I’ll apologize in advance for the length of this post – I’ve been working on the side rods and they were complicated beasts! It’s taken me almost two weeks to finish these guys. In addition, I got my 2nd shot and that took me out for a day or so. Anyway, here it goes...
The side rods were made from lengths of 1/4" x 3/4" 1018 CRS. Before machining, I stress relieved them by heating them up with the torch till they were nice and cherry red all over. After keeping them hot for a while so they got a nice soak, I let them cool slowly. This is my attempt to keep them from going banana-shaped when machined.
While the parts were cooling, I made a 7/16” counterbore. This will be needed for the side rods in a future step. The guide is 9mm (0.3543”) and the upper part with the cutter is 7/16”. I made it a single tooth cutter hoping it would work OK. And it did – not excellent, but good enough. I tried to file in a little relief in the single tooth then harden the steel (this was done with W-1 tool steel). Also, that little divot right in the tip of the guide is a mistake. I didn’t have the mill pulled back far enough while I was setting the height. Ah well – I just made sure to file that down so there wasn’t a sharp edge. Didn’t really affect the performance of the tool.
After the stress relief, I needed to machine the 1/4" width down to 0.200”. I first tried the face mill, but I didn’t like how that sounded with the interrupted cut.
So I switched to using my standard method for this kind of op. I took some off of each side, then went back and did one final pass of a few thou on each side. They stayed nice and straight. So the strain relief and the symmetrical operations on each side must have helped (he says optimistically).
Next, I blued the parts and did a little layout work. Here are the two nascent side rods, the drilling jig, and the 7/16” counterbore. You can see how it will be used to create the counterbore shown in the A-A section drawing on the right side of the sheet.
Now to use the drilling jig. First, I drilled and reamed one of the 9mm holes.
Then, using the drilling jig that I’d set previously, measured out exactly where to drill the second hole in the side rod. As it turns out, it was EXACLTY 5.5000”.
Go figure. I could have skipped the whole drilling jig after all! But now I know for SURE that my processes were tight enough that I ended up where I expected. Not always the case, but this time, it worked out.
After drilling and reaming both holes, I lined up the two side rods, back to back, using a 0.354” gauge pin and the guide on the counterbore, then clamped them in the mill vice and milled a rough top profile in the parts. I did actually remove the counterbore before I did the milling. I just put it back in for this picture.
Following this step, I counterbored the outside front hole in each side rod. As of this step, the side rods are officially left and right-handed. They are no longer interchangeable.
You can see the basic profile in the rods here. And see that one rod is LEFT and the other is RIGHT.
To round the ends of the rod, I used the rotary table. I zeroed in the center of the table, then positioned one of the end holes directly over it using the 0.354” gauge pin, and clamped it in place. With that, I plunged a 1/4" mill around the outside edge of the circle – about 20 thou bigger than my final size. (I did a bunch of trigonometry before this to know what angle to start and stop each of the sections – and I was pretty close!)
Then I went in and took off the peaks and the final few thou just rotating the RT. The final cut was climb-milled to give a better finish.
All four holes rounded off.
The next step is to take the sides down to size. For this operation, I needed yet another simple jig. This one required a couple of bushings – 9mm bushing with 1/4" holes.
I drilled and tapped (1/4 – 20) two holes in a length of 1”x1” aluminum stock. This lets me securely hold the side rods on edge so I could bring the width down to the required 1/8”. Here it is all set up waiting for the first side to be carved:
And just after the first side was carved. I was only taking off about 37.5 thousandths, but I did it in a few passes, with the last pass being a small climb cut. Notice that I left about 1/8” along the bottom at full width. This is to provide additional rigidity while machining the other side.
Then I flipped the rod around in the jig, put a few shims behind the cut-off portion to help give it additional rigidity, and milled off this side exactly the same as the first.
Here’s the current profile of the side rods after that last step.
Back into the holding jig, but on its side this time. I used a roughing mill to take off the bulk of the material that was left after the last step. I deviated from Kozo’s instructions here. He says to use a slitting saw to take off that portion, but I couldn’t figure out how to get a slitting saw in there without damaging the round holes on each end. So I just went with milling it off.
Switched to a standard mill for the last few passes.
To clean up the tooling marks, I wrapped some sandpaper around a 3/16” rod and slid the Jig back and forth. This helped to clean up all four sides (though on further review, I think I need to do more sanding).
The last step is to drill and tap holes in each end of the side rods (2-56). I assume these are oil holes, though it doesn’t ever quite say. And I’m not sure why they are taped. Nothing ever screws into these holes that I can see. Maybe it just helps with making the oil drain more slowly or something?
And the final beauty shot of the side rods.
Thanks for sticking with it through the end! It was a long story, but a lot happened
And thanks for checking in with me,
Kim