The "fix" in November left me with a mill that works better than ever, but in the process of doing that, I just put the lathe back together so I wouldn't lose any parts, and somehow did four or five other projects without ever getting back to the lathe. Well, no more - I decided I wouldn't work on anything else until the lathe was done!
In that previous post, I told of how my friend Phil Oles had gifted me some special bronze to use in making the new parts. I was following instructions purchased at this link, and since he sells the instructions to support his site, I won't be going into huge detail on how it works. But I will say that it works - buy the instructions if you have a lathe similar to mine!
I got started by completing the process of milling the bronze to the correct thickness, length and width:
Once that was done, I did a lot of careful marking, aligning, drilling and tapping to make two bronze "saddle plates". These are shown with the original iron ones, and I've also included the remainder of the chunk of bronze from Phil to show how it looked in the beginning:
The holes are different, because that's part of the upgrade - that's what makes it special. And yes, you can see one extra hole in one of them where I made a boo-boo.
Once the saddle plates were complete, then came the scary part: modifying the saddle of the lathe. I had to take four existing tapped holes, and drill them out to a slightly larger size, and extend them all the way through the body of the saddle. Definitely non-reversible, and definitely requiring careful alignment. Fortunately, I have a tool that made it pretty easy to do.
This doo-dad is called a center finder. The part (in this case, the lathe saddle) is roughly aligned underneath the point, and then the point is lowered into the hole:
The two pictures below illustrate how it works. Once I lowered the center finder until the point seated in the hole, the point moved sideways to compensate for the fact that the alignment wasn't perfect. In the left picture, you can see a little "step" where the bottom part of the center finder has moved. All you have to do is carefully adjust the mill table until there is no step (right picture), and you're guaranteed that the drill chuck is now centered above the hole.
After that, I could switch to the right size drill bit, and carefully drill all the way through the saddle. I did this four times, and then reversed the saddle and drilled 0.200" counterbores on the top side, so the head of the new adjustment bolts would fit flush.
When it was all done and installed, it looked like this from below:
The center bolt holds it all together, the set screws on either side allow a rough adjustment, and the new threaded holes on each end allow the final adjustment from above. After this picture was taken, I went back and used shorter set screws on the side with the gear to ensure that there wouldn't be any clearance problems.
From the top, you can see two of the four adjustment screws (red circles), nestled in the counterbores I drilled earlier:
After a bit of fussing and adjusting, it was all reassembled and ready to test. I started with aluminum. I still wasn't thrilled with the finish I was getting, until I switched to the style of cutter in the photo below. After a few more adjustments, I managed to take a clean cut of 0.002", which is probably about the limit of accuracy I can hope for on this cheap little lathe:
As a final test, I tried to cut a piece of steel that Phil had given me. I had chewed it up pretty good in prior trials before I started the modification, but after a few passes, I achieved a nice finish. All in all, worth doing, and I learned a lot about my lathe in the process!
Good work E. You now know your lathe inside and out.
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