Bernie,
Thanks for digging that up. I had lost my copy in a disk crash.
Actually, I was the one who told Bud that around 100*F would do it for an
overnight cure. I remembered that over 100* would be faster, but didn't
remember how high was "too high" -- that is, past the peak of strength -- so
I didn't mention higher temps. Actually, Bud and I are practically neighbors
(live about 3 miles apart, and have played a few rounds together); so the
context of 100* was the temperature in my garage on a hot day... Which is
where I leave clubs to cure during the summer if I want them overnight.
Bottom line: sounds like a 75w bulb will be close to maximum strength
(stronger than just left for 24 hours), and cure in under 3 hours. Note that
the answer came from Golfsmith, and refers to THEIR shafting epoxy. I'm not
sure that the numbers are the same for, say, Dynacraft's. But I bet the
shape of the curve is similar and the numbers are not terribly different.
Cheers!
DaveT
----- Original Message -----
From: Bernie Baymiller <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, September 08, 2002 11:36 AM
Subject: Re: ShopTalk: Coffee can oven
Bud,
Here's an old post from GS Tech dept. to DT with a table that might interest
you:
"Date: 10-DEC-99
Author: Golfsmith Technical Dept. (Golfsmith)
Subject: Re: Re: Epoxy and cold weather
"Dave:
"Here is some information we obtained from the our epoxy supplier. "All room
temperature (ambient) cured epoxies can be accelerated by moderate heat
(66C-82C) to speed the reaction between the epoxy resin and hardener.
However, curing these systems at very high temperatures may adversely effect
bond strength because of the following:
a.. The heat from the reaction exotherm combined with the externally
supplied heat may char the epoxy system or cause outgassing and bubble
formation, resulting in poor strength.
b.. Premature system gelation or interlocking of molecules restricts
mobility of the molecules within the matrix and may result in an incomplete
reaction.
"On the other hand, most room-temperature, cured epoxy systems give better
bond strength at moderate heat cure as compared to room-temperature cure.
This is because of the better "wetting" of the substrate because the surface
energy of the mixed epoxy is lower and the viscosity is lower." Our standard
24 hour shafting epoxy cures to a shear strength of 3500 PSI at 18 hours at
25 C. When the temperature is increased to 82C (180f) for one hour, the
strength is 3650 psi. At 66C (150f) for two hours the strength is increased
to 3800psi.
"As a table (DMT added): Temp*C Temp*F Cure Time Shear Strength
25 77 18 hr 3500 psi
66 150 2 hr 3800 psi
82 180 1 hr 3650 psi
I hope this helps.
Mark Ehly"
Bernie
Writeto: [EMAIL PROTECTED]
----- Original Message -----
From: bud and marie
To: [EMAIL PROTECTED]
Sent: Sunday, September 08, 2002 9:42 AM
Subject: ShopTalk: Coffee can oven
All
I've been getting a ton of great ideas and experience from you guys.. now
it's time for me to pass something along that perhaps you might find
helpful...if you haven't stumbled on this idea already.. was wanting to
accelerate the epoxy curing of a driver head I had put together for use the
next day.. from what I have learned approx. 100 deg.. is a good temp to heat
the head for that purpose... so I experimented and stuck the driver head in
a 3 lb. coffee can and laid a drop light on top of the can face down with
the bulb pointing towards the can opening.. ..not shoved in.. but just
laying on top.. first a 75 watt bulb heated the inside of the can to 140
deg... too much.. went to 40 watt bulb and it reached 120 deg... went down
to 25 watts and the inside temp of the can stabilized at 103 deg... that
was done at room temperature.. left it over night and the club worked
fine...
FWIW
Bud
