Oven Build

colu41

colu41

Joined
Dec 24, 2014
Messages
1,598
So I pretty much am set with everything. Wiring is nearly done. Just need to put the coils in, and assemble the refractory walls, and attach the control box BUT. Anyone have tips on how to attach the coils inside the walls? They fit very nicely into the routered grooves, but they dont stay in them. I was hoping they would sort of snap in but, that was a pipe dream. I've heard of people using Kanthal staples. Which I have a ton of kanthal wire left but, I'm afraid of that shorting out the elements.

Any tips?
 
The wire is resting against the firebrick when it is operating. The staples won't short it out.
 
You just make a u shape and staple the element into the brick

Don't go through the brick into the case
 
colu41 said:
I'm afraid of that shorting out the elements.
Click to expand...

I'm concerned you may not know what that means. Shorting the elements to what?

Kanthal staples work ok. Use a lot of them. I assume you've stretched the coils so they won't move around too much at temperature. You really don't want the coils moving enough to touch each other.
 
Make the staples about an inch long and with a tight radius at the bent U-end. I make them out of thinner Kanthal (or Nichrome) than the elements themselves, because it's easier, I have the wire and it reduces the chances of shorting out a coil. I use long-nose pliers to push them into the IFBs and they only hold the brick side of the coil.

If you get the U narrow enough and have enough stretch on the coil, there is no significant risk of the staple shorting a turn of the element. Using the thinner staple wire obviously helps.
 
timgunn1962 said:
Make the staples about an inch long and with a tight radius at the bent U-end. I make them out of thinner Kanthal (or Nichrome) than the elements themselves, because it's easier, I have the wire and it reduces the chances of shorting out a coil. I use long-nose pliers to push them into the IFBs and they only hold the brick side of the coil.

If you get the U narrow enough and have enough stretch on the coil, there is no significant risk of the staple shorting a turn of the element. Using the thinner staple wire obviously helps.
Click to expand...

Ok. Any suggestions on how I can put a staple in the refractory? I wish I had fiber board for the element walls but its rock solid refractory.
 
With IFB, the staples just push in. If you've got hard refractory, I can't see them going in at all, but it's not a good material for the job anyway: 2300 IFB will take even the highest "normal" HT temperatures and insulates pretty well. Hard refractory is a lousy insulator and has lits of thermal mass. Heat-up will take an age. I can't really see any reason to choose hard refractory over IFB. Most of the insulating refractories I've encountered will also take staples.

I've thought about using fiber board, but the idea of routing grooves in it with my limited dust extraction capability is outside my comfort zone. YMMV.
 
timgunn1962 said:
With IFB, the staples just push in. If you've got hard refractory, I can't see them going in at all, but it's not a good material for the job anyway: 2300 IFB will take even the highest "normal" HT temperatures and insulates pretty well. Hard refractory is a lousy insulator and has lits of thermal mass. Heat-up will take an age. I can't really see any reason to choose hard refractory over IFB. Most of the insulating refractories I've encountered will also take staples.

I've thought about using fiber board, but the idea of routing grooves in it with my limited dust extraction capability is outside my comfort zone. YMMV.
Click to expand...

The refractory I got for free. And it's used at a company that produces carbon inside of reactors that reach 2500-3000°. Why wouldn't it work?
 
colu41 said:
The refractory I got for free. And it's used at a company that produces carbon inside of reactors that reach 2500-3000°. Why wouldn't it work?
Click to expand...

If it's not soft and crumbly it's the wrong stuff. I made the same mistake. Even if you solved the coil mounting issues you'll never get it up to temperature. Though you somehow routed it for coils right? A pic might help clear this up.
 
There are two types of firebrick: hardbrick and softbrick. Hardbricks are very dense and durable and used for their structural qualities. They can be found most often as the main building component of large kilns, chimneys, fireboxes and burner ports—any- where around direct flame. Softbricks are lightweight and made from a refractory clay body containing combustible materi- als. When fired, the materials burn out leaving a sponge like matrix of air pockets, which serve to provide insulating qualities to the brick. Also known as insulating fire- bricks (IFBs), these bricks absorb about half the energy as hardbricks during a firing. Softbrick range from 2000°F to 3300°F and are used as the brick of choice for con- structing electric kilns or as insulating liners in reduction kilns.
 
colu41 said:
The refractory I got for free. And it's used at a company that produces carbon inside of reactors that reach 2500-3000°. Why wouldn't it work?
Click to expand...

When I built my oven I purchased JM28 bricks used for the highest temps, longstory short, I ended replacing them by Morgan Thermal Ceramics K23. The ones I used first where made for high temps but they absorved a lot of heat instead of reflecting it back to the chamber, this resulted in a very slow oven.

You can look at the photo gallery here http://imgur.com/a/7IUCe the first bricks where white, the ones I ended using where creamy and chalky in their texture. And for the keeping the coil in the grooves, look for the photos, mine had a M shape and couple of years later they still do their work fine.


Pablo
 
This is a classic example of why we recommend reading and studying a ton of info until you COMPLETELY understand a new concept before starting any build. Just posting all your plans and materials would have saved you a lot of heartache.
 
Pablo, what a GREAT job of building an oven. That is real craftsmanship. I saw the chart showing 1000º reached in 21 minutes (rounded off time) - was that ºF? OR, ºC? ºF is still faster than my Everheat oven will do, and if ºC it's phenomenal!!! BTW, your work on drawing up plans in 3D sure are nice - what program did you use? What wattage (amp draw) are the coils? This is 240VAC?

One other question, what prompted you to use the "drop down in front" style of door as does the Paragon vs the "swing to side" door style as does the Evenheat oven?

Again, GREAT WORK!!!

Ken H>
 
Well, at least no money was lost. Just a little time. I actually grooved the coil paths while the refractory was still still setting. In the process of ordering some IFB now.
 
Ken H> said:
Pablo, what a GREAT job of building an oven. That is real craftsmanship. I saw the chart showing 1000º reached in 21 minutes (rounded off time) - was that ºF? OR, ºC? ºF is still faster than my Everheat oven will do, and if ºC it's phenomenal!!! BTW, your work on drawing up plans in 3D sure are nice - what program did you use? What wattage (amp draw) are the coils? This is 240VAC?

One other question, what prompted you to use the "drop down in front" style of door as does the Paragon vs the "swing to side" door style as does the Evenheat oven?

Again, GREAT WORK!!!

Ken H>
Click to expand...

Thanks Ken, I have a fully commented WIP on another forum (mistakes included), if its OK with Stacy I can repost it here.
I used solidworks and all my readings are in C

Pablo
 
PEU said:
Thanks Ken, I have a fully commented WIP on another forum (mistakes included), if its OK with Stacy I can repost it here.
I used solidworks and all my readings are in C

Pablo
Click to expand...

Very impressive! I'd love to see that WIP
 
WOW Pablo - 1,000 ºC is over 1800ºF in only 21 minutes? That's a FAST heatup. I wish my oven was that fast, but I'm sure it pulls several amps. Great work - feel free to PM a link to the WIP. I'll let Stacy comment on posting a link (OR full WIP).

Ken H>
 
I would also like to see the WIP. Could definitely help me get on the right track here.
 
Im posting it right now, only one post to go :)


Pablo
 
You must log in or register to reply here.
Back
Top