Homemade Lathe Part 4

Homemade Lathe Part 4

Carriage Assembly and Ball Crank

This is the carriage base that will travel the full length of the bed. As always it has started off as a rough chunk of 2 " thick construction foam.

After much fiddling with the Drill press and router bit and various fence arrangements, I have an arrangement that can be easily adjusted and offers a flexible work space.

The key factors are 2 (two) sides that meet at as close to 90 degrees as possible. These become the reference faces that ensure that all subsequent faces are either parallel or perpendicular.

The channel that runs through the center is where the lead screw will turn into from a tapped 3/8ths #16 thread. Nearly all threaded rods will be 3/8th with a #16 thread pitch. This rod is heavy enough for the bed, carriage, compound and tailstock lead screws, and common enough at Canadian Tire. It also matches a Die and Tap that I already own.

This is the bed-side of the carriage base, the dark section are the wearpads after testing for fit.

A 1/4" has been allowed for a brass shim that can be adjusted for smooth movement along the bed.

As you may have guessed this is a close approximation of Dave Gingery's design. I have a debt of gratitude to Gingery for writing the Metal Shop from Scrap series, as I doubt I would ever have been exposed to such a rewarding hobby as this.

The Bed ways are at exactly 90 degrees to the cross-slide on the top.

This a 3/16ths piece of 3" wided stainless steel that will form the bed that the cross-slide will ride upon.

This material was readily available, and only selected because it was. I will have to scrape down the edges for smoother motion, as it's a bit rough like a shear cut.

If I was buying metal for this purpose, I definitely would have gone with 1/4" as this piece will pose problems with edge shims and adjustment screws.

The cross-slide is designed for approximately 7" of travel.

The donut shape is for a swivel base that will have a bed for a compound slide. This piece will have to have it's matching insert created before it is cast to ensure an accurate fit.

Another piece out of the way...

Unfortunately these pictures are short on detail due to the lighting.

I picked-up some foam spheres at the local Dollar Store, 6 for a dollar, then cut and fit a couple of foam connectors. I did want to have brass handles, but didn't want to start getting to brass yet.

I thought that a nice touch would be to use a couple of spent Winchest 32 Special cartridges for handles. the primer is drilled out so the handles will fill with metal and be solid.

One large 2" sprue feeds 3 distinct runners that were pinned to the top of each sphere.

This was one of the pieces that i thought would force me to get into cavity casting into molded sand. Obviously I've dodged that bullet yet again, and gained even more confidence in Lost Foam Casting.

The center shaft is a 1/2" diameter piece of stainless steel pipe with a 3/8ths inner diameter. I lucked into 6 ft of this super high quality tubing from Sandvik steel. It wasn't up to the strict standard required for nuclear reactor parts and was scrapped.

I also have the matching 1/2" inner Dia, 9/16ths outer Dia tubing for making very smooth journals or bearings. Seriously, this tubing is so finely finished when the tubes turn inside each other their like precision roller bearings.

Everything seems to have cleaned-up nicely. The cartridges did fill-up completely with metal and seem to be quite sturdy.

I think this is more of a proof of concept than a finished piece. I suspect that the center shaft really should be totally embed through the center sphere. The handles also should have been embedded further for more strength.

Also I'd like a variety of sphere sizes for single handled ball cranks.

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