DIY Oven Build for Ceramics

[ZeroDrift]

DIY Oven Build for Ceramics: Retrofitting Used Oven!

Looking to ask a few tips on this potential project of mine. I am looking at building medium sized oven to coat ceramics. May dabble a little with powder coating as well.

Internal dimensions are either going to be:
30" x 18" x 14" (W x D x H)
30" x 20" x 20" (W x D x H)

I've done some basic searching for heating elements for the slightly smaller enclosure and was pointed towards two 500w strip heaters such as these:
http://www.omega.com/ppt/pptsc.asp?ref=OT_HEATER&nav=

Not entirely sure if this is enough, but the Rep at Omega seemed to think that it would suffice. I believe it will transfer more heat to the inner walls and make the majority of the inner surface a heating element. If any of you can comment on this I would be greatly appreciative!

As for oven and insulation I am thinking of 2" on all sides and fiberglass or mineral wool insulation. The oven walls will be 18 gauge steel and I will ceramic coat them for corrosion resistance.

To control cycles I am looking at the following PID controller: http://www.omega.com/pptst/CN7200_Series.html
And a few DC input solid state relays to provide power to the heating elements. Due to the electrical system that I have access to this has to be a 120v system.

Any thoughts on the setup would be greatly appreciated!

Project Quick Links: Links below are for those who wish to skip to actual progress of this project.
Oven Purchased: Post 23

 

[racingtadpole]

What sort of temperature you shooting for, and how long does it need to stay at that temperature?

 

[ZeroDrift]

Max temperature of roughly 350°f and total the longest soak time is an hour and a half.

 

[superspec]

following, im in the same boat or want to be at least.

 

[racingtadpole]

Effectively you want to roast a decent size slab of meat, time and heat wise. Just to throw a random idea out there, could you not use a large second hand oven out of a kitchen? Comes with a couple of built in parts shelves too

 

[superspec]

sure but IDK about your over but i cant put a long tube header or a 4 ft pipe in my oven.

 

[FMC]

you might get powdercoat to work but will need over 2000 degrees for vitreous enamel or ceramic

 

[justanengineer]

Why not buy an old industrial/lab oven? $1-400 well spent and should handle those chores nicely.

 

[jim faston]

Looking to ask a few tips on this potential project of mine. I am looking at building medium sized oven to coat ceramics. May dabble a little with powder coating as well.

Internal dimensions are either going to be:
30" x 18" x 14" (W x D x H)
30" x 20" x 20" (W x D x H)

I've done some basic searching for heating elements for the slightly smaller enclosure and was pointed towards two 500w strip heaters such as these:
http://www.omega.com/ppt/pptsc.asp?ref=OT_HEATER&nav=

Not entirely sure if this is enough, but the Rep at Omega seemed to think that it would suffice. I believe it will transfer more heat to the inner walls and make the majority of the inner surface a heating element. If any of you can comment on this I would be greatly appreciative!

As for oven and insulation I am thinking of 2" on all sides and fiberglass or mineral wool insulation. The oven walls will be 18 gauge steel and I will ceramic coat them for corrosion resistance.

To control cycles I am looking at the following PID controller: http://www.omega.com/pptst/CN7200_Series.html
And a few DC input solid state relays to provide power to the heating elements. Due to the electrical system that I have access to this has to be a 120v system.

Any thoughts on the setup would be greatly appreciated!

I have no experience with these, but would something like this work for you?

http://www.harborfreight.com/powder-coat-oven-46300.html

110 volts and ready to go. I don't know if they ever go on sale or can be bought using a coupon.

 

[ZeroDrift]

Thank you all for the comments. I think the laboratory oven may be the way to go for an enclosure. Just wire in some modern controls and perhaps some paint and insulation and I can have a very simple and effective oven! Should I get the better half's approval to push forward with this project I'll continue to update this thread with the project.

 

[sabercatt]

i thought ceramics needed over 650. powder is about 385.

 

[ZeroDrift]

i thought ceramics needed over 650. powder is about 385.

Ceramics for items such as pistons, valves, combustion chambers only need about ~300.

 

[R.Anderson]

Look for kiln plans and maybe parts like the heat coils.
here is a crude homemade kiln for an idea.
http://www.instructables.com/id/Electric-Kiln-the-cheaper-ever/

 

[Nostraquedeo]

Might look into using mineral insulated cable as a heat source. Not sure how hot it gets, but I have done some design work using it for decorative ground gutters to melt ice. I think you can get it it in very hot temps, but not very knowledgeable of the product, might be worth some research.

 

[cyato]

I built a powder coat oven from scratch a couple years ago. I think the internal dimensions are about 28" x 28" x 60". It was fun, but it is lot of work. I did a lot of research on the powder coat oven forums and placed a lot of orders with McMaster.

http://www.thepowdercoatingforum.co...forumdisplay.php?19-Powder-Coat-Oven-Building

http://forum.caswellplating.com/oven-building-forum/

If you want to do it on a budget, do a google search on "pregnant powder coat oven". There are a bunch of guys that have "converted" a regular oven to fit larger part.

Here are a couple shots of ours...

