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Thread: Making a Heat Treatment Oven
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22nd Nov 2013, 04:21 PM #16
I spent some time this arvo ringing around asking about bricks. Seems I can get plenty to line my wood fire or make a pizza oven......the name isolite just confused them.
I was also just looking at kilns on eBay, there are a few about but the sizes are really all wrong for what we do.
I'm thinking I might make a small one first that can become a tempering oven, just so I can het my head around the design. Also to see if the blanket in really needed or not, I like the sound of putting the bricks in an oversized box and filling the voids with vermiculite.
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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22nd Nov 2013, 04:29 PM #17Member: Blue and white apron brigade
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The loose fibres can be bound to the board using liquid rigidizer. This is a colloidal silica suspension sprayed on and dried that when fired sticks the loose fibres back to the board. It is quite expensive (~$30/L) but it goes a long way. I used about 500 mL to do my forge and I have plenty left over to undertake follow up repairs.
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22nd Nov 2013, 07:45 PM #18Senior Member
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Hi Ewan. Have you seen this for commercially done ideas? Ceramic Kilns, Glass Kilns, Pottery Kilns and Many Other Specialty and Custom Kilns 1
Gameco in Sydney bring them in; Australian Knifemaking Blacksmithing Materials and Tools | GAMECO
Corin has valuable advice on materials to use and where to get them.
IIRC, Field Furnace Refractories in Sydney (Wetherill Park) are the go for us.
enjoy,
AndrewOC'Waratah' spring hammer by Hands & Scott c.1911- 20, 'Duffy, Todd & Williams' spring hammer c.1920, Premo lathe- 1953, Premo filing machine.
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28th Nov 2013, 11:08 AM #19
Thanks Andrew,
Good to have a supplier with prices online to give me a rough idea of what i'm up for.
So far this is what i'm looking at, comments appreciated!
Controller, JLD634 Ramp/Soak PID Temperature Controller for FURNACE KILN OVEN. 64 set timer control
Thermocouple, Type K Thermocouple Block Ceramic Kiln Probe Sensor 2372°F 11G Cone Temperature | eBay
Terminal blocks, but not sure whether it would be better to do what Ray did? High Temperature 2 Pole 15Amp Terminal Block Connector X 2 Heat Resistant 550OC | eBay
Wire, Heat Resistant 2 5mm Fibreglass Wire Cable High Temp Cater Spares 5 Meter | eBay
Heat shield for wire, Gantry Light High Temp Heat Proof Sleeving 500 DEG PER Meter Black OR White | eBay
As for Elements i was just going to go for a cheap Kanthal A1 like this, 3000W 31 5" Kanthal A1 Heating Element Coil Heater Wire Nunal | eBay
I can run the 3kw off a 15A outlet.
My internal dimensions are looking like 460x190x155 or there abouts. 3kw should be more than enough, if i've calculated it correctly that is. I am wondering though if it would be better to go with 2 1500w elements wired in parallel, one for each side of the kiln? Saves having to cross over the back wall.
And of course a cheap ebay SSR and heatsink (although i may have something already in my bits box)
I need some Rope seal too, all the ones i can find only seem to go to 1000degC.
I think thats about it (except bricks and mortar of course!)
Cheers,
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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28th Nov 2013, 11:16 AM #20
Some interesting details here, click on the "construction" tab
Heat Treat Standard
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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28th Nov 2013, 11:36 AM #21
Hi Ewan,
List looks ok, you probably don't need the ceramic terminal blocks, since the TC comes with a terminal block already. But you'll need some high temperature crimp terminals to terminate the kanthal elements.
6mm Heat Proof Resistant High Temperature Eyelet Ring Crimp Terminal Crimp Part | eBay
Regards
Ray
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28th Nov 2013, 12:40 PM #22
Hi Ray,
I was thinking of using the terminal blocks for the element, rather than the way you did it with the crimp terminals.
In the end did you just double up the element where it went through the bricks and out? Halving the resistance should more than halve the temperature of the wire shouldn't it?
Cheers,
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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28th Nov 2013, 12:55 PM #23
Hi Ewan,
Yes, you double up the Kanthal as it goes from the slots inside the furnace, to the terminal strips on the outside, you could put a heat shield and allow for some air circulation around the terminals, check the plating used on the screw terminals used in those ceramic connectors, I found the tin-plated copper ones just vaporized... the nickel plated steel ones are better.
But the wire you are getting is only rated at 200C so you'll definately want to make sure you can get cooling into the terminal area, so maybe it won't be the problem for you that it was on mine?
Regards
Ray
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28th Nov 2013, 01:54 PM #24
Hi Ray,
I figure since the crimp terminal is rated to 500deg and the ceramic terminal block rated to 550deg it should be fine.
Can you point me in the right direction for the high temp wire you used?
Cheers
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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28th Nov 2013, 02:47 PM #25
Hi Ewan,
I used MGT wire from these guys 12 High Temperature MGT Electric Wire Heaters per Foot 1000°F 600V Ovens | eBay
It's nickel plated copper wires with mica layers and fibreglass braid. MGT High Temperature Wire
Probably overkill for this application..
Regards
Ray
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