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Hello everyone,

I've started dabbling in pottery about three years ago, making bonsai pots. This fits with another hobby of mine, you can guess which  :).

Point is, after firing my works with some acquaintances, I've decided that my own kiln is a must in order to really progress in the craft. The problem is that I my backwater location the chances of buying a second hand one are next to none, and I can't really justify spending almost $2500 for a new one. So I came up with the idea of actually building one from scratch. Yes, I know it's hard, yes, I know it can be dangerous but I'm trying to be as smart about it as I can and mitigate all the risks as much as I can. 

I would really appreciate it if you ladies and gentlemen would be willing to part with some knowledge to help me have the best possible outcome for this project. 

Now for the tech specs:

In order to fit the nature of my work, I would need a 50x40x30cm interior.  (19.7x15.7x12 inches)

The temps needed would be around 1240°C (2264°F)

The power I can get away with as a household consumer in my location is 230V 16A ~ 3600W

This takes me to my first point: As far as internet wisdom goes, the Wattage needed for a pottery kiln is 0.6W/cm2  which would place me at a needed Wattage of around 5600W. Waaaay above what I can provide. But then I read specs for kilns produced on Germany like Nabertherm that for a 60L pottery kiln with a top temperature of 1300°C produce single phase 230V 16A models, which makes me believe I can do it.  I'm assuming that I'll need to go with more insulation and longer firing times, but it's doable. Is that accurate?

Next up, elements: luckily I have a provider for Kanthal A1 wire near me and prices are decent. Would 1.6mm  1380°C max,  0,721 Ohm/m be suitable? With this diameter I seem to be able to juggle the resistance, wattage, length and placement of elements as close to optimal, with 2 elements running in parallel. 

Thirdly the most amusing topic... Well not amusing but maybe the most complex. The controller. 

Being in IT i'm a sucker for gadgets. Usually buying them, true, but this time I'm thinking about building :). I saw a lot of projects on the web with Raspberry Pi kiln controllers. The features they provide, the adaptability and the connectivity of the systems sounds amazing. Question is: does anyone fire with something like this? How does it compare to commercial controllers that are super expensive and in the stone age as far as features go. Are they worth the trouble? An example project that stuck with me is below. But there are many more

 

Thanks for the help, and looking forward to chatting with you.

Mihai

Edited by Jeryko
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Hi Mihai!

I started out with a used electric two years ago. Its capacity is about seven cubic feet; it came with a brand new shelf set, fairly new elements (~15 firings) some old shelves, an assortment of posts, and glaze material. There's no controller - three switches for low, medium, high only - so takes some attention and care, for sure. I spent almost twice as much on a wheel, and another basket of money on clay, glaze materials, tools, and equipment. I am having fun!

If I were to build a kiln, for sure it would be gas fired, no question there. Have you considered gas?

The other question that comes to mind - are you considering going larger than ~2 cubic feet? That seems rather small for big pots!

Several active members here have cobbled together controllers, relays, etc. as upgrade to a manual kiln; you might find some of the threads...

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ya know I get it, I'm a thirty-five year IT guy and a gadget person so it's always fun to consider this stuff but man you could be setting yourself up for a huge distraction from your 2 passions and before you know it its been a couple of years since you made any pots. I know I do this stuff to relax after spending 8-9 hours programming all day.

If I were you before I went down the electric kiln route I would maybe take Hulk's advice and explore a propane conversion if you can score an old kiln to gut or maybe a small wood kiln. I can't remember the book off hand and my copy is buried somewhere but I think it was alternative kilns or something like that and there was a design for a 10-12cf wood fired kiln that the guy claimed could be fired with a half cord of wood. Could be fun and not IT related which for me would be appealing.

Sprung-Arch-Kilns.jpg

 

Just a thought.    

Edited by Stephen
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11 hours ago, Hulk said:

Hi Mihai!

I started out with a used electric two years ago. Its capacity is about seven cubic feet; it came with a brand new shelf set, fairly new elements (~15 firings) some old shelves, an assortment of posts, and glaze material. There's no controller - three switches for low, medium, high only - so takes some attention and care, for sure. I spent almost twice as much on a wheel, and another basket of money on clay, glaze materials, tools, and equipment. I am having fun!

