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+--- Thread: First casting (/thread-3353.html)
RE: First casting - Pete O - 10-21-2016
I remembered to have a look at the degassing tablet I have, it is Nitral 10 which is intended for aluminium, perhaps I didn't use enough of it and from watching some more youtube clips I probably didn't mix it into the pot enough.
I've read online that 'lite salt' can be used for degassing, or even injecting nitrogen into the pot which apparently brings impurities to the surface. I wonder if using MIG gas would work?
We're having a very wet spring this year so opportunities for running the furnace have been limited, getting a fine day when I'm not at work or having to spend it on other tasks around the property have been rare. I may have to experiment with the furnace inside the shed with the roller door open, perhaps a brief run and see whether the roof gets hot or I smoke myself out.
Makes a lot of sense about the exhaust flame not helping melt metal.
RE: First casting - dallen - 10-21-2016
swimming pool tablet broken up and pushed to the bottom of the pot works really well for flushing the oxides out of the melt, BUT BE WARNED that the gas created is CLORINE gas and can harm you in lots of ways so wear a respirator (one rated for hazardous gasses) when plunging any kind of chemicals into hot molten metal.
There you been warned.
No sense trying to heat up the country side when all your after is to melt a little aluminum.
My furnace sits half way under the shed roof, that is about 6 feet up hasn't melted it yet, I knew one guy that did his melting inside of his 2 car garage with no problems to his gypsum board ceiling, if I remember correctly you have a really tall shop.
RE: First casting - Pete O - 10-21-2016
Yep my shed roof is pretty high. Might have to give it a try. I have a wood strip canoe with about a million hours labour in it that is suspended from the roof with nylon cord that goes across the roof and down the wall, will have to make sure I don't melt the cord
A chunk of swimming pool tablet would certainly be easier to source than some more Nitral 10.
RE: First casting - awemawson - 10-22-2016
I used to bubble argon through my aluminium melts to degas it.
Dry tools and feed stock before melting, and once molten don't hang around too long before pouring.
RE: First casting - Dr Stan - 10-22-2016
As a result of my poking around I found this meter at All Electronics. http://www.allelectronics.com/item/dvm-890/lcd-multimeter-w/fahrenheit-thermometer/1.html
IMHO the temp probe is way too short so I continued my search yesterday and found a probe that is about 8 1/2" long plus the leads. Tried finding it again on Ebay with no luck. However found this one today: http://www.ebay.com/itm/New-3-Meter-High-Temperature-100-1250-C-Thermocouple-K-type-100mm-Probe-Sensor-/161320380555?hash=item258f71a88b:g:KBoAAOSwTZ1XlvVx
Certainly has the temp capacity, but I'm not sure as to its life span when used to measure the temp of molten aluminum.
RE: First casting - EdK - 10-22-2016
At that price you could purchase a few of them and have spares.
Ed
RE: First casting - dallen - 10-22-2016
with aluminum the easiest way to handle the temp is to be ready to pour the mold within about 3 minutes of the last piece of solid turning liquid, also have on hand some clean dry small bits to help cool the pot off if you think its too hot.
if you have a tig welder you can take a hunk of 16 gauge K type thermal couple with and weld the ends together to make a probe, that's all the probes are anyway. incase it in a piece of carbon gouging rod to stop the aluminum from eating it up, you can plug this into a multimeter that will read millivolts and then download a chart from the internet to convert the millivolt reading to temperature.
RE: First casting - oldskoolron - 10-24-2016
I recon you done great being 1st time pete .I used my small furnace the other day to heat some 2inch x 3inch up so I could shape it .I thought id take ages but it only took about 15mns and it was orange hot and the kao wool inside didn't even change colour .
today im going to have a go at my first pour of alloy .ive made some flasks and have about 140 odd Harley pistons which I ground the carbon off an then degreased them an put them in my powdercoat oven to dry out .I made a crucible from a 1kilo gas bottle and welded a spout on it .im gunna use a mix of playsand from bunnings 6 dollar per bag an bentonite clay dust with water for the mould .
1st pour will just be a bit of round bar 2inch by 9 inch long then if all good after cooling an running a few cuts on lathe I will attempt to make some rocker covers for a Harley motor im building .Harley cases some barrels I made yrs ago at a mates factory I want too make the heads and run an over head cam on each head just something to do rocker boxes will be based of a mix of twincam and evo so gaskets can be easy to buy ect .if my first pour turns out like yours pete ill be happy as .
when my dad was alive he was here with me an my sons an he said if the pour comes out in one piece to start your on ya way he also said they used potatoe as the degasser .have anyone heard of that before
cheers ron
RE: First casting - Pete O - 10-25-2016
Ahh spuds- is there anything they can't do??
Hope to have another go at this casting over the next few days, I plan to make a bigger crucible, thinking I might weld together a hexagonal tube out of some flat bar I have left over. Having material at hand is always a problem for me with these projects, i don't have a ready supply of scrap except my own offcuts.
I appreciate the information and everything but I really don't want to start playing with thermocouples if I can avoid it, just one more complicating factor and another thing to learn about. I'm hoping to keep it simple for a while yet.
RE: First casting - oldskoolron - 10-25-2016
if its molten its ready lol .well ya not the only aussie on his own I done the melt after spendin yest cleanin pistons .had it all nice n ready had my flasks ready gloves lether apron lether spats ova thongs [joking] started to make the mould n bugga don't that green sand compact mmm so poured some ignots an spent all day making greensand lol my son said he knew iwont have enuff but wanted to see me crack the shirts with the world lucky I had good dose of meds this morning hey ..
I recon the secret to it is as pete said nice n simple all I got is one them hand held thermometer things you point at the oven when coating but surely keeping it simple should make it a lot easier