In reviewing your Kanthal Calculator spreadsheet, what is the unit of measurement for the "length of coil at wind size" and what is that specifically referencing? it would appear that the total length of coil that you installed in the channels you carved was roughly 50" or so by rough estimation, but the value in the spreadsheet in 16.
It's in inches. Looking at the example (start with 33 inches of wire, end up with a 17" coil). Think about it: The mandrel is 0.156" OD. Multiply that by pi and you got 0.48 INCH needed to get around the mandrel. 33 inches times 0.48 is roughly 16 or 17", which would stretch out a great deal for install.
Took me a second to grok the use of 2 relays, but then it clicked, north america -> split phase. Oven looks good, i'm thinking about building my own in the coming months. My house just happens to have 240v 3 phase, so I might just take advantage of that to really make it sing
Thanks for including some of the issues you had, like the coils coming loose. I am in the process of building a pottery kiln. Pretty much the same design as your HT oven, just a little larger with 4 coils. Now that it is finished and used, is there anything you would have changed?
I don't understand why you need two relays? But then again I have no experience with this. I see other people using just 1 ssr. Looking to build one for myself, but needs more research.
"refractory seament" lol i dont know where you live but around here its seh ment nice build though. i watched a friend build a micro kiln and used a food can as a crucible. The can ended up exploding when he lifted it out of the micro kiln. it sent molten aluminum flying around his living room. no one was hurt, but it burned his laminated floors a bit. the burning floor was doused within seconds. these things are extremely easy to build. Don't think you cant. also use a real crucible if melting anything. you can build this in your house just dont use it in there. And i know some if not most people who read this will think "duh" we knew the risks and were ready for it.
Great video I’m looking at making one to hear treat knives. Have a few questions. Yours still going strong. ? Anything you would change? Did you use the cement because it’s not totally enclosed by metal? Thanks for the build and info
Great project! I'm using it as a base to develop my own heat treatment oven. I have just one question: how come are you using 2 SSRs? I will plug my oven at 220 V socket. TIA!!!
Ciao Samuele, vorrei realizzare un fornetto anch'io. Sto facendo la lista della spesa, tu sei riuscito a trovare tutto? Non capisco perchè usa 2 relè... eventualmente hai un contatto dove ci possiamo sentire?
Thanks for your build log, I'd go with confining the coil within its own space, no staples needed, and yeah man you can weld :) aluminum welding, it like playing with butter. How are your coils doing after 5 years?
My understanding is that running the heater element across the back creates a hotter region because it's being heated on three sides. This can cause the far end of the part to see higher temps that the rest, potentially leading to differing heat treatment. That said, I haven't built an oven yet so maybe it's not a problem.
Anyone know what size mandrel was used to coil the a1 wire? The calculator excel doc is not clear on the size. I'm trying to sort out the coil diameter, and length of coil to hit that 40 ohm mark. Thanks in advance.
I have a couple suggestions that might help you out with the coils but I’m not an expert by any means so take it for what it’s worth, we have banks of muffle ovens at work and they all have a layer of refractory over the top of the elements it gives them a layer of protection and I’m assuming would help hold the coils in place? Also there are interlocks on the door so you don’t have to remember to shut the power off while loading unloading.
Thanks, that's a great idea that I thought about, but I went with the staples so that if I had to ever replace the coil, hopefully it'd be easier to do. I also thought about the interlock, I've seen some people include that, but I avoided it for simplicity's sake in this project. Thanks for watching!
Gj, but that 3d printed terminal block is sketchy. Depending on the material and how the bolt connect to the 3d part this could happen: The contact resistance increases, because of the large current the fastener heats up and the 3d printed part softens, partially releasing the torq on the fasteners. That increases the contact resistance and the block heats up more. Then it melts and fails (fire hazard).
That's definitely a good observation and worthy of pointing out! In this, the terminal block is holding the bolts which have nuts on them that secure the wires from the power cable to the internal wiring, and the strain is relieved further up the wire so it's not pulling on the block. This means that if for some reason the bolts were to come loose, the connections would remain solid and since they were covered in insulation (heat shrink and electrical tape) risk of short is very minimal, and even in that scenario it would be with the grounded case. Luckily, also, the amp draw of this oven is surprisingly minimal, and all wiring used from power cable thru the entire control box far exceeds the minimum rating for this load by at least a factor of 2, so heat generation should not be a problem throughout the wire or any connection point. it's always important to be wary of things like this though!
While it is true that you are drawing only ~6.6A the problem is that if the bolts were to come loose, the contact resistance between the 2 ring terminals may increase and cause heating. Maybe keep it in mind for next time. This image shows heat generated from a loose connection on the top wire. bit.ly/2LksVhX
Great job! I bought a big Paragon Heat Treat oven. But you have the satisfaction of building your own! I just wrote a check. Not much fabrication pride in that!
Hey Jeff, Thanks a bunch for this video. I have a heat treat project that I really want to do, but it's been on hold for a couple of years because of the cost of commercially built ovens. I'm inspired again! thank you so much.
Excellent build. I was eondering why you are using two SSRs to switch both ends of the coil, security reasons? I have built a PID controller for my LEE pot using just a single SSR (basically the same application). The phase is switched by tje SSR, the other end just connected to neutral. The main power switch double pole, of course.
I really appreciate this video and all the info you shared!!! How is the accuracy at lower temperatures? I just built a VERY similar oven and I'm having a difficult time with the temp reading... I have the Inkbird PID that will display in F/C, but other than that, its nearly identical to yours. However, room temp is reading about 150°F, when it's actually about 60° in my garage. I swapped to another K thermocouple I had on hand and have the same result +/- 1°. The Inkbird instruction manual is a joke and not much help. Is there a way to calibrate the input?
