Mini electric kiln project

[Mark Reich]

You are certainly welcome, Mr. Jan.

I have been thinking of your small kiln, which you probably would use to HT one blade at a time.

As long as you place the elements equally, you could probably get away with just putting them on the walls, but the closer the elements are to the blade, the less I like things.

Mainly, as long as you don't put elements across the back wall (which is nothing but an easy way to run a circuit), I think it would work.

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here is another link  http://www.duralite.com/store/scripts/pr...roduct=108   they have elements in stock , a 115v 1600watt is $29.  these folks and Joppa Glass also sell all the connector, rods, insulators, and such to make a kiln.

Mark:
For my second furnace I looked at lab furnaces rather than modified pottery kilns.  i found a used one of these with controller https://www.lindbergmph.com/light-indust...ox-furnace  for a very low price.  has elements top, bottom, and walls.  the elements are embedded in special compound so they are not exposed to the air and can't flex.  works fine.  just need it to get above freezing here so I can go to my shop and use it.

Hello Mr. Scott, and Thank You Very Much for your input around here lately! Great appreciation, and much respect for your words.   

Very interesting type of industrial oven. I haven't heard of such thing, so please feel free to take some pictures and tell us more about it! Yikes! It gets REALLY hot! 

I would imagine lab furnaces are normally way  expensive, so congrats for acquiring one! 

What are the inside dimensions? Do you do one blade at a time? How do you hold your blade in place? Does it have coils on the back wall, and if so, are there coils on the door too? 

The website doesn't show much, but I'm going to punch in some numbers and see what else I can find out, like price, for one thing...

Thanks again, and I'm sorry that I don't think I've said, Welcome to the Forum, it's great to have you here! 

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Hmm. I don't know why my posts seem to have been conjoined...

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Testing.... I tried hitting the "New Reply" button, which I don't normally do....

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WTH?

Assistance in the techy isle, please, I've forgotten how to post...

[Jan]

Mr. Mark, thanks for your additional input.

The dimensions of my chamber are not fixed yet. My intention is to be able to work with two blades at a time. Do you think I can put one blade over the other using some ceramic separators?

I understand your worries about blades positioned very close to the elements, because the temperature field may not be uniform there. 

Because my kiln will be very narrow I do not plan to heat from the ceiling or from the back wall. It is not wide enough (only 3") for one heating loop. To get the temperature even along the whole blade length (10-12"), I consider to make the chamber depth larger, say some 15". In this way, I hope, the lower temperatures near the doors and the back wall could be compensated.

Jan

[scott.livesey]

the lindberg 51442 I have is 7.5x5.25x14 inches inside.  the elements are in sides, top, and floor.  i do one blade at a time. the time at temperature for O1, O2, O7, or 52100 is so short, it is easier for me to do one at a time.  I think new this furnace is $6000 and a controller is $3000 to $5000 depending on options.  I bought the furnace and controller from an electronic salvage firm for less than $100 and since the business was on my trip route, I didn't have to pay shipping.  bargins are out there on eBay and other sites if you look daily and are patient.
to hold the blade inside the furnace I have pieces of stainless angle iron with slots cut.

[Jan]

Mr. Scott, thanks for sharing your experience. It is very important for me now, esp. your info that you harden your only one blade at time.

Your Lindberg is top laboratory furnace with special refractory plate heating elements.  I cannot believe your price. I have paid some $80 for a box of 20 special insulating bricks. Next on my budget is the Kanthal wire and an inexpensive controller for some $75.

Jan

[admin]

In this post, http://bessex.com/forum/showthread.php?t...62#pid1962 Mr. Mark stated,

“Hmm. I don't know why my posts seem to have been conjoined...
________________________________________
Testing.... I tried hitting the "New Reply" button, which I don't normally do....
________________________________________
WTH?

Assistance in the techy isle, please, I've forgotten how to post...”

WTH is the correct question!    I have noticed the same thing, and currently don’t understand exactly what is happening.  It seems to be related to how much time has passed between the original post and the following post.  If the period between the two posts is short, the following post will be appended, but if the period between the two posts is longer a new post is created.

Mr. Mark, I’ll check it out and let you know.

[admin]

If a poster replied to their own post, without an intervening post by another author, within a 60 minute period the two posts by the same author would be merged.  

This behavior has now been disabled.  Replying to your own post should now always create a new post.

[Mark Reich]

Thank you kindly for the explanation, Mr. Admin.

[grepper]

I'm glad you finally got around to fixing that Mr. admin!  Personally I found it to be annoying when my posts were merged.

[scott.livesey]

Mr. Scott, thanks for sharing your experience. It is very important for me now, esp. your info that you harden your only one blade at time.

Your Lindberg is top laboratory furnace with special refractory plate heating elements.  I cannot believe your price. I have paid some $80 for a box of 20 special insulating bricks. Next on my budget is the Kanthal wire and an inexpensive controller for some $75.

Jan

one blade at a time just works best for me.  O1, O7, and similar steels only require 10 minutes or less at temperature to harden, I do not pre-heat.  hardening is a function of temperature and time.  it takes 2 minutes to quench and clamp a blade.  If I did 5 blades at once, blade 5 would be a temperature almost twice as long as blade 1, which can effect grain size and quenched hardness.
I bought the furnace from an electronic salvage house, imagine dozens of  4'x4'x4' boxes overflowing with keyboards, displays, cables, and laptops.  I guess that did not know how valuable the item was and just wanted it gone.  
I posted links to several places that sell Kanthal elements already coiled, it should save a lot of time over having to make your own coils.

[Jan]

Thanks Mr. Scott, now I understand better why you harden one blade at a time despite the fact that your chamber is large enough to do five blades at once.  

In my understanding your furnace has a large reserve in the installed heating power, 4 kW I guess. What time do you need to heat the furnace to 1650°F?

I have visited your links to Kanthal elements and found many inspiring things there. My problem is that I live in Europe and not everybody is ready to ship over the pond. Shipping costs and custom fees also often lower the profitability.

Many Kanthal heating coils are offered here for prices lower than the price of good quality Kanthal A1 wire necessary to coil them. I am afraid they are not made of quality wire.

Even more I have derived a formula for Kanthal wire diameter, which will support the requested Watts and respect the typical wire loading (max. 18 Watts/sq inch), and I would like to test it.

Jan