Author Topic: NeoTechs newbie melting endevours. ;)  (Read 16375 times)

Offline Mayhem

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Re: NeoTechs newbie melting endevours. ;)
« Reply #25 on: August 11, 2013, 04:25:01 AM »
Sounds like you are making some progress Neo.  More pictures would be helpful.

MetalCaster - have you posted any info on your oil burner on here at all?  Oil is my only fuel option, as I have an abundance of it and propane is too expensive.

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #26 on: August 11, 2013, 03:00:13 PM »
So.. well. burner experimentation continues.. and some.. figuring out.. I guess cuz i cant really find this info myself and had to read some gas physics.

Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #27 on: August 11, 2013, 03:01:42 PM »
Reference regarding venturi gas speeds..
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline ironman

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Re: NeoTechs newbie melting endevours. ;)
« Reply #28 on: August 11, 2013, 08:30:39 PM »

MetalCaster

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Re: NeoTechs newbie melting endevours. ;)
« Reply #29 on: August 11, 2013, 08:49:43 PM »
Thanks Ironman, I did not notice that post, yep, the details of the oil burner are at that post.

I used my propane burner again yesterday.
It started the oscillation and then burning in the burner tube, and I had to remember to close the choke down quite a bit to start it.

As I said before, this type of propane burner is very sensitive to choke position.
I have to start mine with the choke open about 1/4".

Once things start to heat up, I can increase gas pressure and open the choke a relative amount.

If I open the choke too far, the burner goes unstable.

But with the correct choke opening, the burner should work fine and not blow back into the burner tube.

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #30 on: August 12, 2013, 01:04:54 AM »
Well there is many people using this type of design in some way. I just gonna do some mods to it making it easier to use. As you say its sensitive in my case crazy sensitive for small changes. I hope make it a bit more "blunt" so to speak. :)
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline Mayhem

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Re: NeoTechs newbie melting endevours. ;)
« Reply #31 on: August 12, 2013, 06:12:39 AM »
Thanks Ironman

Offline vtsteam

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Re: NeoTechs newbie melting endevours. ;)
« Reply #32 on: August 13, 2013, 06:55:46 AM »
If it's burning in your burner tube -- and you don't want it to -- your gas speed in the tube where it is burning is too low.

You can increase that gas speed two ways. Increase the speed of propane coming in, or decrease the diameter of your tube.

A flare added to the end of a burner is basically a tubing size increase -- which allows the gas to slow and burn where you want it to -- at the end.

But if your tubing is too large before that point it will burn before it reaches the flare. Then the flare is pointless.


I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #33 on: August 13, 2013, 07:03:07 AM »
Hmm the tube is 28mm inside and the gas travels 25cm. So basicly shorten the tube or reduce the inner diameter until it stops acting up. Well i give it shot and go by an assortment of tube pieces. :)
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline vtsteam

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Re: NeoTechs newbie melting endevours. ;)
« Reply #34 on: August 13, 2013, 07:09:14 AM »
Shortening it is not what I mentioned as one of the two ways to increase the gas speed.

Shortening it will shorten it.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #35 on: August 14, 2013, 10:59:57 AM »
So i went and made this.. flare type thingymajig.. It seems to have done 2 things..

1) Now i can feed the tube with more gas. (Ergo increase gas speed without blowing out).
2) I can open the choke up to about 25-30% depending on heat in the flare thingy, and thus increase the heat output - alot..

And the flame broaden alot but maintained the almost cant be seen deep blue color at this state. I tried to force it to start pulsing like it did before by taking the compressed air and simulate a strong "gust" from the side of the intake.. It didnt bite.. Buut if i turn off the gas on the tube but let the burner continue (running out of gas test). It starts to pulse when the gas tends to go out as suggested the gas speed was an issue. And the flare reduced the speed of it at the tip alot so now i can actually feed it in the speed it consumes the gas. Balance is achieved.


Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

MetalCaster

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Re: NeoTechs newbie melting endevours. ;)
« Reply #36 on: August 14, 2013, 11:07:20 AM »
Now that you mention it, I have to run a flair on the end of my propane burner also.

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #37 on: August 14, 2013, 11:23:21 AM »
Well i thought i wouldnt have to, i choose a pretty big piece of pipe.. 35mm outside, 28mm inside. But its just straight and straight is good i guess if you need to project the gas far away.. there is actually a complete thread regarding gas speeds and consumptions on the physicsforum..  It was an interesting 60 pages read of what i could understand 10% of it maybe.. But i got the gist of the venturi principle.  Its really a weird amount of math going into making a properly balanced gas burning tool..