If I were to build a kiln, for sure it would be gas fired, no question there. Have you considered gas?

The other question that comes to mind - are you considering going larger than ~2 cubic feet? That seems rather small for big pots!

Several active members here have cobbled together controllers, relays, etc. as upgrade to a manual kiln; you might find some of the threads...

Heyya @Hulk. Thanks for the answer. I would love a gas fired kiln. The concept scares me a bit, but would love one. Only issue there is with management (please read the Mrs ) . She agreed to an electric one but will probably divorce me if I make what she calls 'an improvised bomb' in the backyard. Except for that, she's pretty cool :)). 

Totally get the equipment buying. I do the same for all my hobbies and then milk them for all they're worth :). 

The 2cubic ft is probably the max size for which I could squeeze out sufficient Wattage from my electric system. I'm limited to 230V and 16A. So it's gotta be electric and it's gotta be small. Good part is that I only do it for a hobby and occasionally take on a pot commission but the size should be enoughish. 

About the controller, looked through 30 pages of this forum, and a whole lot of internet. I found a couple of interesting ideas and implementations. Was wondering if I can get a little more first hand feedback as to how they behave. Most of the threads are a couple of yeas old and look quite dead. 

Hello @CactusPots. Thanks for the reply. I actually found shelves that fit my proposed kiln size :D. So i'm hoping to be able to stick to it. Did the math already, so it's just that I need confirmation about whether the power is enough or not and if the wire gage is suitable.  I'd kill for a discussion with someone who owns a Nabertherm Ecotop 60. That's the one that has 60L with only 3.6kW. There aren't really any speciffics about the model on the internet except for some basic stats. 

 

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Posted (edited)

@Stephen hello! Thanks for the reply. Aaaa... Wood fired. That would be awesome sometime in the next 10 years but I don't think I can commit to that right now. Electric... sure, gas... Maybe if i get the missus onboard. Wood is out of my league at the moment. I'm pretty new to pottery as it is and I feel that adding the complexities of woof firing to the mix a bit too much to chew. 

Concerning the IT business, oddly enough, if it's not really SAP administration related (my current field)  I find it relaxing. Spent the last two days playing with an arduino and a K type thermocouple just for fun to get it to post to an IOT platform in preparation to building the actual controller. I did not expect C++ and Python to be entertaining :)) . Worked :)). 

About the book... Started looking around for The Kiln by a Mrs Olsen that I saw recommended. 

 

Screenshot_20200421-180844.png

Edited by Jeryko
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Unless you're really set on building your own, I would keep a lookout for a decent used kiln. From a time and money standpoint it would be the best way to go, even if you have to drive a bit to get it. The most difficult part is cutting the grooves in the bricks. Brick dust chews up anything it gets into, so know that any power tools you use may be sacrificed. Build the controller box so it can be wall mounted, not mounted to the kiln. Have a jumper cord coming off the kiln that plugs into the control box. The boxes I've built run about $200 for a 50 amp kiln, including everything but the controller. For a 20 amp kiln you could drop $30-40 off of that since you'd only need a small relay, outlet, etc. You can get a good 3-button kiln controller for $200.

The big questions are how much work do want to do, and how quickly do you want to be firing? Building your own electric kiln is about 10 times as much work as a small gas kiln. There are a lot of little parts needed to make it work. A control box alone uses about 20 different parts if you count wire as one part. There's also all the little terminal ends, screws, nuts and bolts, etc. I'm not trying to discourage you, I just want you to realize what you're getting into. I'm assuming you know enough about electrical systems to do it all safely? Start making a list of everything you need. It will be lengthy, and sourcing all those parts in small quantities can get expensive.

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2 hours ago, Jeryko said:

Most of the threads are a couple of yeas old and look quite dead. 

