Elmer's Wobbler #25

[Apprentice]

Here we go again guys.

Im about 90% sure a few of you are in need of more 'high-calibre' projects to engage in. But, Im sorry being this is my first attempt and I would class myself as a beginner. I will be going for Elmer's #25.

I have also opened a thread 'Apprentice Engineer' in the Welcome section, if anybody would like a brief background about myself.

So, I've taken Elmer's design's and started converting all the measurements (inches to mm) and have used these measurements for my CAD designs. I am aware that I will be changing alot of the measurements, but this will be my re-engineering stage. For now I just want to get the #25 engineering drawings into CAD.

CAD so far has been attached. (Frame/Bearing/Crankshaft) - Assembly

 

[Apprentice]

Bearing in mind guys I do consider myself as a beginner, not only in the area of machining, but understanding.

Hence my reason for taking up this project. The reason I say this is perhaps some questions I might ask may seem quite simple, but my attention to detail, quite frankly gets on my own nerves sometimes.


Understanding the #25
On the frame - there are two (1.5785mm) holes vertically in line with one another towards the left end. From what I understand there will also be another hole on the width of the same end of the frame where air will enter, this will enter the top hole, and then into the cyclinder.


Resulting in the osciliating movement, whereby the cyclinder would move in line to the bottom hole on the frame, releasing the air and the cyclinder repositioning itself to the top hole.


Therefore - we can say, on the frame, the top hole will only penetrate the frame to the point it meets the hole from the width (where the air inserts). Where as the bottom hole will be through the frame completely. Also there will be a hole on the cyclinder allowing air to enter and leave.


Please correct me if this understanding is incorrect.

 

[Tin Falcon]

Im about 90% sure a few of you are in need of more 'high-calibre' projects to engage in. But, I'm sorry being this is my first attempt and I would class myself as a beginner. I will be going for Elmer's #25.

JR no need for apologies or or self defacing comments. this board is about building model engines, It is about learning it is about the journey and sharing the journey. All skill levels are welcome here an encouraged to share there journey in model building.

And us experienced builds do like seeing how the new guys progress. so procedd with confidence. if you stumble so what get up move on. if you need help just ask.
Tin

 

[Apprentice]

Cheers Tiny! My engineering report, project management report and #25 have to be handed in by May 2013. So hopefully I should be able to post it all up once it's done!

For now - I'll keep everybody posted on progression on this thread.

 

[Propforward]

The Elmer number 25 is a great engine to start with. It is not without its challenges either. Looking forward to seeing your progress. I am working on the number 25 too - stalled at the moment because I have a habit of jumping around between projects at home, but that's just me,

 

[thayer]

JLR,

You are correct. The upper hole is the air/steam inlet port to the cylinder and is just deep enough to catch the threaded inlet coming in from your compressor / steam source. The lower hole is the exhaust and goes through to the back of the main block.

One of the great things about Elmer's engines is that once you identify the critical bits, you can modify the rest as desired to personalize your work a bit. Take for instance the main frame. Since I had CNC available I radiused the upper bevel near the main bearing, as well as the corners near the air inlet. I also radiused the corners of the foot and and added a third hole through the center of the foot into the main frame to attach it to its wooden base without having visible screws. Yes, the radiusing could all have been done with a file or rotary table as well.

Similarly, on the cylinder I turned the closed end round for a little under a millimeter as a decorative accent to echo the turning on the other end. I chamfered the cylinder as shown on the plan, but you could also leave it squared off or radius it along its full length as you desire.

My last change of any significance was to the flywheel. I didn't want to pierce the outer perimeter so put a set screw at an angle through the hub.

You can see my efforts at this link. http://www.homemodelenginemachinist.com/f14/elmers-2-25-a-8201/

The main changes on the twin vertical were to move the exhaust port to the same side as the intake to keep one face clean and to add a little v-groove pulley to the flywheel hub.

Enjoy the process.

Thayer

 

[Apprentice]

Right guys, I'm sure with Christmas fast approaching, machining wont be on the agenda due to my workshop being at college.

So - I thought I'd take the time work on my reports; I have uploaded the 'Table of Contents', of course this will change over due time.

At this moment of time, my main concern is the Literature Review. Besides Elmer's Engines, which my Library have said they will try to order through various libraries abroad, responding if they manage to get hold of a copy, fingers crossed.

