Big Oven for powder coating and ceramics
02-18-10, 09:39 PM
#1
Big Oven for powder coating and ceramics
As if I don't have enough projects going with the new shop space I decided to build a big oven. The flowbench project is for when I'm stuck at home, this is being built at the shop.
Specs: Inside space is 4'x4'x8', 50,000btu propane heating, metal studs covered with 20ga galvanized sheet metal stuffed with 4.5" of 10lb density mineral wool in walls 6" on top. Electronic control.
Use: Powder coating always intrigued me and ceramic coating is an added bonus at this point.
The oven is spec'd to reach 700F in about 40 min and hold it for an hour without getting above 140F on the outside. Powder coating only needs 400F so that will be no big deal. Some ceramics need the higher temps. The key is to control heat in its three ways of transfer; conduction, convection and radiation. Conduction is limited by not having the studs touch both the inside and outside skins. Convection is handled by sealing it up tight, radiation, well not much I can do except polish the inside metal lol.
I found the mineral wool on craigslist cheap, that is what put this project in motion
That's a shot of the littlest one, he held the clecos for me.
Specs: Inside space is 4'x4'x8', 50,000btu propane heating, metal studs covered with 20ga galvanized sheet metal stuffed with 4.5" of 10lb density mineral wool in walls 6" on top. Electronic control.
Use: Powder coating always intrigued me and ceramic coating is an added bonus at this point.
The oven is spec'd to reach 700F in about 40 min and hold it for an hour without getting above 140F on the outside. Powder coating only needs 400F so that will be no big deal. Some ceramics need the higher temps. The key is to control heat in its three ways of transfer; conduction, convection and radiation. Conduction is limited by not having the studs touch both the inside and outside skins. Convection is handled by sealing it up tight, radiation, well not much I can do except polish the inside metal lol.
I found the mineral wool on craigslist cheap, that is what put this project in motion
That's a shot of the littlest one, he held the clecos for me.
02-19-10, 03:33 PM
#2
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Wow you seem to be doing all the things I want to do 
Next you're going to post about how you just bought a larger cnc mill
Nice work. Powder coating is fun and once you have the equipment the materials are very cheap. The transparent powders are amazing and you can do some really cool things with them.
Next you're going to post about how you just bought a larger cnc mill Nice work. Powder coating is fun and once you have the equipment the materials are very cheap. The transparent powders are amazing and you can do some really cool things with them.
02-19-10, 05:53 PM
#3
Here is a pic of my new Haas mill!
Darn can't get the pic to work.... jk
The new shop does have 3 phase power though, I was thinking about a nice Bridgeport with a digital read out to set in the corner. I used to have a 1946 Southbend lathe that could spin a 24" face plate. Real nice, fully loaded for the age with taper and thread attachments. I sold it with a company I had about 5 years ago. Now that I have room in the new game room I've been searching craigslist for goodies.
Darn can't get the pic to work.... jk
The new shop does have 3 phase power though, I was thinking about a nice Bridgeport with a digital read out to set in the corner. I used to have a 1946 Southbend lathe that could spin a 24" face plate. Real nice, fully loaded for the age with taper and thread attachments. I sold it with a company I had about 5 years ago. Now that I have room in the new game room I've been searching craigslist for goodies.
03-22-10, 08:29 PM
#4
Update:
I've been bouncing around on a bunch of projects. The oven is at the shop/"game room" and I've had more time there in the last week or so.
These are from when I was putting the outer skin on. The rock wool insulation fills the first 3 1/2" of wall thickness and the outside is some fiberglass I had from another project. The seams in the rock wool are set so they don't meet up and create a heat passage through to the outside. The last layer of glass keeps the outside skin off the structure so heat can't transfer through the metal studs.
The window in the door is the size from a regular oven. I made the chamfer around it so I can see more of the interior through the small window in the 4" thick door. It is also removable so I can take part metal temps without opening the door.
The door is over 150lbs!
For reference, that is an 8' tall ladder.
I've been bouncing around on a bunch of projects. The oven is at the shop/"game room" and I've had more time there in the last week or so.
These are from when I was putting the outer skin on. The rock wool insulation fills the first 3 1/2" of wall thickness and the outside is some fiberglass I had from another project. The seams in the rock wool are set so they don't meet up and create a heat passage through to the outside. The last layer of glass keeps the outside skin off the structure so heat can't transfer through the metal studs.
The window in the door is the size from a regular oven. I made the chamfer around it so I can see more of the interior through the small window in the 4" thick door. It is also removable so I can take part metal temps without opening the door.
The door is over 150lbs!
For reference, that is an 8' tall ladder.
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03-24-10, 06:40 PM
#9
I should be coating in a week or so, I'll post pics. The main motivator for this project was the suspension/subframe/rear end housing on my RX2 vintage racecar. I already have a box of chassis black powder just waiting for the oven to be finished. You can see my sandblast cabinet in the picture with the ladder in it. It's 6' long so I can fit just about any car part that could be coated short of a whole tube frame.
The ceramic coating will be secondary for now. I have a couple guys that have headers they want done and I think I have a supplier for internal engine coatings. I want to do a few engines for myself first before I do any public stuff, I've heard all kinds of horror stories about poor quality work on the internal stuff and I don't want to 'practice' on other people's engines.
The ceramic coating will be secondary for now. I have a couple guys that have headers they want done and I think I have a supplier for internal engine coatings. I want to do a few engines for myself first before I do any public stuff, I've heard all kinds of horror stories about poor quality work on the internal stuff and I don't want to 'practice' on other people's engines.
03-31-10, 03:26 PM
#10
Well, DAMN!
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Nice! Another use for this oven would be for carbon fiber projects. Pre-preg would be your best bet because you wouldn't have to worry about proper resin coverage as much. Just a thought.
~Mike
~Mike
04-03-10, 03:29 PM
#11
I do fiberglass work and I've used CF with regular polyester and epxoy resin. I thought prepreg stuff needed pressure as well for most things its used for, I'll have to look into it.
The other thing I thought of was forming polycarbonate windows etc. My controller will hold temps within a couple degrees.
The other thing I thought of was forming polycarbonate windows etc. My controller will hold temps within a couple degrees.
04-05-10, 01:59 AM
#12
Well, DAMN!
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I believe vacuum-bagging is more important than the pressure of an autoclave. Depending on the parts' intended usage, you do not necessarily need pressure, although the vacuum-bagging does remove air bubbles from the piece you're building, yes, an autoclave will help remove the tiniest of part-weakening bubbles.
10-17-10, 10:34 PM
#14
I use a home made propane burner after I tried a forced air/propane heater and it didn't work well. My burner is made from a few pieces of black pipe but for a small oven I would go electric. My burner puts out way too much heat for anything smaller than a big oven. I did some math and it works out to be about 250,000Btu. It will take my oven from 90F to 400F in about 6 minutes. To give you an idea of the power it has, guys use the same design burner for a forge to melt metal. I have gathered the parts to build one myself so I can do some aluminum casting this winter.
Here is what the basic electric element used looks like.
http://www.partselect.com/PartDetail...6&SourceCode=6
They run on 220V over here, I don't know what power is available to you. An oven as big as mine would probably use 4 of these. An oven 3'x3'x3' would work well with two of these.
Here is what the basic electric element used looks like.
http://www.partselect.com/PartDetail...6&SourceCode=6
They run on 220V over here, I don't know what power is available to you. An oven as big as mine would probably use 4 of these. An oven 3'x3'x3' would work well with two of these.
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