I finally got a mini metal lathe, as well as a new mill. I really wanted a used 10x toolroom lathe, and searched on and off for one for about 4 years now. But after getting realistic about the expense of shipping an industrial lathe from somewhere in the Rust Belt, how worn-out a machine in this class and my price range would probably be, rewiring my shop to use a 3 phase machine, and insulating and heating the shop to protect such an investment, I finally just bought some new import machines that will run on my shop’s 120v/20A circuits.
I feared that the 7×16 mini lathe would be more or less a toy, but it’s not that bad. It has a brushless DC motor with a lot of low end torque, can easily take a .03″ cut on stainless steel at low rpm. The spindle run out is pretty decent at .0008″. But the cross slide, compound, and tailstock do seem pretty woeful out of the crate. I spent a lot of time taking it apart and cleaning everything and adjusting the gibs. I’m a rank plebeian with lathes, but it does seem like it has potential, so I’m looking forward to tinkering with it to see if it can be improved. I do wish I’d gotten at least an 8x lathe though, a nominal 7″ lathe seems to suggest you can handle some fairly large stock, but the cross slide travel is pretty minimal so it’s difficult to turn stock larger than 1.5″ in diameter between centers.
I’d planned to wait on a new mill, but with shipping costs being the same for one or two machines it made sense to get both at once. Glad I did, the mill is pretty impressive for under $1000. It also has a brushless DC motor that’s suspiciously quiet. The R8 spindle run out is only .0005″. The spindle is keyed, which may simplify making my own concentric tool holders and adapters on a less-than-precision lathe. It has decent XY table, 18″x 4.7″, a huge step up from my micro mill where I’d have to reposition the workpiece to finish any feature over 3.5″ long. The head column seat was pretty poorly machined though, the head was out of square to the table almost .0027″ at the high point of the far side of table. I surfaced a chunk of 4″ wide aluminum with a 2″ face mill and the step between passes was pretty bad. For now I just shimmed the column base and got it to within .001″ at the far end of the table. I’ll probably reset the column in epoxy at some point to embed the shims permanently and make the column more rigid. X and Y capacity are pretty generous, almost 12″ and 5″ respectively, and the head raises and lowers with a few spins of the drillpress-style quill wheel, so tool changing is quick and easy. The micro depth feed on the head needs some work, but the XY table ways are quite smooth and slop free. One disappointment about the mill is there’s no spindle reverse, but may be able to modify that without too much trouble.
After years of blowing fuses on the tiny micro mill, and having to spend a lot of time searching around online for stock knobs and other cylindrical parts, I’m pretty excited to put this new stuff to use. But I’m not very excited about keeping the dust and rust at bay. It’s a little tricky to have a combination woodworking and machine shop, especially in an unheated space with no dust collection. The next project will have to be getting some dust collection plumbed to the woodworking tools. For now I’ll just bag off the mill and lathe when ever I fire up the table saw, and coat them with some LPS2 for long spells between projects.
For my first project I wanted to make some knobs for the new 5×7, but ordered the wrong sized collet chuck for the lathe, so for now I modified the existing knobs. On the lathe I made an aluminum arbor to fit in an ER32 hex block, and drilled a bolt circle pattern on each knob on the new mill.
The knobs are 1″ diameter, and ER32 doesn’t accommodate that, so I made a stepped aluminum arbor that fits in a 11/16″ collet. It has a 1″ diameter sacrificial flange to support the high aspect ratio of the knob collar to hub and prevent drilling into the collet itself. The arbor was bored for the diameter of the knob’s hub, and then was slit along the length with a hacksaw to provide clamping pressure and for easier removal from the fixture after drilling. Setting up a registration stop for the collet block in the vise made pretty quick work of drilling 78 holes. (The hex collet block isn’t the highest quality- note the crown of the face that’s against the front jaw.)
Didn’t reduce the weight of the knobs by much, but the camera certainly looks much busier now. Oh well. I’ll probably keep these knobs for the base tilt on both standards and maybe the front swing, and make smaller knobs for the other movements. As it is, it can be tough to tell them apart when I’m under the darkcloth.