Myrick Eclipse one-third scale model part two

[Myrickman]

Part one was to construct the model shown and is described in a build log on another site. These were common pumper engines in the  oil and gas fields. About two years ago I happened onto another full sized, early engine like this one except with a ported cylinder. I took the model to several shows and got several requests for castings. This past winter, I had the patterns cast for those requests and also made with a modified ported cylinderfor myself. Since I had built one already, I could now get the port location right. Number one was built with no plans, just a cutaway drawing of the full sized engine.
The model has a 2" bore and 2-1/4" stroke. Fuel is propane and ignition is via hot tube. The hot tube is a piece of  1/4 stainless tubing about 2-1/2" long. She's a hefty girl weighing in at about 65 pounds finished. Governing is hit and miss via a lollipop weight pivoting about the flywheel. I'll be starting this one in the next few weeks as I have to add some sketches for the parts not documented in the original build.

[Admiral_dk]

Very nice - but not quite a model in my eyes, since she is big enough to do real work 

.... then again, where do you divide sizes ...?

Looking forward to the build 

[Myrickman]

Getting back to this build after a busy summer. First task was to square up the cylinder and turn the base for boring in the mill. Here it is in the lathe. The dimensions are shown as an aid to help the half dozen others with kits under construction.  I made a set of sketches for the first one I built and these add details to those sketches.  The cylinder goes in a steel ring which is clamped to the mill for boring. This ring also allows me to center the bore in the casting relative to where the core was. The ring locates on the 2.25" step.

[Myrickman]

Starting on the arch which supports the cylinder. Four 1/4-20 SHCS hold the cylinder to the base and go underneath. Here the top hole is bored  to receive the cylinder and then flipped over to mill the pockets for the screws.

[Myrickman]

One of my friends requested more detail on the intake chest. Here it is being machined out of the casting. This engine had a series of small holes in the intake valve seat to simultaneously admit air and natural gas in the oil patch. On the model, two 0.042" holes perform this function. Excuse the dimension cards but I find it an easy way to record my work for later use by others since I do not have formal plans.

[Myrickman]

Been off this build for a while and wanted to post some progress. Finished the piston and rod. Piston was straightforward. Indicate off the bottom end ID to ensure a uniform wall thickness in the four jaw. Once this surface is cleaned up, flip piston around, knock in a center and machine the OD. Rings are 1/8" wide so roughed out the grooves with a 0.093 parting tool. I made a nice holder for some teeny carbide inserts to finish to 0.001-0.002 side clearance. Rod is silicon bronze and it'll  receive Babbitt in the lower end. The wrist pin is stationary being retained by two 10-32 set screws. This one is going much smoother as I have an earlier set of sketches and am adding refinements.

[Myrickman]

I'm off on vacation until Christmas so I'm able to plow through some of the big parts of the build. Here I'm putting in the holes to mount the cylinder to the arch which bolts to the base. On the full sized engine, the arch and cylinder are one piece. Here they're attached together with four small SHC screws on the arch underside. I kept measuring and remeasuring everything so the center of the arch is concentric with the bore and ultimately, the base and crank. My DRO readout was acting wonky and needed to warm up for an hour to keep from skipping. Since I just bought it from DRO Pros just three months ago, they graciously and quickly are sending me a new one. As long as crank slow and double check with counting crank revs, it seems to be working.

[Myrickman]

After carefully referencing my xy datum marks on the base, I temporarily attached the caps to the base and machined the spacing between them to locate the crank. Tomorrow I'll flip the base 90 degrees and drill the caps for the Babbitt to be poured in. The nice thing is I have the jig to pour the mains to size with a plastic simulated piston to ensure the mains ar perpendicular to the bore. A test fit up of the base, arch and cylinder showed me they are all concentric to the bore....whew.

[b.lindsey]

I an envious of the holiday shop time, but you are sure putting it to good use. Great update!

Bill

[Myrickman]

Here Are the bearing caps being bored to 1". The crank is 3/4" so there will be 1/8" of Babbitt on the mains. Had my angle plate pre drilled from the last one I built so setup was a breeze. Lower cap center was spot on the center when it punched through the top with a pilot drill.

[Myrickman]

The fan side of the arch which supports the cylinder gets a cutout to access the rod. Since I didn't have a 3.8" hole saw, I cut the offending piece out on the rotary table using an end mill. With the rotary table centered in I took the opportunity to also cut the cam on the cam gear.

[Myrickman]

The cam is cut on the side of a standard 16DP gear with 40 teeth. On the original, full-sized engine, the cam is a simple tangential affair with no additional radii. On the rotary table with a sharp 3/4" end mill, I was able to cut it in one pass albeit going slowly. The shoe which rides the cam is rather long so this should help it open more smoothly as opposed to it being a true, what is it, constant velocity or something like that cam. Also, this is a ported engine so there is very little exhaust load on the valve. Having the wax mockup helped in turning the rotary in the correct direction. My work with the rotate table is done so it is unbolted and hefted back into the cabinet. At close to 90 lbs, my back was thanking me for only making one trip.

[b.lindsey]

More nice work and the cam came out especially nice!!

Bill

[yogi]

Coming along nicely!!!     
Looking forward to see more...

[wgrenning]

Great Progress!  It wont be long now