Furnace build regarding moly's largely

[Lawrence Duckworth]

How's that dip stuff working out for you guys when changing pots and mollys? Is the stuff just to keep the insulation in place and If so what woild you folks think of using something like a fire blanket instead.

[Pete VanderLaan]

Jeez, we just used a 5/8th spade bit with an extension on a drill press.

[Lawrence Duckworth]

Originally Posted by Pete VanderLaan

Jeez, we just used a 5/8th spade bit with an extension on a drill press.

3.875 over! How do you live with yourself...

[Pete VanderLaan]

Well, I've learned from bitter experience that the elements are really easy to break, your math not withstanding and that IFB expand when heated ...

[Lawrence Duckworth]

..so the math is good until ya flip the switch.

Are there any recommended torque specs for the support clamps and strap connections to the mollys. I’m worried they can be over tightened and crush the tubes.

[Pete VanderLaan]

I will look in the super Kanthal Handbook but I don't recall any. Make them good and snug if that helps. Once the thing has been turned on and run for two days, go back and tighten everything again. Use the Noalox but never on the elements.

[Jordan Kube]

The elements aren't hollow Lawrence. Don't worry about crushing them.

As far as having an element made up I guess it's a personal choice. It's one less thing I have to deal with when an element goes out. It's what I recommend to people when I do installations. Why waste fifteen minutes doing it when you can do it in five? It's also a bad time to have to hunt around for stuff, clear some space, etc. You know you've got one ready to go. The blowing session doesn't have to be totally lost.

[Rollin Karg]

I in the corner of having one ready to go and all the tools necessary in one place. Just in case it breaks at an inopportune time. Let's make it as easy as possible.

[Lawrence Duckworth]

Ready for dip stuff and straps.

[Jordan Kube]

Forgive me for asking but how do you plan on getting those elements out? They look like they're completely fraxed over. I wouldn't cover any metal parts.

I agree with Jordon. Did you cut the frax out from around the top of the brick? The element would get too hot covered like that.

[Lawrence Duckworth]

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.

[Pete VanderLaan]

It is a problem. If you leave them covered they will fail very quickly - possibly in less than two weeks if you run hot at all. The clamps and the straps need to be completely exposed and air cooled if you want any life from them at all. What you are doing is great for my boat payment plan, but it offers no other benefit at all. Steve and Brent built air cooling manifold which help keep the straps cool. I would strongly suggest you do the same.

Don't ever try to cover up metal with insulation in a furnace. It usually takes just a few days for it to vaporize.

[Tom Bloyd]

Rollin Karg posted a air cooled manifold awhile back. Look in the archives it looked pretty nice.

[Lawrence Duckworth]

See what you guys think of this.

Tom, i'll look at tat tonight...thanks. (just now learning to type with my thumbs)

[Pete VanderLaan]

That seems fine to me.

[Tom Bloyd]

Lawrence, it"s under the thread "moly cooling". If I wasn't such a ludite I would link you to it,but.......

[Lawrence Duckworth]

Originally Posted by Tom Bloyd

Lawrence, it"s under the thread "moly cooling". If I wasn't such a ludite I would link you to it,but.......

Thanks Tom, I found it. Good discussion and information, great photo of the strap connections too.



Transformer showed up today........could get ugly

[Hugh Jenkins]

I have to agree, electric gets ugly really quickly!!!

[Lawrence Duckworth]

Actually....electrical work is simple. It either works or it doesnt.

[Brian Wong Shui]

Originally Posted by Lawrence Duckworth

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]

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]

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]

So do you really need a door kill switch?

Originally Posted by Pete VanderLaan

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.

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?