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  #26  
Old 12-04-2003, 09:15 AM
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Quote:
Originally posted by Richard Huntrods


Actually, you got three good responses right off the bat.

-R
I agree with Richard, you got plenty of valuable response, mostly qualifying that load limiting is the way to go doing this stuff and then it works. As I said, I run both and electric is slower and weirder, but it comes out fine. In the good old days, which weren't all that good, we simply went out and tried it and had no one to talk to at all. The first wire furnace I ever saw was in 1970. It's nothing new.
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  #27  
Old 12-04-2003, 10:18 AM
Dave Bross Dave Bross is offline
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Forgot one detail in my post. I'm using an SSR and a digital controller set up to fire it at one second intervals.

The lack of temp swings with the tighter control is supposed to prolong element life 400 times in the case of an SSR and up to 4000 times with SCR control. I'm sure these numbers were achieved somewhere more element friendly than the glass environment but you get the idea.

The best electrical heating stuff I've seen on the web is at Watlow's site and you have to search around for it because they keep moving it. It's called The Watlow Educational Series and has THE BEST explanations of all things resistance heating and control with pros and cons and simplified explanations.
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  #28  
Old 12-04-2003, 11:33 AM
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I didnt mean to insult anybody over their responses. I was hoping someone had melted batch for a year in a well designed wire melter and had some insight on element life.

To further the moly debate a little, consider this:

My furnace consists of less than 90 insulating firebrick, 3'' X 4.5" X 9" each, a few bags of insulating castable for the floor, and a few boxes of fibre blanket. Total cost was not a lot more than the $600.00 for 4 moly elements, and that doesnt include the expensive transformers that moly needs.

My furnace draws about 5 KW at 2150F, apparently half of a small moly furnace. The trick is that I have no crown, reducing the interior space to be heated by about 50%. The lid is made of 3" thick IFB mortered together in an angle iron frame, with 1" of fibre on top. The lid rolls back and forth on angle iron channels. I intend to automate it using an air cylinder.

Perhaps you can see where I am going with this: For a similer construction and operating cost, you could run two wire furnaces for the price of one moly furnace. I am not sure at that point that there is any advantage to moly at all. In fact the reverse would seem to be true.
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  #29  
Old 12-04-2003, 11:37 AM
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Quote:
Originally posted by Dave Bross
...
The best electrical heating stuff I've seen on the web is at Watlow's site and you have to search around for it because they keep moving it. It's called The Watlow Educational Series and has THE BEST explanations of all things resistance heating and control with pros and cons and simplified explanations.
I found this stuff at http://www.watlow.com/literature/prodtechinfo/index.cfm

Just select "Information Type": Training and Education and you can pick any of the 7 PDF file books.
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  #30  
Old 12-04-2003, 11:51 AM
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Quote:
Originally posted by David Paterson

To further the moly debate a little, consider this:
Perhaps you can see where I am going with this: For a similer construction and operating cost, you could run two wire furnaces for the price of one moly furnace. I am not sure at that point that there is any advantage to moly at all. In fact the reverse would seem to be true.
I don't consider it a debate at all, it's a choice. The first one of these that I built is now over six years old, costs less than $250.00 monthly to run at $.065 KWH and has the origional elements.

The only maintenance it has had is to replace pots.

For short term use or projects etc, I would heartily reccomend a wire melter, I am using one right now because I didn't have the power or money available to build the big moly that is under construction right now, I am looking at the next ten years, and using really good castables, great electronics, high quality componants. When this thing is up and running, I want to blow glass out of it and I know it will make the best quality I can have because it will reach the temps I need every day and it will not have to be torn down until the pot change.

Can you blow lots of glass out of a wire melter? HELL YES! Parker Stafford and Sam Davisson do it all the time, and they know thier maintenance schedules religiously and stick to all the little tricks to make it work.
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  #31  
Old 12-04-2003, 12:07 PM
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Quote:
Originally posted by David Paterson
For a similer construction and operating cost, you could run two wire furnaces for the price of one moly furnace. I am not sure at that point that there is any advantage to moly at all. In fact the reverse would seem to be true.
According to the temperature ranges Pete listed in the Building Shop Stuff thread (http://talk.craftweb.com/showthread....&threadid=2065) about melting SP batch, a good melt is 2250, which is about 86.5% of the Kanthal A1's operating maximum. He also cites approx. 2350 to finish the reaction, which is about 88% of the 2552 F max for A1.

