Big confusion on Elmers 33 cylinder ??!!

[compressor man]

Hi Guys, I have started work on elmers #33 mill engine. I am having a lot of trouble making heads or tails on the cylinder portion of the plans. The cylinder is a little bit oddly shaped, it appears to have 2 flat sides and each end is circular in order to accept the round heads. My questions..
1. The upper left drawing seems to be the layout for one of the flat sides, where is the layout for the second?

2. Rather than giving the hole spacings as measured from the edge of the piece, they seem to be measured from the centerline of it (example, in the upper left drawing there are 4 holes that are 3/8" apart. Are they centered on the centerline of the actual block or the centerline of the bore (they have different centerlines)?

3. In the left side drawing that is second from the top what is the dotted line with the arrows on each end suppossed to represent?

In my mind it seems that these drawings are incomplete but I do not think that is the case. Rather it is my inexperience that is unable to fill in the blanks so to speak. If anyone has built this engine and can fill in those blanks for me I would be quite grateful.

Sorry for the fuzzy drawing, it just seemed to copy and paste that way.

Chris

 

[arnoldb]

Hi Chris

1) The layout in the upper left shows the port face to which the valve plate and steam chest will be mounted. The layout for the other flat face actually ties in to your point 3.

2) The holes that are not explicitly shown measured from any of the edges are all spaced around the center line of the bore, and the cross-sectional center of the cylinder block.

3) The picture 2nd down on the right shows a cut-away as if you were to cut the cylinder along the dotted line with the arrows you mention for the one to the left of it (cut B-B). Imagine sawing the cylinder along those lines, and looking at it from the right to the left with the right-hand "sawn off" portion gone. - that would give you the picture 2nd down on the right. The top part of the cut-away shows the port layout, while the bottom part result in a section through a mounting hole (the #4-40) in the other flat face. If you look at the 3rd picture down on the left, it gives the spacing for the mounting holes in that face.

Hope I didn't confuse you any more!

Kind regards, Arnold

 

[Groomengineering]

1. The upper left drawing seems to be the layout for one of the flat sides, where is the layout for the second?

2. Rather than giving the hole spacings as measured from the edge of the piece, they seem to be measured from the centerline of it (example, in the upper left drawing there are 4 holes that are 3/8" apart. Are they centered on the centerline of the actual block or the centerline of the bore (they have different centerlines)?

3. In the left side drawing that is second from the top what is the dotted line with the arrows on each end suppossed to represent?

Chris

Hi Chris, I'll see if I can make some sense of it for you (no promises : ) I'll start with #3, the line with the upturned arrows means there is a sectional drawing of a slice through the part at that point. You'll notice the one on the top left has A's on either side, which corresponds to sectional drawing A-A below it. The one in that drawing shows a B-B section, which is shown to the right of it. B-B happens to be an offset sectional, it goes through the mounting hole then jogs to the left and continues through the port. These can be confusing if you're not used to them, but it's an easy way to show features.

#2 When dimensioned like this it's in relation to the drawn centerline, in this case the actual centerline of the part and bore. These particular dimensions are basically for reference anyway, the holes should be spotted from the steam chest.

#1 Again these should be spotted from the frame (or whatever), but the holes should be on the centerline of the bore (middle drawings), and the distance between is shown on the lower left drawing.

Hope this helps. scratch.gif Reading drawings takes quite a while to get used to. In most drawings all the information is there, but it takes some inference to get the dimension you're looking for.

Well, looks like Arnold beat me to it, what he said too.... ;D

Cheers

Jeff

 

[Brian Rupnow]

Here is a link to my build of that same engine. I did change the cylinder a bit, but you can read thru the thread and it may shed some light on the way that cylinder looks.---Brian
http://www.homemodelenginemachinist.com/index.php?topic=7340.0

 

[Troutsqueezer]

Elmer's plans usually call out the dimensions relative to the center of the part so you'll find that some simple math is involved to get many of the dimensions you might want. Especially if looking to get hole distances from the edge of the part, rather than the middle.

Keeps the ol' brain working. Part of what's good about this hobby, no?