 

[bauschracing]

My daughter is a potter. She has bought 2 kilns and uses them both everyday. She goes to 2100 degrees with her glazes. These are 4 foot tall (inside) by 40 inches and 60 inches in diam. These use less than 35 amps - 220 and are insulated well. They both have computer controls for gradual heat and cool down. I think she paid $1650 each. This might be the way to go.
Mike

 

[JonBoehman]

You could repurpose an old frige or freezer

 

[ZeroDrift]

You could repurpose an old frige or freezer

That is a really interesting idea. Going to look into this as I would welcome the extra room. Any thoughts on the door weather stripping?

 

[JonBoehman]

You could use some stuff from these guys.
http://www.jacksonoven.com/index.php/oven-miscellaneous

A fifteen year old built this one.
http://forum.caswellplating.com/oven-building-forum/4137-refrigerator-oven-done-check-out.html

 

[bauschracing]

If you build a kiln, you need to use fire bricks and a heat type seal. Don't think that a rubber seal on a fridg. will work. What cone are you going to heat to with your glazes?

 

[ZeroDrift]

Not going to be using a kiln. The ceramics that I am using are applied coatings to items such as pistons, valves, manifolds, and combustion chambers. Maximum temperature is below 400° (320° for ceramics) but if I decide to apply any powders a little overhead is always good for the high temp epoxy type of coatings.

I may have found an oven from a restaurant that could be an ideal enclosure. It's a low temp oven on wheels. Only would need new electronics and a quick conversion from 220v.

 

[bauschracing]

Sounds great, Good luck

 

[ZeroDrift]

Time to update this thread! After a few weeks of searching, I finally settled on this oven:

This will be torn apart, refurbished and I will re-evaluate going with a 220v system. The oven is in decent shape, but will be a project. Those with a keen eye will note the top of the oven is slightly askew, from what appears to be an add-on. The door is missing its handle and a latch. The interior of the oven will be modified to promote a smooth airflow and heating via an internal squirrel fan.

One idea that I would like to implement is an internal filter to remove any particulates from the airflow. Asides from a traditional paper/foam filter the only thing I can think of is one of those bar/plate filters that charges particles, then screens those particles against a positively charged plate. Any thoughts on what may work for a basic filtration system?

 

[Hotz]

Good equipment ..
What are internal measures?

 

[ZeroDrift]

Internal dimensions are 21" x 19" x 14", but could make it wider by removing the fan and opting for a different design of heating element.

 

[Hotz]

Thanks for information...Great job possibilities..

I'm studying to make my electric oven to heat engine cylinder heads, welding

 

[djkeev]

Sadly, I threw a ceramics kiln away a few years ago, couldn't find a "home" for it.

Dave

 

[ZeroDrift]

Oven finally arrived. Looks great from initial inspections!

From first glance I need to sort out a handle, a door latch and a new seal for the door. The upper table surface could use some new hardware to secure it as well.

 

[Hotz]

very nacy...

 

[ZeroDrift]

Quick pictures of today's progress. Had to start tearing into the insulation as it is very nasty and has what I assume was grease/fat that leaked into it. Also has some corrosion on the main frame, so that will be addressed as well.

It was at this point that I could see the corrosion and some stray wires that were not connected to anything.

Temperature probe:

While I am here I will sort out a variable speed controller for the internal fan. Any leads here would be helpful.

And here is a rather nice feature. This is a door ajar sensor. As of the moment I am thinking of using this sensor to trip the internal fan only as I may want the oven to stay on should the door be open briefly.

Also have to make sense of how they wired the heating elements. Any way to figure out how many amps an element needs? Also, the wires were horribly burnt and very brittle.

By now I've taken most of the exterior panels off to inspect the insulation. At this point I took a few pictures and started tearing all of the insulation apart. The camera was put away as it was dusty work.

I am thinking of using rockwool insulation as it is much more durable . Would like this oven to stay efficient in the years to come. If you know of any other quality insulation I'd love to hear some ideas.

 

[ZeroDrift]

This is where the project currently stands:

For the life of my I cannot get the two hex screws on the fan blades to come loose. I am going to try using a mini pulley extractor on this. Once that is removed I can get to the last bit of insulation. New insulation should arrive early this week and I can start reassembling everything!

 

[Hotz]

Nice job so far ...

Good photos, many ideas for my oven ....

progress report ...

 

[ZeroDrift]

Haven't updated this in some time, but its back together and I am currently working on the PID programming. Installed a heavy duty sliding tray in the base for heavy parts such as blocks and such.

Final details are to wire in a fan controller and address electrical systems before closing everything up.

 

[DoghouseForge]

This is a great solution to low temp heat treating ...we have a surplus used restaurant store about an hour from me so I think a visit will be in order.

Only suggestion I have in regard to the temperature is to run a thermometer inside the oven and cross check its readings with the digital read out on the display .. you'll be amazed how inconsistent and off the digital will be... sounds like you need constant temp for your purposes and regular oven heat elements waver significantly throughout the heat cycles ...

When doing heat treat cycles on blade and tool steel my mentor noticed the variance causing inconsistent results in the blades... our tempering cycles are only 350deg. For 1.5 hours so the variance was significant enough in a small timeline to cause problems .. he now has a small programmable kiln...

Thanks for posting and I hope you get good results because this is a very obtainable solution for baking my blades...

JP

 

[ZeroDrift]

As of this moment the oven is not heating evenly as the fan is not yet operational. The controller I have installed has a learning cycle that determines how to best control the elements (and a cooler if I choose.) The temperature probe I have is accurate, however I will be purchasing a longer probe in the near future, and will be calibrating/testing the accuracy on that one.