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Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/17/23 3:33 p.m.

Yup... brain still in overdrive on this.

I watched an Eastwood video about their 4x4x6 oven.  According to the vague video description, they use 35,000 BTUs split over three oven burners.  Carry the two, divide by pi... that's around 11,000W for a 96 cu ft oven.  To me, that sounds like if I did three burners at about 3000W, that will keep me just under 40A.

Now the last thing I need to figure out is if I can find something that I don't think exists - a straight, non-bendy oven element.  If I put four straight elements in each corner, then it doesn't really matter if they provide primarily radiative or conductive heat.  It will all hit the part at mostly the same intensity...  provided I can properly circulate air and prevent cold/hot spots.

Anyone know where a guy could get something like a straight oven element in the 2300W range?

Like this, but not bent to fit in an oven:

1988RedT2
1988RedT2 MegaDork
11/17/23 4:04 p.m.

Some food service equipment uses straight Calrod-type elements.  Might find something for Hatco, maybe on ebay.

https://www.amazon.com/Hatco-R02-08-118D-Element-Gr72-1725/dp/B00EMJXP4S

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/17/23 4:11 p.m.

How did you...

Nevermind.  That's exactly the kind of thing I'm looking for.

Mind blown.

jgrewe
jgrewe Dork
11/17/23 6:14 p.m.

I would go with a couple oven elements on the back wall and put a shield of some sort to keep the heat from getting directly to the parts. It could be something as simple as a piece of sheet metal 6" wide to hide the element. Don't over think it and over spend. You aren't going to get all the parts in there at once anyway. Save your money and get a real powder gun, not the HF or cheap Eastwood stand alone gun. If you are going for a metallic it will need to be clear coated. The second coat of powder needs less voltage. Some have a clear built in the mix but I've found it is tough to get even coverage.

I don't worry about hot or cold oven to start. I can bring the temp up more than fast enough. If you start cold, and it comes up slowly because you are short on Btu's, the metal temp will be close to the oven temp for cure timing. I don't bring my oven up as fast as I could, the metal temp is what matters and the 10 extra minutes I wait for the metal to get to temp isn't a concern.

 

Welly
Welly New Reader
11/17/23 7:17 p.m.

https://asbheat.com/

You might get some ideas here.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/17/23 11:04 p.m.
jgrewe said:

I would go with a couple oven elements on the back wall and put a shield of some sort to keep the heat from getting directly to the parts. It could be something as simple as a piece of sheet metal 6" wide to hide the element. Don't over think it and over spend. You aren't going to get all the parts in there at once anyway. Save your money and get a real powder gun, not the HF or cheap Eastwood stand alone gun. If you are going for a metallic it will need to be clear coated. The second coat of powder needs less voltage. Some have a clear built in the mix but I've found it is tough to get even coverage.

I don't worry about hot or cold oven to start. I can bring the temp up more than fast enough. If you start cold, and it comes up slowly because you are short on Btu's, the metal temp will be close to the oven temp for cure timing. I don't bring my oven up as fast as I could, the metal temp is what matters and the 10 extra minutes I wait for the metal to get to temp isn't a concern.

 

I love all of this.  I noticed a lot of DIY ovens have them on the back/sides.  Is there a reason for that?

Do you have a recommendation for a gun?

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/17/23 11:05 p.m.
Welly said:

https://asbheat.com/

You might get some ideas here.

Oooo.  Tons of ideas.

jgrewe
jgrewe Dork
11/17/23 11:49 p.m.

Element location is about keeping them out of the way while letting the air flow around them as much as possible. For your box I would stack them near the bottom in back or put them one above the other up the wall to spread the output more.

As for a gun. I tried the HF one and threw it in the trash after one experiment. I think I coated a construction square with some of their red powder. I found a Hypersmooth set up on Craig's List that was about $750 new, I paid $350 for it. It came with a bunch of wild colors the guy had left over from doing custom bikes. I ended up doing a few bikes as a side way to make a few bucks and ended up making enough to more than pay for what I have in my whole set up.