-Trout

 

[compressor man]

I cant thank everyone who responded to this post enough. It reminds me why I enjoy this site so much, the friendly and eager to help people here are such a breath of fresh air. I have not had time yet to apply what I have read here to my actual part but I hope to do so this afternoon.

Probably will be back with the next tier of questions!

Thanks again guys,
Chris

 

[compressor man]

Hi guys, was able to look at the drawings with the benefit of the wise counsel received here. Yes, lights are beginning to click on and the drawing is starting to make sense now, well a little sense Learning about the drawings being sectioned off and shown as cut-aways really helped out a lot. I have a couple of new questions though...

1. In the top left drawing, the series of small holes in the very center are (I think) the exhaust ports. Is
this correct?

2. The second from top drawing on the right side shows another view of those ports. There is a 5/64 hole
drilled in from the side to access them. I see however that there is another hole at right angle to this 5/64
hole drilled in from the other face. I cannot find the diameter of this larger hole. Also, what plugs the
entrance of the (now unneccessary?) 5/64 hole?

If I seem to be particularly ignorant then it is because I am. I have never before built this type of valve and it is completely new to me.


Thanks, Chris

 

[kvom]

Hi guys, was able to look at the drawings with the benefit of the wise counsel received here. Yes, lights are beginning to click on and the drawing is starting to make sense now, well a little sense Learning about the drawings being sectioned off and shown as cut-aways really helped out a lot. I have a couple of new questions though...

1. In the top left drawing, the series of small holes in the very center are (I think) the exhaust ports. Is
this correct?[

b]That's correct. In reality there're no reason why they can't be a slot[/b]

2. The second from top drawing on the right side shows another view of those ports. There is a 5/64 hole
drilled in from the side to access them. I see however that there is another hole at right angle to this 5/64
hole drilled in from the other face. I cannot find the diameter of this larger hole. Also, what plugs the
entrance of the (now unneccessary?) 5/64 hole?

That face is attached to the frame by the 2 5-40 screws, so presumably the original hole is sealed off by the frame. In any case, an extra exhaust hole wouldn't cause any harm. Note that the new exhaust hole shown in the cross section doesn't even appear in the top view. The diameter isn't really critical, so I'd just use the same 5/64 or larger.

If I seem to be particularly ignorant then it is because I am. I have never before built this type of valve and it is completely new to me.

It's a slide valve, something used in lots of double acting engines, esp. locomotives.

Thanks, Chris

 

[Troutsqueezer]

That cylinder and slight variations of it are commonly used in Elmer's designs. Here's one I did (slightly different version perhaps).

http://www.homemodelenginemachinist.com/index.php?topic=9084.30

 

[mzetati]

Chris,

in the files section ("ShopWisdom" subfolder) of the Elmers_Engines_4 group, on Yahoo! servers, You will find the appendices of The Book, containing some more information about the cylinders, valves, etc., together with some ideas for making some tools to ease the job.

URL: http://groups.yahoo.com/group/Elmers_Engines_4/

Marcello

 

[AlanHaisley]

2. The second from top drawing on the right side shows another view of those ports. There is a 5/64 hole
drilled in from the side to access them. I see however that there is another hole at right angle to this 5/64
hole drilled in from the other face. I cannot find the diameter of this larger hole. Also, what plugs the
entrance of the (now unneccessary?) 5/64 hole?

As mentioned previously, the hole in the back will be blocked by the surface that you mount the cylinder to. The hole in from the top is shown in the appendix under "Basic Cylinder, Type M" as #5-40. That would make it drilled and tapped to match a piece of threaded 1/8" tubing I believe. You could use that if you wanted to route exhaust steam away or perhaps route it to a condenser or some other part of a model.

Alan

 

[prof65]

Hi Chris

The blocked hole is visible in the bottom-left corner on pag.143



View attachment blind hole.bmp

 

[compressor man]

Just wanted to thank everyone who responded to my question. I could not have built this without that advice...advice that I printed out and brought to the shop with me! Now it just needs a little clean up work and I am on to the next part.

Thanks guys,
Chris