The Home Machinist!

It is a wise man that seeks council before spendin his fortune on dreams and disasters...

yup, I am a collector and junkyard artist. Call it a fixit guy if you want, it is all the same. Bottom line is I always work with an eye toward cost, labor, and end capability to fill the need. I often give up labor to cover other time and cost, and use odd materials, rather than bought. Air conditioner cases, home furnace shells, and the like, provide quite sturdy sheet metal to base many pprojects on. I am my own junkyard, with generic materials waiting to be used on some porject. A 'new' furnace, can be a major cash outlay, for only occasional use, and then gather dust, and eventually move the family car into the drive permanently for lack of space in the man cave. When that happens, you open the voting booth for the catagory of NUTJOB. Neighbors that dont do anything but mow grass and trim hedges, wont understand, until you do an OH-WOW thing. That will quickly pass like a Circus in town, to maybe be revisited later. Piles of sand, roaring furnace, smashing BBQ Grilles, will only prove you to be Neanderthal in vision. Tell me how I know.

O course you could buy a furnace. Hard on the Wallet, Mom may demand a new living room set, that would cost as much. And what fun would that be?

_________________
Big Dave

Be Alert! The world needs more Lerts.

Yes, Dave I am in awe of people such as yourself that make something out of junk. There are numerous examples I've seen now that I am regularly on the net. Some very creative ideas and works get posted. My current furnace is a Gingery type with a Michael Potter 1" ID propane burner. Originally I made a smaller burner but it took too long to get bronze to melt. I cranked up my furnace yesterday, put in a tiny amount of cast iron and checked the temps of the outside walls after the iron started to melt. It did take quite a while but anyway I used 2 different low temp solders to check with. Tix solder which is down around 200 melted readily but "Hi Force 44" 475 deg., did not melt on the side walls but did on the top cap. So assuming the inside temp was at least in the 2300- 2500 deg range, it appears that the 2800 deg Noxcrete castable does, in fact, give about 500 deg per inch insulaltion value. What I don't get it is the huge heat loss going out the top. I understand the need for a vent to prevent the furnace from pressurizing into bomb but it seems almost counter productive. Oh and the iron tested out to be readily drillable with a HHS drill and fractured at its weak point maybe a little easier than it should, but I am not sure on that point. I used the same tiny crucible again which has now become the sacrificial lamb. Yes these temps are not easy on clay graphite. Here are some pics. Doug

With a few variations, you have a setup as I described. To get more heat value, you must get more heat in, that means more fuel/air mix, into the chamber. Either a larger burner, (limited by constant fuel supply) or more length on the gun, to start the burn before the chamber, Is about the only way to get more heat, now.

Looks good, go play.

_________________
Big Dave

Be Alert! The world needs more Lerts.

I hope you understand, you need to fire lean and mean. A venturi gun is ok, once balanced. The commercial furnaces like to use a small blower to kick the gas with air. Remember air is only 15% oxygen, or the like, and the majority of the Nitorgen, and trace gases, do absolutely nothing for the burnprocess, except demand you put more volume through to get the burn you want. So where the flame actually reacts, and is momentarily retained, is a big deal. Once you leave the very tip of the reaction area, the temps begin to fall from the flame front.

A good furnace will show a light blue almost invisible gas just flowing up out of the vent, where it hits cool atmosphere, and inside would display bright straw color, nearing white, with red-orange edges where the exhaust works up over the brick. I should be bright enough, that furnace glasses should be worn to look in. They are blue. Gaps in the brickwork, will show up as black in high contrast. Easy to see cool spots.

_________________
Big Dave

Be Alert! The world needs more Lerts.