What would be a good heat source for curing prepreg and being able to control the ramp time and temp?
kitchen oven coil? and then some type of heat safe fan would be needed to circulate the hot air… any ideas on where to get one?
I want to build an oven 6ft width x 3ft depth x 2ft height
I don’t need computerized controls as I can turn just adjust the heat manually.
That one link with the industrial heat guns was good, but his heat gun idea does not work.
Funny you should ask, I am planning on building a large walk-in type in the near future.
I will be useing heaters from here:
http://www.mcmaster.com/#heat-elements/=2th7q5
And a blower from here: http://www.grainger.com/Grainger/wwg/productIndex.shtml?L2=High-Temperature&operator=prodIndexRefinementSearch&originalValue=high+temp+fans&L1=Blowers%2C
I for get the type of controls that were recommended but can try to remember.
Out of curiosity, why just that size? I figure larger is better (up too a point;))
Most parts i do will fit into the size oven i mentioned. Bigger can be better, but also more $ to operate.
I will check out those links, thanks 
Controlling the heater will require something sturdy! But a fin/blade heater, maybe even a hot water heating element, with the air blowing over it. Maybe if you get bored and tired of adjusting, you can control the heater with a PID. Attach a TC, the relay, and it will keep itself steady!
or this. http://www.mcmaster.com/#33215k75/=2triml
As for the box, I know some people use that pink/blue building insulation foam. Check what the top temp limit is!!! Else a steel box, with some fiberglass insulation around it would be good.
That’s not a bad price for a temp controller… $102 for that dial set.
How do i determine which heat element strip I need to heat from 100F - about 400F? I see they are listed by watts. My oven size will be 6x3x2ft.
This is probably the temp controller I would buy for my oven ( first one on top of the list for dial controlled:http://www.mcmaster.com/#catalog/115/588/=2ufccn
edit: holy crap… expensive thermocouple needed, type J is $200.
Any other ideas for a heat controller that doesn’t cost so much?
I probably would use fiberglass… do i use the same type as for home construction? or is there a special oven type? Hopefully I can get my friends to help build the steel frame and sheet with steel sheetmetal. I’ll just paint the outside with high temp engine paint or bbq paint.
Also can you help me find a seal strip for the door… that will withstand 400F. I want the door to be rectangular 6ftx2ft. and air tight.
I found the oven door sealing strip
http://www.mcmaster.com/#door-seals/=2ufk35
The cheap homebuilders foil faced foam sheeting will only withstand 300F and who knows for how many hours. So I found this- high temp fiberglass insulation:
http://www.mcmaster.com/#high-temperature-insulation/=2uflzm
McMasterCarr… your homemade oven headquarters! lol
damn it… now I want to build it!
http://www.powdercoatoven.4t.com/construction%20page.html
just tossing out some ideas of others.
I do not understand the use of this electrical component AC converter or whatever that two pronged AC thing is?? pictured in the pdf.
machinebuilders.net/plans/gallery/Big Kids/PowerCoat Oven1.pdf
Also I am wondering if using high temp fiberglass insulation if my leg could get burned to the touch of the outside of the oven heated at 375F? The oven will be sheeted in 14 or 16g sheetmetal. My thinking is maybe I can build a workbench around/over the oven. I work in shorts and do not want my leg burned though.
I was planning on insulating my W/in on the inside and then faceing that with fiberlass sheet and epoxy. alternatively I would do the outside w/ mineral wool and face it the same way to eliminate the inevitable degradation of the insulation from people brushing it w/ carts and things.
Fastrr I might recommend you look into the mineral wool insul it is not too expensive and will provide superior proformance.
just my 2 cents
where do you buy the mineral wool from? will it withstand 400F?
I was reading someone elses specs on some foam sheet insulation and the mfg of that brand claimed it was good up to 450F. How long it would last I have no idea.
I do like this one guy’s idea of using metal framing studs for the frame, much cheaper than buying steel tubing and having to pay to have it welded up.
uh…you can get a J-type thermocouple for like 10$…what in the world are you looking at for 200$? a reader and heavy duty system should be only 200!
dunno about the heating…i’ve always ran across that problem. I dont understand how to estimate a heater wattage into a min/max temp I am trying to get too.
Mineral wool is good for 230’c+ before encountering any problems.
Lagging your oven in this way is not only to stop yourself from being burned! It:
Cuts down on your fuel bill dramatically.
Heats the part and not the workshop for your own comfort in Summer…
Will get up to temp quicker and hold it easier.
Acts as a fire barrier.
I would recommend getting it in slab form: http://www.thermatechinsulation.com/Pictures/Rockwool-Board.jpg
For what we want it is perfect - cuts easy with an old carpenters saw or knife, holds its shape and you can clad it afterwards with more insulation board or just some fireboard because of the rigidity it has.
