Summer project - new mill

I picked up this little knee mill last spring, and have spent the summer rebuilding it. As near as I can determine, it's a 1984 Enco 6x26 vertical knee mill, made in Taiwan. The overhaul  consisted of a full disassembly, replacing every bearing, many of the bolts and nuts, turning a 6" riser block to raise the head and installing an Arduino-based TouchDRO digital readout. It weighs about 600lbs (I brought it home in my Subaru!) and has a 1.5hp reversible motor that'll run at 120 or 240. (That's true 1.5hp, it pulls 18 amps on 120V.) There's still some work to do, but it's operational now. It's a great match in size and functionality for my 9" South Bend lathe. More to come...

Cherry tables

A couple of cherry side tables.

Finished tables

Specs:
Overall height: 28"
Top: 18" x 18"
Apron width: 14"
Apron height: 4"
Legs: 1.25" taper to .75"

The legs are mortised with 3/8" tenons and pinned with 1/4" dowels. 3/4" thick top, edged glued from 3 boards, hand planed and scraped flat. The bottom side of the top has 1/4" deep, by 2" long bevel, leaving a 1/2" thick edge. Finish is a seal coat of thinned shellac topped with  multiple coats of danish oil. The top surface was wet-sanded with 320 grit and oil to fill grain pores.

Some photos:

Many shavings

Pinned mortises

Attaching the top

Lathe DRO Installation

Finally decided to add a DRO to the old South Bend Lathe. When looking for info on how to add digital scales to a '40s era lathe, I didn't find much, so I thought I'd share what I came up with. The inexpensive digital scales I chose are not terribly accurate, but they're good enough for the majority of the work I do. 

The X axis was fairly straightforward: there's room on the back of the lathe to hang the scale. The Y axis was more challenging: tight clearances on the carriage led to mounting the crossfeed scale behind the carriage. Fortunately, on this SB with the rear-mounted countershaft/motor assembly there was room behind the lathe. 

 

Cheap but decent digital scales

Aluminum angle bolted to the tapped holes for the taper
attachment I don't own.

1/8" aluminum  extension bolted to the crossfeed carriage. The side
of the crossfeed casting was milled flat and holes were tapped
in the cast iron.

X axis hanger clamped to the rear ways.

X axis scale attached to y axis aluminum angle

New CNC

A new CNC has been taking shape in my shop over the last several months. It's a major rebuild of my previous router-lathe that adds another axis of movement and a lot more capability. I kept quiet about it until it was actually running because the design is a little unusual and I wasn't entirely sure if it was going to work -- I wanted to avoid having to say "that new machine I'm building? umm, never mind...".

It's still under construction, but far enough along that I can use it to make parts for itself.

Configured for flat work

Configured for 4th axis (lathe)

It's basically a standard 3-axis router built around an old 11" x 36" wood lathe. It has two configurations: a 3 axis router, or remove the table to access the lathe for 4th axis work. As with previous projects, most of the design work was done in Sketchup before and during construction.

Configured for rotary work on the lathe

With the table installed for flat work.

Here are the first cuts:

 

Rotary axis test.

The rotary axis (lathe) drive. 16:1 ratio -- kevlar belts.

Detail of the bearings on the gantry sides

Fabricated lathe bed and side rails

New Bowls

Some hand-turned and CNC machined bowls.

Redwood burl. About 11"

12" cherry dyed black

5.5" mystery wood, dyed green

5.5" mystery wood, dyed black

Walnut spiral. 6.5", CNC

5" walnut, CNC

10" red cherry

Wind wave sculpture

I'm working with friend on a wind-powered kinetic sculpture. This is a half-scale model out of wood to verify the mechanics.

And here's a road test with the sail attached. I'm calling out engine RPM to estimate speed because the speedometer is not very accurate at low speeds. 1900 rpm equals somewhere between 9 & 10 mph.

This test provided great information about how it behaves in the wind. We're going to try less offset on the crankarm and reduce the amount of travel in the rods. Oh, and make it stronger, too.

Router lathe – upgrades and wood sign

Router lathe – upgrades and wood sign.

Here's a wood sign I made for a friend's woodworking shop, Artsubstrates. This is the first time I've wrapped a 3D shape around the rotary axis. It worked better than expected.

 

(note: from here on is going to be pretty dull for anyone not building a cnc machine. ...and maybe for those who do, as well.)

I generated the text using "FEngrave" a great piece of software for generating gcode for signs. It does one thing and does it very well. Highly recommended. Then I used another piece of software to take the output from FEngrave and wrap it around the rotary axis.

Recent upgrades:

Some upgrades were required to convert from arduino 2 axis control to 3 axis CNC. Added was new z  axis assembly with stepper motor and controller, new belts and pulleys on the rotary axis to increase the gear ratio, and limit switches on the linear axes.

New Z axis assembly with motor.

The new Z axis assembly has 3/8" aluminum plate for the base and the carriage platform, 5/8" O1 tool steel rods for rails and UHMW bearings to slide on. I made another UHMW nut and used the acme threaded rod left over from the X axis. I'll have to re-think the UHMW bearing though -- they slide really smoothly by themselves but take a lot of adjustment to get the carriage to slide without binding with all 4 attached.

Limit switches on Z axis

Motor and switch wiring

Showing the limit switches and motor wiring on the Z axis. I used ethernet cable and jacks for the limit switches, and heavier 22g wire for the motor.

New rotary axis belts

 The big automobile timing belt and diy pulley were replaced two XL timing belts and pulleys. increases the motor/ axis ratio from the previous 4:1 to 16:1. This provides a lot more holding power against the router and gives smoother rotary axis travel and much finer resolution. With the old belt, there was more backlash that I liked and at larger diameters, one step on the motor translated into as much as .003" of travel. With the new belts and gear reduction, resolution at large diameters is still very fine and I see less chatter during heavy cuts.

The current belts are neoprene with polyester fibers, which do stretch a little and is more noticeable with the double gear reduction. I purchased new belts with kevlar fibers that have very little stretch, but haven't installed them yet.

All this is because these 285 oz/in motors are OK for the two linear axis, but a bit puny for the rotary axis. A motor upgrade on the rotary axis may be in order, but would require a bigger power supply and new controller as well -- not in the current budget.

 

Wiring to the electronics enclosure. 5 pin XLR connectors with 22g stranded cable for the motors and ethernet cable and jacks for the limit switches and e-stop button. There's a vented cover for this enclosure, but after an overheating incident where the cooling fan lost power and the controllers started making real funny noises and smelling bad, I don't have the courage to close it up yet. I'm thinking of putting in a temperature monitor, but that may be overkill.

< Router lathe -- converted to CNC