NeoTechs newbie melting endevours. ;)

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NeoTech:
then i wonder.. should the burner tube be shortened.. my tube is 30cm.. and has 4 slots of 14mm wide and 10cm long..

But yes, it seems like the pulsing is a combination of different things.. i dont have a flare on the tube could that affect performance? Its weird anyway it works for a long time until it gets to hot and the gas feed cant keep up.. or as you say a windgust comes by and suprise feed it to fast..

Like the performance when it runs right though.. 20min from cold to pouring temperature when it hit 760 i just stirred it a bit while in the furnace without taking the lid off pushed all the slag to the bottom of the crucible and then opened it and poured it.. i cut one of the ingots in half and found no pours in it.. and its no pours on the surface either.. So far very happy with it.

MetalCaster:
Propane burners are notorious for cooling off the propane tank, with a resultant drop in vapor pressure.

And when that happens, the burner gets too lean, and yep, you can certainly start the pulse thing with a lean burn.
You may have to watch the pressure, and adjust the choke as the pressure drops off a bit.

If you are doing large melts, you can avoid the problems of propane by using an oil burner, but I still use propane for aluminum melts, and with little trouble even with the pressure drop.

Here is my burner.
It is a commercial unit, but quite long.
I use it with a flair on the end, but I don't think that is critical, but you never know.
I have seen a lot of short REIL type propane burners, and they seem to work well also.
One thing I have heard about aluminum, heat it fast, skim it, and pour. Don't stir, you are just getting gas into it (according to others).
If you are not having any gassing (pores?) or inclusions, then that is good.

Aluminum pours are very forgiving generally.

NeoTech:
Ah yeah, when it start to pulses, i choke down the air intake a bit and it stops pulsing, but when i do that i cant reach melting temperatures.. so i need to figure a way of make it stop pulsing.. Which i guess i easier said than done..

Yeah i put a bunch of charcoal in the bottom of the furnace that i used yesterday for cooking the lining.. i poured a bit of it in powdered form in the bottom of the furnace.. It produces alot of co2 gas so if you stir it and you dont "open" it up the furnace enviroment is basicly without oxygen or well very very lean anyway..

vtsteam suggested putting some stuff onto the melt i figured it just should be inside the furnace and burning producing gas - and well i got no pours so maybe it worked. =)

MetalCaster:
You can get a larger tank, or parallel two smaller tanks (requires two regulators), or put your tank in a tub of warm water (water is the last thing I want to have around a pour).

Perhaps an easier method would be to put a fan blowing on the tank to warm it.

My philosophy is:
1. Don't solve problems that you don't have. Use the most simple solution with the fewest parts, and if that works, then don't add complication just for the sake of doing it like someone else mentioned.
2. Find a base setup/arrangement that works, and then experiment after you get a working arrangement. Some people change too many variables too quickly, and it can be difficult to figure out cause and effect doing that sort of thing.
3. Some like to experiment and learn as they go. For me, I would rather look at a number of working systems, and then combine the best of all those systems into a hybrid design that works better than any individual design, or at least combines the good parts of a number of different designs.

I don't use additives, charcoal, crucible covers of any kind, stirring, etc.

What works for me is using clean aluminum only, melted as fast as possible, skim and pour.
Don't make it more complex than it has to be (is my philosophy).

There are methods that can be used for degassing aluminum, some very toxic, some expensive, but if you don't have gassing problems (I don't) then don't solve problems you don't have.

Just my approach; everyone has their own method to the madness (or should I say MadModderness).

NeoTech:
Well yeah, i have a bunch of lettercombinations that let me think lateral i tend to be category 3 there.. i read a ton of information and then i break it down and ask myself - why.. what is the endgoal by "doing it like that".. and if i see logic in it i try it.. if it works fine i keep it.. if not its discarded..

But yeah, clean aluminium is problem the best way to go.. problem all my aluminium scrap atm is either lathe swarf or cast car parts, like transmission housings, pistons, intake manifolds and such.. i break em up and just pour them into ingots.. but well i need to make a larger crucible.. cause i get like slightly less than a kg of aluminium in 3 pours. =)

But when it comes to my burner.. i think i will get myself a PA11 tank.. its a 11kg aluminium tank. I can heat that with my NOS tube heater from the race car.. And then go do another test.. and see if it will "pan out".. or if the pulsing problem will come back.. and if it keeps going and its like you say it explodes in the burner tube.. i guess i could back the tube out a bit. And i should take into practice cooling it between runs - or just make several tubes i can swap between.. *they are not welded or screwed together its just a slipfit that friction sticks*

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