That speaks loads ;)

Do you have only 16 amps available for a reason?  That seems like a very weird amount.  If it's a 16 amp breaker in your breaker panel, you are limited to more like 12 amps of continuous duty.  And 2500 watts isn't a lot to work with, less than 2 small space heaters ;)

I don't know how things are in your country, or if there's any sort of home insurance, but another drawback of building your own kiln, is that it won't have any sort of safety certification, and if it happens to burn down the house, you may be hosed.

Anyway, just a lot of fun stuff to consider.  LPG is not a very good explosive, maybe build a small raku kiln in the back yard first to "warm" her up to the idea of a bigger one ;)

Google "Ian Gregory flat pack kiln" for a quick and cheap design.

 

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3 hours ago, Jeryko said:

Heyya @Hulk. Thanks for the answer. I would love a gas fired kiln. The concept scares me a bit, but would love one. Only issue there is with management (please read the Mrs ) . She agreed to an electric one but will probably divorce me if I make what she calls 'an improvised bomb' in the backyard. Except for that, she's pretty cool :)). 

Totally get the equipment buying. I do the same for all my hobbies and then milk them for all they're worth :). 

The 2cubic ft is probably the max size for which I could squeeze out sufficient Wattage from my electric system. I'm limited to 230V and 16A. So it's gotta be electric and it's gotta be small. Good part is that I only do it for a hobby and occasionally take on a pot commission but the size should be enoughish. 

About the controller, looked through 30 pages of this forum, and a whole lot of internet. I found a couple of interesting ideas and implementations. Was wondering if I can get a little more first hand feedback as to how they behave. Most of the threads are a couple of yeas old and look quite dead. 

Hello @CactusPots. Thanks for the reply. I actually found shelves that fit my proposed kiln size :D. So i'm hoping to be able to stick to it. Did the math already, so it's just that I need confirmation about whether the power is enough or not and if the wire gage is suitable.  I'd kill for a discussion with someone who owns a Nabertherm Ecotop 60. That's the one that has 60L with only 3.6kW. There aren't really any speciffics about the model on the internet except for some basic stats. 

 

Here is my take:

Yes you can build and super insulate a kiln (compared to typical 3” brick kilns). It is most likely needed for your electrical restriction.  Fiber is certainly king with respect to having to heat a bunch of brick mass each and every firing.

Arduino or equal is fine if you have the time, lots of very nice  temperature controllers out there though for super cheap (20.00 - 50.00 usd) PID, Fuzzy logic, auto tune, and I find their type K interfaces more industrial compared to Arduino. If you are contemplating the arduino then likely  are anticipating solid state relays.  They are very doable and will actually add some capacity to your kiln. They need to be done right though, so use the manufactures cooling data and design conservatively with protection for your SSR.

I personally like using low cost PLC because it’s super easy and proven super reliable by industry but, it’s sort of old technology. Having said that even the most basic have web interface capability, standard k type inputs, data gathering, email engines, etc... without too much custom  effort.

And finally, this is a lot of design work with adaptation of available hardware so getting a used kiln to use as is, or to modify seems to me to be  something I would  seriously contemplate. 
 

Finally - finally, an economical  Raku kiln sounds really doable and fun as a warmup step.

At one time a few folks asked what does it take to design an SSR retrofit for an existing kiln, to which we made a very general video so folks could get a real feel for some of the thought that goes into just that part. You might find it interesting.

 

Edited by Bill Kielb
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Posted (edited)
1 hour ago, liambesaw said:

That speaks loads ;)

Do you have only 16 amps available for a reason?  That seems like a very weird amount.  If it's a 16 amp breaker in your breaker panel, you are limited to more like 12 amps of continuous duty.  And 2500 watts isn't a lot to work with, less than 2 small space heaters ;)

I don't know how things are in your country, or if there's any sort of home insurance, but another drawback of building your own kiln, is that it won't have any sort of safety certification, and if it happens to burn down the house, you may be hosed.

Anyway, just a lot of fun stuff to consider.  LPG is not a very good explosive, maybe build a small raku kiln in the back yard first to "warm" her up to the idea of a bigger one ;)

Google "Ian Gregory flat pack kiln" for a quick and cheap design.

 

Hello Liam. 

