Shop Project – Small Lathe Rebuild Part 3

Merry Lathemas!!!

UPS finally delivered: The quick change tool post with tool holders, boring bars, carbide insert tooling (up until now I had 1 single high-speed steel tool that the lathe came with), centering bits, and a dial indicator (and a few other odds and ends). This’ll be a HUGE step to making this machine productive. The only problem is that my tool-post wasn’t designed to take this kit, so I’ve had to make an adapter that threads over it to make it work. I’m not done with that yet, but I’m SUPER stoked to have some proper tooling for it.

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I next took some time to get the quick change tool post set up. This is going to make life SO much easier. As with most bolt on stuff, this kit was made for similar lathes, but not this exact lathe, so it wasn’t exactly a bolt on affair. It came with an M8 internal thread – 9/16 external thread adapter, because the newer versions of this lathe all came with M8 tool posts from the factory. Well, mine came with an M10 tool post. Fortunately, I have this handy-dandy lathe! So I chucked it up and drilled out the M8 internals to 11/32 (which is the standard drill size equivalent of an M10 tap-drill size), and then drilled a much shallower bore to compensate for the M10 post’s longer unthreaded shank. After that, I tapped it as deep as I could go with my M10x1.5 tap. Unfortunately, that tap wasn’t long enough to thread the full shank, but it was long enough for PLENTY of thread engagement, so I simply cut the top 8mm off of the stock tool post (yeah, taking a hacksaw to my tools? Not my favorite.), smoothed out the top of the post with a flap disk, and then ran the die back up the threads to clean them up.

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All that done, and she fits like a glove!

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And since I just cannot and will not leave well enough alone, I had to set up a few of the tools, get them aligned and make a few chips. The insert tooling is going to working with this machine A LOT easier.

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The quick-change tool post set came with a boring bar holder for a 3/4″ boring bar. The tool set that came with it came with…. 1/2″ round-shank boring bars. The last part is important because I can’t just throw them into one of the normal tool holders as it would be held in by 2 set screws against a round surface. That sketch-factor is outside of my comfort zone.

I’ve got a bespoke holder on its way, but that will then tie up one of the normal tool holders. That’s fine, I guess, but I’d like to use the boring bar holder I’ve got.

I says to myself “self… you know a guy with a lathe. He’s near and dear to you. I bet he’d make you a sleeve to fit the 1/2 boring bars into a 3/4″ bore!”

So I turned down a piece of 3/4″ stock to just under 3/4″ OD, then drilled it out to 1/2″ ID, and broke all the edges and parted it off:

It’s a decent fit, plenty good to do the job:

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The way these tighten down is that the sleeve would have a slit cut along its length, and a hex screw pulls this thingamabobber (technical term) up and clamps everything together. The concern is that the sleeve has a 1/8″ wall thickness, no matter how tight I make it, it probably won’t deflect the sleeve enough to adequately hold the boring bar, which brings me back to my original problem of sub-optimal sketch factor.

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After consulting with some much more experienced fabricators, the recommendation came to essentially make a collet out of it (something like this). So I got to work and cut 8 opposing slits on the bandsaw. The slits aren’t perfect (…they were cut by hand on the bandsaw), but it gets plenty of bite on the shank of the tool now.

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I took advantage of having my brother in town this week for Christmas to do a bit more work on this. We cleaned up the shop a bit and re-organized the messy tools area to make room for the newcomer.

We also made a couple of risers with machine leveling feet to go under the feet on the lathe. With the feet and risers, it’s about 3″ taller. And with it being already top heavy, I made the feet a few inches wider than the machine’s feet to give it a wider footprint.

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We used the engine hoist to pick up each side to measure for the feet, and managed to find a good balance point to move it across to the other side of the garage. To get it turned to be along the wall, we just used a 2×8 under the lathe bed and muscled it into position.

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And finally, I made a couple of parts for the race car! A pair of steering-rack stops to keep the 10″ wheels and tires from ramming into rubbed the front sway bar at full lock. It’s *usually* just a concern in paddock and grid, but: with the power steering and the faster rack, I really want to make sure we’re not smashing hard parts together.

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I got a nice, snug fit on the rack. It’s not really STRICTLY necessary, but I do like knowing it won’t be moving around much:

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As with any good project, there’s plenty left that I want to do to / for it, but this was a huge chunk of work to make this into a useful tool. I’m really stoked to get a bunch more trigger time on the machine.

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