Two-Bot: My modified version of Elmer's #2 Twin Vertical Wobbler

[Metal Butcher]

On November 1st I started by building Elmer's #2 as my first project. I chose this simple model to get my winter building session off to a start. Since It was two years since the last time I had machined anything, I needed to refresh my memory and get into the swing of things. I found building this model to be an enjoyable experience and got a little carried away! Since a picture is worth a thousand words the link below will explain what happened.

Link: http://groups.yahoo.com/group/Elmer...ode=tn&order=ordinal&start=1&count=20&dir=asc

The picture below is a closeup taken today of the earlier version of the #2 I built in November. I simplified it by eliminating the pulley next to the flywheel, the cross head guides, and the milled details on the cylinders.

I will build this new version named Two-Bot 50 percent larger and change it's character by adding a few simple ideas.

Day 1: Once the spindle center line was properly located on the workpiece and a vise stop set up, I Simply indexed the base to drill all four corner mounting holes. These will be used to mount the engine to a wooden base.

Below is a picture of the finished base with all the machine work complete and ready for final surface finishing.

Picture below shows the dimensions I used. Note the addition of the four corner mounting points.

If you have any comments, suggestions, or questions please feel free to ask.
-MB

 

[Metal Butcher]

Day 2: Today I took a block of aluminum and roughed out the column. I also made the drilling jig from 1/8" x 1/2" wide steel.

Bellow are pictures of the column and drill jig.

-MB

 

[Metal Butcher]

Day #3. After I finished milling the large column it seemed a little plain and needed the addition of some visual interest. The idea of a reversing valve would be a nice feature that would add to the otherwise plain area on the column below the flywheel. I drew up a rough sketch and used it as a guide to complete the drilling and tapping.

The photos below show the modified column and the sketch that I used to guide me..

-MB

 

[Davyboy]

MB That's some mighty fine work. :bow: The reversing valve looks interesting, a way to put YOUR mark on the engine. Please keep posting the progress. Just one question, How do you keep that mill vise and table so clean? ;D

DB

 

[Metal Butcher]

Thanks Davyboy!

The photo was STAGED after cleaning up with a chip brush and shop vacuum.

I can't seem to follow some one else s plans without alterations, maybe I'm trying to make them my own.

I just came up from the shop after milling a 6" x1" x1" down to 6' x.850 x.750.

It's really ugly down there now! :big:

-MB

 

[Bernd]

I just came up from the shop after milling a 6" x1" x1" down to 6' x.850 x.750.

-MB

You made it 6 feet long from 6 inches and still had chips left over? scratch.gif Rof}

Bernd

 

[Metal Butcher]

Hi Bernd.

That's how I build up my supply of raw materials. I simply machine it down in size and end up with a whole lot more! :big:

Seriously tho, I made a simple typo. It Should have been 6" not 6'.

One of the reasons is a DESIGN FLAW in the keyboard . BOTH symbols (" & ') are on the same key!

You see what I mean? Defiantly not MY FAULT! Also, adding to the problem was an undelivered command to my left hand due to a minor brain malfunction. Again, defiantly not MY FAULT ;D

Any way, these are my OFFICIAL excuses. :big: :big: :big: :big:

-MB

 

[Metal Butcher]

Day #4. A lot of distractions yesterday only allowed me to mill the 2 plain rectangular blocks that would become the cylinders.

Day #5. Today I roughed out the cylinders and cross head guides. Due to the lack of a four jaw lathe chuck these were made from two pieces drilled and reamed before assembly using Loc-tite. The cross head guide was made to include the full length of the bore and acts as a cylinder liner. After the parts had time to bond the details on the cylinder and cross head guide were milled. All that's needed is a final clean up with file and sand paper.

Although this engine is scaled up 50 percent some of the dimensions have been altered such as the .850'' on the cylinder to accommodate the combination cross head guide and cylinder liner. The rounded detail on the bottom of the cylinders is a cosmetic preference.

