This mission has been on my to invent listing for pretty some time. About three years ago I sold the beneficial properties wished to salvage it performed, but never did predicament apart the time wished to basically invent it. I will give all types of causes for now not constructing it sooner, but primarily I didn’t own a honest want for it and no particular projects that employ it, except now. There’s a knife that I want to plan and having this warmth treatment oven will plan particular that that the blade will seemingly be properly hardened.
My first step became to put together the insulated fire bricks to create a chamber that will seemingly be broad passable for a single blade that could also very nicely be a most of 15″ long. These bricks are 9″ long, 4-1/2″ broad and 2-1/2″ thick and are rated for 2300 levels Fahrenheit:
This leaves a chamber that’s 4″ broad, 4-1/2″ high and 15-1/2″ deep, which is masses of discipline for any single blade that I’d plan. Pointless to claim, knives aren’t the last be aware thing that desires warmth treating – plane blades and chisels or other tools can additionally relieve drastically from right hardening.
I’m making the outer case of the oven from 18 gauge sheet steel salvaged from doorways that I lower windows into, aid whereas doing my extinct day job. I lower the beneficial properties and tacked them together so that the bricks would fit inside of snuggly, then honest tacked the beneficial properties together using the welder:
I made a take care of to without bid slump the oven. Review that it is miles offset toward the front to plan up for additonal weight of the door:
Speaking of the door, it is miles swung on inexpensive tee hinges that I welded on. I feeble a fraction of sheet steel to shim the door up to discipline it a ways off from the case slightly so that it won’t bind:
To act as a take care of and double as a latch, I welded on this strip:
I added the rectangular nuts to the side for the latch to trip into. This mainly offers beef up for the door when closed to expend it from sagging:
With the out of doorways of the oven performed for now, I turned my attention to grooving the bricks for the heating part to fit into. To invent that I made this easy instrument:
Appropriate a fraction of sheet steel the factual width screwed to a block, with yet any other block that acts as an edge info.
These bricks are remarkably refined, and cutting again the grooves became easy:
The final be aware sophisticated fragment became the curve where the one part returns:
The stretched out part became then build into the groove and I feeble staples fabricated from the part wire to expend it in establish apart:
After I had it and the bricks installed in the oven, I crooked up a cord temporarily to envision it:
Next up, the controls for the oven centre around a PID to alter the temperature, a thermocouple to sense the temperature inside of the oven, and a relay to alter the part on and off. This schematic reveals the standard circuit:
My oven operates on 120VAC and has a factor that’s around 1500 watts, so I feeble a 15 amp circuit breaker slightly than the fuse and change aggregate.
The establish apart the part leads arrive thru the side of the case, I connected the connectors and feeble a fraction of heat resistant perf board to behave as an insulator to expend the connectors from touching the case:
The connection right here ought to be mechanical, corresponding to shown and the wires that join to it’ll additionally be warmth resistant.
The aid panel of the expend watch over field is a fraction of 1/8″ thick aluminum that additionally acts because the heatsink for the solid bid relay:
I lower out the front panel with tabs on the threshold to lock it to the case with sheet steel screws. In the videos near the bottom of this page I demonstrate how I lower out the square gap for the PID and the rectangular gap for the circuit breaker / change:
The wiring is carried out before the expend watch over field is assembled, since it’s more straightforward to salvage all the pieces crooked up and test for errors. Reward the bottom wire (green) that’s mounted to the aid panel of the expend watch over field. All exposed steel surfaces of an appliance love this must be connected to this ground wire:
With all the pieces connected, I ran a test to plan particular that all the pieces became working properly before striking on the duvet:
I predicament the PID for 1000 levels Fahrenheit and it had no bid reaching that and preserving it there.
Next, I did a more helpful test. I own this extinct file that I want to plan a knife from an dit desires to be annealed (softened) before I will invent that:
To anneal a hardened steel, you warmth it up to the factual temperature after which leave it to chill slowly:
Since this file steel is discontinuance in properties to W1 steel, I feeble that and heated it up to 1400 levels before shutting it off and leaving it to chill overnight:
The next day the file became softened to the purpose where it’ll be filed with yet any other file. It’s now willing to be worked and shaped into the knife I want to plan.
The next test became to witness if the oven would attain basically the most temperature that I want it to, and that’s 1900 levels Fahrenheit for warmth treating stainless-steel:
It took a whereas, but it did salvage there.
Running it at that prime temp did warmth up the case and the expend watch over field, so I opinion that some vent holes would be desirable to let some icy air trip:
I drilled holes in the bottom as nicely.
Also at high warmth, I seen the door became coming slightly birth, so I added these screw clamps to expend it tightly closed:
The oven will seemingly be more efficient if it retains in as worthy of the warmth as imaginable.
The done oven:
I’ve no plans to paint it, since it is miles solely a utilitarian plan and besides, I style of love the industrial witness it has.
I made an large series of videos:
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