Selected Projects

done for myself, for fun

Below are some of the design/build projects that I've done, just for myself.   Some of my more 'official' projects can be found on my projects for work page.  Questions welcome -- 

Lathe mostly in pieces, after a lot of cleaning and reassembly of the carriage. 

Lathe stand, in progress.  Brazing is fun, somewhat like painting, but slow going with all the prep and cleanup.  

Headstock reassembled with replacement spindle and new belt and bearings.  The stock spindle (right) has a strangely undersized 1/2-8 thread -- likely a "price point" decision as Powermatic also sold an 11" lathe w/ the larger spindle.  I replaced it with a 2 1/4-8 thread spindle from a Logan, giving a larger through hole, greater stiffness, and allowing use of 5C collets. 

Lathe completed on stand.   Leadscrew is driven by variable speed DC motor, gearbox, and belt drive on right.  

See the Shop page for more pictures of the lathe. 

Logan/Powermatic 11x24 Metal Lathe
2004 - 2005

As the saying goes, "if only I had a lathe...", so I finally bought one.  This lathe came from a school and it showed (low use, high abuse).  

I brazed a tubular steel stand for it. "Lightweight" (~500 lb) lathes like Southbend, Logan, and Atlas have some torsional flexibility in their beds, which can contribute to chatter.  This surprised me at first--it's a hefty piece of cast iron--but looking closer at the bed, it makes sense:  the bed cross-section is basically two mirrored and inverted "L" sections connected by a number of lateral stiffeners.  The stiffeners look massive, but since they are straight across and not diagonalized (zig-zag), the "L" sections between them are still torsionally flexible.

So, I used 4x4 square tube for the main rails to give the bed a torsionally stiff foundation. 

I powered it with a 2.5HP DC motor from a broken treadmill, controlled by a Reliance MinPak Plus Regenerative (4 Quadrant) drive.  Being a regenerative drive, it allows reverse and spindle braking.  

The kiln reaching cone 6.  The top line shows the actual temp (in deg F), the bottom shows the programs target temp at this point in the firing.    

PID Controller for Pottery Kiln

After doing the PID controllers for the SATEC test machine, a pottery kiln was fairly straightforward.  I used a Partlow 1166 controller/profiler, and set the PID parameters using the simplified method.   Auto-tuning doesn't work so well for a kiln, since it has to go from room temp to 2200+ deg F.  I found that one set of PID params would work from 600F to top temp.  The 1166 controls a set of solid-state relays for the 240V current. A fan inside keeps it all cool.  

Pottery wheel and one of its "children."  Nothing fancy, just function.  Standard AC motor drives infinitely variable speed transmission, below.  Speed controlled by foot pedal and linkage.

Left side of pottery wheel showing linkage from foot pedal to Zero-max transmission, and belt drives.  Here is a closeup of the mechanicals. 

Pottery Wheel

Throwing is one of the most enjoyable activities I know, so I built a pottery wheel to be able to throw at home.  To keep the cost down I mainly used parts from the local metal recycling yard (motor, pulleys, main wheel bearing) and eBay (transmission).  A Ford Explorer front wheel hub and bearing carrier make up the main wheel bearing.  Pottery wheels are ideally infinitely-variable in speed adjustment from 0 to ~250RPM, which is done commercially by DC motors/drives or mechanical ring/cone transmissions.  I like the pedal feel of a mechanical transmission, and I found a Zero-max transmissions for $40 on eBay, so that was my choice.  Parts and materials ran about $90 total. 

It works quite well, though the Zeromax has more vibration than I would like.  If I were doing it over again for low cost I would probably use a DC motor/drive from a junk treadmill.  After using it for a while I wrote up some advice for anyone wanting to build their own.

Examples of my finished work are found on my Interests page.

As received and homely.

Porsche 914-6 Conversion

I wanted to keep my 911 (below) stock, but also wanted to build a track car.  So I bought a 4 cylinder 914 that had had an engine fire but was otherwise decent, and grafted in 911 engine, suspension, brakes, plus some structural reinforcements.  Fortunately I had the '72 911E engine from my 911 which needed a new home.  In the lighter 914 it did 0-60 in a little less than 6 seconds.  And yes, a midengined car does handle a lot better than a rear engined one, but when it spins, it spins a lot faster.  Um... theoretically speaking, of course.  I sold it, along with the 911, when I went to grad school. But that owner still drives it today.

'73.5 911T awaiting the '72E engine.  If only it went in in that orientation!

Here's Jay O'Connell, lending a hand with the engine.

Finished, and I even let my Dad drive it!

Porsche 911 Engine Rebuild

I bought this '73.5 911T with the engine out of it and half-apart, needing a valve job.  First put in a '72 E engine to get it going, with help from Jay O'Connell (below).  Then after a while I rebuilt the original engine and swapped motors.  The '72E motor went into the 914, above.

Bicycle Disc Wheel

Disc wheels were the hot item back then, so I built a few for fun.  The first was Kevlar/epoxy with some carbon fiber, but it turned out out-of-true.  For the second, pictured, I added a few spokes to keep the rim true while the epoxy cured, and it turned out quite well.  I did some testing which seemed to show it was a little faster on downhills.