Author Topic: Bilgram's valve diagram a graphical method to design a steam valve  (Read 2260 times)

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 1163
  • Dripping Springs TX USA
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #60 on: April 20, 2022, 11:29:22 PM »
I picked a number, 5048. That is not a Shop number it is a slide valve drawing number. I chose that one because it says to refer back to CD #3. I know that card very well it is an early Shay drawing with complete details for 8" x 8" Shay cylinders.

Now to the file cabinet to get the folder for 2- 8" x 8" Shays. the first one in the folder is shop number 50.

Valve Travel 1 1/2"
Angular Advance 220

Now I will draw the Bilgram diagram with approximately 1/16" lead.

Thanks for playing 'Stump the Chump'.

Cheers Dan


ShaylocoDan

Offline crueby

  • Full Member
  • *****
  • Posts: 14273
  • Rochester NY
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #61 on: April 21, 2022, 12:13:27 AM »
I was tempted to pick something like 123.567 since you didn't specify a whole number...   :LittleDevil:




Looking forward to seeing the diagram.   :happyreader:

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 1163
  • Dripping Springs TX USA
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #62 on: April 21, 2022, 12:26:55 AM »


Chris, that number is below 200 so no brass ring for you  :ROFL:

 :Director: Bilgram hot off the press!!!!!!!

Valve travel 1.5
Angle of advance 220
Lap .25
Lead .031
Cutoff 1.312/1.5 = 0.875
Port opening 0.5

I believe that port opening is equal to port width. I will have to check card #3 tomorrow to see.
Not bad information for two numbers and an approximate lead.

Cheers Dan
ShaylocoDan

Offline crueby

  • Full Member
  • *****
  • Posts: 14273
  • Rochester NY
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #63 on: April 21, 2022, 12:44:12 AM »
Okay, thats a very interesting diagram, now I'm finally getting to visualize how changing one parameter would ripple through the other ones.  It would be interesting (as well) to draw the resulting ports and valve to scale with those numbers and see what the parts would look like - thats the direction I have been coming from (since I didn't know this type of design tool).

Seems like it would be possible to code this all up in a spreadsheet, and have it take the design parameters in and do the drawing for you? That would allow for playing with the lead/lap/advance/throw/etc and see the results, to help wade through all the design possiblities.

 I've seen that sort of thing done, but have never gotten that deep into line drawing/chart drawing in spreadsheets. I could dust off my C++ compilers and libraries and do it that way, but thats not very portable for sharing with others. Maybe even code it in PostScript to generate a PDF picture. HTML and have a page for a web browser? Hmmm. Must be a good tool for that - don't have MatLab any more, that would do it in about 20 characters of incomprehensible but powerful code...  GCode that would print it or CNC it on a plate?!   :insane:   Uh-Oh, my past life as a software geek is leaking out!!   :paranoia:

Edit: What does the distance 0.281 represent again?

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 1163
  • Dripping Springs TX USA
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #64 on: April 21, 2022, 01:05:01 AM »
Okay, thats a very interesting diagram, now I'm finally getting to visualize how changing one parameter would ripple through the other ones.  It would be interesting (as well) to draw the resulting ports and valve to scale with those numbers and see what the parts would look like - thats the direction I have been coming from (since I didn't know this type of design tool).

Edit: What does the distance 0.281 represent again?

Chris, you hit the nail on the head. That is the reason that Bilgram is so powerful-------it is visual. Don't make the mistake of hiding the visual math in a spreadsheet.

I knew the lead was approximately 1/16" so I drew a line from the end of the angle of advance to the flag pole. That is 0.281 and the nearest fraction is 1/4".

Case closed for shop number 50. I just have to check the answers on card #3. The first thing I will check is the length of the valve found on card 952-A-5048 which is 4 11/32" against the distance between the steam port outer limits. It should b 0.5" longer or twice the lap.

Cheers Dan
ShaylocoDan

Offline crueby

  • Full Member
  • *****
  • Posts: 14273
  • Rochester NY
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #65 on: April 21, 2022, 02:35:20 AM »
The idea of the spreadsheet I had was to speed up trying different parameters, having the code draw the diagram so its still visual, just quicker to see what happens if I went to a longer or shorter lead, or whatever. Just a timesaver but still ending with the same diagram. Just a thought!

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 1163
  • Dripping Springs TX USA
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #66 on: April 21, 2022, 07:05:55 PM »
Seems like it would be possible to code this all up in a spreadsheet, and have it take the design parameters in and do the drawing for you? That would allow for playing with the lead/lap/advance/throw/etc and see the results, to help wade through all the design possiblities.

 I've seen that sort of thing done, but have never gotten that deep into line drawing/chart drawing in spreadsheets. I could dust off my C++ compilers and libraries and do it that way, but thats not very portable for sharing with others. Maybe even code it in PostScript to generate a PDF picture. HTML and have a page for a web browser? Hmmm. Must be a good tool for that - don't have MatLab any more, that would do it in about 20 characters of incomprehensible but powerful code...  GCode that would print it or CNC it on a plate?!   :insane:   Uh-Oh, my past life as a software geek is leaking out!!   :paranoia:

Edit: What does the distance 0.281 represent again?

Hi Chris, yes if you know how to code any program to do this it would be great. Something stand alone or on the web so others could use it with the normal software on a computer would be fantastic. I think that if it was like Docksteader's Zeuner module it would be very handy. If the program could start the construction with only 3 key variables it would be even better.

It is not really hard to construct a Bilgram diagram but to do multiple constructions to see 'what if' could get a bit tedious.

