OK, this week I worked on the bearing caps which seem pretty straight forward. The caps come as a joined casting which should make the machining a bit easier.
I started out by marking the metal I needed to shave off the bottom to achieve a proper radius to match the diameter...
The facing mill cutter made short work of the surface job. I am quite impressed with the power of my new mill :0)
Now that I have a clean surface to lay out on I scribed the bolt hole locations using a square.
I used a #2 center drill to spot each location...
I followed the CD with a #18 drill...
I flipped over the caps and used the wiggler to find the center of the holes, one at a time for spot-facing.
A 7/16 end mill was used to spot face the caps.
I decided to face off the tops of the oiler bosses at this point.
I laid out the centers of the oiler bosses and used the #2 CD to spot both holes although I will not drill them until I bore out the caps.
And now to band saw them apart.
The caps will be left rough on the sides until they are mounted on the frame.
The next step is to align the frame to the travel of the table. I did this by inserting a tool steel rod that fits the bore of the cylinder (1.249). I then used my dial indicator to square up the frame by measuring the movement as I traversed the table left and right. After a few taps with the nylon hammer I was able to eliminate any difference on the dial indicator as the table traveled.
I locked down the clamps and rechecked the dial indicator. The frames bore is now square with the travel of the table.
The next step is to machine the bearing cap flats to a 25° angle as the prints show. This could be done by mounting the frame at the 25° angle however my machine has the option of tilting the head so I rotated the head as seen below.
I had to remove my coolant misting nozzle to clear the water hopper.
I used my facing mill to trim off the bearing flats as seen below.
I milled just down to where the flats merged into the frame of the engine.
The next step was to drill out the bearing cap bolt holes in the frame. I used the tool steel rod to measure out precisely where the centers of the holes would be (about .594 out from sides of rod). This will evenly space the caps on either side of the bore.
To drill the caps I needed to swap out my 5/8 chuck with a 10 mm chuck from my micro mill. The larger chuck will hit the water hopper.
I used the wiggler tool to find my center marks I made earlier for the first set of holes. I then laid out the holes where they would intersect the center line using the caps as a reference (not shown).
I used a #2 center drill to spot the hole...
A #29 drill was used to make .5 deep holes in four places.
You can see how close the 10 mm chuck comes to the water hopper.
Once the holes were drilled I used a 8-32 tap to thread the holes.
I did not used the machine to power in the tap but only used it as a guide to hand tap the holes.
I could now insert the 8-32 studs in place for a fit check.
I decided to drill and tap the fuel tank filler at this point as I will need the smaller chuck to fit next to the water hopper. I used a 5/16 end mill to spot face the hole as seen below.
I drilled out the filler hole with a 1/4 drill (plans call for a D drill).
I threaded the hole with a 1/16 NPT tap to finish the job.
The next step was to machine the bearing block sides so I mounted the caps on the frame with a little blue Locktite so the blocks dont shift during the operation.
I tightened down the blocks as seen below.
I had zeroed out the table on the center of the test rod earlier so I could figure out where the crank will need to be in relation to the cylinder bore. I then mounted a 3/4 end mill into the collet and milled both inside faces of the bearing blocks so they were evenly spaced on the bore of the cylinder. This measurement was about .688 out from the center of the bore (about .313 travel off of zero with the 3/4 end mill).
The 3/4 end mill and my new machine made quick work of the blocks :0)
I reinserted the test rod into the bore to check the clearances and I was spot on in center.
Before I moved on to the outside of the blocks I decided to machine out the drip oiler slot and threads. Since I already had the table zeroed out I could easily locate the center of the drip oiler slot and hole.
I used a 3/8 end mill to cut out the oiler slot as seen below.
The next step was to drill a small flat with a 3/8 drill on the top of the cylinder to aid in centering the smaller drill later. I did not have a long enough center drill to do the job so a regular 3/8 drill was used.
To reach the bottom of the water hopper I had to make some bit extensions out of tool steel. These extensions will allow me to use a regular tap and drill to finish this operation.
I mounted a 3/32 drill into one of my extensions and drilled through to the bore. I then mounted a regular 7/32 drill and made a .3125 deep hole for the tap (not shown). The 7/32 bit did not need an extension.
I now could use a 1/4-40 tap to thread the oiler nipple threads.
Now that I was done with the center line work I could move out to machine the outside of the bearing blocks. I mounted the 3/4 end mill and trimmed off the blocks so that they were 1.0 wide as seen below.
The end mill left a beautiful finish so I wont have to clean it up later on.
I am making progress, slowly but surely ;0) Please join me again for the next episode of the Red Wing Project.
