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-   -   Furnace build thread (http://talk.craftweb.com/showthread.php?t=7292)

Brian Wong Shui 04-19-2011 09:37 AM

Quote:

Originally Posted by Lawrence Duckworth (Post 96053)
There is one inch of insulation covering the ceramic/metal clamps. In the duckbill photos I have it appears to me to be covered in dip also... Its not a problem to cut the insulation out of the way if you guys think leaving them covered is a disadvantage.

Lawrence,

It isn't covered. The frax is right up to the edge of the brick. We use diplag to hold everything together. Cool the elements. Don't bore the bricks too tight. Things expand.

--Brian

--Brian

Lawrence Duckworth 04-19-2011 10:58 AM

Thanks Brian
I reamed the brick with a half inch all thread rod to give some breathing room....might have been over kill

Pete VanderLaan 04-19-2011 07:14 PM

You have to make sure that the clamp is tight though. I had an element slip through the clamp on my first furnace and it dropped down and touched the pot. That proved to be pretty exciting when I had been gathering all morning and saw the contact. That furnace did not have a door kill switch. Nothing happened. You just don't conduct below 50 volts.

Kenny Pieper 04-19-2011 08:05 PM

So do you really need a door kill switch?



Quote:

Originally Posted by Pete VanderLaan (Post 96110)
You have to make sure that the clamp is tight though. I had an element slip through the clamp on my first furnace and it dropped down and touched the pot. That proved to be pretty exciting when I had been gathering all morning and saw the contact. That furnace did not have a door kill switch. Nothing happened. You just don't conduct below 50 volts.


Julian Duerksen 04-19-2011 08:21 PM

pot height
 
I am replacing the pot in my #300 molly and I am wondering what the best height is for the pot in relation with the rim to the sill. Previously the rim of the pot was about an inch bellow the sill. With the bricks I have I can go with two inches below the sill or with the lip of the pot almost level with the sill. Will it be harder on the pot the closer the rim is to the sill and the elements? How close can the elements be to the rim of the pot?

Pete VanderLaan 04-20-2011 06:46 AM

I would never advocate for not having a kill switch ( what an appropriate name for it). I am simply telling you what happened to me when I made contact with the crucible while it in turn was touching the element live. There is such a thing as liability.

On my existing furnace, if you open the door far enough, it makes the kill switch roll over and the furnace goes live again, which I find useful in my continuing mistreatment of this great tool. I was over at Josh Biernbaums studio in Vermont yesterday and was amazed to see how clean his moly is. Mine on the other hand has crap all over it, a sticky door, and generally looks pretty trashed, sort of like the rest of my shop. Josh's is pristine.

As to the crucible, I don't like it getting closer than one inch from the lip. I do think that the torch heat up through the clean out will help enormously on any size pot.

I really have to clean up that glass I spilled in December...

Lawrence Duckworth 04-20-2011 11:07 AM

Well I'm in a holding pattern till I get an electrical parts list and a plan of attack .

I ended up using a fire blanket to cap the insulation. Hope it works,, they have a melt temp of 1000

Oh yeah, I did put another quarter turn on the clamps:)

Lawrence Duckworth 04-22-2011 07:18 AM

Quote:

Originally Posted by Julian Duerksen (Post 96112)
I am replacing the pot in my #300 molly and I am wondering what the best height is for the pot in relation with the rim to the sill. Previously the rim of the pot was about an inch bellow the sill. With the bricks I have I can go with two inches below the sill or with the lip of the pot almost level with the sill. Will it be harder on the pot the closer the rim is to the sill and the elements? How close can the elements be to the rim of the pot?

Based on the drawings I've seen there should be a brick or something to elevate the pot, but that would put mine too high so I spread a bit of sand under t o lift and help hold it from rocking . I'd say the pot is about an inch below the sill.

Charles Friedman 04-22-2011 10:59 AM

Quote:

Originally Posted by Lawrence Duckworth (Post 96122)
Well I'm in a holding pattern till I get an electrical parts list and a plan of attack .