A better answer to "What does the distance 0.281 represent?" is it is the linear advance. This is shown in Audels Fig. 388 Pg 213. Now to the answer to the question "What is linear advance?" see Fig.387 Pg. 206. to see that linear advance equals lap plus lead. So we can add linear advance to the things we learned from the Bilgram diagram for S/N 50.

I mentioned one fact found on the slide valve drawing I cherry picked out of the drawing drawer but there are a few more dimensions that will be useful for this slide valve design.

I mentioned that the outside width of the valve is 4 11/32", the inside exhaust cavity is 2 1/2" wide, the outside length of the valve is 7 63/64", and the inside length is 7". The card number is 7404 and the superseded card is 942-A-5048. This valve was used for 8" x 8', 9" x 8", 8" x 12" and 8" x 10", so I could have picked several Shay engines to make the Bilgram diagram for. The note "REFER BACK TO CD. #3." is what made me pick that valve on the card with 8 different slide valves on it.

So without peeking at the answer sheet card #3 what else do we know about the valve design of S/N 50? To start I have to make some assumptions:
1. Port opening equals port width and bridge width.
2. Inside lap is equal to zero.
3. The width of the port is equal to the width of the bridge.
4. At the end of the valve travel, the outer edge of the valve completely opens the valve no more no less, so we do not have over travel or under travel. Port opening is a confusing name. If we look at the angle of advance line it is clear that port opening plus lap is equal to 1/2 the valve travel. By saying port opening is equal to port width when the valve travels the port width then travels the lap distance, it should be clear that that distance traveled is equal to 1/2 the valve travel.

Wow, that was a lot of beating around the bush but I really hope that it made the difference between port opening and port width a bit more clear. This is also covered in the book on Pg. 205.

Okay, the valve inside length is 7", so Pg. 184 the length of the ports are usually 0.8 times the diameter of the cylinder. Cylinder bore 8" times 0.8 equals 6.4, so a bit shy of 7" which has to be the dimension on card #3.

Assumption #2, no inside lap makes the width of the exhaust port the same as the inside width of the valve or 2 1/2".

The distance between the valve face steam edges is the valve outside width minus twice the lap or 4 11/32 - 1/2" = 3 27/32".

Port width = port opening = bridge width = 1/2".

Now, this should all add up. to 2 x port width + 2 x lap + 2 x bridge width +exhaust width = total valve length.

1 + 0.5 + 1 + 2.5" = 4" which leaves us 11/32" short. That means that we have inside lap or the bridge width is not 1/2" or a bit of both. The port opening might not equal the port width, so it looks like assumptions 1 & 2 need to be checked for truth.

Well, that is all I can think of that we know from the Bilgram diagram and a few assumptions. Time to check the answer sheet card #3.

Cheers Dan

I think I finished the edits to this so now to pull card #3 for real.
« Last Edit: April 21, 2022, 08:01:25 PM by Dan Rowe »
ShaylocoDan

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 1163
  • Dripping Springs TX USA
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #67 on: April 21, 2022, 08:41:24 PM »
 :cussing: :censored: well dang so much for card #3 it has every engine part on a single sheet EXCEPT for the cylinder. :facepalm:

Now I have to find card 108 for the 8" x 8" cylinder or card 138 for the 9" x 8" cylinder. I never finished putting all the drawings back in the proper drawers after my last reorganization and I am paying the price for that bad decision.

Cheers Dan

ShaylocoDan

Offline crueby

  • Full Member
  • *****
  • Posts: 14273
  • Rochester NY
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #68 on: April 21, 2022, 09:16:27 PM »
Turn off the fan and close the window so it doesn't blow the papers around and mix them up more!!

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 1163
  • Dripping Springs TX USA
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #69 on: April 22, 2022, 12:54:58 AM »
Hi Chris, it is going to take a very strong fan to get that stack o paper moving. It is close to 3/4" of mostly C size sheets with the cranks which are all special sizes.



The top sheet is 7404 which is a slide valve group card. I checked the slide valve on card #3 and the outside width is not the same card #3 says 4 3/8" and card 7404 set 3 says 4 11/32". The angle of advance has to be different for the two versions of the 8" x 8" valve and I will be able to spot the change in the records.

It looks like port opening does not equal port width, and there is inside lap.

I have drawn this engine before I just have to locate the drawings. I drew it for the article I wrote about Bilgram's diagram for "Steam in the Garden". I think the article used the shorter version of the valve.

I will post the article and show the valve design tomorrow and talk about over and under travel. Kozo used over travel and he said why when he built the second Shay. Does anyone remember his logic?

Cheers Dan
« Last Edit: April 22, 2022, 01:06:15 AM by Dan Rowe »
ShaylocoDan

Offline crueby

  • Full Member
  • *****
  • Posts: 14273
  • Rochester NY
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #70 on: April 22, 2022, 01:06:54 AM »
I didn't remember anything about overtravel on his New Shay, so just checked the book, couldn't see any mention of that....

Offline Dan Rowe

  • Full Member
  • ****
  • Posts: 1163
  • Dripping Springs TX USA
Re: Bilgram's valve diagram a graphical method to design a steam valve
« Reply #71 on: April 22, 2022, 01:13:25 AM »
Chris, I am not sure where it is in the book but I would guess near the Zeuner diagram. I think it was something like 0.5mm over travel to compensate for pin wear so the valve will still fully open with some pin slop. I had wondered about that for years so it made an impact on me something like a hammer. WhamO. :slap:

Cheers Dan
ShaylocoDan