Need HT Furnace Info

C

Cooter DeGraw

Joined
Jan 13, 2005
Messages
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I plan, in the near future to take a step up in my knife making and buy a HT furnace. I am leaning toward the 18.5" Evenheat at this time. I have one seemingly dumb question to ask---Are there hazards involved with removing a blade from the furnace with the power still on? Is there a possibility of electrocution if there is contact between the blade and the heating coil while doing this? Thanks, Cooter
 
Not sure about the commercially built ovens, but I'd think there would be a safety so that when the door is opened the power to the elements is switched off.

I built my own oven, and if I don't kill the power to the coils before opening the door, they are live and unshielded. I always turn the master power off prior to opening the door to remove/insert a knife.

--nathan
 
Paragon has a switch in the door to turn off power when open. I do not believe the Evenheat does; my 5 year old Evenheat doesn't, at least.
That said, you'd have to be a real klutz to hit the coils in the large chamber of an Evenheat.
 
Maybe that wasn't such a dumb question after all---Better to play it safe and cut the power--I have been witness to some of the horrible results of industrial electrical accidents
Thanks again, Cooter
 
Thanks for asking the question Cooter. I've been scrambling for an answer. On Evenheat Kilns (and I presume others) the elements are live and should not be touched when inserting or removing blades.

The recommendation is to turn off the power switch when handling blades. When turned on again, the program should continue from where it left off if you still have more blades in there.

The kiln can be provided with a door switch, but at $80, the option is seldom selected - and the main switch is used instead.

I wasn't aware of any of this, so I thank you for asking. I'm quite sure I have inadverntently touched coils with a foil envelope. So why am I still here? I suspect that between gloves, insulated handles on my long pliers, and shoes on my feet, I am not even close to the path of least resistance to ground. Having said that, I will turn off the switch in future.

Rob!
 
I am not too sure of any real danger in touching the elements. You won't get electrocuted by touching the element on a common kitchen range. They are in regular contact with metal pots, ect. Why would there be a difference? Besides, as was mentioned, the elements are out of the way. You would almost have to touch the Evenheat element on purpose. They are well recessed in the side walls. Has anyone heard of such an incident happening? I doubt it. If it was of great concern, Evenheat would have to do something about it, or risk lawsuits.
 
The Sugar Creek ovens also do not have a turn off. I just take the blades out and close the door asap. I'm more worried about exposing the elements to cool air than getting shocked. I've never had an issue hitting the elements.
 
Stove elements are insulated and so are safe. Kiln elements - mostly used for pottery - are in an environment where the door is normally opened when the cycle is complete. (Power off) Stick a knife in your toaster to see how live elements react. You kiln is one powerful toaster. Treat it accordingly.

Rob!

(In case it needs to be said - and it probably does - I am not really suggesting you stick a knife in your toaster. Please don't)
 
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Yeah, no shielding around kiln elements. They are live, usually at 220V (depending on your model), making for a bad day if touched.

--nathan
 
Unless you suffer severe shakes, taking a knife out should not be a problem??
 
It SHOULDN'T be a problem, but there's this fella named Murphy who shows up at the absolute worst times. For instance, let's say you use your trusty oven tongs or long reach plier, etc to grab your blade, and for whatever reason, your blade shifts as you're removing it from the oven, maybe tipping up to graze the elements. Maybe you want to trust the dipped on rubberized handles to insulate you, but I don't.

Better safe than sorry, even if sorry happens (or doesn't) way down the road. I'm not questioning anyone's safety or competence, but just because you don't plan or having a car accident doesn't mean you shouldn't wear your seatbelt. My chances of getting bit by a great white off the coast of Hawaii are slim to none, but on my honeymoon, I'm staying my white-tastes-like-chicken-yum-yum butt out of deep water. :D

--nathan
 
When I built mine I mounted a push sw (only on when pressed) on the oven and a thread piece of angle on the door. I threaded a 1/4" bolt in the angle and it is adjusted so when the door is closed it presses the sw. I connected the switch on the wire running from the PID to the SSR. When the switch is allowed to open it shuts down the SSR and turns off the elements. I am sure you could do exactly the same thing with a commercial oven for less than $10 . You touch a blade or some foil to a live 22o while you or the blade are grounded to the ovens frame or case and your NOT GOING TO LIKE IT.
Basic oven wiring

power to SSR (or a relay contact set) and one side of element. The SSR (or relay)is really a electrically controlled switch that needs a signal to turn on. That comes from the pid. The pid have a power in and also reads the temp from the thermocouple. When the themocouple reads low the pid sends a small voltage to the ssr and it turns on the element. The pid should have 2 wires to the ssr. One is negative. It doesn't matter which of these wires has the push switch on it. Either will shut the ssr off or on. BTW SSR stands for Solid State Relay. It is a relay with out mechanical contacts.
 
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