I ended up using a fire blanket to cap the insulation. Hope it works,, they have a melt temp of 1000

Oh yeah, I did put another quarter turn on the clamps:)


Lawrence, That top looks beautiful, outstanding job on the whole build!

Would using a torque wrench be of use at this point?

Lawrence Duckworth 04-22-2011 08:22 PM

Thanks Charlie, but itz a bit to early to be celebrating the furnace….needs to get wired and melt some glass first.
So far though its been good and from building this thing its become purdy clear that a lot of thought was given to the design....so ya gotta kinda tip yer cap to the cat that did the castings, design and development work on these things.

Btw I tried finding torque specs on the clamps but couldn't.. so I decided to just tighten them till i heard the ceramics start to groan :)

Scott Novota 04-25-2011 03:41 PM

Lawrence,

I find your whole journey very interesting. From the building to the equipment it has been fun to watch.

I am sure everyone here, even those that think you might have done it anouther way here or there, will be toasting your success come opening day.

Always looking forward to your next set of pictures. All the best and I hope everything fires off without a hitch.


Scott.
.

Lawrence Ruskin 04-25-2011 04:10 PM

Where do you get that dip lag stuff?

A search of the archives turns up zilch.

Pete VanderLaan 04-25-2011 04:53 PM

EG Bartell Seattle.

Lawrence Ruskin 04-25-2011 07:10 PM

Thanks for the help...

Lawrence Duckworth 04-25-2011 07:52 PM

Quote:

Originally Posted by Scott Novota (Post 96237)
Lawrence,

All the best and I hope everything fires off without a hitch.
.


thanks Scott,...me too:)

Lawrence Duckworth 04-27-2011 07:37 PM

Question....

The castings I have, have just one hole for the thermocouple. All the pictures that I have show two, presumably the second is for a temperature limiting device. My question is is there a device that does both and that’s why there is only one opening?

Rollin Karg 04-28-2011 04:27 AM

It's possible to have two thermocouples in one tube. Talk to these people and ask for Richard Roberts.http://www.precision-measurements.com/

Lawrence Duckworth 04-28-2011 07:13 AM

Good idea. Thanks Rollin.
Looks to be about an inch dia. hole.

I'll give him a call

Pete VanderLaan 04-28-2011 10:05 AM

Be prepared for serious sticker shock. Don't succumb to the temptation of getting a finer than 22 gauge platinum wire. It's just too damn delicate and you'll break it looking at it. . Get a spare thermocouple protection tube while you're at it and inspect once a year. They melt eventually. You can get by with type "s" on the thermocouple type. When you set up your controller make sure it's programmed for type "S". You get lots of choices.

Lawrence Duckworth 04-29-2011 01:27 PM

$856.00 for type s or $27.50 for a type k.......They don't give those watlows away either.

(And to think I could have had a new set of clubs and a membership at a cheap course.)

Jordan Kube 04-29-2011 04:04 PM

Wait till you figure out the cost of operation.

Larry Cazes 04-29-2011 05:15 PM

Quote:

Originally Posted by Lawrence Duckworth (Post 96346)
$856.00 for type s or $27.50 for a type k.......They don't give those watlows away either.

(And to think I could have had a new set of clubs and a membership at a cheap course.)

Membership? That is truly a cheap course :)

Pete VanderLaan 04-30-2011 05:25 AM

Well, the signature hole is being rebuilt right now so it's discounted. The nose on the clowns face needed some termite damage repair and the mouth needs sanding from all the misplaced putts.

Lawrence Duckworth 05-07-2011 07:36 AM

Here's the transformer. About $1,800.00 dilivered but that might eventually work out because of the less expensive controls and power savings down the road.

Judd, from watlow will be here tuesday to help work up a control system and pricing....

Lawrence Ruskin 05-09-2011 12:55 PM

So I'm still looking for a small amount of ''dip lag''

At Bartells you have to buy a whole box for $550.

Any more ideas?

Does dip lag have another name? Is it rewettable cloth or something like that


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