Furnace Failure again, What a day

The plan was to pour new pulleys for the master mill.  Put the cruciable in the furnace.   Started to ram up the mold then realized the flask was to shallow to do it as I wanted.  So I made a flask extension.











Then I noticed the furnace/oven was not heating.   The coil repair, weld had burned away.  It was not just the weld point but the most of the exposed wire around the weld. Hmm 



I pulled the heating elements, ceramic plates.  This time I am trying a small screw to hold the wires together.




About now I noticed one of my DIY bricks had disintegrated!  It  came out whole but was clearly comprimised.  It did not take much to crumble it.

Needless to say this was disapointing. An OH SHIT moment even!   But I realized that the brick that died was an early brick, one without lime put it as a test.  Sheesh.

This brick was a bit short and I had filled in the area above it with the mix including lime but not perlite.  It looks very sound.  In fact so much so that I am starting to think that the perlite is a bad deal.  Yeah I know it insulates.   But maybe on an electric over where you need groves for the coils it should be emitted from that layer of refractory.



I recently learned that adding larger particles to a mix reduces its fluidity.  So you need a higher ratio of cement because you need to coat these, larger particles.  So I am wondering if maybe I should up the cement ratio in my mix.  Well thats what experimenting is all about.

The UPS man delived a tub of Rutland 601.  It only needs one day to air dry.  So I maybe using that.

Foundry furnace burner.

Opted to build a naturally aspirated burner along the style of a Reil.

Tip.
I used to make PCBs and have a good number of .030" carbide drills.  It is very difficult to drill steel with these.   A small hole was drilled in a 1/8" cap.  The hole was soldered shut and drill with the PCB bit.   While not as fast a change as mig tips it is not all that hard to resize the hole.




Input flare.
Lost foam casting was used to make the flare.  Several Styrofoam cups were stacked to approximate the shape. 

 

 The casting was drilled to take the 3/4" pipe which threaded into the unthreaded drill hole.   The inside and outside shape were refined on the lathe.

The burner is running rich.  I may replace the 1/8" pipe cap with something that does not block so much air.  It is defeating the cone.

Tub Muller cylinder cut to size.

It was a bit too cold to run the lathe today so I cut down the tank I plan to use for the sand muller.  I made the sides 15" tall and the tank is 30" in diameter. 

If I mount it on the frame I have repurposed the top of the tub will be at 43".

Need to remove the legs and cut a trap door to remove the sand.  Need to research this.  Recall someone had a slide door that did not bet fouled by the sand.

The double worm reduction I found earlier.  150:1 so a 3450 RPM motor will result in 22 RPM.  Still thinking about using a garden tractor variable speed between the motor and the gearbox so I can use a 1725 motor and dial in the speed. Just thinking.

Also have the 23" x 1.5" shaft with bearings but it maybe too short.