The Home Machinist!

Those of you following Kvom's build of his Kozo A3 may or may not know there are a couple others doing the same. This weekend brought me to the moment of truth with the marking of dead centers, setting return cranks and making the final eccentric rods. Sunday night I tried getting it running but it would move a little bit then seemed like it wanted to run backward. After looking it over I had discovered that the left hand return crank was backward (following instead of leading). I fixed that and gave her about 10 psi and off she went. I have not spent any time timing her yet, just eyeballed it and the reverse gear has not been properly set yet so she's running a bit "hooked up". Enjoy..

Should there be much residule air leakage through the blast nozzle? I get quite a bit of air through the nozzle and am wondering if my cylinder gaskets are not working.



Ken

Excellent!

Congratulations!

When you say residual air- what part of the cycle, or is it just escaping all the time?
Is your lubricator hooked up- covering that hole?

Greg

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Greg Easter

Turn off your blower..................





B

Thanks guys. The air through the blast nozzle seems to be escaping all the time. If I pull the reach rod back and put it in mid gear you can feel air coming out of the nozzle. Not a huge amount, but it's there. Just as if the blower was on. I'm pretty sure there should be just distinct beats so I'm going to investigate re-sealing the cylinder mounting surface. I think something went wrong there. I've got the normal leaks in the chests because I haven't fully sealed them yet and I'm only running on less than 10psi. If I turn up the pressure the leaks are a bit more obvious.

Ken

Perhaps with some hot steam things will expand and self correct?

you have two possibles. Out of time or the valve surfaces just need to wear in.

John B.

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http://www.ngshay.com/
Shay drawings and castings

i think John has it right. the "D" valve may not be seated on the port face and is allowing air to escape under it. try turning you air up to 100 PSI and see if that will force the valve down and seal it. if not try to determine which side is leaking and pull the chest cover and look at the valve.

from the vid. you don't have the timing set correctly and it may be that the valve isn't closing all the way.
just some thoughts,

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Fred V
Pensacola, Fl.
home track:
http://www.waleswest.com

FWIW, I sanded my valve and cylinder surfaces on the surface plate with 1000 grit wet-dry paper, since there were a lot of milling marks on both. Can't say I tested it for leaks at the time, but will do so when I get it back together.

That process has the potential to yield a less than flat surface. I'm not suggesting that's the cause, however, due in part to the fact that you used such fine paper. However, if you stayed at it for a prolonged period of time, you may well have created a bow instead of a flat surface. Depending on the amount of area between the edges and the pressure area, you may have relieved the edges due to the paper rolling up in front of the movement. You get something similar when using a belt sander. Might be a good idea to check the surface for rounding.

If you find error, you'd be best served to use fine abrasive and a lapping plate.

Harold

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Wise people talk because they have something to say. Fools talk because they have to say something.

I tried pumping the air up to 100psi and it still leaks. Giving a little press to the valve spindles doesn't seem to do anything. I did finish off the tops on wet/dry but I had checked them on the plate and a square and didn't notice anything wrong. There is quite a bit of play in the valve spindle. I checked the nut to valve but that doesn't look like it. Seems to be in the radius rod which mans probably the link block. There is about .015" total play on each side. Seems a lot but probably not what's causing the leak. Will probably make a difference for timing though. May need to remake the blocks so they fit closer. Need to recheck my dead centers too.

Ken

Are you sure it's leaking through the valve(s)? What about the joints between the tee and the cylinders?