Author Topic: Vertical steam slide vale size as function of port size?  (Read 695 times)

Offline Reggleston

  • Full Member
  • ****
  • Posts: 28
Vertical steam slide vale size as function of port size?
« on: August 05, 2018, 01:35:19 AM »
Earlier this year at the NAME expo I purchased a set of castings from a well known US supplier of a Prototype Vertical bottle frame type of engine he hopes to sell sometime in the future. The castings are of decent quality but BP's have been very poor, some duplicates of hand drawn shop sketches. The castings don't match the limited and poor prints that were provided. I have successfully built the engine up to the point of trying to get it to run which I haven't been able to do at this point. The cylinder had the ports cast in and the crank has finally been fitted with a suitable connecting rod to achieve smooth rotation. The piston will traverse up and down with application of a burst of comp. air at the upper and lower intake ports. Cylinder is cast iron, frame and flywheel are aluminum. I suspect the cylinder is a Stuart product as it had a S cast into the steam chest cover. Construction of the slide valve first try was based on the poor BP's which didn't come anyway near correct. I redesigned the slide valve incorrectly as it still won't run. When air is applied you get full output thru the external exhaust port, the slide valve has no effect whatsoever. My theory is that I have made the slide valve opening TOO large and all the applied comp air is directed to the exhaust port due to being grossly oversize. Have done a comparison with another casting BP set for a similar vertical type of engine and determined that the slide valve cavity area is approximately 66% of the port opening area consisting of the upper & lower intake openings and the center exhaust area. I am wondering if this ratio is correct or suitable in applying to my errant engine project? Any insight members could share would be appreciated.
 
As you might guess I won't be purchasing any additional casting & BP's from  that supplier again as his promises for an updated and correct BP's have not materialized. Nothing quite like being left in a lurch situation and basically having to design as you go to achieve a running engine! If any of you are interested in who this less than creditable supplier is PM me and I will be glad to share that information with you.

Offline chucketn

  • Full Member
  • ****
  • Posts: 378
  • East TN, USA
Re: Vertical steam slide vale size as function of port size?
« Reply #1 on: August 05, 2018, 03:04:41 AM »
I may have some design info in my notes. I'll check. Meanwhile what do you mean by BP?
I am currently redrawing some engines in Fusion to make 3d printed patterns to cast. Lots of fun and learning a lot more than I ever dreamed...

Offline Jasonb

  • Full Member
  • *****
  • Posts: 5836
  • Surrey, UK
Re: Vertical steam slide vale size as function of port size?
« Reply #2 on: August 05, 2018, 07:14:10 AM »
BP = Blue Prints

Can you give the cylinder bore and stroke, then one of us may have the details of that particular Stuart engine and could help with valve size and eccentric stroke. I would not size the valve by area but by the spacing of the inlet and exhaust ports.
« Last Edit: August 05, 2018, 08:47:52 AM by Jasonb »

Offline Maryak

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1803
  • Aldinga Beach South Australia
Re: Vertical steam slide vale size as function of port size?
« Reply #3 on: August 06, 2018, 10:33:56 PM »
If the ports are already cast into the cylinder it is possible that a bad casting would give rise to the inlet and exhaust ports being connected, i.e. the vital bit of metal separating the two is missing or broken inside the block.

This may be your problem as you have full exhaust pressure when applying air to the inlet port(s), when you should have no pressure from the exhaust port, i.e all the air should be going to the cylinder.

HTH


Regards Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3609
  • Springfield, Tennessee. USA
Re: Vertical steam slide vale size as function of port size?
« Reply #4 on: August 06, 2018, 10:46:45 PM »
Great info in this video


Eric

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 723
  • Dripping Springs TX USA
Re: Vertical steam slide vale size as function of port size?
« Reply #5 on: August 07, 2018, 12:38:17 AM »
The question of slide valve size as a function of port size is usually calculated with one of the classic valve diagrams. The information needed valve travel, angle of advance, valve lap, and the port face dimensions to design the valve. 

My go to valve diagram is the Bilgram diagram, I can construct one for this engine with the data mentioned. As Jason said lots of us have Stuart prints on file so the bore and stroke are needed. I have Bilgram diagrams for every print set in my collection.

Dan
ShaylocoDan

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 9276
  • Central Massachusetts, USA
Re: Vertical steam slide vale size as function of port size?
« Reply #6 on: August 07, 2018, 01:48:03 AM »
Port width 0.8 x piston diameter

Port Height sized to allow steam to flow at under 6000 feet/min

Valve travel gets driven by these parameters

Dave

"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Zephyrin

  • Full Member
  • ****
  • Posts: 301
  • near Paris, France
Re: Vertical steam slide vale size as function of port size?
« Reply #7 on: August 07, 2018, 10:23:25 AM »
The sizes and spacing of the ports in the cylinder portface are enough to deduce the valve dimensions and eccentric stroke required for this engine, give the data...
but the engine will work only if the cast exhaust and inlet channels are not communicating as stated above by Maryak.

