I Took the Plunge - New Oven

[34by151]

Photos please.

Building the oven

20211104_09264A.jpg

Inside oven

20220202_083847.jpg

Coating booth

20220131_075121.jpg

[Joe Jones]

That is a absolute min in reality you need 2-3 times that (500w per cubic foot)
You will need about 40kw which will be 180amps on 220v power

I don't have that much power.

Do yourself a favour and get a Riello burner. You can get Propane and Diesel. I went diesel
Exhaust and oven vents are routed outside using 3in exhaust pipe covered with insulation

I will do this for oven #2

With 12Kw as you plan it will take over an hour to preheat. It will take about 30 mins to recover after putting your parts in
Say another 30 mins to heat the parts. So about 2-3 hours to cook a batch.

Sobering truth. so I have planned poorly?

With 500w per foot your batch times will be 45mins. A Riello burner will give you what you want, output is adjustable. The G10 is perfect for your oven (54 - 100 KW) All you need is a Riello burner and a PID controller.

... reaching for my credit cards ...

The PID has a temp probe (thermocouple) in the oven. It triggers a solid state relay (SSR). The SSR provides power to the Riello Burner. When the burner gets power it starts.

See, now I am beginning to get REAL ANSWERS! You and Robert certainly know more about this than I do.

I have already purchased the things for this first oven. I will build it and see if it FAILS me. If it is lackluster in performance, I can always reduce it's size and use the same burners, etc. IN FACT, you have given me an idea! I will build this modular style, so if the planned size is too large for the 12,000 watts I have purchased, I will simply remove the top, take out a module or two to reduce the height (and volume) and put the top back onto the shorter oven! Then prop it up on legs for a comfortable work height!

So, if I choose to build a LARGE oven with a moveable interior wall to adjust the volume, how hard is it to find a heater and burner BANKS that will give me perhaps four different options, 5 feet, 10 feet, 15 feet and 20 feet interior space? I am THINKING that the same controller could handle all four scenarios, while simply opening more gas valves so the burners in Bank 2 also fire, or Banks 2 and 3, or banks 2,3 and 4. Am I wrong about this? Since the air is presumably circulating inside, wouldn't ONE controller work the same, regardless of the number of burners that it fires during a heat cycle?

Robert talked about a three-stage PID controller. I am confused. I thought a controller measures the internal temperature with a probe, and fires burners to bring the temp back up to the desired range. To quote the Wicked Witch of the West ... "What difference at this point, does it make?!" whether 2, 4, 6 or 8 burners ignite when the oven calls for more heat?!? After all, my home has several rooms, but only ONE thermostat.

Joe


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[Joe Jones]

Another question: Pre-Heating the Oven.

What is the protocol for powder coating? I thought you:

- bring the oven to temperature.
- open the door, quickly roll the part(s) into the hot oven.
- close the door and wait for it to reach temperature again.
- wait for the PARTS to reach temperature via a thermal probe.
- start a timer to cook the powder.

Am I missing a step?

Joe

[Joe Jones]

Building the oven
20211104_09264A.jpg

Inside oven
20220202_083847.jpg

Coating booth
20220131_075121.jpg

Okay ... maybe this is a STUPID question ...

Why does EVERY powder coat oven look like it was recovered from a swamp after WWII? I know ... "It is all about HEAT, and "pretty" does not change the finished product, Joe!" right?

Maybe it is just me, but I need my oven to LOOK like someone cares about it. It is a personal pride thing. I am bothered by a scratch on my FORKLIFT. OCD much?

Ridiculous costs side, what are you thoughts on using stainless steel for the skin? I have a whole pallet of 14 ga. stainless steel that I COULD USE, I suppose.

Joe


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[Joe Jones]

Here is one more thought I will throw out there ...

Since everything HANGS in an oven, WHAT IF the rear wall of the oven was wall mounted on a pivot? Picture an engine stand with a V8 engine block bolted to it. It is HEAVY, but you can rotate the block as you build the engine.

In this way, the oven could be rotated 90 degrees to give you BOTH a 4wx3dx6h roll in oven, and a 3dx6wx4h oven at waist height.

Electric heating elements do not care about orientation and the fans would work the same, except that the hot air would be pushed from right to left instead of from top to bottom..

Hmmm .....

Joe


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[34by151]

Another question: Pre-Heating the Oven.

What is the protocol for powder coating? I thought you:

- bring the oven to temperature.
- open the door, quickly roll the part(s) into the hot oven.
- close the door and wait for it to reach temperature again.
- wait for the PARTS to reach temperature via a thermal probe.
- start a timer to cook the powder.