The 16Amps : Couple of reasons. First and foremost, modern contractors in Romania are cheap idiots. The ones that built the house I live in at least...  I have a 3x2.5mm copper wire cable going from a 20A breaker (easy to replace) to my detached basement (completely disconnected from the house, next to it below ground level rather than under) . According to code, the cable is rated for 20A when enclosed, 32A in the open... So 20 in my case. 

Secondly, single phase wall sockets are all rated 16A in RO.  If i hardwire I can go past 16 but with safety margins on the current cable I wouldn't really want to do that. The other option would be to replace the cable with thicker gage, but that involves an electrician and if the tubes inside the walls are not done properly and the old cable can't be used to pull in the new one, it might cost a small fortune.  

The basement situation above explains why I'm not overly concerned with fire. The whole thing is concrete below ground, detached from the house. If any mishap should happen worst thing that can burn are four car tyres and two stools :)). 

Edited by Jeryko
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In that case, I would run new heavier gauge wire to the basement and make the kiln so that the power draw is not the limiting factor.   In my mind it would be easier to build an electric kiln capable of cone 10 if you have enough amperage, instead of trying to beat industry on engineering the most energy efficient kiln on the market.  

And then in the future if you end up buying a bigger kiln or find something used, you can hook it up without any power issues.  

I think everyone here has had to pay that electrician bill or do the work themselves, I don't think there's a home in the world set up to run a decently sized kiln straight from the wall.

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On 4/21/2020 at 8:17 PM, neilestrick said:

Unless you're really set on building your own, I would keep a lookout for a decent used kiln. From a time and money standpoint it would be the best way to go, even if you have to drive a bit to get it. The most difficult part is cutting the grooves in the bricks. Brick dust chews up anything it gets into, so know that any power tools you use may be sacrificed. Build the controller box so it can be wall mounted, not mounted to the kiln. Have a jumper cord coming off the kiln that plugs into the control box. The boxes I've built run about $200 for a 50 amp kiln, including everything but the controller. For a 20 amp kiln you could drop $30-40 off of that since you'd only need a small relay, outlet, etc. You can get a good 3-button kiln controller for $200.

The big questions are how much work do want to do, and how quickly do you want to be firing? Building your own electric kiln is about 10 times as much work as a small gas kiln. There are a lot of little parts needed to make it work. A control box alone uses about 20 different parts if you count wire as one part. There's also all the little terminal ends, screws, nuts and bolts, etc. I'm not trying to discourage you, I just want you to realize what you're getting into. I'm assuming you know enough about electrical systems to do it all safely? Start making a list of everything you need. It will be lengthy, and sourcing all those parts in small quantities can get expensive.

Hello @neilestrick . Thanks for the reply. That's the issue. There are literally none second hand  to be had in Romania.  Two posts on the web at this time: 1000L and 850L for $7K and $5K. obviously out of scope. I've been looking every day on all the sales sites for the last five months. Nothing. Closest I can find second hand is in Austria or Germany, and that's a minimum 700 mile drive.  

About the brick cutting, haven't figured it out yet but I'll get to it. Baby steps. Concerning the work, well that doesn't frighten me one bit. I love manual labor and buying crap :). Kiln parts count :D. I'm compiling a BOM as we speak. The kiln sans electrics/controller gets me to  $400. I'll post everything once I get them all down on paper... well excel I mean. $200 sounds like what i'll be looking at for the control box as far as I can tell so far.

I'm not an electrician, but I think I know enough not to kill myself by a small margin :)). 

On 4/21/2020 at 9:31 PM, Bill Kielb said:

Here is my take:

Yes you can build and super insulate a kiln (compared to typical 3” brick kilns). It is most likely needed for your electrical restriction.  Fiber is certainly king with respect to having to heat a bunch of brick mass each and every firing.

Arduino or equal is fine if you have the time, lots of very nice  temperature controllers out there though for super cheap (20.00 - 50.00 usd) PID, Fuzzy logic, auto tune, and I find their type K interfaces more industrial compared to Arduino. If you are contemplating the Arduino then likely  are anticipating solid state relays.  They are very doable and will actually add some capacity to your kiln. They need to be done right though, so use the manufactures cooling data and design conservatively with protection for your SSR.

