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First Build - Octagon pit

Posted: Thu May 28, 2020 5:05 am
by AG.AUS
Hey all, or G’day

Here is a quick rundown of my first build.. so far...
Too difficult to find a decent piece of tube/cylinder
So have to try for an Octagon.. (and all the associated welding!)

Ordered my initial metal order.. waited a few hours and picked it up..
8 pieces of 750x200x6mm
(29.5”x7.8”x1/4)
2 pieces of 1500x150x6mm
(4’11”x5.9”x1/4)
1 piece of 2000x50x6mm
(6’11”x 2”x 1/4)

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And some RHS for the eventual legs..

Started prepping the cook chamber, ended up after 4h tacking the 5 main pieces together, and getting a start on the door pieces..

It’s quite a heavy unit so far.. wonder what it’ll end up at, at the end...

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It’ll be a slow build.. got about 6h planned for tomorrow.. try and get the doors and ends on.. (if time, try to design a wheeled leg base..)

(Also, apologies if the metric to imperial isn’t correct.. it’s a pain in the behind converting from metric to imperial decimal then onto imperial feet & inches.)

Andrew


Total build time so far: 4h
Costs: $200AUD

Re: First Build - Octagon pit

Posted: Thu May 28, 2020 5:12 am
by OldUsedParts
Howdy, Andrew, and Welcome to the Forum :texas: :cheers: :salut:

I'm looking forward to your updates on the Octagon Pit :wav:

Re: First Build - Octagon pit

Posted: Thu May 28, 2020 5:28 am
by Fooldancing
Welcome. I am also looking forward to more pics. This is a great place to get advise. I've learned a lot here.

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Re: First Build - Octagon pit

Posted: Thu May 28, 2020 11:21 am
by Ken226
Nice work. I prefer the angular, welded plate style over the round tank style as well.

Keep the pics coming as you progress, I'm eager to see the result.

Re: First Build - Octagon pit

Posted: Fri May 29, 2020 5:05 am
by AG.AUS
Hey All,

So, day 2.. (well, working on pit - Day 2)

Got a good hit at it today.. weather was kind, and a bonus.. kids were at childcare..

Image


Slowly bringing it round..

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Got it attached/done..
(Some notes of issue..)
Had to use a ratchet strap to keep the last two pieces close enough + some wood screws to leverage off..


Whilst slowly putting the main cook chamber together, I had a start at the base..

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Not the greatest wheel / base.. maybe it’ll be a temporary one for now.. (it has a lean back towards the rubber wheels)

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It took longer than expected to get this far..
however, I have added the overlapped section for the door (to add some gasket tape under) so it was worth it..

No ends on it yet.. but getting there..
Maybe find some time over the weekend.. maybe...

Andrew

Total Hours : 10
Total Costs : $260AUD ($175 USD)


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Re: First Build - Octagon pit

Posted: Fri May 29, 2020 6:36 am
by GRailsback
Lookin good

Re: First Build - Octagon pit

Posted: Fri May 29, 2020 11:43 am
by k.a.m.
Very nice work Sir. :salut: :salut: :salut: Looking forward to following your progress.

Re: First Build - Octagon pit

Posted: Fri May 29, 2020 12:12 pm
by Rambo
Awesome Mate

Re: First Build - Octagon pit

Posted: Fri May 29, 2020 8:38 pm
by AG.AUS
To all out there with significant more knowledge than I,
With regard to the Feldon Calculator.. my current firebox design (square with some 45* bends - too look similar to the cook chamber) is running at ~142% of the cook chamber.

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Is this/will this be a huge issue?

What are the outcomes of a ‘too large’ firebox..
* too much heat?
* hard to stabilise?

I’m planning on double walling the firebox to help conserve fuel.. and also hopefully to keep it slightly cooler to touch (kids around)

Maybe I can just create a smaller inside box...
- closer to the calculated box size..


Any help/knowledge on these things would be appreciated..

Thanks

Andrew


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Re: First Build - Octagon pit

Posted: Fri May 29, 2020 8:45 pm
by GRailsback
KAM will be able to give you top notch advice on the sizing. But I can tell you that my fire box is insulated, which means it is double walled, with High heat insulation in between the 2 walls. It makes a huge difference on fuel consumption, and it will also benefit the little ones.

Re: First Build - Octagon pit

Posted: Wed Jun 03, 2020 7:04 am
by k.a.m.
I missed this question. Andrew sent me a P.M.
Here is my reply for everyone.
Good Morning Andrew.
If you are going by the calculator meaning that recommended is 100% and you are 125% to 130% That is a good size in my opinion. I like a firebox about 20% to 25% over recommended.
I hope this helps.

Re: First Build - Octagon pit

Posted: Wed Jun 03, 2020 7:17 am
by AG.AUS
Thanks again k.a.m,

I’m pushing through with the build again tomorrow (AUS time) and aiming to get the kart built up, maybe look at the end walls of the cook chamber & if time permits, also build a chimney..
.

Going to use some 100x50 RHS - 4”x2” box section

It’ll hopefully be a reasonable looking chimney.. plan A.. (let’s see where I end up! Ha)

Thanks all..
A


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Re: First Build - Octagon pit

Posted: Thu Jun 04, 2020 1:03 am
by AG.AUS
Hi all,

I picked up some more metal yesterday, so got a chance to do some more work on the octa-baby..

(Scrap yards here generally sell on scrap straight away to be recycled.. so all new metal for me)

Today got a chance to get the kart up and running..

I cut the uprights 100x50x2 (4”x2”x0.8”) - thin wall box section..

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Duplicated the design for the other leg set..

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Welded them onto the base.. then mocked the CC onto the legset..

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This will hopefully be the way it finally sits.. with a firebox sitting over the rear wheels (for stability - hopefully)

** I might rotate it, so the firebox is on the right hand side of the cook chamber..**

I was hoping to get onto the chimney, but Zoom meetings bounced up..

Andrew

Total Hours - 13h
Total Cost $ 360AUD


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First Build - Octagon pit

Posted: Fri Jun 12, 2020 3:33 am
by AG.AUS
Hi again all,

I had my brother come over and have a look..
(He is a fitter & turner by trade, and a uni grad in mech engineering)
He was not overly impressed with my welding skills.. but then again.. I’ve only just started! Ha


Finally got some more time to work on the cooker..

Trimmed down the legs (made it actually fit on proper..)
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Also picked up some more permanent wheels.. (also brings the height up to where I want it..

In addition.. fabbed up the chimney.. went with the slow bends upto 90*

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Now just need to cut it down to height.. (I’m guessing the length in the calculator is based on height above horizontal, not just the full length?)

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I picked up the firebox metal.. there goes more $$ ah well!

Next on the list..
* need to build the firebox..
* build the cook chamber end walls
* build the second skin for the firebox (with insulation between)

Thanks for reading..

Andrew

Total Hours - 16h
Total Cost $ 720AUD


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Re: First Build - Octagon pit

Posted: Fri Jun 12, 2020 6:41 am
by strength_and_pow
Nice work.


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