Re: I slotted my 1256B variac core, now...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Mark Broker" <mbroker-at-thegeekgroup-dot-org> 

How are you clamping the laminations together?  A couple nuts and bolts?

Adding even a very narrow air gap should virtually eliminate the chance of 
saturation.

A friend went through several SawzAll blades before taking it to a machine 
shop, who I guess also went through a good bandsaw blade.  I have since 
mused about mounting a 3-stack on a "good-sized" vertical end mill and 
using a 1/2" cutter to make a gap.  But then we got a dedicated reactive 
ballast that limits the 240V line to 80A (so that was a 19kVA Jacobs Ladder 
for those who attended our event last weekend!), and we lost the desire to 
slice variacs.

Mark Broker
Chief Engineer, The Geek Group


On Wed, 03 Nov 2004 20:47:58 -0700, Tesla list <tesla-at-pupman-dot-com> wrote:

>Original poster: "Terry Oxandale" <toxandale-at-cei-dot-net>
>
>
>Today I undertook the painful venture of slotting my variac core to reduce
>the tendency to saturate when used to vary inductive ballasting. After
>searching the archives I was unable to find any reference to a recommended
>width of the gap that now exists in the core. Is the width of this gap
>critically important, or just the fact that one has been created? Currently
>the gap is about .060" (the width of the blade used to cut it) and as has
>been mentioned many times, it is a coiled band of strap that is straining at
>the clamps wanting to bust open. Should I widen this gap some, or will this
>be sufficient.
>
>Thanks,
>
>Un-Terry
>
>
>