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#1
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heater control for curing oven
I'm into recumbents and am exploring building a mold for a prepreg
carbon setup. This looks like an active site for composites. Can anyone recommend a heater control to adjust the heating/cooling ramp rate (5 degrees a minute, etc)? I'm obviously trying to keep costs down so something surplus or homemade would be best. Also, if I do a pressure bladder inside a female mold how do I apply the vacuum between the composite and the inner mold line (so that the bladder inflates)? Or should I just only apply pressure to the bladder and not try to pull a vacuum on the mold? Thanks airplane guys. Joe |
#2
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Check both the Grainger and McMaster Carr listings. They both have
fairly reasonably priced ($90- $400) temperature controlers that can be programed with ramp rates and hold times. Add in a solid state relay and a thermocouple (another $40) and you can build a nice curing oven. They are simple to set up and use. Eurotherm is one brand name that I remember from my lab days........ http://www.eurotherm.com/ =============== Leon McAtee Building bents for kids and experimenting with my first bent trike |
#3
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Make your oven out of urethane foam insulation. Line it with aluminum
foil. Install 100 watt lightbulbs as needed to get the desired heatup rate. I used 8 or 10. Put aluminum foil reflectors over the bulbs to keep them from shining directly on the part and creating hot spots. This is the oven I used to bond some honeycomb repairs to a Gulfstream G-II flap, a 250° cure process. Of course, I used a hot bonder to control and monitor it, but a simple thermostat would work just as well. The biggest factor in your heatup rate will be the mass of your mold. Less massive will make life easier. You'll need to have thermocouples right on the part you're curing. Don't use vacuum with a bladder. Apply pressure. About 2 atmospheres. Make sure you consolidate your layup by applying pressure at elevated temperature for a few hours before the cure cycle. I have two Vision R-40's. wrote: I'm into recumbents and am exploring building a mold for a prepreg carbon setup. This looks like an active site for composites. Can anyone recommend a heater control to adjust the heating/cooling ramp rate (5 degrees a minute, etc)? I'm obviously trying to keep costs down so something surplus or homemade would be best. Also, if I do a pressure bladder inside a female mold how do I apply the vacuum between the composite and the inner mold line (so that the bladder inflates)? Or should I just only apply pressure to the bladder and not try to pull a vacuum on the mold? Thanks airplane guys. Joe -- J Kimmel www.metalinnovations.com "Cuius testiculos habes, habeas cardia et cerebellum." - When you have their full attention in your grip, their hearts and minds will follow. |
#4
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#5
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Good info, thanks.
This post brings up a couple of questions... 1. Do I need breather with a bladder (to allow the air to be forced out)? 2. Is there any concern with vapors building up in the oven and causing a fire? 3. Perhaps it would be a good idea to put 2 bars in the bladder and then put the whole thing in a vacuum bag so that the mold only sees approximately 1 bar? This would keep the fumes out of the oven too. 4. Can thermocouples be joined together to "average" without using software? 5. What is a very affordable PID controller (preferably under $100) that will allow the ramp rate (up and down) to be set? Thanks again folks. Joe |
#6
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#7
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"Dan, U.S. Air Force, retired" wrote in message news:1KiYe.29212$dm.24132@lakeread03... wrote: Good info, thanks. 5. What is a very affordable PID controller (preferably under $100) that will allow the ramp rate (up and down) to be set? Thanks again folks. Joe Try e-bay item 7546821715. I have one which I have used a couple of times and am satisfied with. Dan, U.S. Air Force, retired 47 bucks delivered with the thermocouple! Does it do PID? Heck of a deal it looks like... |
#8
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..Blueskies. wrote:
"Dan, U.S. Air Force, retired" wrote in message news:1KiYe.29212$dm.24132@lakeread03... wrote: Good info, thanks. 5. What is a very affordable PID controller (preferably under $100) that will allow the ramp rate (up and down) to be set? Thanks again folks. Joe Try e-bay item 7546821715. I have one which I have used a couple of times and am satisfied with. Dan, U.S. Air Force, retired 47 bucks delivered with the thermocouple! Does it do PID? Heck of a deal it looks like... I'd be able to answer if I knew what PID is. Dan, U.S. Air Force, retired |
#9
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Dan,
Does this unit allow you to set the ramp both going up and coming down? Does it work with a solid state relay? How easy are the directions to follow (assuming I can't read Chinese!)? PID is described in the message below. Joe |
#10
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