Jake's In Mass (Started July 3, 2011)

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Also, the design works with any type K thermocouple, I have purchased from Auber before and their price is good and the quality is just fine.

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

Looks like a simple enough setup, plus my son (who's a senior in high school) is looking for project for his engineering class this year. I wonder if this would count?
Then I wouldn't have to count it as a cost for the oven either! Hmmm, I wonder if the dear wife would agree?

Jeff

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

So, in a couple of days I should know, but I reworked the design with an analog/digital MUX to use a single temperature IC to read from up to 16 thermocouples. I also dropped down from an Arduino($20) to a PICAXE($4). Overall savings of $50-$60. If it works the way I think it will I'll post some schematics. I am using Eagle PCB for the design which is free for small designs if your son is interested.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

So, a good weekend of pouring the hearth. My insulating layer needs more, I misjudged the compaction of the vermiculite. I would post pictures, but my phone managed to get tossed in the wash last night and isn't quite right.

Wife helped out with this pour and it went quite well.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Here are some of the pictures, the insulating layer is being poured, no pics of that until I get a new phone.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Doug,
Thanks so much for that information. Completely makes sense. I tweaked my thermocouple reader so I can easily adjust up to 16 thermocouples. The top one makes sense, though at an academic level I might like to see those temps! However, I think as I go forward 6 seems good and your placing suggestions make sense.

I left a full 3/4" core in the middle of my hearth, I used a pvc pipe so I can bore it out later(if I cannot just pull it out). Up this I will be running two thermocouples one for outside brick. The other one will actually go all the way through the brick and is itself encased in a ceramic sheath. The smallest bit of the tip will be even with the floor and there is about 1/4-1/2" of material to the actual thermocouple. It is the same idea used in a kiln. The other ones will actually be screwed into bricks, I'll use a thin nut embedded in the brick and take out only a little bit of brick material.

The ceramic sheeth and the screw access make almost all of the thermocouples easily replaceable. The air temp one will probably be anchored to my angle iron of my opening and extend into the oven a little bit. That one will be easier to tweak over time.

In the mean time, need to finish the hearth!!

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

So, a good weekend of pouring the hearth. My insulating layer needs more, I misjudged the compaction of the vermiculite..

At what point did you misjudge the compaction?
Is is evident as you 'pour' it? Or does it occur as it is drying?

How much compaction did you wind up with? 10%? 30%
I'm targeting a 5.5" perlcrete using 2x6s for the frame.

Thanks for the help,

Jeff

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

So, I am doing 5". The vermiculite compaction was evident as I mixed it and poured. No shrinking when it dried. Looks like I got about 30% of what I expected with raw 0% loss calculations. I'll post the final "real" number after this weekend when I am done with it.

If you are using perlite and not vermiculite you may have better luck since it is harder.

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

So, I am doing 5". The vermiculite compaction was evident as I mixed it and poured. No shrinking when it dried. Looks like I got about 30% of what I expected with raw 0% loss calculations.

Wow, that is a lot of compaction. I'm glad to know it doesn't shrink more as it dries.

If you are using perlite and not vermiculite you may have better luck since it is harder.

I hope you're right about perlite - otherwise my 3 bags aren't enough LOL.
-jeff

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

OK, I'm back, new phone and recovered lost pictures. At the end of this build I'll post a full gallery of all the pictures I have taken.

Here are two pictures of the hearth and insulating layer. Like I said above the vermiculite compacted way more than I expected.

So, what did I do? Well the first two bags of vermiculite I got from my Dad. He ordered "super coarse" from the supplier he orders from. This was a very coarse vermiculite, pieces 1/4" or larger. While it was nice and very "airy" it compacted quite a bit. With this I was able to get about 2" of the 5" I hoped to get. A 60% loss was definitely more than I expected. Given, I was never exact on what I should expect in the first place.

So, my dad had surgery and I decided to hunt down vermiculite on my own. Agway was selling 20lb(4cuft) bags of "coarse". I decided I'd go for it and I grabbed three more bags. I did not look inside when I picked it up, but it felt "chunky".

When I got home and looked at it, it was significantly less coarse than my first two bags. However it was less consistent with fine material and larger material. I decided to mix it up and live with what I got. Overall it mixed much better and compacted significantly less.

So, what I ended up with when it all settled is about a 4" layer of the "chunky" stuff. Which is the right size insulating. Then about 1" of the smaller stuff, when I mixed it I mixed it wet and it naturally settled this way.

So chat away, let me know your thoughts. It looks good to me and I don't feel like I need to also include any type of fiber board too.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Oh, and that was all mixed about 5:1 vermiculite to portland.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Next, to nerd it up. This is a picture of my lates thermocouple reader. This uses an analog/digital MUX in order to cut down on the number of very expensive MAX6675 ICs for temperature sensing.

I also dropped from an Arduino Pro to a PICAXE 14M2. This wend from about a $20 part to about a $4 part. There are definitely cheaper ways to go, but I am not an "embedded" programmer so I need at least a little hand holding and both Arduino and PICAXE are very hobbyist friendly.

I am working on redoing my schematic and board layout and will post those if anyone is interested.

What you don't see in the picture is the Bluetooth modem and the LiPo battery supply, but they are both part of the design.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

One last note for tonight:

I ended up using 4 1/2 bags of vermiculite for the hearth That's about 18 cuft of material and my form was about 11 cuft. That is about a 60% yield/40% compaction. Not too bad I guess. I hand mixed some and machine mixed some, compaction was the same.

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

Glad you got the new phone. Keep the pictures coming!

So you used 18 cf of vermiculite and at 5:1 that means you used 3.6 cf of portland cement. By my calculations that's about 7 94# bags.
Is that right?

I'm not trying to challenging you on this, it's just that this is my next step and I have 12 cf of perlite ready to go (hopefully this weekend) with 1.5 cf of cement (3 94# bags) to fill 9 cf. Sounds like I need to plan to mix it all together and use as much as I can - and hope I have enough. Worst case is I'll leave a 'hole' in the middle and fill it in when I get more perlite and cement.

Thanks,
-jeff

[rodeair]

Re: Jake's In Mass (Started July 3, 2011)

Jeff - Be careful of the portland, 1 94# bag is 1 cubic foot the way I understand it.

Leigh