High Pressure Steam Table Engine

[Jasonb]

To save you anymore misunderstanding Roger, my comments yesterday were not even about the exhaust passage around the cylinder so not sure what Jo is poking at.

However what Jo is doing and what I have just done on the Real is trying to replicate a passage that would have been cast into a full size engine buy the use of a core. At our sizes it would be quite fiddly to try and do it that way so we have to use other methods to get the exhaust steam from the port to the outlet on the opposite side of the cylinder.

[Jo]

Holding the cover by the upper surface the bottom was turned flat:



Then we can turn first the top surface that the 8 mounting studs/nuts act on before turning the centre boss. As I am going to hold this cover on that surface in a collet I can also drill and ream for the piston rod:




And finally drill for the gland:



I then held the cover in a collet, turned to diameter and took the lower face down but thought better of it and turned the cover back round and finished off the fancy shaping while there was plenty of metal to grip on in case I found a hard spot 



Back in the collet to turn the bottom register:



And making sure it fits:



I checked this before I added the 44mm diameter under cut under the cover. I did consider taking the undercut in a little bit more but the positioning of the steam ways comes out to 40mm, the same diameter as the 8 studs and the cover is only 46mm diameter. I think it works 

I need to turn up the gland before I drill any more holes 

Jo

[bent]

Wow.  More like sculpting than machining...lovely work, Jo. 

[Jo]

Thanks 

I am still recovering from the show but it is time to make some more swarf. First find a bit of scrap-bin-ium, mount it flat and find the centre:



At the lower end of the side frame is a round decorative hole which is a nice 27mm diameter so I have made a bush to fit into this and the clamp goes through the hole in the centre. It also acts as a pivot so I can line up the casting and decide on the position of the top mounting hole:



With the top and the bottom of the side frame securely mounted I can now look at the slot. Looking at the drawing other than the width there are no dimensions    The engraving shows the slot goes up to the point that the curve matches the curve of the side frame. I have dropped a washer there and the same at the bottom 



Now I can drill two 6.35mm holes for clearance at either end of the slot:



The slot is 5.5mm wide, but I am going to first cut a 5 mm slot then open it up after:



After a strong cuppa and I have changed that cutter for a slot drill 

Jo

[Jo]

I've found a nice new carbide 4mm three flute cutter so I decided to mill the centre of the slot out with that.



I took this slowly and shallowly because I wanted the cutter to cut a true line. Even so you can see the ridges where the cutter moved slightly sideways in the slot in front of the 5.55mm cutter which is here on power feed doing a single cut taking 0.8mm off of either side:



Before moving the side frame I milled the bottom. I also remembered to take off the bottom clamp afterwards so you can see the big pivot mounting that was hidden under the clamp:



And when we turn it over it looks  horrible:



But that is not a problem we can sort that out shortly 

Time for the second one:



I am pleased to report having put the big pivot clamp in place the top has lined up  Off we go again 

Jo

[Admiral_dk]

Great info and to see that you're making progress Jo 

Looking forward to see the next steps     

Per

[Jo]

Thank you Per, the next steps 

Second frame up:



All the same machining was done on this one. Then both were turned over and the back was faced on the sliding surface and behind where it attaches to the cylinder.

I then chose to mill the bottom to size so it matched the width available next to slot on the table and between the two stops:



The a quick check on the model:



There is still lots to do on these but I need to make the tie bar so I can look at if I need to adjust the backs of the frames or the location on the table for the 20 10BA holding screws studs  .

One note: These side frames did not have much spare on them   

Jo