Mako Burner

[bmac2]

Hum. Looks like I have to find something to keep me amused for the next 5 or 6 months. Good thing winter doesn’t start until Dec 21/22.

 

[bmac2]

I’ve been thinking about getting into metal casting (aluminum) for some time now and recently discovered that my wife is not totally against the idea. As in, when she saw I was looking over a web site on making a small (paint can) foundry said “oh. Weren’t you going to make one of those?” I’m going to take that as a green light to start tooling up. Thm:
It’s going to be too cold and way to wet outside to get right into pouring metal but I figure I can start by trying a couple of burner types.
I stumbled onto the Gypsy Tinker (https://sites.google.com/site/gypsytinker2012/info/foundry) and thought the low pressure Mako Burner (https://sites.google.com/site/gypsytinker2012/rantings/blog/makopropaneburnerdesign) looked interesting and gave it a go. Only took about an hour or so to scrounge/make up the parts and put it tougher.

 

[bmac2]

The flare looks like crap because I heated it up thinking it would make forming the bell easier and in the process had the tube crush down a bit. Now I’m thinking quality not quantity here but to me the flame looks pretty good. I don’t think it would melt anything but I just used a spare BBQ regulator so that’s what, 6 - 8 ounces? I have to get some proper hose and fittings before I can test it out with my adjustable regulator.

 

[Brian Rupnow]

Bmac--You haven't got the market cornered on snowfall----it snowed 8" at my place yesterday in about 3 hours. Good luck with your casting.---Brian

 

[jasonh]

You might find the following interesting:

http://youtu.be/l697pB9X5TI

Lot's of people use naturally aspirated burners- I made one, but I had trouble getting enough heat out of it. I've since gone to forced air (with a hair dryer) and while it might not be as clever- it gets the job done and gives the possibility of cranking up the heat by cranking up the air and fuel.

 

[bmac2]

;D

Bmac--You haven't got the market cornered on snowfall----it snowed 8" at my place yesterday in about 3 hours. Good luck with your casting.---Brian

Thanks Brian
I think you’ve followed enough of my builds to know that if I‘m working from castings I’d better be able to make a second one. :fan:
On average we don’t really get a lot of snow our here, it’s too dry. We do say strange things like “it’s not going to snow, it has to warm up first”. You’ve got that Great Lakes effect thing going and I’ll take my colder but dry over your cold but damp any time. Hell I bought my first snow blower last year (used it twice) and that’s only because I’m getting lazy.

 

[bmac2]

Hi Jason thanks for the link.
I was reading Myfordboy site (again) the other day and see that he has added a blower to his furnace and it sure looks impressive.
[ame]https://www.youtube.com/watch?feature=player_embedded&v=ZjGT8ZAVnts[/ame]

 

[bmac2]

Got the Mako paired up with an adjustable regulator today and gave it a try. Played with the position of the bell a bit and to me the flame looks good at about 4 lbs. pressure.

 

[bmac2]

I couldn’t see most of the flame with the lights on and turning them off helped but only a bit. I’m assuming that’s a good thing, clean burn?

 

[bmac2]

Well I woke up this morning to Environment Canada issuing a weather warning of “Extreme Cold”. It’s January. It’s always cold in January.
Today’s forecast: “Sunny. Wind up to 15 km/h. High minus 17. Wind chill minus 41 in the morning and minus 29 in the afternoon.”
Oh. . . . . Looks like a good day to start on my Coffee Can Foundry.

 

[bmac2]

Please keep in mind I don’t expect this to last forever it’s more of a test bed or proof of concept than anything else. If I get into casting I’ll have to make something more substantial. My game plan for now is just casting ingots from some scrap aluminum I’ve started hording. Then I have a couple of ideas I’d like to try using lost foam. If that works out then I want to try making some simple patterns and sand casting.

But before I can do anything I need something to melt stuff in.

This is going to be my 49th parallel Foundry. The outside is a Kirkland coffee can from Costco (USA) and the inner liner is good ol Canuck Tim Hortons. This should let me use a 3” by 6” high crucible. The burner support pipe/ tuyere is an old plumbing fixture and a nice fit for the Mako Burner. I cleaned it up and cut it to intersect the inner can on the tangent.

 

[bmac2]

Playing around with this setup I’ve rediscovered that I can’t juggle. I just couldn’t keep the 3 pieces lined up so I tack soldered them in place. The solder is going to survive the first light up but it will hold everything in place while I ram up the refractory.

