Short Stroke; Long Cylinder Casting..

[BClemens]

Question: If a cylinder casting is used for a given piston stroke and your project engine's stroke is shorter, Is it detrimental to leave that extra bore length at each end of the cylinder? Or - should a thicker piston be fabricated which will take up the extra space or close up the open area of the piston stroke? The cylinder casting in works right now is intended for 3.5" stroke but the drive wheels and locomotive too are for 3" stroke. The stroke could be stretched but not the full 1/2". Will it matter or what should be done here?

Thanks, BC

[LVRR2095]

You could make the cylinder covers so the portion that extends into the bore does so in a way to reduce the area available to steam. You want a locating register anyhow...make it thicker.

Keith

[gwrdriver]

By whittling a weensy bit off the cylinder ends, adding equally to the four faces which will see steam, and leaving a little bit of steam clearance space, I don't think it would be difficult to take up 1/2" on a 3.5" stroke cylinder. Of all of these options I would try to get as much out of the cylinder and heads as possible and try to make the pistons the last place to add weight. But even then it's not all that much weight.

[Kimball McGinley]

Either way, you definitely don't want a big open space when the piston is at either Top Dead Center (TDC) as that will waste a lot of steam.

[BClemens]

Thanks for the replys and recommendations. The cylinder cover idea is probably how this will be solved. The OA block length is 4 1/2" and could be shortened a bit and the absolute maximum stroke is 3 1/4" - but would rather keep it at 3". The problem may not be as drastic as I was thinking..... Although; cannot afford to waste any steam with this small boiler-ed engine.

Thanks again,
BC

[Marty_Knox]

Where are the ports? You should make sure the longer registers on the cylinder head don't cover them.

[LVRR2095]

Where are the ports? You should make sure the longer registers on the cylinder head don't cover them.

You can also cut a relief in the register to allow steam flow.

Keith Taylor

[BClemens]

Marty,
Good point. The ports are cored in and exit out pretty far at each end - why I can't just cut the cylinder block down narrower. The longer registers will need to be relieved at those ports.

[BClemens]

I need to quit my job or just retire and go home and work on my Chu-chu train.

[ironhorseriley]

I had questions along the lines of this post last year, see: http://www.chaski.org/homemachinist/vie ... 8&t=102926

Steam cylinder stroke, Feb 02, 2016 for more options from the readers.

[BClemens]

I had questions along the lines of this post last year, see: http://www.chaski.org/homemachinist/vie ... 8&t=102926

Steam cylinder stroke, Feb 02, 2016 for more options from the readers.

Very good! Thanks - That will be some good reading.

BC

[Fender]

I need to quit my job or just retire and go home and work on my Chu-chu train.

I highly recommend it!