Hello again folks! This week I am going to finish most of the machining on the engine frame. In the last episode I finished the bearing blocks where I had to rotate the milling head to 25° to machine the flats. Since I disturbed the vertical alignment of the mill I will have to “tram” out the head to restore vertical plumb of the spindle. There are a few ways of doing this although I have adopted a simple solution to the process. I made a shank that a typical dial indicator holder can clamp on to and then mount it into the chuck of the mill. I then lock down the spindle and take a measurement to the table on both the left and right sides with the dial indicator positioned as seen below. I carefully lift the probe and swivel the indicator to each side of the table noting the elevation measurement of the indicator each time. This will show any angle the spindle may have to the table. I can then adjust the head’s position to equal out the left and right measurements ensuring proper alignment.
Now that the mill is aligned I can get into boring the bearing blocks for the crankshaft bearings. This procedure has to be ultra precise or else the crank will be at an uneven angle to the travel of the connecting rod. This will promote premature wear of the engine an be a real bummer overall.
Before I mount up the frame on the mill I decided to clean up the edges of the bearing blocks with the Dremel tool. I contoured the bearing caps to the engine frame and broke off the edges of the outer faces of the blocks as seen below. Note: The bearing caps have not been removed since they were last installed with Locktite. This is to prevent the caps from shifting during the boring process.
The next step is to mount the frame back onto the angle bracket as before...
Using my granite surface plate and a height gauge I was able to align the frame to the horizontal plane. The 1.249” diameter test rod was inserted into the bore of the cylinder and measurements were taken at both sides of the rod. Once the measurements were equal I was ready to lock down the clamps and move to the mill. Note: It is worth mentioning that the test rod used on this project has a snug fit and does not sag in the bore. If one were to use a rod with more tolerance it could produce an erroneous alignment.
A quick recheck of the alignment ensures a proper setup ;0)
The next step is to find the center in the bearing blocks for the crankshaft. Since the prints do not show an exact measurement for the crankshaft center I will have to locate it at the average center of the bearing block bosses.
The bosses are not even to each other so laying out this location can be tricky. I ultimately ended up using the two outer faces of the opposing blocks to find my measurement which was about 2.6” up from the frame’s base. Of course the hole must be located in the center of the two sides of the block as well...
The next step was to drill the blocks with a 19/32” drill bit. I ran my bit at 360 RPM which worked well. I did use a #3 center drill to spot the hole before drilling (not shown).
I used a quality Union Butterfield drill bit for this operation...
The next step was to ream out the hole with a .625” chucking reamer (Union Butterfield). I reamed out the hole at 180 RPM...
I zeroed out the table on the center of the crankshaft hole and then moved down 1.495” and to the right .130”. This location puts me in the timing gear center which is 2” from the crankshaft center for a proper gear mesh.
I spotted the hole with a #2 center drill...
A 19/64” drill was used to pilot the hole (not shown) followed by a 5/16” chucking reamer.
I used a 3/4” end mill to trim off the face of the timing gear block to almost flush with the side of the frame.
I decided to face off the valve rod support block at this time although I cannot finish it off until I have built a few more parts. I would suggest leaving this step for later.
I repositioned the frame on the table to work on the spark plug hole at this point.
I used my facing mill to face off the boss as seen below.
Using my calipers (not shown) I found the best center for the plug hole and zeroed out the table on this mark with the wiggler tool.
I spotted the hole at this point with the #2 CD.
I used a 11/32” drill to drill through to the bore of the cylinder. The prints call for a “T” drill of which I did not have so a slightly smaller 11/32” was used.
I now used a 5/8” end mill to counter bore the hole exactly .187” deep. The digital spindle depth gauge on my new mill is coming in handy on jobs like this one ;0)
I now used a 10mm x 1mm plug tap to thread the hole to about .3” deep.
I moved the table to the left (and right) .4375” from center for the two bolts that mount on either side of the spark plug hole and drilled with a #47 drill to .25” deep. Note: I am guessing that these side holes were once used to mount an “igniter” on the original engine. They were probably abandoned when the use of spark plugs became more popular. These holes will serve no purpose on this engine other than to add to the scale appearance of the project.
The next step is to drill out the hole for the gas tank sump line. I located the hole at 1” back from the end of the base by .365” up from the bottom.
I used a 1/4” drill make the hole (not shown) and then tapped it out with a 1/16” x 27 NPT tap.
I removed the frame from the mill and tapped out the two igniter holes with a 3-48 plug tap as seen below. I used my 3/8” chuck to carefully feed the tap into the holes...
At this point I removed the bearing caps from the frame and proceeded to drill out the oiler holes with a #21 drill.
I followed the drill with a 10-32 tap....
I opted to drill out the set screw hole for the timing gear shaft at this point as well. I used a #29 drill which was centered on the hole in the frame (not shown) followed by a 8-32 tap.
Now the next step is completely cosmetic although I was compelled to follow the drawings :0P I speaking of the water hopper drain hole which is nonfunctional. The full size engine’s water hopper wrapped around the cylinder with a water jacket and could be drained in the winter. This model does not have a water jacket so this hole is for scale appearance only. I figure that it can’t hurt to add the “drain” so I will include it in this build. I drilled a #22 hole exactly .350” deep as seen below.
I tapped the drain hole with a 3/16-40 tap which will hold a brass drain plug later on.
I decided to see if the 3-48 “bolts” supplied in the hardware kit would fit into the spark plug boss’s holes. Unfortunately the bolts did not fit due to their shoulders so I couterbored the holes with a #40 drill bit as seen below.
I installed the CM-6 spark plug for a fit check...
I also tested the fit of the crankshaft bushings at this point as well. Looks good so far :0)
Well the Red Wing Project is moving along although not quite as fast as I would like it to. I have been busy with more family matters than I am used to but that comes with having two kids. I hope to get into the engine frame’s base casting as well as the crankshaft next week so wish me luck and be sure to check out the next episode of the Red Wing project. Until then be safe and follow your dreams to completion!!!
