Re: [bolger] Thoughts on FG butt joints
I think if you make the butt block or glass patch diamond shaped at a 2
to 1 length to width with at full width portion in the middle about 8
times the thickness your joint will be stronger and fairer.
Gordon
Gordon Cougergcouger@...
Stillwater, OK www.couger.com/gcouger
405 624-2855 GMT -6:00
From: "Richard Spelling" <richard@...>
Building a Michalak Larsboat, and using FG butt joints.
One 2" strip of 6oz on each side of the 5mm Lauan.
Did my standard break test on a piece of the scrape to get the warm
fuzzies... It snapped at the FG joint! Repeated the test, and it broke in
the wood.
Recalled an email conversation with someone awhile back where he said all
his testing with FG butt joints, the joint would snap the glass.
Repeated the experiment numerous times and made the following
observations, which may be of interest to the group.
1) If the two supporting points, and the pressure point, are ALL inside
the bounderies of the FG/wood sandwitch, the joint will break apart at the
butt.
2) if one or both of the supporting points are OUTSIDE the bounderies of
the FG/wood laminate, it will break in the wood where there is no FG.
After reflection, this is obvious. The weakest part of the FG/wood
laminated section is the butt joint. However, even this weak area is
stronger than the unlaminated wood.
So, the joint is stronger than the wood, and the person who reported them
breaking all the time was probably applying pressure ONLY in the laminated
section.
Comments?
Richard Spelling,http://www.spellingbusiness.com/boats
From the muddy waters of Oklahoma
to 1 length to width with at full width portion in the middle about 8
times the thickness your joint will be stronger and fairer.
Gordon
Gordon Cougergcouger@...
Stillwater, OK www.couger.com/gcouger
405 624-2855 GMT -6:00
From: "Richard Spelling" <richard@...>
Building a Michalak Larsboat, and using FG butt joints.
One 2" strip of 6oz on each side of the 5mm Lauan.
Did my standard break test on a piece of the scrape to get the warm
fuzzies... It snapped at the FG joint! Repeated the test, and it broke in
the wood.
Recalled an email conversation with someone awhile back where he said all
his testing with FG butt joints, the joint would snap the glass.
Repeated the experiment numerous times and made the following
observations, which may be of interest to the group.
1) If the two supporting points, and the pressure point, are ALL inside
the bounderies of the FG/wood sandwitch, the joint will break apart at the
butt.
2) if one or both of the supporting points are OUTSIDE the bounderies of
the FG/wood laminate, it will break in the wood where there is no FG.
After reflection, this is obvious. The weakest part of the FG/wood
laminated section is the butt joint. However, even this weak area is
stronger than the unlaminated wood.
So, the joint is stronger than the wood, and the person who reported them
breaking all the time was probably applying pressure ONLY in the laminated
section.
Comments?
Richard Spelling,http://www.spellingbusiness.com/boats
From the muddy waters of Oklahoma