If you can justify the expense, look for a Hypersmooth or Spectracoat. Even their basic ones are real systems that will do whatever you want.

I by small quantities of powder from "powder by the pound"

You may also want to look into Benco B17 stripper. It is the only thing that will make powder fall off parts.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/18/23 1:01 p.m.

In reply to jgrewe :

You're an angel.

I'm going to rewire my outlet to get enough amps and I'll order some elements to total around 9000W.  That will be around 31,000 BTU.

Y'all are makin me shop and I like it.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/18/23 2:27 p.m.

Ordered Mica wire, BBQ felt tape, three 3000W broil burners, and hi-temp ring terminals.  Total so far is $118 and change.

 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/18/23 11:03 p.m.

jgrewe, thoughts on this gun?  Reviews look pretty good.  Wide range of kV.  Downside is it's European/Asian, but it comes with adapters.

https://www.facebook.com/marketplace/item/1484725902329141

jgrewe
jgrewe Dork
11/19/23 12:08 a.m.

I've never heard of the brand but its probably made in the same factory as the rest of them that have a similar look.

I've opened my Hypersmooth up and its pretty simple inside. Mainly a transformer with a rheostat controller and an air pressure flow control w/gauge. Being able to adjust the voltage is huge. There are times when two intersecting pieces will create a Faraday cage and the powder won't get to the part. You can turn down the voltage and hit the problem area. Mine claims 100K V  but I never run it that high, usually around 60K is enough for the first coat, 35K ish for a second coat. Another option is to preheat the spot with a torch and have no voltage, the powder hits the area and sticks because it melts.

The air flow is almost set and forget so not having that on the machine isn't a big deal. More flow will get you a big cloud of powder that will end up on the floor anyway.

Having a good ground is more important than super high voltage. I ran a rod into the ground through a hole that was in the slab of my shop. There were times pouring water down the hole around the ground rod fixed a powder not sticking issue!

 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/19/23 9:25 p.m.

In reply to jgrewe :

Ok, thanks.  I watched a video review from a professional shop that claims they bought one to try as opposed to "they sent us a freebie in return for a glowing review."  I think I'll pull the trigger on it (pun intended)

Disappointing part of my day is that the 3000w burners I ordered came today and are quite clearly marked "2400W" on the element.  Back to the drawing board on choosing one of three million offerings on Amazon.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/19/23 10:03 p.m.
jgrewe said:

I've never heard of the brand but its probably made in the same factory as the rest of them that have a similar look.

I've opened my Hypersmooth up and its pretty simple inside. Mainly a transformer with a rheostat controller and an air pressure flow control w/gauge. Being able to adjust the voltage is huge. There are times when two intersecting pieces will create a Faraday cage and the powder won't get to the part. You can turn down the voltage and hit the problem area. Mine claims 100K V  but I never run it that high, usually around 60K is enough for the first coat, 35K ish for a second coat. Another option is to preheat the spot with a torch and have no voltage, the powder hits the area and sticks because it melts.

The air flow is almost set and forget so not having that on the machine isn't a big deal. More flow will get you a big cloud of powder that will end up on the floor anyway.

Having a good ground is more important than super high voltage. I ran a rod into the ground through a hole that was in the slab of my shop. There were times pouring water down the hole around the ground rod fixed a powder not sticking issue!

 

Good tips.  I think this one grounds through the gun, but if I don't get a good ground the grounding peg for the building is not far from where I will be spraying.  I could run a redundant or replacement conductor to it.  There shouldn't be many faraday spots on this rack, but that's good to know for other sprays. 

This Redline gun adjusts from 20-100 kV and has a air/powder mix dial.  

I'll need to do some test parts, so if anyone wants some really crappy coating done while I hone my skills, send them to Berkley St.

 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/19/23 10:05 p.m.

