Base, Magnet and Column

The final base will be built with the electromagnet.  For now, a simple aluminum disc will be used.  The column shaft is .750" drill rod, instead of the .500" that Jerry specified.  As mentioned elsewhere I am up scaling the machine.

The clamping method was a bit exotic IMHO, but was reproduced faithfully because it looked so darned neat.

Finished Base Assembly

The first step was to face the 6" aluminum disc that I had sliced at AZ Metals in Mesa.  The next step was to drill then ream to fit the column hole (0.750").

After this, the two holes at the future ends of the slot were drilled.  Mounting the disc vertically in the milling vice, I then cut the countersink for the Allen bolts.  Then I drilled for the threads.  I marked off the saw cuts and cut them using my vertical metal band saw that I made from an old cast off harbor Freight horizontal band saw.  The end results are above.

added 7/26/2016

Electro Magnet Assembly

I elected to add the electro-magnet as this makes using the tool maker's vices much easier.  I ordered the needed wire from Amazon, though it turned out that I could actually get the Magnet Wire at Fry's Electronics

The first step is to make the spool to wind the coil on.  I found a round bar of black plastic in the hoard and proceeded to machine the spool.  I think i like turning aluminum better than plastic.

Coil Spool

Building the stuff to wind the coils...

Winding hub parts

I cut three discs from 1/4" hardboard, one of them was cut to 11.459" diameter to be used as the center and the other two to 12.500" for the sides. The wire is wound on the carefully measured center of the hub assembly. 

π is our friend and π*diameter yielded a single turn being exactly 36".  Earla kept track and we wound 47 turns onto the hub.


Winder and supply spool

Here is the setup used to measure out the 140 feet of magnet wire.  The supply spool is positioned on a 3/4" copper pipe union and two pieces of sticky back 1/4" weather stripping put a slight drag on the spool.  This drag keeps the wire taught while winding.  The friction of the wooden hub was also set to prevent any loss of tension.  If you stopped cranking (note the cool handle) the wire would stay taught.  It was straight forward and easy to wind off the wire.  I did the winding and paid attention to the wrap and tension while Earla kept track of the amount of wire.  I am almost absolutely positive I would have lost count trying to do it all by myself.

The next step was to wind the measured wire off of the wooden hub onto the magnet's coil spool.  I used a spindex with an expanding collet to hold the coil spool.  The wire was wound off the hub, onto  the coil spool.  The windings came out pretty good, next time I would wear my Opti Visor magnifier so I could get the windings real even. 

Here's a
video of the winding taking place.


Completed coil and bobbin

Here is the completed coil after wrapping it with a narrow strip of Rescue Tape.  The time spent cutting and gluing up the measuring hub more than paid off with the finished part.  It took about an hour to build the hub (plus gluing time) and about 15 minutes to measure the wire and wind the coil.

I cut a new slot so both leads came out at the same place and finished the coil.  Plans called for about 18Ω and I was at 19.9Ω.  Playing with the magnet, the grip was a bit weak, I got out my lab power supply and started cranking up the voltage.  At 9 Volts it is drawing right around an amp and tops out at 145° after running about 1/2 hour.


Core & Bobbin

I turned a piece of steel to make the magnet core.  Here the coil is test fit on the core.  I will machine a groove for the coil wiring next.

added 8/7/2016