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Designing steam engines-oscillators specifically

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vtsteam:
Chuck, I'm not sure what the three engine types that you mention are.... are these existing designs someone else is showing. Or are these engines you designed through this program?

I would think that ideally the ports should fully line up at TDC and BDC, otherwise port area is wasted. It's the nature of the beast that a simple oscillating engine will always have symmetrical opening around TDC, whether the ports line up perfectly or not.

Whatever lead the inlet has will be mirrored by the time it takes to close after TDC. So timing is always symmetrical around TDC. No point in wasting valve opening size in order to try to change lead, just reposition the opening. This of course changes the period it's open for, as well.

On the other hand, it doesn't absolutely hurt anything to offset the opening further than the cylinder opening can reach (ie partial opening) , as long as the openings are large enough to transfer enough steam at the RPM desired to do the work you expect. But I don't see any advantage in  it.

Chuck in E. TN:
The 4 engines in the simulator aren't my design. As far as I know they were designed by the programs author.  I have created a couple designs with the simulator by printing out a design, calculating a scale increase for each dimension and entering the new dimensions and adjusting everything as needed to make it 'look' right.
I asked the question on the piston covering the ports because the models included in the program show half the port covered in 3  and not covered in 'Steve's Workshop' model.
So, either of those port options are good? I have built a couple of simplified wobblers, but now can't remember how much, if at all, the piston covert the port at TDC. I wasn't concerned then, I just built the models to plan. I have questions now because I'm not following a plan, I'm designing my own.

fcheslop:
When drilling the steam ports from personnel experience and lacking the ability to mark out and drill the holes where I want them I use a simple jig that canbe seen to the left in the pic.This engine is to power a gauge1 loco single acting
when the piston cover the port a tdc or bdc it shouldnt be a problem if it is then drill the passage ways as per the Duval I gave the link for on another channel .
cheers

Chuck in E. TN:


I'm working away at my design. I'm 3d printing some parts and machining others. Have one cylinder(3d printed), both cylinder covers(3d ptd), gland nut(brass), piston(3d ptd)Flywheel(3d ptd 2 pc pattern for casting), Cylinder pivot(steel), and a partly completed piston rod(steel). Having a ball, and learning lots... Thanks to you all.

vtsteam:
 :worthless:

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