Making a Mini Metal Lathe

March 2020

I have a great old Logan lathe with a 10" swing. It's spring and I decided to clean it up and organize the lathe tools. I also had to rip out old wiring, probably the orignal 1942 wires. I rewired it and it's ready to go. Here is a video of me cleaning the old lathe and chip tray:

https://www.youtube.com/watch?v=fqe-I-wz5zw

I have a small work area in the attic and have wanted a small lathe to work on small projects like clock repair. I would like to test the old adage, if you have a lathe, you can build a lathe.

So here I go. First I decided on the size, somewhere between an old Unimat and a 7x10 mini metal lathe. Any big stuff or thread cutting I can do on the Logan. A simple small benchtop lathe for the attic is what I want. Here is a website offering ancient plans for making lathes:

https://www.vintageprojects.com/lathe-milling-plans.html

I chose the model maker's lathe as a starting point, here:

https://www.vintageprojects.com/machine-shop/lathe-modelling.html

I always try to use to use what I have lying around. I cut two 26" long, straight pieces of 1x1" angle iron for the ways. I cut some pieces of 1/4" flat iron bar for spacers, welded them to one piece of angle iron. Then I clamped the two pieces of angle iron to a straight piece of 2" square tube iron, to ensure straight, flat ways. Ready to weld:

Ready to sand:

The ways look flat...

... but I thought it wouldn't hurt to sand the tops and edges. I put a big piece of sand paper on the flat band saw table and hand sanded the ways and edges until I got tired of doing that, maybe 10 minutes, maybe less:

The sanded ways:

I welded pieces of C-channel to each end for feet:

Here is one end:

I picked out some bearings from Fazzio's, ended up using the pillow block bearings, even though they were slightly different sizes:

I used the old power hacksaw to cut off a piece of angle iron from the scrap bin:

I drilled holes to mount the bearings. Here is an early test fit:

I drilled and filed a center hole in the anle iron until it was slightly larger than the bearing ID. Almost there:

I cut a piece of 1" CRS rod, started turning it to fit in the bigger bearing:

Fits a little too well... that is, it is a slip fit as opposed to a press fit. My lathe skills need improving in many ways:

I brushed up on my tool sharpening skills by watching This Old Tony and other lathe enthusiasts. You can see the difference between a dull or improperly sharpened tool on the left and a sharper tool on the right:

Here is an old pulley from my "old pulley" drawer. I flattened the shaft, then drilled a dimple for a set screw, trying stuff out:

Another test fit:

This is one of the few parts I had to buy, a no-name 3" 3-jaw chuck from China, $45 on ebay:

I cut a disc of iron out of iron scrap to become a back plate for the chuck. Here I bore a hole in the center so it will be more or less centered on the spindle I turned on the lathe:

I determined the approximate location of the mounting holes by tapping on the chuck while its pointy mounting screws were touching the plate:

test fit while drilling the holes...

Plate drilled:

I tack welded the plate to the spindle:

Test fit, seems OK:

Plate welded:

Cleaning weld spatter:

 

Try it on the headstock:

Drilling holes to mount the bearing bracket:

Aligning headstock:

Sewing machine motor and motor mount, test run!

OK. it looks like a lathe. There are two fatal errors which do not show in these pics. One, the spindle is slightly out of round. It is nearly impossible to correct this problem. Two, the back plate is not cut accurately enough to correctly center the chuck reliably. Further research suggests that this type of chuck requires a backplate with a raised "boss" onto which the chuck is centered.

Back to the drawing board. I am not discouraged. I am enlightened. OK, first I was discouraged, now I am enlightened. Here is a new drawing of a new spindle with the old spindle below:

I rough cut a thicker piece of iron for the new back plate since it will have a raised "boss" for the chuck:

The rough edge, ground with the bench grinder:

To prevent a wobbly spindle, I decided to try a technique recommended for long straight shafts (live and learn): turning between centers. This method requires drilling a center hole on each end with a center drill, then holding the piece between a center in the chuck, and a live center in the tailstock:

The L-shaped clamp is a lathe dog. It is clamped to the rod and is driven by one of the jaws of the chuck.

Cutting, chips flying: