REFLECTOR: structural adhesive in low temperature
Ron Brown
romott at adelphia.net
Mon Feb 13 11:28:36 CST 2006
Grigore,
You can build a tent or other enclosure to cover the fuselage bottom - then use a small electric heater or halogen lights in this tent. Many small electric heaters have thermostats as well as high temperature cut offs. You could also temporarily put the fuselage top on, and cover openings with plastic or whatever.
I purchased an electronic thermometer from Radio Shack that had "outdoor" or remote sensor. Then I placed the sensor inside the tent to monitor temperatures. I was able to get temperatures up to 100 degrees or more (do not exceed 140 degrees!) using this technique. 24 hours at 100 degrees will cure the epoxy fine. The halogen lights (300 or 500 watts x 2) can be used for small areas without the tent. Just get it close enough to the part being cured that the temp gets up to the point that it is too hot to touch. Too Hot to the Touch is about 140 degrees.
I did a lot of this as it gets pretty cold in NC during the winter too.
Ronnie Brown
N713MR - 173 Elite RG
http://home.sprintmail.com/~romott/
----- Original Message -----
From: Gregotto at aol.com
To: reflector at tvbf.org
Sent: Monday, February 13, 2006 11:10 AM
Subject: Re: REFLECTOR: structural adhesive in low temperature
Grigore,
From my experience working with Rutan RAF, SafeT Poxy, Alphapoxy, Aeropoxy, T-88, 3M 2216, etc., Scott is correct in that some epoxies can restart the cure process after dropping below 60, but the majority will not do well if you stop the cure process. What you end up with is a semi-cured part. It may feel hard to the touch, but will not obtain the target structural properties. I would wait for warmer weather if you cannot heat the area for at least 24 hours. And removing semi-cured epoxy to start over is hard to do as it gums up the surface of your abrasives.
Also, you will want to stay away from using the kerosene-type jet heaters like Reddy heaters as they produce particulate combustion matter in the air that still retains a minute amount of pretroleum(oily). While it shouldn't hurt the epoxy, it is definitely hard to make sure it will not get into a finished area causing a potential for fish-eyes in the paint (if pre-cleaning isn't really-really thorough).
From Experience,
Greg Otto
Velocity STD FG
Grayson County, Sherman, TX
In a message dated 2/11/2006 6:57:01 PM Central Standard Time, scott at tnstaafl.net writes:
No 40 degrees is way to low.
The minimum will depend on the accelerator that is mixed with it and can
very. There are low temp epoxy's.
The aeropoxy I use has is a normal range accelerator with a min of 60
F. It will take much longer to cure at 60 than 77.
However, the good news is, the temp can fall below 60, it will stop
curing, then when you raise it above 60 it will start curing again. I've
been told you can only do this so many times and then it will stop
curing, I don't really know.
So you need to put a heater in the fuselage and get the temp up. The
keel is major structure, so I would want to see at least 70 degrees for
a couple of days, or as it says heat it up to 140 for a couple hours.
Watch out for a thermal runaway at a 140 temp though. If your fuselage
is not one piece yet, use plastic sheet as a top so you can get it hot
in there.
Scott
Grigore Rosu wrote:
> The structural adhesive that came with my kit is called Aeropoxy
> ES6228 Epoxy Adhesive, so it is indeed an Epoxy.
>
> A quick search on the web tells us that it cures in 24-36 hrs at 77F
> (way too high for Illinois till May or so) or in 2 hrs at 140F. How
> about at 40F? Forever? Is it OK to just put it on at 40F, fix the
> keel with clecos and let it there for 1 week, heating it occasionally
> with a heat gun? Or I should better wait till May?
>
> Grigore
>
> On Sat, 11 Feb 2006, Scott Derrick wrote:
>
>> The structural adhesive is probably an epoxy.
>>
>> whether it is or not, it does have a minimum temp and curing time on
>> it. If not contact the manufacturer.
>>
>> Scott
>>
>> Grigore Rosu wrote:
>>> Is structural adhesive sensitive to low temperature? I know epoxy
>>> is ...
>>>
>>> I'd like to permanently fix the keen fin and we have about 45
>>> degrees here in Illinois now. I ordered a heater and a highpower
>>> lamp to warm the epoxy, but they have not arrived yet.
>>>
>>> Thanks,
>>> Grigore
>>>
>>>
>>> On Fri, 10 Feb 2006, John Overman wrote:
>>>
>>>>
>>>> Hiroo;
>>>> There is a Pilot here at Port Angeles named Mel
>>>> Rudin. He bought a Velocity RG and took a CFI with him
>>>> to the factory to get checked out in the Velocity so
>>>> he could check Mel out. The CFI is named Fred but I
>>>> can't think of his last name. The instructor is also a
>>>> pilot for Horizon Airlines. He is a really nice guy
>>>> and thorough. I got my instrument rating from him but
>>>> his last name won't materialize. Anyway Mel should be
>>>> in the phone book. Tried looking in my log book but he
>>>> should have been a doctor the way he scratched out his
>>>> signature. I can read his CFI number if that helps. If
>>>> you can't track him down let me know.
>>>> --- Hiroo Umeno <humeno at microsoft.com> wrote:
>>>>
>>>>> I am sure this has come up before but...
>>>>>
>>>>>
>>>>>
>>>>> Are there any Velocity qualified CFI on the West
>>>>> Coast who can give
>>>>> transition training? It looks like my engine is
>>>>
>>>>>
>>>>>
>>>>> Does anyone know of someone?
>>>>>
>>>>>
>>>>>
>>>>> Hiroo
>>>>>
>>>>>> _______________________________________________
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> _______________________________________________
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