Now this can weld stuff together.. im happy with it.. tomorrow if the weather gods let me, im gonna melt a couple of intake manifolds.
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #38 on: August 15, 2013, 09:53:06 AM »
So now my burner works as intended.. i took the opporunity and started to break up and melt some pistons and a transmission housing..

The colorblind dragons saids; Goooold!

Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline vtsteam

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Re: NeoTechs newbie melting endevours. ;)
« Reply #39 on: August 15, 2013, 10:07:27 AM »
Flame stability and gas speed are two separate problems. You still have the capability of burning inside your burner tube, though you've increased stability at the flare. You now have two stable modes of burning. Outside and inside the tube.

If you sleeve your burner tube starting at the choke and extending to the tip down to say 24 mm ID you will likely eliminate tube burning mode and increase safety. You may also mix a little better.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #40 on: August 15, 2013, 12:25:39 PM »
hmm, i will try that.. It actually did some pulsing when i didnt open the valve fast enough  So if can void that completely i would be one happy camper.

But yes, the flame stability is second to none now, it was really fast up to melting point as well, from cold to 740C it took about 15min. So im happy with that. The crucible do go over to redhot and oxidizes like crazy though. But i guess thats a problem with steel crucibles.. It gives off alot of scales that need to be removed before pouring.

Its all an experiment i feel.. But im now considering doing my ingots in a sand mold.. the damn ingot mold is badly constructed and i need a crowbar to get them out of the mold.

Thinking of making a permanent ingot mold that can be easily rammed up from some profiles i have lying around.. Couldnt find a muffin tin without plastic in em, or made out of steel for that matter.. its all some flimsy aluminium things covered with teflon. ;/
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline awemawson

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Re: NeoTechs newbie melting endevours. ;)
« Reply #41 on: August 15, 2013, 12:40:44 PM »
You could use a refractory wash to coat your crucible to avoid the oxidisation. I used to use Zircon washes on my skimmers etc. Get the tool or crucible reasonably warm and just paint it on - as the water evaporates it leaves a chalky deposit that protects the metal.
Andrew Mawson
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Offline vtsteam

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Re: NeoTechs newbie melting endevours. ;)
« Reply #42 on: August 15, 2013, 01:52:30 PM »
The crucible do go over to redhot and oxidizes like crazy though. But i guess thats a problem with steel crucibles.. It gives off alot of scales that need to be removed before pouring.

That's also a problem of excess air in the furnace. One great advantage of charcoal melting of aluminum is that you automatically tend to get a reducing atmosphere around the crucible. It's surrounded by glowing pieces of carbon. So oxidation is much less.

I found that when melting with a propane burner vs melting with charcoal that propane created more fuel expense, much more aluminum waste due to dross formation, and steel crucibles oxidized rapidly on the outside. Cast iron crucibles seem to last indefinitely compared to steel in a charcoal furnace. Your crucible is very thick so it should last for quite a few melts.

I don't think I will be using propane for melting in future. The iron furnace starts on diesel or kerosene, and burns waste or vegetable oil, and I'll use charcoal or even wood for melting aluminum. The setup for charcoal is also simpler. No tanks, burners, plumbing, or starting fuels. Just a blower. And in 20 minutes, molten aluminum with little dross.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #43 on: August 15, 2013, 02:36:23 PM »
I actually tend to have very little dross though. But most of my aluminium is sourced from car parts. It has alot of other shiet that burns off during the melt, but the dross skims off easy and is less than a table spoon per melting run. (did about 20 ish runs today).
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline vtsteam

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Re: NeoTechs newbie melting endevours. ;)
« Reply #44 on: August 15, 2013, 03:58:44 PM »
Sounds good then.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline NeoTech

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Re: NeoTechs newbie melting endevours. ;)
« Reply #45 on: August 15, 2013, 04:07:35 PM »
As i said earlier i have crushed ashes of charcoal in the bottom of the furnace, it seems to produce a alot of Co2 inside the furnace. When it burns off i see more dross form so i just crushed some more and put in there.. It works wonders if you have a spill as well it doesnt let the molten metal fuse to the lining of the furnace..

Dont know if it really does anything but i think it does.. the metal acts differently with the charcoal dust inside then if its nothing of the stuff.
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/