# Elmer's Wobbler #25



## Apprentice (Dec 14, 2012)

_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_


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## Apprentice (Dec 14, 2012)

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.


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## Tin Falcon (Dec 14, 2012)

> 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


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## Apprentice (Dec 14, 2012)

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.


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## Propforward (Dec 14, 2012)

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,


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## thayer (Dec 14, 2012)

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


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## Apprentice (Dec 15, 2012)

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


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## Tin Falcon (Dec 15, 2012)

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


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## weez (Dec 15, 2012)

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


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## thayer (Dec 15, 2012)

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


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## Apprentice (Dec 15, 2012)

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.


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## Apprentice (Dec 15, 2012)

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._


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## thayer (Dec 15, 2012)

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


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## weez (Dec 15, 2012)

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


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## Apprentice (Dec 16, 2012)

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.


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## Tin Falcon (Dec 16, 2012)

> 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


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## Apprentice (Dec 17, 2012)

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?


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## Tin Falcon (Dec 17, 2012)

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


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## Apprentice (Dec 17, 2012)

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?_


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## Apprentice (Dec 17, 2012)

Is this right?


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## Propforward (Dec 17, 2012)

Your diagram is correct.


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## Apprentice (Dec 17, 2012)

Propforward said:


> Your diagram is correct.


 
_Cheers prop_


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## thayer (Dec 17, 2012)

Yes, although with the piston in that position my guess is the inlet port would have already been closed.


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## Apprentice (Dec 20, 2012)

CAD so far -



I was thinking of having a vertical osilliator - I have found some designs for this on the net. Or perhaps I could scale Elmer's units up to the nearest whole figure. 
 
_Next step (re-egineering)_


During my CAD, I noticed the Shaft Bush was slightly over, I had to reduce the dimension by 1.16mm, to ensure the piston and rod fit within the cylinder and connect to the crankshaft pin correctly.


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## Propforward (Dec 20, 2012)

Nice work there - but I notice that your pivot hole is still being machined from the wrong side of the frame. The counterbore should be the other side to the cylinder.

What solid modelling program are you using out of interest? Is it solidworks?


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## Apprentice (Dec 20, 2012)

thayer said:


> Yes, although with the piston in that position my guess is the inlet port would have already been closed.


 
_Cheers Thayer - I have ammended this on my report_


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## Apprentice (Dec 20, 2012)

Propforward said:


> Nice work there - but I notice that your pivot hole is still being machined from the wrong side of the frame. The counterbore should be the other side to the cylinder.
> 
> What solid modelling program are you using out of interest? Is it solidworks?


 
Perhaps its the CAD Platform I am using potrays this differently? _Solidworks. _I have ensured the countrebore is on the opposite side to cylinder.


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## Propforward (Dec 20, 2012)

But your bottom diagram shows a counterbore as well - I think that surface should just be a plain hole, otherwise flush to the cylinder. I'm going from memory (often a bad idea), I'll have to check.

Your top diagram looks like a countersink to me rather than a counterbore.

EDIT: Yes, the original Elmer plan calls for a through hole on the cylinder side of the frame, with the counterbore on the other side, which is what holds the compression spring in place. I don't think the way you have it would be a problem as such, but the counterbore in the bottom image of the previous post doesn't actually do anything.

Very nice execution of the solid model though. CAD is an artform of its own in my opinion.


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## Apprentice (Dec 20, 2012)

Oh! My tutor has just specified what exactly you mean - I guess I'll have to get back to it after the Holidays! Cheers for the heads up Prop.

_Enjoy your Christmas everybody!_


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## Propforward (Dec 20, 2012)

Cool! Merry Christmas, and enjoy your holiday!


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## gjrepesh (Dec 22, 2012)

Here's  a picture of the Wobbler I made for my nephew's son. I mounted it on purple heart wood.  It was a birthday gift and I included a small air compressor as well as a booklet of the construction with photos. A fun project. Gary R.


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## thayer (Dec 23, 2012)

Very nicely done Gary. It looks like a wonderful present.


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## Apprentice (Jan 7, 2013)

Hello Guys,

Was wondering if anybody had any information concerning material selection for the wobbler components?

_Gary - nice wobbler mate. _


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## Brian Rupnow (Jan 7, 2013)

Aluminum for all body parts, mild steel (cold rolled) for the shaft, brass or bronze for the flywheel and cylinder. Aluminum for the piston. The flywheel can also be made from mild steel.


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## Apprentice (Jan 7, 2013)

any particular reason as to why those materials?


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## Apprentice (Jan 7, 2013)

Previous to this thread, whilst I was searching through other threads - I came across a table; I believe this was like a material comparison table. 

But I cannot seem to find it now


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## Brian Rupnow (Jan 7, 2013)

Because---Aluminum is comparitively cheap and very easy stuff to machine compared to steel. Brass is expensive as Hell, but can be polished up very nicely for some "Bling",and it too machines a lot easier than steel.


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## Apprentice (Jan 7, 2013)

Brian Rupnow said:


> Because---Aluminum is comparitively cheap and very easy stuff to machine compared to steel. Brass is expensive as Hell, but can be polished up very nicely for some "Bling",and it too machines a lot easier than steel.


 
_Cheers Brian_

Is there any particular type of steel, brass or aluminum that I should be comparing e.g alloy 2007 aluminim etc?


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## Brian Rupnow (Jan 7, 2013)

6061 for aluminum. Don't know for sure about brass. I just buy what my local supplier has available in bar or round stock, but I've never asked about a grade for it.


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## rleete (Jan 7, 2013)

For brass, get 360 free machining. Other grades are a little cheaper, buy 360 is so much easier to cut that it's worth it.


Edit:
Oh and try some 2024 series aluminum if you get the chance.  It's great stuff to work with


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