I personally like using low cost PLC because it’s super easy and proven super reliable by industry but, it’s sort of old technology. Having said that even the most basic have web interface capability, standard k type inputs, data gathering, email engines, etc... without too much custom  effort.

And finally, this is a lot of design work with adaptation of available hardware so getting a used kiln to use as is, or to modify seems to me to be  something I would  seriously contemplate. 
 

Finally - finally, an economical  Raku kiln sounds really doable and fun as a warmup step.

At one time a few folks asked what does it take to design an SSR retrofit for an existing kiln, to which we made a very general video so folks could get a real feel for some of the thought that goes into just that part. You might find it interesting.

 

@Bill Kielb hello Bill. That's a super helpful answer and the video is very educational. Thank you. 

The insulation I'm looking at is 3"IFB backed up by 2-3" of ceramic fiber blanket and a 4"  ceramic fiber board lid. 

I am indeed thinking of SSRs. Two of them with  copper heat sinks and a fan to tie it all together. I'm adding a PDF with my rough sketch of the wiring to the post if you have time to take a look. I didn't factor in a contactor but the SSRs in series should take the chance of the system getting  stuck on the ON position to next to 0, and lid switches should provide extra safety. If this is not enough I can always change approach.

Wow. PLC. This is a topic I have never touched, even in passing . I just know what the acronym stands for :)). 

 

23 hours ago, liambesaw said:

In that case, I would run new heavier gauge wire to the basement and make the kiln so that the power draw is not the limiting factor.   In my mind it would be easier to build an electric kiln capable of cone 10 if you have enough amperage, instead of trying to beat industry on engineering the most energy efficient kiln on the market.  

And then in the future if you end up buying a bigger kiln or find something used, you can hook it up without any power issues.  

I think everyone here has had to pay that electrician bill or do the work themselves, I don't think there's a home in the world set up to run a decently sized kiln straight from the wall.

@liambesaw you're probably right of course. The first instinct tho' is to try to make due with the wiggle room that's there :). An electrician is possible in my future :D.

If you guys are bored, here's a PDF of the wiring. Suggestions welcome, pointers on how not to die, more than welcome :)). No details of the microcontroller GPIO wiring because that feels besides the point at this time.

Have a good one! Mihai 

 

Kiln Wiring.pdf

Edited by Jeryko
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17 minutes ago, Jeryko said:

Hello @neilestrick . Thanks for the reply. That's the issue. There are literally none second hand  to be had in Romania.  Two posts on the web at this time: 1000L and 850L for $7K and $5K. obviously out of scope. I've been looking every day on all the sales sites for the last five months. Nothing. Closest I can find second hand is in Austria or Germany, and that's a minimum 700 mile drive.  

About the brick cutting, haven't figured it out yet but I'll get to it. Baby steps. Concerning the work, well that doesn't frighten me one bit. I love manual labor and buying crap :). Kiln parts count :D. I'm compiling a BOM as we speak. The kiln sans electrics/controller gets me to  $400. I'll post everything once I get them all down on paper... well excel I mean. $200 sounds like what i'll be looking at for the control box as far as I can tell so far.

I'm not an electrician, but I think I know enough not to kill myself by a small margin :)). 

@Bill Kielb hello Bill. That's a super helpful answer and the video is very educational. Thank you. 

The insulation I'm looking at is 3"IFB backed up by 2-3" of ceramic fiber blanket and a 4"  ceramic fiber board lid. 

I am indeed thinking of SSRs. Two of them with  copper heat sinks and a fan to tie it all together. I'm adding a PDF with my rough sketch of the wiring to the post if you have time to take a look. I didn't factor in a contactor but the SSRs in series should take the chance of the system getting  stuck on the ON position to next to 0, and lid switches should provide extra safety. If this is not enough I can always change approach.

Wow. PLC. This is a topic I have never touched, even in passing . I just know what the acronym stands for :)). 

 

@liambesaw you're probably right of course. The first instinct tho' is to try to make due with the wiggle room that's there :). An electrician is possible in my future :D.