Joe

That is correct but the slower the oven the more issues you get with that.
Open door- you loose a lot of heat, takes a long time to get back to 200c
Parts are then slow to soak up the heat.
powder starts to flow at 180c
You open the door to check parts, still under 200
You have now introduced a rapid cool and adheasion will be effected

The cycle goes on you have marginal coating

For a fast oven likemine I dont open the door and check the parts temp
I often cook with a cold oven as the temp rise is so rapid no need to preheat
Parts come up to temp with the oven.
Either way I monitor the pid screen
I look ath the oven temp not the target temp
The temp will rise and go a but over (4 degC on my pid settings)
Then it will drop to 1deg c under and stabalise on 204C
At this point the parts are at temp and I start the timer

[34by151]

Why does EVERY powder coat oven look like it was recovered from a swamp after WWII? I know ... "It is all about HEAT, and "pretty" does not change the finished product, Joe!" right?

The outside does not matter, it just for looks
Some dont bother to skin the outside at all
Use what you have outside
Its the insde that matters
Go as thick as you can, think about how you will hang you parts

[34by151]

Since everything HANGS in an oven, WHAT IF the rear wall of the oven was wall mounted on a pivot?

Your overthinking it
If you need wider build it wider
A riello burner will be more than enough for an oven twice what you plan
With a gas burner you dont install fans, the burner is a fan
The burner forces hot air in which circulates and goes out the vent

[adbuch]

For comparison, here are the specs on the Eastwood oven.

https://www.eastwood.com/images/pdf/p33 ... 1_inst.pdf

Eastwood Powder Coat Oven Specs.jpg

[adbuch]

My small oven 2x2x2 is electric
My bigger oven 8x4x4 is powered with Propane GAS heater (40kw)

You need a min of 150w per sq foot

but figgure on double that of you fast recovery
This gets the oven up to temp in 18mins
Replaced with 2 stage diesel heater (Riello 40) 120Kw max
Heats up the oven in a few mins costs almost nothing to run when compared to gas and electricity
So fast heating it not worth preheating the oven

My coating booth is directly opposite the oven so part go from coating directly to oven
Coating booth has suction fans and lots of lights
The rack I hang parts for coating can can change in height and rotates to get all around the parts

Do you mean 150W per cubic foot of oven volume, 150W per square foot of oven wall area, or??
David

[adbuch]

Since everything HANGS in an oven, WHAT IF the rear wall of the oven was wall mounted on a pivot?

Your overthinking it
If you need wider build it wider
A riello burner will be more than enough for an oven twice what you plan
With a gas burner you dont install fans, the burner is a fan
The burner forces hot air in which circulates and goes out the vent

Where do you place the burner with respect to the oven? Does this mean that the interior of the oven is vented to the outside and the heat from the burner flows thru the oven?
David

[adbuch]

Maybe you could show us some pictures of your burner placement and vent arrangement.
Thanks,
David

[34by151]

Maybe you could show us some pictures of your burner placement and vent arrangement.

You can see the vents in the pic I posted that has not changed
Ill get you a pic of the Reillo Burner as soon as I can

We are flodded in at the moment, so Ill get some when I can get to my shop.
The river at my gate is 2m above the bridge
Topical QLD Australia, it rains!!!

I have a pic with the 20kw torpedo heater
This was replaced with the 40kw torpedo, still not enough
Then to the Reillo 40-100kw diesel unit

The notes on the door are my logs for tuning the PID

Oven.jpg

[adbuch]

Here is a smaller gas fired oven build that looks interesting.
David

https://www.powdercoatingforum.net/foru ... oven-build

[Joe Jones]

The outside does not matter, it just for looks. Some don't bother to skin the outside at all. Use what you have outside.

I cannot look at a big box wrapped in dirty insulation. I'd have to wrap it with something.

Its the inside that matters. Go as thick as you can, think about how you will hang you parts.

Inside ... 14 ga. stainless? Aluminum diamond plate? Would an aluminum skin work FOR or AGAINST me for the baking process?

I will have a rolling cart that moves from the spray booth to the oven. The cart will have the hanging options. If I put it on the concrete pad, I could wrap it in red barn tin and it won't need a floor. Okay Monty, I think I'm going to put the oven and booth behind Door #3, as well as the Ranger parts washer I bought. That will put the oven inside, and very close to the breaker panel for easy wiring.

