Pre-Pregs not curing

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Pre-Pregs not curing

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Hanaldo	Hanaldo posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Placing thermocouples in direct contact with an aluminium mould can also cause trouble though, as the PID thinks the oven isn't heating up and so it tries to crank the heat as fast is it can. This heats the air up to extreme temperatures, so you can lose control of your ramp rates and your soak temp.
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Fasta	Fasta posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	+x Hanaldo - 6/22/2018 12:19:04 AM Placing thermocouples in direct contact with an aluminium mould can also cause trouble though, as the PID thinks the oven isn't heating up and so it tries to crank the heat as fast is it can. This heats the air up to extreme temperatures, so you can lose control of your ramp rates and your soak temp. This is the exact reason I read from the air with a heavy metal mould. I also cook multiple parts/moulds of different sizes in the each cooking session. When oven goes crazy trying to heat a metal mould at 2 deg per min the heat from the elements just run flat out can fry the other parts a bit with near burnt bags from the radiant heat. Just adding an extra hour to the cure time means that all the parts get enough and work out. In the end all that matters is that a part gets it correct cure temp for at least the minimum time. Fastacraft Facebook page
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Jeff Clemmons	J Jeff Clemmons posted 6 Years Ago Post Details
J Group: Forum Members Posts: 6, Visits: 45	So what I have done is drilled holes up through the bottom of the mould which are 1 1/2" deep in 2" mould. My plan is to run the mould empty through a cycle and testing various places in the mould as it heats. Once I see that the entire mould is up to temp, I will add that amount of time to the "soak" time. That way my air inside the mould isn't ramping to quick and I will know everything is leveled of at the correct soak temp. I plan on running this test this weekend. Thank for the comments guys! JC
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Jeff Clemmons	J Jeff Clemmons posted 6 Years Ago HOT Post Details
J Group: Forum Members Posts: 6, Visits: 45	+x MarkMK - 6/21/2018 8:10:05 AM I'd also recommend buying a remote thermocouple unit. You can buy these fairly cheaply on places like Ebay If you get one that has two probe wires, long enough to extend outside of your oven, you can gum tape the ends onto selected places on the part in the mould and monitor actual temperatures there rather than reply upon the fixed thermocouple on your oven set-up These will, hopefully, provide you with much better assurance of the temperature your mould is running at My idea exactly Mark, I already have a remote thermocouple unit. I have drilled holes about 3/4 the way through the mould from the bottom and plan to manually read the temperatures of the mould itself at various points in the mould during a dry run through a cycle. I put 9 holes in it, some close to the cavity, some near the edges of the mold. Once I know how long it take to get the entire mould to the soak temp, I should be able to merely add that amount of time to the suggested soak time and everything work. I plan on running this test this weekend. Thanks for your suggestions! JC
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f1rob	f1rob posted 6 Years Ago Post Details
Group: Forum Members Posts: 237, Visits: 4.8K	Just get a remote thermocouple or you pid one and tape it to the bag of your laminate at it's thickest point. You won't be too far off the temp of your laminate. If your final cure temp is 1hr at temp at the very least allow 1.5 hrs,preferably 2hr extra as an allowance for an Ali tool
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nreindel	n nreindel posted 6 Years Ago HOT Post Details
n Group: Forum Members Posts: 8, Visits: 145	+x Fasta - 6/19/2018 2:10:48 AM Could just be your aluminium mould is sucking up much of the heat so assuming you are just measuring the air temp and timing from this your part is under cooked as it takes 45min to heat a mould like that. I usually put my oven controller thermocouple in the air and just set my cure time to be 1 hour more than the cure time stated. You can't overcook it but you can under cook it. How did you come up with 45 min. extra cure time for OP's mold size? Is there a good rule of thumb to calculate cook time to add by mold mass/volume?
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