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TopicStatusOriginatorLast Posted by# of replies
• "Ice Embers" Sculpture  DonovanDonovan0
• wire gauge  myglassDonovan1
• gathering out of a wire melter  ztheis04Donovan1
• wire lenght  myglassDonovan8
• elements for an electric furnace...  glassgirlDonovan3
• Measuring magnification  hellogreenhellogreen0
• BioDeisel Powered Glass Equipment?  DonovanDonovan0
• Annealing misinformation  David WilliamsDonovan1
• C ball work if you want it  David WilliamsDonovan8
• Donovan, your Warmglass post  David WilliamsDonovan2
• Store Bought vs. Small Shop Bought  DonovanDonovan0
• G-032 Emerald Green (gaffer)  DonovanPoncaCreek Glass3
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LATEST (8) POSTS within the "Off-Hand Glass" Category!

Donovan Brooke

Donovan Brooke
group:
registered: GMT - 05/09/2007
You need to be logged in to reply 		Go To: Subject: "Ice Embers" Sculpture


This is a pic of a sculpture that was I was commissioned to do a while back. The flame comes from an ethanol burning fireplace. My task was to create "ice embers".

Thanks for looking.

Donovan
DATE: GMT - 01/18/2010 | 05:40 AM    

Donovan Brooke

Donovan Brooke
group:
registered: GMT - 05/09/2007
You need to be logged in to reply 		Go To: Subject: Re: wire gauge
:-) I think in between there somewhere.. what Kanthal calls 11ga. is actually about 12ga... or 2.7mm.

Donovan
DATE: GMT - 06/12/2009 | 04:07 PM    

maria


group:
registered: GMT - 03/19/2009
You need to be logged in to reply 		Go To: Subject: wire gauge
hi donovan as I read you use 11 gau wire.When I read kanthal handbook there are two wire standard according to one 11 gau equal to 3 mm other writes 2.3 mm may I learn what thickness you use.
DATE: GMT - 06/03/2009 | 04:18 AM    

Donovan Brooke

Donovan Brooke
group:
registered: GMT - 05/09/2007
You need to be logged in to reply 		Go To: Subject: Re: gathering out of a wire melter
Hello,

No, the angle of gather is no different than a beehive type of system, and also no :-), the gather is much much cooler than traditional front gather furnaces. In fact, the only negative aspect that I can think of regarding a top 'lid' that slides is that you get schmutz in your glass on occasion (from the fact that your lid has motion over your pot). The end result is that you probably get more pebbles of refractory in your glass than you would with a more traditional furnace... though ultimately, it depends on how well the furnace is made.

Once you learn how to gather without stringing glass on your sill (retention ring), and once you learn how to engineer your lid well, it really is not that much of a problem. You may have to go in with a bit rod on rare occasion and grab a pellet of refractory, but that has rarely been an issue for me.

Bottom line, in my opinion, there is no better gather than from a top lid design. Also, you can build it so you have full access to the entire pot if needed (for larger gathers and easier emptying of the pot etc..)

To each his own, but I will always tout the pleasures of gathering out of a top lid design, having used both types. You may hear reports to the contrary, but ask those folks if they've ever used a top lid design at any length of time. ;-)

Donovan
DATE: GMT - 06/03/2009 | 04:37 PM    

Zach


group:
registered: GMT - 05/27/2009
You need to be logged in to reply 		Go To: Subject: gathering out of a wire melter
I've never gathered out of the style furnace you are using donavan. I was wondering if its hard to get a good gather since you have to stick the pipe down into the thing vertically. also it would seem like all the heat is going right up at your hands.
DATE: GMT - 05/27/2009 | 05:05 PM    

Donovan Brooke

Donovan Brooke
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registered: GMT - 05/09/2007
You need to be logged in to reply 		Go To: Subject: Re: wire lenght
maria wrote:
hi donovan yes I am planing 9 feet cube furnace for glass melting thanks for your interest



O.K., I think we are on the same page now! Now, time for waaaay tooo much information. ;-)

9cu. ft. is close to the interior volume of my old furnace, so this is pretty easy actually. I had best luck with 9 coils and by coiling up to 4.7 ohms for each coil. I used a 3/8" arbor to coil around which makes approx. 5/8" di. coils. This of course is only if you want to "roll your own" (literally). You can order them from a place like Duralite as an option.