-MB

 

[Metal Butcher]

Day #6. If I were to move any slower on this build it's likely that rigor mortise would set in. So to avoid the possibility I scurried down to the shop and made the pistons. :big:

The last time I added piston grooves there locations were eye balled and didn't look all that good comparatively . This time I used my lathe mounted dial indicator to find their locations precisely.
I guess you CAN teach an old dog new tricks! ;D
-MB

 

[Metal Butcher]

Day #7: After I machined the valve from aluminum, the lever hole was drilled first to line up the work piece during the milling operation. Then the curved port passages were milled using the same method described in my post, "My Modified Build of Elmer's #3 O.C.R."

The 3/32'' lever and stop pins were chemically blackened along with the valve spring as a precaution against corrosion. The lever, lever knob, and stop pins will be installed using Loc-Tite during the final assembly.

Below is a photo of the drawings used as a guide, and the completed parts.

-MB

 

[Metal Butcher]

Day #8: Today I made a few more parts for my Two-Bot project. I made the crank discs from economical 6061 aluminum. The crank shaft and crank pin were made from 303 precision ground stainless. I used 3/16" 1018 cold rolled steel (not the 303 S.S. shown on the drawing) for the pivot studs, which made the thread cutting very easy.

Below are pictures of the finished parts and the drawings I followed.

-MB

 

[Metal Butcher]

Day 8: Late yesterday and today I built the flywheel.

The recess and stepped details are cut out from one side on the 1/8'' over sized flywheel blank. This excess on the back side will be removed later.

I drilled six holes to create my double three-spoke pattern flywheel using a spin index. This flywheel design came to mind while I was working on the post titled “My unusual spoked flywheel build.” http://www.homemodelenginemachinist.com/index.php?topic=4363.0

The six 3/16’’ spokes were attached with J.B. Weld at the hub. At the outer rim the spokes were attached with Loctite and then peened to assure a tight fit.

I went back to the lathe to cut-off the 1/8th inch left behind the recess. This excess held the hub and rim together as one piece.

With the 1/8th inch trimmed off, my question of whether it would stay together and be a fly-wheel or a fly-apart was answered.

Next I drilled and tapped for the 5-40 set screw. It will be used to hold the flywheel on a mandrel for final truing.

Voila! The flywheel is complete and ready for final sanding and painting.

-MB

 

[RobWilson]

Great Fly Wheel design :bow: :bow:

 

[bearcar1]

MB, pretty cool looking FW. Thm:

 

[Metal Butcher]

Day 9: Today I did the final assembly and test run. The engine ran great after I hooked up an airline and gave the flywheel a nudge. After a few minutes of running I dropped the pressure down to about two pounds to do some tests. First I tested the valve to make sure the engine would run at an equal speed in forward and reverse. The next test involved switching pistons, followed by rotating them 180 degrees, this proved the machining on the pistons and cylinder bores was done accurately. Swapping the cylinders back and forth proved their pivot points were perpendicular to the port faces on the column. These simple tests were carefully executed and would have made any minor error apparent.

I did find one problem; the valve is leaking. I forgot to lap the valve and the column face to remove the overspray paint that got on the face directly under the reversing valve. To give the engine some visual interest I added a double three-spoke pattern flywheel and a reversing valve. A visual flow was created by using aluminum as the predominate construction material. The column and base were painted one color to define them as the supporting structure. I hope you enjoyed following my build. Below are the final pictures of “Two-Bot.”

This picture shows the differences between my version of the standard sized “Elmer’s #2 Twin Vertical Wobbler” and my upsized version named “Two-Bot.”

-MB

 

[Shopguy]

Nice looking engine, the contrast between the bare metal and the paint sets it off well. I especially like the flywheel design.
Regards
Ernie J.

 

[Davyboy]

OOOH That engine is sweet! You really did make it "your own". :bow: Thank you for sharing.

DB

 

[kvom]

While the esthetics are great, what really impressed me is your being able to make both pistons and cylinders interchangeable! :bow:

 

[ozzie46]

While the esthetics are great, what really impressed me is your being able to make both pistons and cylinders interchangeable!



That got my attention as well!!

Great job :bow: :bow: :bow:


Ron

 

[Metal Butcher]

Thanks to every one for all the positive comments. I am also amazed with the piston to bore fits. Since I consider my abilities to be some what mediocre a well made part is 50% effort and 50% luck. But seeing an engine I built run is a very satisfying experience that inspires me while I struggle to improve the quality of my work.

I really need to get rid of my teacher!, he doesn't seem to know any more than me! :big:

-MB