Great video¡¡ Congrats¡¡. Would you/anybody recomend a PID model which will be valid for 1000 degrees like this. The model in your list is no longer available and I can't find another that confirms it gets to 1000 degrees. thanks in advance.
How would the parts list of this change to accomodate vertical placemnt and increased lenght, up to 4 feet long and 6 inch wide for sword making? Please keep in mind i cannot afford 240 power. i only have standard 120
I watch RU-vids all evening preferring it over television. I can say you made a great video in every respect...........I didn't have to watch it at double speed !! LOL Count me as a subscriber.
Good eye! Yeah the South Bend is easier to keep ready to go for most projects but the little grizzly is still in the shop and plugged in! You can even see it in various background shots I’m sure, it lives right next to the other lathe
You are like a half a brick away from making the best home Pizza oven ever! I see these guys build a behemoth wood fired pizza dome out in their back yard. So if they just want a simple pizza, its only worth the preparation and wait time to have multiple people over for many pizzas. It takes like 3 minutes to cook a nice pizza in a 900 deg oven. With your invention adapted to size, you could still use it for work, then at the end of the day, throw a pizza in there man.
Nice! I think we operate on the same wavelength lol, it started with Grizzly 7x14 when I first saw your channel and I had issues with mine, than you threaded a marlin, than you did muzzle device, than you got South Bend at some point you got milling machine and now you build high temp oven. I did all of that as well just not as elaborate and fancy and I didn't even see what you did only saw it later :) I've had firebricks and wire sitting in my garage for couple years, I've been putting this project off for a while, I actually been using my pineapple can forge to heat treat couple dozen of small parts with ease. I want to build electric metal melting forge to melt zinc and aluminum and possibly brass. I noticed you used same brand of wire that I got except I got mine in 16 gauge as it's not easy for me to access 220v so it will run on 110v. I've been looking at same terminal blocks on ebay but the ratings are confusing. Some sellers list it as 5A only and some higher so I didn't know who to trust. Regarding PID the first one I build for my lead melting pot about 3 years ago I also ended up with one reading in Celcius and while it worked great I found it annoying so I bought MYPIN and it can read in both, it also has 2 rows of display, I like it much better. It only $20 on ebay. I also noticed all people used more liquid dark grey cement to "glue" the bricks, it's more liquid, I'll look in to that. Another thing I was trying to find was ceramic tube insulators for wires coming out the back, but I guess it's not really necessary.
so it's been a couple of years what would you have done differently? Maybe thicker Kanthal and more of it to get the same ohm resistance? What was the over all ohm resistance for the length of wire you did go with? A heat up time of 15 - 17 minutes is really good. You should be happy about that.
One trick with refractory cement is that you normally want as small of a junction as possible not like mortar you would see normally between red bricks. The refractory cement doesn't have near as good thermal properties and sounds just be used as a glue more than anything
@@jakelevis8453 ist this because the ssr's he uses are rated for the 120 volts? Cause I have 230 too but mine are also rated for it so it should be fine using just one?
Make sure, if you haven't already done it put a switch on the door so when you open it, it kills the power to the heating coil. Sooner or later you will touch the coil as you take metal out of the oven and BOOM you could be history!!!
I love it, not the first I have seen but your delivery was second to none. I've always been a bit sketch about getting things in and out whilst on incase of touching a coil!! Would have to turn it off every time!!
Yeah a switch on the door would be easy to do, I just skipped it since I'm the only one using it and I play with my fun little on/off switch every time I open the door :)
That turned out great man! Awesome job! Gotta say I'm a little jealous too... Its on my list of things to make but there are other projects that must be made first. Ugh..... only so much time in the day (sigh)......
Very nice project Jeff, I like the angled design of the control housing. Good first build to work the bugs out, I'm sure you have inspired others to create their own ovens. Great to watch, keep them coming. Cheers
I thought this a really great video! Something about your style fits the questions in my mind. Lots of practical detail! Thank you! I'm wondering one thing, though: for someone with as many advanced skills and tools as you have, if a putty knife or small trowel might have helped you in your mortaring of the bricks? Not a criticism, just wondering. maybe you like to feel things. I know I do sometimes too. You make it clear to me where I need to study up, and I picked up clues from how you did things....considering ohms was a missing link where I knew I needed to know something more to buy my wire and calculate length, but wasn't sure what the missing factor was! Thank you again!
I really enjoy your videos man. I gotta say I've tried and failed at this same project 2 times already, I think this video might make me go in for a third.
Thank you! I wish you the best of luck if you try it again, email me at practicalrenaissance@gmail.com if there are any specific questions you might have, I can at least give them a shot!
For electrical isolation I use a combination of a SSR driving a DPST contractor (relay) to power the heating element. As others have said, for safety, a door interlock to isolate and disable power to the heater is also advisable.
Do you know of an expensive book, or some place I can find referenced information on what temps to heat treat or weld temps for various steels? I'm planning on making my own forge and have no idea what temps it will be experiencing or what to get for thermometer.
you could improve by add, either a second coil or thicker wire to crank up the Watts. You use "only" 1400W but you could go up to 3500W from the mains ( i would suggest 2400-3200watt). also check the outside walls Temperatur maybe they dont isolate the heat as the advertisement says. Or the box isnt airtight ( most arent), but the less air flow is possible its a second way of improvement.
Yeah, a ceramic wool blanket wrapped around the kiln really helps improve the insulation. Firebricks are pretty good insulators (0.2-0.3), vs 0.1 for ceramic wool (lower is better). But the seam mortar isn't generally as good. Which causes thermal bridges.
I really enjoy watching a skilled person working! I just don't have the patience to do that ! Great video sir ! And the bass clef suggest that we have a passion in common !!! ;-)
