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Pete VanderLaan 12-12-2011 07:27 AM

First loads always go like that Lawrence. It seems like this gaping maw that you just dump 40 tons of material into and it never seems like the level rises either.
Also, glass likes glass. Without some in the pot it distinctly takes longer.

Lawrence Duckworth 12-20-2011 08:45 PM

For what its worth… finished the second 200lb. charge and this time halfway through I called larry @ watlow to see if we could speed up the recovery time. Turns out the scr was set @ 37 amps…turned it up to fifty and the temperature recovered to 2250 in 30/35 min.

The clamp temps range from 85f/140f

The little porcelain bushings are real hot…320+/-

Some spots in the cable are as high as 140f

Temperatures of the furnace sides ranges from 140f/180f

:) Peeking in the door at 2350 cooking temperature…something like staring into the SUN......

Pete VanderLaan 12-20-2011 11:52 PM

I just finished the electrical panel for a moly and I oversized all the cables. Drawing 295 amps all night, the cables , all 350 MCM were stone cold.

Fans, think fans. We installed one right on the screen of the transformer and simply put two blowers on the top of the furnace. Charlie did the heat transfer calcs and found it would have less than a 1 percent loss up there.

So, we're one percenters.

Lawrence Duckworth 03-16-2012 05:26 PM

here's a peek at the first piece of glass art out of this furnace. working on the Etsy listing now:)

Ben Solwitz 03-16-2012 06:17 PM

Awesome, everyone loves pumpkin$... see what I did there? :)

Someone around the bay area told me they made $200k on a pumpkin patch every fall.

Paul Bevilacqua 08-30-2012 12:02 AM


Originally Posted by Pete VanderLaan (Post 99649)
I just turned Charlie Correll on to lubed fiber, which if you have never used -it is really nice. No dust at all, no water, it's sprayed with lanolin and is really the best when packing fiber.

Pete, why is lanolin better than water and how do I do it?

Hugh Jenkins 08-30-2012 01:23 AM

Lanolin is slippery, water is just wet. When you heat up with wet fiber, a lot of moisture is given off. That can exclude the use of some materials like microporous. It can take days for a thick furnace wall to stop dripping. Use the lubed if you can get it.

Pete VanderLaan 08-30-2012 06:47 AM

Also, the lubed doesn't transfer heat well at all. Water sure does.

Lawrence Duckworth 09-26-2014 07:43 AM

just completed the first pot change on the 200lb moly. I found 3 air tubes partially blocked with debris….(no inlet filter at blower)...something to keep an eye on in the future.

also was able to add 20 sq. ft. of insulation to the top :)

Pete VanderLaan 09-26-2014 08:09 AM

The air cooling methodology is pretty flakey. I think that using the copper buss bar for power distribution is better and keeps those things cooler. I am rebuilding mine this fall and expect to find my insulation to be in bad shape as well.

Lawrence Duckworth 09-26-2014 01:20 PM

I’m okay with the air cooling method, its the delivery system that needs a doooo over....the air cooling system could use a bigger blower and at least a 3/4” radiator type hose and a filter.

Here’s the furnace after 3 winters use (and a little clean up). No problems other than Bussman fuses blowing.

Just finished adding a new pot, air ram to open the door and a ceiling blower to help keep the connections cool.

Lawrence Duckworth 06-14-2015 05:44 PM

a link to some of the furnace build photos I have. (scroll down a bit )

Pete VanderLaan 06-14-2015 06:33 PM

Thanks Lawrence, I think that really helps. James Burt has bought the 22.5 KW electric package from me and I'm trying to convey how that front plate works. I've advised him to get the plate and then design around it since he wants to bring the 24 inch pot out the front ( What a concept) . Mine, on the 28 inch electric package tilts back a bit on the back of that casting but presents in essentially the same way as yours. That's a great sequence, thank you.

I really will miss my moly.

I'm about to start a medium size gas unit using an 80 lb pot and two 11 inch pots for the time Scott and I will melt enamels if there is an interest.I could use it as a permanent smaller furnace as opposed to the larger one. It will use a recuperation system Charlie Correll is building. I'll do it from the first weld if there is an interest.

Otherwise I'll just build it.

James Burts 06-15-2015 09:50 AM


Those pictures are terrific! Thanks for posting them.

As Pete mentioned, I'm going to be taking on a build of a moly furnace, and have been having trouble visualizing some of the casting that Pete has been recommending. Seeing your furnace helps considerably!



Originally Posted by Lawrence Duckworth (Post 124422)
a link to some of the furnace build photos I have. (scroll down a bit )

Lawrence Duckworth 10-26-2015 09:19 PM

here's my high tech soft start controller bungee cord

Michael Ahlefeldt-Laurvig 10-31-2015 02:36 PM

That looks real good- great

Lawrence Duckworth 03-03-2018 10:22 PM


Originally Posted by Lawrence Duckworth (Post 124422)
a link to some of the furnace build photos I have. (scroll down a bit )

This is a link to some of my moly furnace construction photos. I’m deleting this page from my site soon, so if this has any value to anyone feel free to copy it before I remove it.👍

David Russell 03-03-2018 11:28 PM

That some nice work Lawrence my hat is off to you.

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