Epoxy adhesion

John Long

John Long

Member
My firewall has been painted six or eight weeks but I had failed to cut the 2 1/4" hole needed for the brake booster push rod.



I had a 2 1/4" chassis punch so cutting the hole was no big deal. The interesting thing is my son in law, Tim, was here for thanksgiving dinner and I was showing him what I had done. I looked at the plug and realised there was absolutely no loss of adhesion anywhere. The red epoxy on the bare metal, the red epoxy on top of the body filler, as well as the dark red base and Universal Clear had all maintained their adhesion.

The only failure of material on the plug was the body filler fractured from the severe bend in the metal. This is a pretty awsome testimoney to the quality of the SPI line.

Here is the firewall side if the plug. Note, the only seperation is the body filler seperated between the layers of SPI epoxy. The epoxy, base color and clear all maintained adhesion.



Here is the interior side of the plug.



I would estimate the body filler is approximately 1/16 of an inch thick and the plug literally pulled the filler apart.

Pretty cool.

John
 
John, how many ft lbs would you guess it took to pop that hole? I like it. I'll never need it, cool though.
Did it pop or slowly tear steel?
 
EddieF said:
John, how many ft lbs would you guess it took to pop that hole? I like it. I'll never need it, cool though.
Did it pop or slowly tear steel?
Click to expand...

The punch came from my Dad yesrs ago. He fooled with radios in the old days when they used vacuum tubes. I think I inherited about 12 different sizes.

I doubt it takes more than 25-30 ft lbs. The punch cuts the metal like a shear starting at the point and cutting toward the "valley" of the die as it is tightened. It doesn't damage the outside of the hole but curles up the cut out quite a bit as you see in the picture.

John
 
Looks like a knockout punch used for electrical work. They work really well.
 
Yup. Same thing. This set just happened to be made in the forties for vacuum tube holes in radio chassis.

John
 
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