And with all the good information here about SCR, SSR, etc., I don't see any reason for a beginner such as myself to go beyond this type of setup. I think this is the most bang for the buck at this point. At the same time, I do see the value in the molybdenum technology, particularly for large melters, or situations for lots of color pots. The setup at http://www.mountainglassworks.com/Studio.html is nice.
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  #32  
Old 12-04-2003, 12:38 PM
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i have a wire melter, although i melt cullet and not batch. i installed a spare element, that is normally not energized. when an element burns out, i use a volt ohm meter to determine the bad element, and then use the spare element to keep the furnace up until the crucible is empty, then i shut down for service. yes the spare element does age because it is hot, but it does not age anywhere near as fast as a powered element does. this way, i have a way to deal with a burnt element, and save the crucible and the blowing time.
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  #33  
Old 12-04-2003, 12:47 PM
Steve Stadelman Steve Stadelman is offline
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Quote:
Originally posted by Ben Rosenfield


According to the temperature ranges Pete listed in the Building Shop Stuff thread (http://talk.craftweb.com/showthread....&threadid=2065) about melting SP batch, a good melt is 2250, which is about 86.5% of the Kanthal A1's operating maximum. He also cites approx. 2350 to finish the reaction, which is about 88% of the 2552 F max for A1.

And with all the good information here about SCR, SSR, etc., I don't see any reason for a beginner such as myself to go beyond this type of setup. I think this is the most bang for the buck at this point. At the same time, I do see the value in the molybdenum technology, particularly for large melters, or situations for lots of color pots. The setup at http://www.mountainglassworks.com/Studio.html is nice.
Yes it is, I talked Matt through building that (the moly part) a couple years ago.

And yes Ben, you can do this on the cheap and learn alot of stuff along the way. You will learn lots of valuable things about electricity and castables, power supplies and glass types.
I am pulling lots of good ornaments out of my wire melter right now. Once again I want to say that there are TONS of options out there to do your glass with, I am just a proponant of moly.

Watlow has a great website like Dave pointed out and all of thier stuff is also available on cd rom. It gives great demonstrations of WHY different power technologies work like they do.
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  #34  
Old 12-04-2003, 01:11 PM
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I use a Watlow controller and two digital relays on my wire furnace.

The default settings for the Watlow controller have it powering the elements for a small burst every second or so.

I have both my annealer and furnace running the same controller setups (just different thermocouples), and it works great.

Power consumption is not totally known yet, but I can fire up both and the main 40A breaker does not trip.

My furnace is built according to the Mark Lauckner plans, although I use a different element size and configuration.

The nice thing about Mark's plans is that the element heating chamber is covered - this protects it from the "normal" glass environment.

Just not from spillovers

I will be melting batch once the furnace is repaired. According to what I've read here (thanks Pete) and what Ben re-iterated just a post or so ago, there's no reason to avoid batch in one of these units.

-Richard

-R
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  #35  
Old 12-04-2003, 01:15 PM
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David,

One other thing...

While bringing up my furnace for the first time, I emailed a bunch of people with wire furnaces (made using Mark's plans).

Basically, what I found out so far is everyone I contacted has melted cullet only - not batch. However, this seems to reflect convenience and suppliers rather than any inherent problem with batch.

Since I cannot get cullet readily, and all the gas-furnace people in Calgary melt batch (either Seattle Batch or Spruce Pine), I will use batch (Spruce Pine).


-Richard
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  #36  
Old 12-04-2003, 01:22 PM
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Quote:
Originally posted by steve stadelman
And yes Ben, you can do this on the cheap and learn alot of stuff along the way. You will learn lots of valuable things about electricity and castables, power supplies and glass types.
That is invaluable at this stage of the game. I don't take this stuff lightly.

Let me thank you again for the help you gave me, and same to everyone else. This type of knowledge base is not as common as it should be. This is a damn fine board.

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  #37  
Old 12-04-2003, 03:28 PM
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I don't consider it to be a debate unless it's a debate over whether you can afford a Porsche as opposed to a Ford Taurus.
The Taurus will get you there while the Porsche will get you there effortlessly. The Taurus may break down on the freeway on ramp, and while repairable will cause you to curse at the time. Remember those Moly elements cost more, but they have no known life span unless you break it yourself.
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  #38  
Old 12-04-2003, 05:46 PM
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If someone gave me a porsche, I would sell it and buy a good PU truck, and use the remainder of the money to upgrade my glass studio. A friend of mine had a Ferrari. It went really fast, but otherwise was big and expensive and not practical in any way.
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  #39  
Old 12-04-2003, 09:00 PM
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The setup at http://www.mountainglassworks.com/Studio.html is nice. [/b][/quote]


Man,That setup is sweet. Thanks for sharing it with us.
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  #40  
Old 12-05-2003, 04:53 AM
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I see a lot of reference to kilowatts here as a basis for what it costs to run these things. Remember that a kilowatt is just a snapshot in time, an intantainous value. When talking about cost of electricty you must use Kw/Time or kilowatt hours (KwH). Steve and Pete are hip to this.

