heat treat oven help

JTknives

JTknives

Joined
Jun 11, 2006
Messages
8,651
im going to be buying the kiln thats forsale in the forsale page. it takes a little while to come up to temp. im wondering if its posible to replace the elaments as there not exposed. its a kerr 900 any one know where i can look to get info on this. my first oven, i just need it to hit 1525ºf for 5160 and when i get a evenheat or paragon it will be my tempering oven. any help would be great. it hits 1425 after heating 1hr, would there be any way to get more heat. i will do knives in batches. thanks
 
i did come across somthing that said it was a muffle burn out kiln. and to get a new muffle is 565.00, what is a muffle.
 
Those are dental/jewelers burn out ovens. They usually operate in the 1250-1350F range. They are slow to come up to temperature, but should reach 1500F and hold it. Most have a top end rated at 2000F, but it is hard for them to go above 1800F.
The chamber is a complete unit with the coils in the walls. It is changed as one piece (Thus, the $565.00 price)
Stacy
 
JT - if u r 2 spend anywhere close to $100, just make yer own - proper size and dynamics.

Again:

- 20 bricks @ $3 per (can prolly find em cheaper locally)
- 30A SSR - $5
- PID controller - $40
- 1 Kanthal spiral - $20
- 1 Ktype shielded tcouple: $25
- make your own exterior from some sheet metal and angle iron
-----------------------------------
~ $200
 
i did not know it was that easy, any good places for instructions on building one.
 
If you can, lookup some of my old posts on DIY oven. Being a lazy bum, my enclosure is nearly not as nice looking, is a top load with a "lid" cover but it works just fine.

Don't go over board with internal dimensions, but do make sure it is _long_ enough.

To hold the bricks, use "High Temp Mortar" from yer Lows/HD - a tube is something like $4, you'd need 2 of them. The thing is in a regular caulk tube, in caulk section. Black, thick, almost like a shoe polish in appearance.
 
JT
I had one of those Kerr 900 and it worked fine for lost wax burn out.
I used it to heat treat blades for quite a while . It took close to 2 hours to come up to heat. Then if you opened the door you had another halt to 3/4 hour wait again. The elements are in the walls and there isn't much you can do. I built the one in British Blades for about 300$. It gets up to 1500 degrees in 10 min.
It's a good oven. I would reccomend using 3 inch thick bricks and welding the frame. I never drilled so many holes for pop rivets in my life.
Take Care
TJ
 
My electric oven broke last Saturday. I am in process of making new one. I can not figure out how to make it cheaper than $300-$400.
Kanthal is $135(proper gauge and for 4 elements.
Kaowool - $100 to make it well insulated.
PID controller with ramp\soack programming capabilities $100
TC type K - $20-$50
And I will use crushed old refractory with some fresh clay to make the refractory core. If I would buy new it will be another $50.

And what I plan to get is just 1500W that will ramp to 2000-2200 in about an hour -hour and a half.

Sorry guys, but cheaply made is working cheap. Got it from my own experience.
 
Dimitri - I paid $15 for 50' of Kanthal to spin my own. (Ok, actually it was $45 for 150'). To make a 1500W element, it would take less than 50'. The same outfit sells prewound elements for far less than the $135 you're paying.

I'm not sure where you're buying the kaowool from, but $100 sounds like a lot of insulation to me. Even doubling up on 2" thick inswool from Darren Ellis would put me at less than $100 for an oven that runs 1500 watts. The bricks that have been suggested are the ones in use by EvenHeat, Paragon and Sugar Creek. The Sugar Creek is the slowest of all on the 120V model, running about 90 minutes to get to 1950 with a 1500W element.

Your controller price sounds fair for a ramp/soak controller.
 
Dmitry _is_ crazy ! :)

No need for kawool - the bricks are all one needs. I bought a spool of Kanthal and wind my own spirals (~$50 min order) but you can buy just one pre-made spiral.

There's no need for ramp/soak IMO. You can get a decent PID controller for $40:
http://search.ebay.com/search/search.dll?from=R40&_trksid=m37&satitle=pid+controller&category0=

Then you need an SSR:
http://search.ebay.com/search/searc...32&fsoo=2&fgtp=&sadis2=100&fpos2=07070&lsot2=

20A is all you need. May be 25A

Tcouple is $25 from Omega or you can ebay for it. You need inconel-shielded K-type.


On power: if you can, go for 15A @ 240V. With internal dimensions of something like 18" long by 4 tall by 4 wide it will be mighty
fast oven and compact enough not to take much space.
 
I use 14ga wire. My calculations showed I need 2.9lbs of wire to get 4X10 Ohm heating elements that will go in a bridge connection.
I got a full roll of Kaowool for about $350 and I would use at least 1/3 of it to insulate the muffle. My experience shows that 3" of Kaowool is good to keep outside shell within 200F range. I would like to have it even colder.
My wiring is limited to 15 amps, so I have to stay with 110V and 15amps for now at least.
I am not forcing anyone to accept my piont of view. Just described my case.

P.S. It is no need for ramp\soack FOR YOU. I need it.
 
My oven's exterior stays warm to the touch even when firing to ~1900F .
I think I used some silica insulation between the bricks and exterior -
2 feet of mcmaster PN 93435K16 (page 3423 on http://www.mcmaster.com/) .

But again, you don't have to :)

http://groups.google.com/group/rec....b61b309867966bd3?q=home+made+oven+kiln&rnum=2
http://www.knifeforums.com/forums/showtopic.php?tid/752668/
http://www.bladeforums.com/forums/archive/index.php/t-473691.html
I do recommend reducing the current from 20A toward 15-16A, to make sure the spiral last a loooooong time. 20A is too brutal :)
 
Hi Dimitri, I'm calculating just over 45' to spin a 120V/1500W element in 14Ga. wire from Duralite, which will run you $15 plus shipping. A single 115V 1600W element from them would run you $16 and a 240V/1800W element from them would run you $18. Of course, there are other wattage options as well.

http://duralite.com/store/scripts/prodList.asp?idCategory=42

I ordered 15Ga wire from them for my elements, but spoke with them first to make sure it can handle my wattage. If you call them, you can verify the wire size you need.
 
I am F***ed... Those ready to go elements would be cheaper than I ordered. 16X4 plus shipping. Almost twice as cheap.
Well... I payed for my ignorance and stupidity.
 
Newbie question. What are the advantages of this kind of oven compared to a small counter top regular electric oven?

Sorry if this is a stupid question.

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