If you guys are bored, here's a PDF of the wiring. Suggestions welcome, pointers on how not to die, more than welcome :)). No details of the microcontroller GPIO wiring because that feels besides the point at this time.

Have a good one! Mihai 

 

Kiln Wiring.pdf 115.75 kB · 0 downloads

In your wiring diagram, I would switch to a single relay since you're not controlling them independently, unless you have chosen two for a different reason, one less thing to buy and one less thing to fail.

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19 minutes ago, liambesaw said:

@Bill Kielb hello Bill. That's a super helpful answer and the video is very educational. Thank you. 

The insulation I'm looking at is 3"IFB backed up by 2-3" of ceramic fiber blanket and a 4"  ceramic fiber board lid. 

I am indeed thinking of SSRs. Two of them with  copper heat sinks and a fan to tie it all together. I'm adding a PDF with my rough sketch of the wiring to the post if you have time to take a look. I didn't factor in a contactor but the SSRs in series should take the chance of the system getting  stuck on the ON position to next to 0, and lid switches should provide extra safety. If this is not enough I can always change approach.

Wow. PLC. This is a topic I have never touched, even in passing . I just know what the acronym stands for :)). 

 

I would suggest using an economical mechanical switch, dual SSR are an ok idea but theoretically they will have leakage even when good. The definite purpose contactor is an industry established norm and cheap if you take screen shots of the video. Additionally no need for the copper heat sinks, although better you can get larger surface area aluminum for cheap. PM me if and when you decide and I can send you some sources that are very reasonable in price.

Heat sink pic and a PLC teaser of what we build for under 1000.00 at this point.

432099F9-7FB7-4A9A-8251-44BAC52337C0.jpeg

526F672D-37F6-4D09-A1F1-6385501305BA.jpeg

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Hey Brother!

Great Advice here!

700miles ain't too far!

I just drilled some brick to hold a flue wall in my gas joint. Reckon you can do the same to groove bricks. 

Drill 2 holes thru the entire brick, about 2-7mm of the face then saw cut out the top one to expose the channel to the kiln interior. Save the dust!

Sorce

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  • 2 weeks later...

Hi Mihai,

Just wanted to check how you're getting on with this project? I'm planning to build an efficient ceramics kiln for my partner that's pretty similar to yours. My planned specs are: 30cm x 30cm x 40cm, front loader, made from 50mm ceramic fibre board, backed up with 75mm ceramic fibre blanket, and with an aluminium case. We have 16 amp circuits too, so I'm looking to power the kiln at about 3000 watts / 13 amps. Aiming to get it to around 1280 degrees C. I'm shopping around for some 1.8mm Kanthal, looks quite expensive. I bought a ramp / soak PID controller from AliExpress, hopefully that works fine.

Would be very keen to hear about your progress!

Cheers
Ollie

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  • 2 months later...
On 5/8/2020 at 10:32 AM, ojb said:

Hi Mihai,

Just wanted to check how you're getting on with this project? I'm planning to build an efficient ceramics kiln for my partner that's pretty similar to yours. My planned specs are: 30cm x 30cm x 40cm, front loader, made from 50mm ceramic fibre board, backed up with 75mm ceramic fibre blanket, and with an aluminium case. We have 16 amp circuits too, so I'm looking to power the kiln at about 3000 watts / 13 amps. Aiming to get it to around 1280 degrees C. I'm shopping around for some 1.8mm Kanthal, looks quite expensive. I bought a ramp / soak PID controller from AliExpress, hopefully that works fine.

Would be very keen to hear about your progress!

Cheers
Ollie

Hey Ollie. Just completed the build. Turned out better than expected. Only issue is that I did end up using more amps than I previously thought to get it to temperature fast enough. I'll write the specs if ur curious. 

Thanks everyone else for the feedback and great ideas. Rpi controller rocks by the way :). 

@Sorcery holly cow. Glad to see you here dude. Haven't had time for The Nut in quite a while. 

 

The end product:N3NjqAe.jpg

vcscK99.jpg

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