Just because you see something pulling 23 amps (5Kw at 220 volts) when you measure it doesn't mean it does it all the time.
On off on off right?

Then the cost per KwH varies regionally....

$.02

Rick
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  #41  
Old 12-05-2003, 08:42 AM
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more like 8.1 cents and 7.2 at night.

I look at my montly bill divided by days.
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  #42  
Old 12-05-2003, 03:53 PM
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One more thing about wire that has seemingly come down as "rule of thumb" from the combined experiences of Thumb, Parker, Sam, and others...

The wire will last a lot longer if you don't go above 2250F.
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  #43  
Old 12-05-2003, 07:41 PM
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well. I think that trying to convince some folks that moly is a better, yet more expensive system than wire is like trying to convince some people that invested crucible melting really is not the way to go. I'll stop trying on the moly like I stopped trying on the crucibles some time back. The issue about 2250 is absolutely true. Most colors just can't sucessfully be melted that cold aside from fluorines. As Dave has discovered, melting unoxidized glasses without fining agents is an absolute bitch under 2250. The moly is unrestricted as to its performance. You just turn it up. I thought it was all about ease of operation. In it's own way it reminds me of the recuperation issue. They take maintenance, and a fair amount of it. I don't think it's much different with element replacement and shutdowns. I don't want to shutdown more than once a year. I could never maintain that time spent on dinking with elements that a wire unit is going to take. My time has simply gotten too valuable. Strip it all away and a small moly melter can be built very reasonably for relatively little output of cash. Matt Bezark sure did it. Mine is just a big assed expensive hulk but I like them that way.
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  #44  
Old 12-06-2003, 09:51 AM
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I hear what you're saying there, Pete. Another crucial difference is the needs of the full-time -- dare I say professional -- glassblower and the weekend warrior, hobbyist, or the guy who wants to fire up the melter long enough to blow ornaments to sell to coworkers.

The former clearly needs to know the elements will work consistently (and at high temps) and will stand up to the glass. The latter likely has the time to putz around with element changes and other maintenance routines.

I know I just typed a chapter from the Great Book of Duh, but perspective is important.

Last edited by Ben Rosenfield; 12-06-2003 at 10:00 AM.
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  #45  
Old 12-06-2003, 06:01 PM
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I have been blowing glass for over 15 years, and I built my wire melter to melt a higher quality of glass than is available in my invested pot furnace. And also occassionally to melt one or more pots of color.

So far the glass quality is amazing from such a cheap and easy to build unit.

With all the talk of 'porsches', 'hobbyists', and 'professionals', nobody has addressed one issue. The United States is involved in two oil wars at present, and the world is running out of cheap oil and gas.

To quote an article from The Guardian in the UK,

"The oil industry is buzzing. On Thursday, the government approved the development of the biggest deposit discovered in British territory for at least 10 years. Everywhere we are told that this is a "huge" find, which dispels the idea that North Sea oil is in terminal decline. You begin to recognise how serious the human predicament has become when you discover that this "huge" new field will supply the world with oil for five and a quarter days.

Every year we use four times as much oil as we find. The petroleum geologist Colin Campbell calculates that global extraction will peak before 2010. In August, the geophysicist Kenneth Deffeyes told New Scientist that he was "99% confident" that the date of maximum global production will be 2004. Even if the optimists are correct, we will be scraping the oil barrel within the lifetimes of most of those who are middle-aged today."

At least a porsche has a relatively small engine, and goes real fast because of good engineering.

My invested pot furnace, which is five years old, still gives good studio quality glass (even with a few one inch or larger cracks in the botton), melts 150 lbs of glass and runs on about 1200 litres of propane a month (about 320 US gallons). I also reheat out of the crown. My friend has a Correll pot furnace that melts about 150 lbs, used entirely for production work, and even with the heat recuperator, it gulps back close to twice as much propane. Frankly, I dont see the logic.

The reason the Correll furnace is more expensive to run is that it is perhaps double the internal volume because of the need to have a lot of space around the pot.

In reality, very few blowers need better glass quality for the bulk of their work than is available in a tank or invested pot furnace.

If you can get at least 8 monthes out of Kanthal A1, and you should shut down to replace the pot in eight monthes, and the elements are really cheap and easy to replace, and it cost HALF as much to run as a moly furnace or a Correll furnace, then I would directly challenge the logic of using these over-designed energy guzzling and EXPENSIVE units.