I think the coil length ends up somewhere around 28" (if I remember right). I don't know off the top of my head the straight length... it could be figured by downloading Kanthal spec. book at the kanthal website, and finding the ohms per foot value.

However, that value is probably not important unless you have an odd-sized kiln that 4.7ohm coils would not stretch well into.

So:
1.) Coil your wire until you reach between a 4.7 and 5ohm resistance.
2.) Make 9 of them total.
3.) wire in series/parallel (3 parallel banks of 3 in series) for 220 V.

__________________
_______|||_|||_|||

4.) Shoot for a "3 to 1" stretch if possible for optimal performance when installing.
5.) Make an extra set or two [of coils] right off the bat.. incase. ;-)
6.) Best to not melt more than 100 lbs, and optimal at around 75lbs.

Notes: try not to kink or mar the wire during the process.

So, what is the power requirements?:


Formula for finding resistance in series parallel:
R = Ohmic Value of One Resistor/total resistors

Solve: 
3 elements X 4.7 = 14.1 Ohms.
14.1 / 3 (total series banks) = 4.7 Ohms.

Ohms Law
I = V/R

Solve:
I = 220/4.7 Ohms
I = 46.8 Amps.

(note: you could save on amperage space in your panel
by going 3-phase (which changes these equations a bit))

Lastly, What is the power of this furnace?:
Formula:
P = I*V

Power = 46.8 * 220 = 10.2KW (approx)


The above means that you will have a furnace that draws 46.8 amps. and that has a power of 10KW when the elements are on. That is a pretty powerful furnace.. see below on how to save a little money by reducing the power.

Now, from here, you can guess your monthly cost, though it would depend on your usage. However, for example, if you have continual moderate usage, you could maybe guess your elements would be on maybe 5/8 of the day. So, if your electricity costs ¢.11 / KWH:

((.11 X 10.2) X 24 (hours in a day)) X .675 = $18.17

So, with a $18.17 daily cost, that is an approximately $545.1 monthly bill!

**Note, with a furnace like yours (a converted ceramic kiln) that is less insulated, it is likely that your elements would be 'on' a higher percentage of the day.. so your cost may increase a bit.

Now, there are a lot of factors that could affect this 'bottom line' cost. For example, it would be important to decide if this furnace was going to be on all the time, or if it was more a weekend warrior type of thing. If it is a weekend warrior (which I am guessing would be more towards what you are doing because of the converted ceramic kiln), you don't need a whole bunch of insulation as that will just add to the cost and time of getting it up to temperature. However, a well insulated furnace is best for the furnaces that are on all the time, because you retain more heat, and in the long term, that equates to savings. Some other factors that could affect the bottom line I suppose is power. If you are melting only 75 lbs of glass, perhaps you don't need a 10.2 KWH furnace. You could add more resistance to reduce the power... for example, winding 5, or even 5.3 ohm coils instead of 4.7.

Rememeber to allow for some slack with the breaker that you use. I would use a 60A breaker on this line.

Finally, Disclaimer: All this information is from a weekend warrior... which is me ;-) So, I can't guarantee that is all correct. It would probably be wise to run this stuff past your local electrician.

Hope this helps,
Donovan
DATE: GMT - 04/10/2009 | 03:07 AM    

maria


group:
registered: GMT - 03/19/2009
You need to be logged in to reply 		Go To: Subject: Re: wire lenght
hi donovan yes I am planing 9 feet cube furnace for glass melting thanks for your interest
DATE: GMT - 04/10/2009 | 12:15 AM    

Donovan Brooke

Donovan Brooke
group:
registered: GMT - 05/09/2007
You need to be logged in to reply 		Go To: Subject: Re: wire lenght
Or, sorry, you said you are using 1/4 of that size?? That would be 9cu. ft right?

Guessing the size (width/height) using the formula for volume of a cylinder:

-----------
Volume of furnace: 9 cu.ft

Base Formula:
(3.14 * R squared) X height = 9

1.) Inches (assume a radius of 12" (24" di.)):
(3.14 * 12" squared) X height = 15552

2.) Solve for height:
452.16 X height = 15552
height =34.4 inches.
-----------


So, the approx interior size *could* be
width: 24"
height: 34.5"

If so, that is getting closer to the dimensions
of what a wire melter usually is.

Please verify if that is right before I go into
calculating wire requirements.

thx,
Donovan
DATE: GMT - 04/08/2009 | 05:06 AM    
 
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