Brian builds a Corliss

[brian Rupnow]

One thing that I have to redesign and build----The lever which turns the rotary valves. The previous ones were too wimpy, with only a #2-56 bolt providing the "squeeze" to tighten them onto the valve shaft, and this bolt was threaded into a part of the lever which was only about 1/16" thick. This allowed for tightening and readjusting about three times , and then stripped the threads out of the lever. The previous levers were only 1/8" thick. The new design which you see here is 1/4" thick and the squeeze bolt is a #5-40 socket head capscrew, and the part of the lever with threads in it has been bumped up to be thicker so it won't strip out.

[PStechPaul]

This part?


Could it be made with a slot and key? Perhaps a simple Dutch or Scotch key, which is just a round pin in a hole drilled in the circumference of the shaft. Of course, you first need to make sure the adjustment is correct before drilling. But even if you have to change the alignment, you can drill another hole.

https://bbs.homeshopmachinist.net/forum/general/78506-pros-cons-of-various-techniques-to-locate-hold-a-pulley-gear-etc-on-a-shaft

https://www.practicalmachinist.com/vb/general/dutch-pins-how-194062/index2.html

https://www.brighthubengineering.com/machine-design/47133-types-and-designs-of-shaft-keys/

[brian Rupnow]

It probably could Paul, but it's the kind of thing that you have to be able to experiment a bit with to find the "best" setting. Any kind of key put in at this stage would prevent me from finding the "best setting".

[sid pileski]

How about thining up the part that is meant to flex?
Going from a 2 to 5 is going to look like crap.
How do the valves rotate in the first place? They should be pretty easy to move. If not I can see why they can’t tighten enough.
Get to the root cause, rather than bandaids.
2’s should work fine.

[PStechPaul]

It would also probably work better to extend the slot into the other side of the hole to allow more flexion with less torque on the clamp screw.

[J Tiers]

It probably could Paul, but it's the kind of thing that you have to be able to experiment a bit with to find the "best" setting. Any kind of key put in at this stage would prevent me from finding the "best setting".

If I recall correctly, some, perhaps most, Corliss engines had adjustments on the pushrods for length That would amount to an individual valve adjustment, and would allow the valves to be set fairly easily. Your engine seems of a size where such an arrangement seems neither to be obviously do-able, nor obviously impossible.

But, a pushrod length adjustment would seem to be the obvious solution, if it can be done.

[brian Rupnow]

The valves were not tight until I added gaskets under the brass bolt on bushings and cinched down the bolts which hold the bushings in place. So---this morning I made up a special weapon to loosen things up a bit. This consisted of a piece of 1/4" cold rolled steel with about 3/8" of a 1/8" drill extending beyond the end of it. (Drill was loctited into drilled center of rod). The rod was an exact fit for the valve holes thru the cylinder and the 1/8" drill got rid of any interferance from gasket or bushing body. I chucked this up in my electric drill and it made short work of any interferance with the valves. I reset the valves to what I think is the correct position, and added the gaskets and brass cover plates on the far side of the cylinder. so now all of my gaskets are in place everywhere. Instead of making new levers to operate the valves, I simply ran a #2-56 nut up the bolts and tightened the bolts into the nuts, and it seems to be holding adequately. I have disassembled the cylinder from the engine base and am back to turning the "wobble plate" by hand to see the cylinder rod extend and retract. Might have a problem here. If I rotate the wobble plate one direction, the cylinder retracts like a rifle bullet. When I turn the wobble plate the opposite direction, the piston rod is very wimpy about extending--in fact it doesn't until I give it a bit of help to get it started, then it extends fully. I'm not really sure what's going on here, but since there doesn't appear to be any binding of the cylinder rod, I'm assuming it has something to do with this rotary valve set-up.

[J Tiers]

It looks like you could put an adjustable link in each position. A threaded rod and threaded sleeve would be the simplest, but would mean no less than a half turn of whatever thread you use would be the increment. That could be pretty sensitive as an adjustment, actually.

Might not be enough room for an RH/LH threaded sleeve such as found on a turnbuckle, but that would be slick, with a locking nut on one end. Would look a bit like this example full size valve gear:

https://en.wikipedia.org/wiki/Corliss_steam_engine#/media/File:Corliss_valvegear,_Gordon's_improved_(New_Catechism_of_the_Steam_Engine,_1904).jpg

[sid pileski]

Tiers- In fact, it can be done, with readily available rod ends (RC stuff) 2mm.
Not right/left handed, but still, minor adjustments can be made.
This is the direction I'm going.
Looks a lot more prototypical than the bar links.

[J Tiers]

Tiers- In fact, it can be done, with readily available rod ends (RC stuff) 2mm.
Not right/left handed, but still, minor adjustments can be made.
This is the direction I'm going.
Looks a lot more prototypical than the bar links.
......................

I think that looks pretty darn nice. I never thought of R/C stuff, that could be pretty easy. If your CAD model is in scale, it ought to work, and it would look good.

[sid pileski]

Come on Jerry, “if”????

You know it is!

Sid

[J Tiers]

Come on Jerry, “if”????

You know it is!

Sid

Well, I did not know you had access to his CAD file.

But now that you mention it, didn't he say he got the plans from somewhere? So you could get them also, and of course your modified version would be in-scale with his.

[sid pileski]

Yes, the plans are not Brian’s. They are from another forum, Model Engine Maker.
I’ve been modeling this up probably for a year or so, based off of MEM’s design.
I’ve made modifications, like this to make it more realistic.
My model can be animated so that the timing events can be seen.
I work on it as time and other projects permit.


image widget

[brian Rupnow]

Sid--A word of caution. When you machine the cylinder, drill and ream the four 1/4" diameter valve holes BEFORE you put the top and bottom cavities in the cylinder. If you mix up the sequence and do the cavities first, then it pulls the drill for the valve holes off center when you go to drill them.---Brian

[sid pileski]

Got that already done. I did the valve bores first.
Followed my design/ dims.
The cylinder is complete at this point.