The spray booth doesn't need to vent to the outside, does it? Isn't it just a box with a wall of filters and a fan to suck the air through?

Joe


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[Joe Jones]

Your overthinking it

Story of my life. Have I told you about the FrankenBarn?

If you need wider build it wider

Question: It there ANY reason that a wider oven is an advantage? Since parts HANG and are coated and cooked, does it really matter if the part is rotated 90 degrees to fit into a tall, vertical but narrower oven?

A riello burner will be more than enough for an oven twice what you plan. With a gas burner you don't install fans, the burner is a fan. The burner forces hot air in which circulates and goes out the vent

Ah, see ... now I thought the burners were like fireplace burners, just a row of flame that is perhaps adjusted for that perfect blue flame which is the highest temperature, having a BANK of those burners to produce the BTUs. YOU are talking about something like the shop heaters that act like a jet engine, right?

Joe


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[Joe Jones]

The burner forces hot air in which circulates and goes out the vent

So the heat from a propane burner is LOST? It isn't recirculated?

Joe


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[34by151]

Question: It there ANY reason that a wider oven is an advantage?

YOU are talking about something like the shop heaters that act like a jet engine, right?

Taler than wider lets the heat rise better
No that important if your using gas as the air fan forced and will circulate anyway

Take a look here,you can get them cheep on aliexpress
https://www.riello.com/international/pr ... 21BHGAAWRF

[34by151]

So the heat from a propane burner is LOST? It isn't recirculated?

Think of the burner like a giant hair dryer

Fuel is burnt
This heats air
Burner fan blows hot air in

Air forced in creates pressue inside oven
Vent allows pressure to escape

Air travels around oven and out the vent
With no vent its like putting a cap on a hair drier, it cant move any air

The vent for a gas burner is bigger than for electric
Either way you need gasses to escape and to allow for air expansion

A torpedo type heater is a single stage burner
IE exhaust gasses exit with the hot air like a hair drier

A 2 stage burner has a heat exchanger
IE exhaust is sperate from the hot air

2 stage is better but not needed

[34by151]

Here is a smaller gas fired oven build that looks interesting.
https://www.powdercoatingforum.net/foru ... oven-build

If you looking at a torpedo heather like this one here are a few things I learnt with mine before I got rid of them

You need one with auto ignition
Most have pezo push ignition, but you can convert it to auto

Look for one thats at least 40kw
They are all the same (china) and the real output isabout half the stated KW

You need a large vent
If the airflow is slowed you will get black soot and start burning up the burner element inside and possibly melt the fan

This is why the real output is half the stated output. Lots of heat is lost out the vent to keep airflow though the heater

Been there done that, wasted a lot of money. Would have been far cheaper to just get a proper burner like the reillo in the first place.
It did work with a 40kw heater (like the mr heater) but it was slow
Do yourself a favor save a bunch of money, time and effort, get a propper burner

[34by151]

Where do you place the burner with respect to the oven? Does this mean that the interior of the oven is vented to the outside and the heat from the burner flows thru the oven?

That is correct
You flow through
All ovens need to vent to allow for air expansion and to get rid of the gasses produced by the powder
You need a bigger vent for a gas heater so as to not block the air flow though the heater

[Joe Jones]

Well, all dreams aside, I am going to build this thing with the parts I ordered, and see how it performs.

Joe

[adbuch]

Question: It there ANY reason that a wider oven is an advantage?

YOU are talking about something like the shop heaters that act like a jet engine, right?

Taler than wider lets the heat rise better

No that important if your using gas as the air fan forced and will circulate anyway

Take a look here,you can get them cheep on aliexpress
https://www.riello.com/international/pr ... 21BHGAAWRF

I think the same would be true for an electric oven, as long as it has proper convection with fan and ducting.
David

[adbuch]

Where do you place the burner with respect to the oven? Does this mean that the interior of the oven is vented to the outside and the heat from the burner flows thru the oven?

That is correct
You flow through
All ovens need to vent to allow for air expansion and to get rid of the gasses produced by the powder
You need a bigger vent for a gas heater so as to not block the air flow though the heater

Are you saying that electric ovens are vented to outside as well?
David

[SegoMan DeSigns]

everything in my shop has wheels under it so it can be moved with ease as the job dictates.

Yep! That is why I LOVE my little used Toyota forklift!

Joe

My triple mast all terrain fork lift clears the overhead by 1", once clear of the door I have maybe 12" of lift before it becomes a roof raising event