I am sure that one day not too far off, using thousands of gallons of propane or huge amounts of electricity just to make baubles for rich people will be simply outlawed.
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  #46  
Old 12-06-2003, 06:12 PM
Steve Stadelman Steve Stadelman is offline
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David, I just came back inside for a break from dumping some old mercury relays in an aquifer and I just don't understand why you seem so angry. All of the furnaces that I have either built or helped build are very very efficient.
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  #47  
Old 12-06-2003, 08:09 PM
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I am not angry. Sometimes a little exageration helps to make a point.

I have built 6 tank furnaces in my life (3 were invested pot furnaces). And now this wire melter.

If I had known years ago what I know now, I wouldnt have worked nearly as hard to pay the giant gas bills that some of my earlier furnaces sucked up.

For any glassblower that still blows their own glass, big energy bills for that "porsche" simply mean you work harder. North America consumes something like a third of all the worlds energy. Our economy is so closelty tied to oil prices that every run up in oil prices has caused a recession. To work your ass off, instead of life being easier, from the consumption of lots of energy doesnt make a whole lot of sense.

A friend of mine bought a Correll furnace. The price delivered to Canada was about $20,000 Can dollars. I built my wire melter for a little over $1000. I was originally quite impressed with the Correll furnace. The heat recouperator appeared to be almost a stroke of genius. So I was quite surprised at how innefficient it seemed to be compared to a cheap invested pot furnace, or now an even cheaper and safer wire melter.

After you mix yourself a drink from that aquifer, I would challenge you to design a moly furnace that melts 100 lbs of glass and runs on 5 KW per hour instead of 10. It probably is possible.

And further, to find a way around the strange power requirements of moly when first heated that require expensive transformers, perhaps using some type of readily available surplus part.
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  #48  
Old 12-06-2003, 09:16 PM
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well david, you leave out the replacement costs of your elements and you leave out your color bill which for most glassworkers I know starts at about 4000 dollars a year and goes up, and the cost of an assistant to heat it up, or heating it up yourself and losing about 30-50% of your daily productivity doing that instead of gathering the color from the pot.

If you aren't using the SCR for managing your power loading, you will replace a lot of elements. That will still translate into downtime I don't have. My transformer cost 900 bucks and will last the rest of my life. There is no known lifespan on the elements unless you break them yourself. I never have to worry about what I am limited in melting. My furnace gets very hot, way hotter than 2250F which will kill your elements dead and like the energizer bunny just keeps going and going. My electric bill averages 500 a month or so. This is comparable to my gas systems.
I have built wire melters in the past, mostly small ones. They are repair intensive little critters.There is no comparision between the two systems for versatility. It's a question of what you can afford and how much versatility you demand from your furnace. I want a lot.

If you really want to argue about being ecologically sensitive blowing glass is an enormous energy consuming joke on the planet no matter how you do it. No one who blows glass should claim that they are "greener" than someone else.
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  #49  
Old 12-07-2003, 12:47 AM
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Pete,

I actually agree with you on your last point! I am certainly no "greener" than any other glassblower.

However, I am trying to challenge peoples thinking. The energy bill is often an insignificant part of the overall cost on a large operation, such as Chihuly's, where as in a one person studio, it simply means you have to work harder, often making some trinket, to pay the extra costs.

If the gas bill is $1000 a month instead of $500 (mine is about $500 Can dollars), then the extra $6000 in cost for using a poorly designed furnace is an extra 600 Christmas balls at $10.00 each. Perhaps an extra week of work for no reason.

My first wire furnace was very small, ran on the power of two toasters, and melted three little pots of color. It sat on the floor and the lid rolled back and forth, using garage door rollers, so you could gather easily from the top. The lid worked so well I adapted it to my larger wire furnace.

For me, the point of the wire furnace was to use it to melt larger pots of color on occassion, and to do that at a reasonable cost.

When we live in a culture that consumes about a third of all the worlds energy, while famine is still quite common in the world, it oddly still seems easy to argue for "better" over cheaper, when better glass quality certainly isnt noticed on those extra 600 balls.

By the way, the energizer bunny died recently. That poor little guy who just keeps going and going died from too much sex.

Someone put his batteries in backwards and he just kept coming and coming.
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  #50  
Old 12-07-2003, 01:07 AM
Steve Stadelman Steve Stadelman is offline
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Well, that's what I have been saying, my moly setups run just as cheaply as the wire job that I am currently using, and the first moly one is now six years old.

The initial construction cost is higher, but the attainable temperature and lifespan make up for that.

All along, and in everything that I do I admit readily that there are lots of ways to skin a cat and lots of different needs and budgets.

Pete's uses as much electricity because it is in his words "Big Boned" I prefer to say that it has a "Nice Personality".

My 300lb design uses in the neighborhood of 4-5 mwh per month and my first 100lb invested unit idled when new at 1300 watts, my ex used more electricity on her hair.
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