Steam Engine Clearance

[MJM460]

Hi Peter, at least one came through, and is showing a great job.

Are you using Apple to get those file names?  Make sure you are selecting the correct size for each additional attachment before you use it.  It’s like so many things that are easy when you know how.  Many of us have trouble initially but most soon get the hang of it.

MJM460

[Deeferdog]

Another try. I'm using a PC. Pics taken on Android phone, resized from 2.3Mb.

[Jo]

You are a long way into building that engine Peter it would be a shame not to get it running  Being a vertical engine you have a number of options as mentioned earlier that would recover its performance. Lets look at the challenges of each:

• Lengthening the stroke of the crankshaft would mean a replacement crankshaft would be required but it would also bring up clearance issues around the big ends and the soleplate.
• Replacing the two end covers (I am not sure if the lower one is integral with the guide from your pic  ) and making new ones with additional bosses is do-able and no one would ever see the changes.
  
• Making a longer piston is much quicker and easier than either of those, but it adds additional moving weight but as you have made a vertical engine this weight is not pushing against the bore. There are various ways of reducing the weight of the piston - making it in two parts so it can be hollowed out or more like a piston valve/cotton reel with a reduced centre width

Which ever method you choose I suggest you aim for 2.5mm clearance at either end 


If you are feeling overwhelmed by this engine Peter may I suggest that you initially make it without the reversing gear with a single eccentric rod driving the valves on either end.  In that way you can test the engine on air and see it running. And from what you have already done it looks like you are not far off from being able to do that and that may encourage you to finish off the reversing gear or leave it as a simpler working engine 

Jo

[Jasonb]

If you want a simple solution to solve the clearance issues and get the engine running ( may well do without altering anything) I'll stick with my earlier suggestion of filling the voids. Next option up the list would be a new piston about 18mm long which will compensate for teh under size piston and shorter crank throw at one sitting. Lastly if you do go for remaking the crankshaft it looks very slender in those images so think about increasing at least the main shaft, pins can stay the same.

Looking at the drawings there is plenty of thickness in the end covers to drill and tap a couple of small holes say M2 to M3 so that a suitably drilled and CSK infill can be added, for the top cover the plug can be JBWelded into place to fill the excess piston rod nut recess. Make the infills 38mm diameter so air/steam can flow all round and get to the face of the piston.

Talking of air getting to the piston make sure you notch between the cylinder wall and steam passage as per drawing, as it is now the cover will fit tight against the end of the passage.

Looking at a couple of videos of the original JLS engine if notched up it looks to run at a fairly modest speed maybe 50-60rpm so you can see the bits moving and it's not all a blur so there is hope yet.