Bob Eckstein’s Vortex Cold Air Gun

Bob says:

I have recently made several small vortex tubes which provide a stream of cold air that can be directed at cutting heads, lathe tooling etc. where you may not want to use a flowing liquid or spray for purposes of lubrication and/or cooling. The exit air is much colder than can be obtained by adiabatic expansion through a simple orifice. The model shown uses a little under 4 cfm. @ 90 psi. Depending on your source of compressed air, you can attach any of a variety or adapters to the inlet tube by way of compression fittings, solder, etc. Commercially available vortex tubes are pretty expensive, and this one is under $25.00 ( less if you raid the junk box ) The inlet tube is 1/8 brass tubing with an insert of 1/16 tubing sweat soldered inside it. The nozzle is protruding 1/16 tubing cut at a 30 degree angle. The solder I use is a 4% silver bearing alloy. The brass tubing may be found in craft / hobby supply shops ( K&S product ). Bob Eckstein

Bob Eckstein's Handwheels

Bob Eckstein sent pics of his latest mod:

I thought you might like to see a very simple way I found to improve the readability of the scales on Taig lathe handwheels. The diameter of the wheels is approximately 31.46 mm. giving a circumference of 98.85. With the additional thickness of a sheet of good quality paper, the circumference is exactly 100 mm.
I used an open-source graph printing program to print 2 mm gradations on the paper and then applied narrow strips to the handwheels on the cross slide and compound by moistening the paper in thin cyanoacrylate cement. This gave 50 divisions per revolution for a measured advance of 0.001 inch per division. Much more visible than the markings engraved in the metal.

Bob Eckstein's Motorized Taig Lathe Power Feed

Bob sent in his latest project, a motor drive for the Taig lathe power feed.

A few shots of the drive I made for the carriage on the lathe.

The original drive.

I made a little hand-held control box with instant forward / reverse switches.

The motor is used in a majority of HP DESKJET printers. They can be had in thrift stores for usually under $5.00. The whole project cost maybe $15.00.

The motor mount is an "L" of 3/32 brass silver soldered to a hinge.

The friction drive to the gearbox input pulley is via a couple O-rings on the plastic pulley of the motor shaft.

Bob Eckstein's Taig Lathe

Bob Eckstein sent in these pics of his lathe:

It took a bit longer than I had expected, but the Taig lathe is now a going concern.

The tailstock as delivered was a collection of sharp jagged edges. Judicious use of a fine file cleaned up the extrusions and made it a lot more pleasant to deal with. The motion of the ram was somewhat rough and uneven but a session with lapping compound took care of it. The handle is made of layers of CORIAN plastic laminated with epoxy and carved to shape. The knobs are from the hardware store, 10-32 thread. The chuck is a Craftsman keyless 3/8"

I didn't have a boring bar to use in truing the lathe jaws, and a carbide lathe bit made a real mess of it, so I took a cylindrical solid carbide milling cutter and placed it in the drilling tailstock. I closed the chuck very gently until there was the slightest contact and turned it slowly by hand, then tightened it a little more and continued until the jaws had been cleaned up. The milling cutter was small enough that I could run it to the back of the jaws and avoid having to remove them to file off the "lip". The whole process went very quickly. There is still a little run-out but far less than what the chuck had as delivered.

The motor is a 46 volt DC unit. Power supply is a 5 amp Variac with a full-wave rectifier. The motor has a 1/4" shaft and I found the perfect adapter to use the 1/2" pulley: It's a chuck sleeve for Hitachi routers to use 1/4" bits in a 1/2" router chuck. The Hitachi part number is 956-927Z, Model TR-12.


Variac

The little clamp is used to lock the handwheel on the carriage so you don't have to hold it to use the power feed. By the way, the power feed advances the carriage approximately .003 per revolution of the input pulley.