I’ve recently come up with what I think is the ideal solution for us to make our own ovens cheap and safe, I would like to share it and I hope you guys can get the same materials near you.
Here in Europe we make partition walls from metal channel, plasterboard and insulation, this stuff is childs play to construct and needs not much more than a pair of tin-snips, a cordless drill, a knife and saw…
Have a look at the PDF here, it will explain more than I can: http://www.fmb.org.uk/information-and-help/publications/masterbuilder/2008/september-2008/features/?entryid20=3331
Or do this search ‘metal stud partition’ for more info:
http://www.google.co.uk/search?hl=en&safe=off&rlz=1T4DVXA_enGB311GB311&q=metal+stud+partition+&btnG=Search&meta=
There are several grades and thicknesses of plasterboard, in general 1/2" gives 1/2hr fire protection, double it gives an hour etc, there are also specific grades like one which is 15mm and gives one hour of protection. If you wanted something even more sturdy and fire resisting then there are other types of material, just do a search for ‘Fire resisting board’: http://www.longandsomerville.co.uk/custom/shop/category?categoryID=567
As you see it’s more expensive, but then we are talking about potential fire hazards here.
I would strongly recommend fitting a smoke detector/alarm in your workshop, especially if it is in earshot of you or anyone else when you are not in there.
Rockwool house insulation is good to 2000°C. Should work for this. I’ve seen a Pizza oven used for powder caoting. You can likely get one used pretty cheap but might still be too small for what you want. In any case you would have a heating element and thermostat that would work.
If you wanted to save on material costs…you could find in your area where appliances are discarded ((ovens)…and dissemble enough of them to recycle the robust and sheet form of insulation they contain.
That way you could put your cash towards a great controller and not towards insulation.
I’d still then re-cover the whole rig with aluminum faced home insulation ( alum. face inward),then drywall/sheetrock…just for more efficiency.
You’d be smart to make an emergency dump vent in case something goes wrong ( overheat) and you need to lose temps quick.
If your doing hoods and larger parts…a rolling/sliding (inward-outward) rack would be handy too.
Cheers,Vinny
Hello!
I have just finished building an oven from an old clothes drying cabinet. Bought the cabinet used for 5 Euro, it is 180 x 60 x 60 cm (6x2x2 ft) on the outside.
I made the inner walls from steel framing (for indoor wall building), 70mm thick fibreglass insulation and plasterboard.
I use the original heater and fan from the cabinet, it is 2 kW and heats real fast. I control it with a PID controller from Auberins.com, really cheap at 90 $!
The total cost for the oven is something like this:
electrical components (wiring, fuses etc) 15 Euro
PID and freight cost 80 Euro
Plasterboard 20 Euro
Steel framing 30 Euro
Cabinet 5 Euro
Insulation 30 Euro
Total 180 Euro/265$
It is possible to lower the costs by using wood framing instead but i chose steel if something goes wrong and the temp starts to rise fast. I also use a thermofuse that will stop the heater if temp goes over 130 degrees C/266 F.
I will try the oven in the coming weeks, really looking forward to it!
I don’t like the idea of using wood myself… if anything does go wrong it’s a fire hazard using wood, imo.
I have these two heat lamps now, and am considering building a cheap low-heat oven out of foil backed foam sheeting. They sell it at the homestore for like $30 for 4’x8’. I only need it to reach 120F. just to help aid the time in curing of epoxies. Plus if i have an open part with epoxy it will cut down on epoxy fumes if they are enclosed.
The drier cabinet sounds like a good idea… did you keep the small round door? lol
Hello!
My dryer is not a tumbler type
It’s just a cabinet with a heated fan and venting, I don’t know the exact word for it in english.
I tried the oven this weekend, the measuring of the temperature is not sufficient as it is now, i have a big difference in temp between the upper and the lower part of the cabinet.
The sensor is mounted in the top and my fan is only working when the heating is on as it is connected now. It seems all the hot air rises to the top causing a too high temperature reading.
I’ll try connecting the fan so that it is always on to force the air to circulate, i will also exchange the temp sensor placement.
The sensor will be taped to the surface of the composite instead which should give better readings.
Things can only get better!
Ill add my 2 cents: Dont use kerosene as a heat source. Its by products can/will ruin your layup.
Nat. Gas could work i think. I’ve used one oven like that. Bitch to maintain if you don’t know anything about it
When I built my last heat oven, I used plasterboard with a good fire rating, heat insulation and oven elements, with three circulating fans dotted around the inside to keep the hot air circulating.
I had three temp sensors and temp controller to keep an eye on things. Also if things went wrong I had a fire extinguisher sat beside it and it was all wired up to a power cut off switch.
Due to moving premises, I now need to build a bigger one 
Good idea with the smoke detector though
Stu
It’s been said that the by-products of Kerosene burners are bad for composite parts. Does this matter when there is a vacuum bag protecting the part? All the parts I will cure are infused.