Other good news - I found oven elements on Amazon that claim to be genuine GE branded 3000w elements and they're actually cheaper at $18 each.  Let's see if they actually are.

clutchsmoke
clutchsmoke UberDork
11/20/23 11:26 a.m.

I'm sure this is totally obvious. Just wanted to be sure that you're going to powdercoat like... Several things first and once you're happy with results coat your roof rack. 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/22/23 6:31 p.m.

In reply to clutchsmoke :

Yes.  I have all kinds of dumb scraps around I can try.  One of the things I want to do is to take some scrap aluminum and clean it a few different ways - 220 grit, wire wheel, scotchbrite, etc, and maybe also do one half with Alumiprep and the other half without.

Scrap metal is something I definitely have.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/22/23 6:41 p.m.

Got my three cheap ($18 each) GE-branded oven elements today, and surprise surprise... they are actually GE, and they are actually 3000W.

I pulled the trigger on the Redline gun I posted above and it is on the way from NJ.  Well, the guy took my $345 and got back to me with a valid tracking number.  It could be a box full of dog poo, but we'll find out.  Should be here Friday.

In other good news, the cabinet is physically complete.  None of the electrics are in it, but the structure itself is done.  For now I put a piece of all-thread across the top with a bunch of S-hooks.  I'm sure I'll think of some other brilliant idea later, but for the immediate plans I think they'll be fine.

QUESTION OF THE DAY:  All of the seams in the cabinet are spot welded from the factory, meaning that it's far from air-tight.  I was going to go over them all with foil ducting tape, but I was concerned that the adhesive would give up the first time I fired it up.  What would you use to seal up the seams?

RonnieFnD
RonnieFnD Reader
11/22/23 6:50 p.m.

This thing is gonna do a great job and be a keeper.  I like your style,  start off with throw away ideas just to do one job but end up making something awesome that will last.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/22/23 7:01 p.m.

$113.71 is the current total if you don't count welding gas/wire/electric.
Add $345 for the gun
= $458.71

I know I'll need:

  • Insulation
  • Outer skin (optional, but it would prevent ripping the insulation)
  • metal studs
  • appliance pigtail
  • 40A breaker
  • 4' of 8/3 NM-B to rewire the outlet
  • either a scavenged oven thermo/knob or a PID that can take 9000W
  • Possibly an oven window cut into the side for IR thermo checking
  • Probably a handful of oven thermometers placed strategically around the space to test for hot/cold spots
  • Probably a circulation fan.  I might just steal the one from my fireplace because I never use it, it's a compact squirrel-cage fan, and I already know it will take high heat.
     
Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/22/23 7:02 p.m.

In reply to RonnieFnD :

Thanks.  Here's hoping.  It might suck and I'll scavenge the parts for something else, but I'm having fun and learning a lot.

fasted58
fasted58 MegaDork
11/22/23 7:03 p.m.

In reply to Curtis73 (Forum Supporter) :

Hi-temp RTV, IIRC Permatex brand. We used it in sealing industrial NG ovens and in the boiler houses. 600° should be good enough although higher temp is available.

alphahotel
alphahotel New Reader
11/22/23 7:04 p.m.
Curtis73 (Forum Supporter) said:

QUESTION OF THE DAY:  All of the seams in the cabinet are spot welded from the factory, meaning that it's far from air-tight.  I was going to go over them all with foil ducting tape, but I was concerned that the adhesive would give up the first time I fired it up.  What would you use to seal up the seams?

 The aluminum duct tape (the real metal stuff, not cloth) will hold up to 400 degrees just fine, I think.  When my boys were in Boy Scouts, they made cardboard ovens, sealed with aluminum duct tape and it held just fine at 350-400 degrees.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/22/23 7:24 p.m.

In reply to alphahotel :

Just the stuff on the shelf at HD?  Like this?  If so, I have a few dozen rolls of it.  Most of them say they conform to [insert code here], but they all refer to a code that calls out 250F as the max.

fasted58
fasted58 MegaDork
11/22/23 7:32 p.m.
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