Gallery, Projects and General > Project Logs
Building a New Lathe
vtsteam:
Before I did make a new bar, I decided to cut down one of my 1/4" indexable turning tools (from a cheap set that I've never found replacement inserts for) to 1-1/2" long, and put it into the boring arbor.
Man what a difference! It really chews through the sand cast Zamak. Not a pretty cut, but I can take .030 off the diameter in a single pass, no sharpening, at twice the RPM and a decent feed. I was starting to get down about all the sharpening I needed with the HSS. Well, this is a job for carbide only. Obviously the insert and angles aren't ideal for a clean cut, but at least the end is in sight for this clearance bore. Phew!
vtsteam:
As I get closer to finished bore size, the extension of the tool bit has increased to the point where it's moving slightly despite the set screw. So today I hunted up an old piece of cast aluminum sprue, and turned and milled up a little boring head for my arbor, just a 0.1" smaller than the present bore.
This should make the next few cuts out to finished size a lot easier, and though it presently fits the 5/8" arbor, I can open it out for a 3/4" arbor later -- which will be necessary for doing the bearing recesses.
By starting with 5/8" I'm able to keep the tool bit a little longer inside the shell for better support, until the bore is larger and I can switch to a longer tool. And this time the tool is held by two set screws, so I don't think movement will be a problem... at least for awhile.
vtsteam:
It's working very well, much deeper cuts but necessarily slow feed. Otherwise the driven pulley slips. Since I can't fit a carbide tool in the small space, it also means I'm back to HSS, and frequent sharpening. But progress. :dremel:
This is probably unecessary at this point -- the spindle is about one and a quarter in diameter, and I'm nearing 2" on the clearance bore. But I had it in mind to make it to 2.125" and I haven't given up on that....for no apparent reason.
Homebrewer:
So, it looks sort of like you're using a fly cutter like tool, mounted on a mandrel.
I have been watching this thread with great interest because if I ever get out of this apartment and into a house, I plan to go through the Gingery book and build a lathe similar to yours. Following your thread has both given me ideas as well as validated some others that I'd give consideration.
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vtsteam:
Thanks very much Homebrewer. :beer:
Yes, I've made a few similar over the years -- the first was back 13 years ago when I was adding a milling attachment to the Gingery lathe -- I didn't have a milling machine then, so the fly cutter with an arbor mount, instead of the usual stub, was used to level a new milling and boring table:
https://madmodder.net/index.php/topic,8191.msg88064.html#msg88064
I personally think building a Gingery lathe is the best possible kind of machinist self-education, because you're really starting from scratch, and you are forced to use historical methods, hand work and ingenuity to get to the finished product. Buying a lathe is fun because you can get started right away, but it kind of short circuits that education. Turning and threading are all a lathe can teach you -- at least out of the box. There are probably fifty more things you learn building one from scratch.
For me, building that lathe led to many things, including wonderful employment opportunities, that I probably wouldn't have had otherwise. Also, it's incredibly rewarding to build it. In fact, no project I've ever built using that lathe equaled the thrill of building it in the first place.
You're on the right track if that appeals to you. I'll always be grateful to David Gingery for that little orange book I just happened to pick up one day.
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