Are there any other books anybody can recommend that are highly related to this project, to read/browse?

View attachment Table of contents.pdf

 

[Tin Falcon]

JLR getting a hold of a hard copy of Elmers engines could be tough and expensive it is pretty much a rare of of print book.
I heard some rumors rumblings of a reprint but no details.
you may want to look at into

simple model steam engines by stan bray
simle model steam engines by tubal cain
Model stationary and marine engines by kn harris.
all should be available at a reasonable cost.
Tin

 

[weez]

JLR,

It looks as though the counter-drilled? hole for the spring is on the wrong side of the frame. I made the same mistake when making mine. Luckily I noticed before drilling the air/steam inlet hole so I drilled it on the other side which is why my wobbler is a mirror of Elmer's design. If your library is unable to get Elmer's Engines book, http://www.john-tom.com/html/ElmersEngines.html has PDF's of his book.

Randy

 

[thayer]

JLR,

Years ago I downloaded all the PDFs of Elmer's book, printed them and put them in a 3-ring binder. I keep this as my "upstairs" reference and when I need shop copies I reprint the relevant pages. That said, I can't wait to see the reissue. I will definitely buy it if only for the better photo quality to have next to the bed.

Thayer

 

[Apprentice]

Cheers Tin, I think Monday I'll have a look into the titles you have mentioned.

Weez - I'm not entirely sure what you mean? On the engineering designs it specifies a locating pin should this fit on the opposite side to how I have shown in my CAD? In simple terms - IT'S THE WRONG WAY ROUND!

Thayer, what about the few who do have an original print. If they do reprint, I most definitely will be investing in a copy.

 

[Apprentice]

Guys - I was also wondering, why does it seems extremely hard to find any information on Elmer Verburg himself? If I typed a celebrity on google - wiki would have the last place they dined at!

I believe doing some background reading on Mr. Elmer Verburg would be beneficial for my project write up.

 

[thayer]

Those with an original copy are lucky indeed!

As for the counterbore on the frame, the way I read the plans is that the edge view of the frame is showing the lower edge to detail the mounting holes. The 5/16 diameter of the locating pin references the bearing hole and its 3/16 x 1/8 end creates a reference for the steel drill jig. The jig pivots on a 1/8 pin let into the piston pivot hole. It does look like the locating pin is drawn on the back side of the frame though, due to the dashed line. I believe that its small dashes are the same as for the jig, showing that as not part of the frame. The hidden lines for the counterbore, mounting holes and inlet are all longer dashes. The top cutaway on that page should make it all clear.

Thayer

 

[weez]

JLR,

This top down full assembly view should make it clearer. The red line is the 7/32" counterbore for the spring. The green line is the air/steam inlet. They should be on opposite sides of the frame. On your CAD model they are on the same side. I hope this clears it up.

Randy

 

[Apprentice]

Cheers Randy - that makes perfect sense now. I should be able to get at least four hours of CAD in on Thursday. I'll be sure to amend this mistake.

 

[Tin Falcon]

Cheers Tin, I think Monday I'll have a look into the titles you have mentioned.

I have all three books four if you count vol 2 of the tublal cain book . IIRC all published in the UK. So you should have no problem finding them. Powels or Blackwells should be able to hook you up.

FYI I posted some pics of my redesigns in your intro thread.
Tin

 

[Apprentice]

At this exact moment I am writing about Elmer's Wobbler, currently explaing the oscilliating movement.

I was wondering is this all that needs to be mentioned in relation to operation. As I believe bore stroke and performance, belong to 'calculations' rather than 'operation' - perhaps the counterweight and flywheel should be highlighted in terms of operation of the #25?

 

[Tin Falcon]

The distance from the pivot to the ports and the stoke directly effect the valving action and the size and location of the ports. These relationships must be understood to design a wobbler.
IMHO the relationships and precedence should be sited in operation,at least briefly then put the number in the calculations section.
Tin

 

[Apprentice]

So - by the time the cyclinder port has reached the exhaust port the cyclinder should be fully compressed with air - ready to dispense the air, and by the time the cyclinder port has reached the intake port the piston should have no compressed air - ready to get air compressed back in.

Therefore, if done corrently the distance that the pistons undergo in one stroke can be changed.

Any idea what calculations I should be looking at - for this?

 

[Apprentice]

Is this right?