Dia. Mag. Alternator

[z.monkey]

OK, now I am starting the fabrication of DiaMag7-2.  This plate is literally a piece of scrap I pulled off some discarded computer equipment.  It is 3/32 (0.09375) inch thick, about 3.2 inches tall and 10.3 inches wide.  What I need for DiaMag7-2 are two, three inch square end plates.  You can see in the pic below I have the outlines defined for both plates, but only one is marked with the remaining cuts.  I only mark one plate because they will be stacked in process.  Also the slots are just lines, and not detailed.  This is because the end mill will define the sides of the slot, and we only need to follow the center line with the end mill...

The process goes in a structured order so that in the end all the holes will be precisely aligned.  First thing is spotting the two center holes.  Everything else literally revolves around the center holes.  Then we will cutout the outlines.  Once the plates are freed then we can finish cut the center holes to 3/8", the size of my center clamp bolt.  We will also need a sacrificial block, with a 3/8 inch center hole.  Then we will stack the plates up, setup the center clamp, align the plates, and lock the table clamps.  Spotting the four corner mounting holes is next.  Then we will take the stack apart and prepare the stack for the actual cutting process.

I'm cutting on the Palmgren Table this time and not the Rotary Table.  I get much better results on the Palmgren Table.  This time I am using the four corner mounting holes to hold the stack together.  I'll drill the four corner mounting holes to 1/4 inch, and countersink the back of the sacrificial block.  The short, maybe 1/2 inch long, stack bolts will sit inside the sacrificial block so that the stack is free to rotate about the center clamp.  Then I'll use the table clamps on both sides of the stack.  I am hoping that I can actually finish mill the slots this time and not have to file down each slot.

Finish milling the slots takes more time, but with the Palmgren Table I think I can do it.  It was just not possible on the Bitmoore Vise with the Rotary Table.  So this process starts like the other milling I have done, a set of overlapping vertical mill cuts.  Then I'll run the mill down in entire slot as though I were side milling.  I am hoping that this will take off all the scallops, and leave a nice finish.  I may increase the spindle speed of the drill press to improve the end finish of the slots.  Now that I have the slot liners I want improve this process to make it more efficient.  It took a whole Saturday to mill the DiaMag7 plates.  I want to make this next set faster...

[z.monkey]

Well, made a little change.  Decided to do the outline first, and then spot the center hole.  This lets me punch the center hole through all three pieces simultaneously.  When I get back to my Mini-Mill all I have to do is set the stack one the table, align the stack, lock the clamps, and start spotting.  Is it the weekend yet?

[z.monkey]

Got the DiaMag7-2 Plate spotted and ready to cut...

[z.monkey]

A note about efficiency...

Lets look at the power required to run the Dremmel.  Rated at 120 Volts, and it boasts 1.15 Amps on the label.  That is 138 Watts.  In the last test, with the new load, the DiaMag7 put out 13.86 Watts.  A little better than 10 percent.  Is this right?  Yeah, its the rotor physics.  The monolithic magnet has a natural flux field, and as it turns out a natural flux field is not very efficient.  We need to increase the pole surface area, and add more poles to kick the efficiency up.  The NeoMag8, with 8 poles and maximum pole surface area will do this.  I do still want to build DiaMag7-2 anyway, with a different coil configuration, just to have a little more empirical proof that this is the rotor physics.  The rotor is key to the whole device.  Mo betta rotor, mo betta efficiency.  Looks at it the way Spicoli would...

If you want bodacious output, like, you gotta have a schweet rotor, man...

The poles of the monolithic magnet in the DiaMag7 are only an estimated 16 percent of the surface area of the magnet.  The NeoMag8 magnets have 100 percent of the surface area covered with poles.  Do you see a bit more efficiency there?  I am chomping at the bit to get NeoMag8 into fabrication, but I really need to spend some more time gathering data first...  I know, boring, but its the scientific process, and I want a lot of data to support my endeavor...

Also, now that I am starting to measure efficiency, I am starting to build an efficiency testing jig.  I scrounged up a 10 Ohm Rheostat.  Also I have a 12 Volt motor, was the driver for the Bicycle Wheel Alternator.  Then got a 12 Volt, 7 Amp hour SLAB (Sealed Lead Acid Battery) to drive the motor.  I'll add test points for measuring Voltage and Current.  Then I can measure efficiency over a range of power levels and speeds.  I may wind up getting a bench power supply, just so I can play with the Voltage and the Current.  Then I feel that I should be able to get more accurate efficiency numbers.

If we look at the efficiency from the Dremmel test and apply it to the hand drill test (1400 RPM) then the hand drill is putting out about 5 Watts, the DiaMag7 output numbers were around half a Watt...

[z.monkey]

Shredding...

The most fun that I can have is shredding metal...

I am experimenting with finer cuts, smaller increments.  Before I was cutting the next cut more than half diameter of the mill.  Now I am only moving the cut over one quarter of the way over.  This puts the circles closer together, and reduces the scallops.  this is how I have to do the round parts now.  There are still scallops, but smaller, easier to smooth...

On the slots I am using the same method, but afterward I run the mill down the slot like a side cut.  This smooths out the scallops and leaves a nice finish.  Starting to feel Zen with the Mini-Mill...

I'm scoping out a Rotary Cross Slide Table.  It will make the round cuts pretty, like the slots...