Hello Morgan,
Cool! I'm down in Guilford -- used to live in Burlington many years ago. Then took off on a homebuilt houseboat to travel down the coast for about ten years. I haven't used my Gingery lathe for a few years (nor done much machining or casting until this Fall) because everything has been in storage while I built a house. I'm remedying that now, and hope to have a real shop and casting facilities as soon as I can build them this Spring. Right now the work on machines is pretty much determined by the weather -- this last 2 foot snowfall and the week of subzero weather before it slowed me down some! Furnace is buried, etc.
Re the 4 jaw and 3 jaw chucks -- they are quite different in purpose. I always wanted to build the Gingery 4 jaw chuck, but quite frankly, now that I own one for my Craftsman/Atlas lathe, I don't particularly like them! As you probably know by now, with a Gingery lathe you get a lot of experience with the faceplate, plus a lot of fixtures built up and methods to do pretty much the same kinds of things on the faceplate that you would with a 4 jaw chuck. I actually find it easier to adjust a workpiece on the faceplate than I do with the 4 jaw chuck!
Maybe that's just me and I need to learn better techniques with the 4 jaw. But man, adjusting 4 screws with an Allen wrench, constantly rotating the chuck back and forth, trying to estimate how much to loosen one screw while tightening another, and preventing the piece from falling out at the same time is painful! I'm sure someone here can write a whole treatise on using the 4 jaw, and how to make it easy to do that. Please do!!!
A case in point was last week when I was drilling and boring the head valve hole for my 4 cycle conversion. I could never have done that with the 4 jaw -- the casting was too wide. Piece of cake with the faceplate and an angle plate and a few bolts. Tap it a few times with a soft hammer to position it. Check with indicator. Done. I think a part firmly bolted to a faceplate is far more secure than that held by the jaws (fingers really) of a 4 jaw chuck. There is also less overhang, since the faceplate is thinner, usually.
And when I took the faceplate off (with work attached) to switch to the four jaw to try to drill a hole lengthwise in some 3/8" keystock (while making my new boring bar holder) I spent several minutes screwing all 4 jaws in only to find they wouldn't grip anything as small as 3/8"!!!!!
They only close to 1/2". I finally drilled the piece in the drill press.
Finally, you can turn bigger work on the faceplate than you can a 4 jaw (assuming you have a full size face plate).
Now a 3 jaw is very different, and quite convenient. Generally it is for round work (though there ways of gripping square work inside a split collar), and has only one adjuster. So it's a nice additional capability to the faceplate.
So I would go with the 3 jaw as a purchase, and complete the 4 jaw Gingery as a point of interest, if I were you.
Now one thing I will get to in my Gingery lathe thread is that of coming round to the idea of fixtures cast onto interchangeable arbors, rather than keeping a single arbor on the lathe and changing attachments on it.
When I mounted a 3 jaw, I cast the backplate permanently onto an arbor. This made it very simple to true (and keep the chuck true after re-mounting), as opposed to other mounting methods -- at least on something with as small an arbor diameter as the Gingery. It also meant that I had the minimal overhang possible for the 3 jaw chuck mount. The big problem with a 3 jaw is the increased chatter you get in a small lathe because of the extra overhang of the chuck and backplate combination. That can add 3 to 4 inches to the overhang.
To make my style mount, Just take a piece of arbor rod, groove up the end -- maybe even tap in some screws as grips for the casting, and cast your backplate onto that. Mount it in the lathe and turn and face the backplate to suit the chuck. Then bolt the chuck on and indicate it true before tightening the bolts. Get a simple bolt on type chuck, not the fancy proprietary mount types. All that stuff will add to overhang, and is more expensive.
And get the thinnest chuck you can find, you will be able to take deeper cuts without chatter. Well anyway -- that's what worked for me.
Beautiful day today -- sunny and we might hit 50. Must machine.........
