Automotive Rear Upright/Wheel Carrier

Thanks for the likes fellas.

Yes. Trying to decide how frisky I want to get. T5.....easy. Something that approaches a T6 schedule....more risky. All I have is my 14" bore furnace with the resistive electric insert. The uprights are a bit awkward given their dimensions.




In the past for smaller parts in my smaller furnace, I shielded the parts from the radiant coils by placing them inside a can lined with a 1/4" of ceramic paper. For these larger parts, I'm thinking preheat the furnace and get all the surfaces up to as uniform of a temperature as possible and then hang part from the vent hole in the lid near the top and more importantly the temperature sensor. I'll use one of the development parts as a trial.

Best,
Kelly

 

Thanks Gary. My smaller furnace lift is similar, with a counterweight and electric actuator, but just has one post with a rolling carriage and cantilever mounted furnace body. My larger furnace hasn't gotten much use because the smaller one can handle an A20 and has thus far been able to handle all my castings. The larger one , can accommodate an A60 as shown below and I do have ambitions for several larger castings.



An A60 is a whole new ball game when it comes to handling molten metal....even aluminum. I built this trolley but will likely use a walking gantry to handle that molten mother when the time comes.



Best,
Kelly

 

Pretty close. My residential rate is 10c/kw-hr so about .80/hr to operate........at least when it is coming to temperature. When it's at or holding temperature like in heat treating, it's a small fraction of that because there is a duty cycle, but for melting, pretty much 100% duty cycle.......but in any case, less than a buck for me to melt 20lbs of aluminum and still less for subsequent melts.

Yes, if it is a fuel fired furnace, input is the operative word because fuel fired hobby furnaces are usually only in the 10-25% range as far as thermodynamic efficiency. I believe you may be referencing energy release in burning the fuel which isn't what goes into the melt. You do need to raise the combustion air temp too but the majority is lost through the vent and some is lost through the furnace surfaces. The amount of energy to initially bring the furnace and crucible mass to temperature is a loss too that occurs every first melt.......but insulating losses and thermal mass initialization is present in either electric or fuel fired furnace. A well insulated resistive electric furnace/kiln is in the 90s% for thermo efficiency.....and it is instant on....takes me a couple minutes to set up and flip the switch.

I really like my resistive electric, but there are pros and cons. It's really just an aluminum duty furnace. I believe I could do bronze but it would be slow and not sure how long lived it would be. In aluminum duty it's very practical. No doubt slower melt times but I mold and am never at a loss for productive things to do in the shop and unattended operation is safe.....just check in on temp occasionally.

Best,
Kelly

 

Have a look at this thread Gary. Lot's of furnace examples here.....some like you describe.

http://forums.thehomefoundry.org/index.php?threads/the-furnace-thread.276/

The two biggest advantages of the lift off method used on my furnace are you can accommodate a larger crucible, especially if it is resistive electric because you don't need to circulate combustion gas around it, and it tends to retain heat well when you open it. My small furnace is 10" bore and easily handles an A20. It does complicate the build and I would have two think twice about it for an iron duty furnace as material choices and failure modes become a much greater concern.

When you couple the lift off with and open ring shank, you can snatch and pour in just a few seconds......and I like that too!

BTW, the reason my furnace is 8kw is I used the design criteria in the Kanthal handbook. The two limiting factors are furnace wall loading and coil loading. Cant remember which limited it to 8kw but compared to kilns, it's a fair amount of power for the furnace volume.

Best,
Kelly