have  )

Hi Richard: Clarkson went out of business years ago and it took Blackgates decades to finally be able to acquire the rights to the designs and be able to sell their castings. The guys at Blackgates had garage loads of stuff to sort out last I spoke to them about the Clarksons stuff.

I was pleased to see that they had made this set of castings available again at such a very reasonable price. There is nothing I would particularly complain to them about this design but I will document any 'features' I find as I go here on the forum so others can find them. I am sure once this one is done they will point perspective builders here so they can understand the opportunities and pit falls 

A friend is making one of the Clarkson inverted engines and that has lots of interesting features to keep him entertained   

Jo

[Jasonb]

The Draughtsman also produced a revised drawing that does away with that "gap" so they are not all bad just depends which you decide to work from and there may even be more revisions now.

Jo you could always make that 1 1/8" feature "lolly pop" shaped with a bit out the side to cover the passage

[Jo]

Yes you are right Jason the TRACER when they updated the drawing changed the underside of the cover. It is a shame they failed to follow standard drawing office practice and to mark up the drawing to provide the revision and details of what had changed. 

Jo you could always make that 1 1/8" feature "lolly pop" shaped with a bit out the side to cover the passage

You do like to make a simple job difficult    Can't say I have ever seen a full sized one doing that.

Jo

[Jasonb]

But full size CAST the passages so you are unlikely to see it . Your cylinder is DRILLED & MILLED so has to be worked around. It's only a bit of rotary table work.

Difficulty to me is working with these drawings and sorting things as they crop up, with the number of "features" it would be less complicated to redraw in CAD based on measuring the actual castings and sort then there

[Jo]

But full size CAST the passages so you are unlikely to see it . Your cylinder is DRILLED & MILLED so has to be worked around. It's only a bit of rotary table work.

Can't see the point of milling a fancy boss under the cover when you can just turn the boss round on the lathe, to fit it into the round cylinder bore No one is going to see the underside of the cover and a round boss will work just as well in a hole with a cut out for the steam to go through. You seem to be making things more difficult than necessary maybe it is to justify having a CNC milling machine  . If you really wanted to make the port come out a little bit down the cylinder you could add an additional plate on the casting but I am not going to do that either   

Some of us are retired so we don't have as much spare time as you workers  I used to get so much more model engine redrawing time when I went to w**k   

Jo

[Jasonb]

You still have the round boss to locate the cover in the bore and keep things concentric. The one in my drawing is the second larger dia one and maintains the gap to fully expose the studs.

A 1 1/8" round one won't fully seal the port. If you try and close the port off with an enlarged diameter completely round boss then you cover up the studs, minimum dia would be to the green line

[scc]

Thank you Terry, I hope this helps (You might want to delay drilling the three holes to screw on the two side frame until later than I have 

Jo

           Jo,  I  shall be delaying lots while you make progress and I watch and learn             Terry

[Roger B]

I'm still following along and trying to understand the exhaust passage stuff       

I can deal with simple mushroom valves, two stroke ports are complicated, steam valse and valve gear 

[Jo]

Hi Roger, it is not as difficult as Jason is trying to make it out to be   

Think normal slide valve: Three ports, middle one is for the exhaust. The exhaust normally just comes out as a flange fitting at 90 degrees to the port face. 

We can't stick the flange out at 90 degrees on this engine as there will be two side rods waggling about and the two side frames all in the way. The answer is to pipe the exhaust round the back and put the exhaust flange fitting on there. The channel I just cut with the cover provides the 'pipe', or exhaust way,  I still need to add the flange to that cover

Jo