 

[bmac2]

The refractory mix is 1 part Fire Cement to 4 parts Perlite straight off the Myfordboy blog. I’ve seen web pages swearing that Portland cement/ Perlite/Fire Clay as the way to go but I’ve also seen too many pictures of catastrophic failures of that mix to want to try it. I figure if anyone knows how not to blowup a furnace it’s Myfordboy.

 

[bmac2]

I read somewhere that the vent hole in the lid should be the same size as the crucible so I made it 3” but it looks too big somehow?

 

[bmac2]

So far all I have invested in this other than time (and I don’t care much about that on a day like today) is $12.99 for a tub of Imperial Hi-Temp Cement. . . . Oh. . . . and someone just might owe my wife a bag of Perlite from her gardening supplies.:hDe:

 

[bmac2]

Wow. Is that home page ever out of date “August Project of the Month”
Anyhow.
While reading yet another page on metal casting they once again pointed out that soup cans should never be used as a crucible. This started me thinking about the Tim’s can I left in the furnace. Isn’t that a bit like using a food tin as a crucible? I had leftover Hi-Temp Cement so I gave the interior a good skim coat. This should protect the tin from all the direct nastiness of the burner so all it has to contend with is the heat. I’m thinking of asking my wife to hide this somewhere so I can stop itching to light it up . I’m confident that the Mako burner will get it up to a temperatures hot enough to fire it, but with winter temps in the garage (-20 to -9C) I don’t think the last step in firing a new furnace IE letting it cool slowly to avoid cracking would work out very well.

 

[bmac2]

Stopped by Metal Supermarket on the way home from work Friday and dropped $4.50 on a foot of 3” pipe, this will give me enough for 2 crucibles. The walls a tad over 3/16 and I have some 1/4” plate for the bottom. I’ve got a small wire feed unit but my welding skills are second only to my sewing and basket weaving (gob on lots and break out the angle grinder) so I might just get everything cut to size and cleaned up then phone a friend.

 

[RichD]

I'm watching the progress.
Looks good so far. You could use it to heat your shop now.
Someday I hope to make a home foundry as well.
What's Perlite? I'm not familiar with that term.

Rich

 

[bmac2]

Hi Rich
According to Wikipedia : http://en.wikipedia.org/wiki/Perlite
Perlite is an amorphous volcanic glass.
According to my wife: It’s used instead of soil to start plants from cuttings and in the garden to prevent soil compaction.
For a home foundry it gives a cheap (9L bag for $3.19 at Lowes), lightweight insulation that can take high temperatures.
From everything I’ve read a monkey with a book of matches should be able to melt aluminum. Maybe not well but melted. I think judging temperature will be my first challenges. For now I’ll be happy if I can take all the aluminum parts I mess up and cast them back into a usable shape. :fan:

 

[bmac2]

The weather looked like we were heading into a warm spell (this is Alberta, -20 Monday. +10 Wednesday) so I thought I would get a chance to fire up the furnace. I started by hanging a 60w bulb in it for a day then used a heat lamp on and off for a couple of days (didn’t want to leave it on unsupervised) then out to the garage.

Switched out the adjustable regulator for the old BBQ one I first tried the burner with and lit it up. Sorry no pictures. After about 10 minutes I started getting smoke coming out the holes in the pop rivets that are holding the wire running around the inside supporting the refractory. There was no smell coming off it (a hint of hot dirt maybe?) so with the overhead door open a bit I let it run. This got boring after about half an hour so I decided to put the adjustable regulator back on and give it some heat.

So the things I have learned. Don’t use Imperial Hi-Temp Cement. From one of the Yahoo forums I read.
“There are several different binder systems used for refractory cements. The least expensive, and the lowest temperature rated, is sodium silicate. Unfortunately, the sodium silicate will bubble considerably if heat is applied to it. Unless, you go through and add vent holes about every few inches.”

I’m thinking that the Imperial Cement contains sodium silicate. I’ve started calling my furnace the “Troll Forge”. Lots of warts . Shortly after I hit it with the Mako burner the skin started to blister.
On the up side I think it’s still serviceable, the outside wasn’t getting hot, and it didn’t take long to get the inside glowing a nice soft red. With the garage warmed up nicely and the foundry glowing I put a 6” length of the pipe I’m going to make my crucibles out of in it and it started popping. I remembered reading about this, backpressure. It looks like with the size of the furnace and the amount of air space I have around the crucible I can only run the burner at 2 or 3 pounds pressure. At this pressure it still has a full flame wrapping around the crucible and coming out the top.

Next up. . . Finish the crucibles and see if I can melt something.