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3609
  • Springfield, Tennessee. USA
Re: Vertical steam slide vale size as function of port size?
« Reply #8 on: August 07, 2018, 12:27:29 PM »
Dan, thatís the reason for the video link. It shows the Bilgram diagram being used to make a missing slide valve and itís presented in easy to understand terms.

Eric

Offline Jasonb

  • Full Member
  • *****
  • Posts: 5836
  • Surrey, UK
Re: Vertical steam slide vale size as function of port size?
« Reply #9 on: August 07, 2018, 01:47:34 PM »
Other reason may be core sand blocking one or more of the passages, you should always poke some wire down the passages of Stuart Cylinders to get the sand out before it grinds your piston to a good fit ;)

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 723
  • Dripping Springs TX USA
Re: Vertical steam slide vale size as function of port size?
« Reply #10 on: August 07, 2018, 02:02:12 PM »
Eric,
Interesting video, but his explanation of the Bilgram diagram was somewhat confusing and I know how to use one. I did learn of the diagram from the book he mentioned but I also have several other books that explain it including the one written by Bilgram.

I did not ask for the lead as this is most often set to zero for a model engine it was only 1/16" in the video so when this is scaled down zero is a very close number. I also did not ask for the inside lap as this is often zero also for a model engine. I asked for the angle of advance which is usually on the eccentric drawing, and the steam lap which also should be on the drawing or is known from the made up valve, and the valve travel which should also be on the eccentric drawing, I do not need all three two would work fine as Bilgram will work out the missing data point.

The other thing it is not easy to ask questions of a video so if you want to know about Bilgram diagrams ask me on your popcorn engine thread and I will construct one for that engine and explain it to you.

Dan
ShaylocoDan

Offline Reggleston

  • Full Member
  • ****
  • Posts: 28
Re: Vertical steam slide vale size as function of port size?
« Reply #11 on: August 10, 2018, 01:04:49 AM »
Hi Guys & Gals:
Just to give you a little update on progress, I have cured the continuous exhaust issue, seems like I had the gasket between the steam chest and the cylinder just a little too wide on one side which was lifting the valve on one side preventing any kind of seal between the cylinder and valve face. I utilized a clear piece of plexiglass in place of the steam chest cover to give a visible look as to what is occurring there. Now getting Compressed air into both upper and lower cylinder ports as required. Intrigued by  Tennessee's Bilgram valve video. Haven't been able to locate the engineer and Mechanics handbook number 1 as described in the video. If anyone out there knows where to obtain the text or that portion of it I would appreciate knowing the source. Absolutely loved the antique powered shop featured in the video describing the vertical valve construction. Any idea of the title of Bilgram's valve document and approximate location & time period it was published would be greatly appreciated. Also checked the cylinder port passages for continuity and any entrapped sand issues and found none. One of these days I may get the beast running and be able to post a video showing the results of a difficult struggle and then on to the next project which will hopefully be a lot easier with the good quality BP's that were provided with the castings. Thank you all so much for your thoughtfull input.
Regards.
Bob

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 723
  • Dripping Springs TX USA
Re: Vertical steam slide vale size as function of port size?
« Reply #12 on: August 10, 2018, 02:31:03 PM »
Bob the book mentioned on the video is "Audels Engineers and Mechanics Guide 1".

I saw a few downloadable copies of this book, I have my copy handy and as I mentioned I am very familiar with Bilgram's valve diagram which is simply a graphical calculator. The old designers used a drafting board like we use a hand calculator.

If you get stuck I can help or if you can let me know the data I asked for I can show you how to construct the diagram and explain the construction steps.

Dan
ShaylocoDan

Offline Reggleston

  • Full Member
  • ****
  • Posts: 28
Re: Little Mo now running
« Reply #13 on: August 21, 2018, 02:05:31 AM »
Finally got the errant lil Mo Vertical to run successfully. My valve size redesign worked, aka known as a seat of the pants modification. Had the opportunity to look at Keith Appleton,s video on how to set the valve on a vertical steam engine. Most helpful video I have seen on you tube, now if I can get my phone camera to load up the running video will post it at a later date. The cylinder is cast iron and the piston is made of Delrin material and exhibits a surprising amount of torque using the hand method of applying a load. Especially remarkable considering the piston has no rings, slip bore fit only. Piston is showing signs of abrasion in the CI honed bore, lube application has eased it somewhat. Next step is to tear down, paint and work up a suitable wood base, may go with some stone facing for an early foundation type base appearance. Engine is running on compressed air and seems to run well over a fairly wide speed range.