Re: Chebacco and other masts
Jamie Orr wrote that... "PCB suggested this construction when I wrote
to him to check on wall thickness for a conventional hollow mast."
Jamie! Would you kindly send to Bill Samson all the facts on the
Bolger described hollow mast, in excruciating details, for the rest
of us Chebacco builders? I'm sort of sure Bill would want to publish
them as well as discuss Fraser's problems in an upcoming Chebacco
Newsletter.
Woah. I've been thinking about a birdsmouth mast.
Dick Burnham
to him to check on wall thickness for a conventional hollow mast."
Jamie! Would you kindly send to Bill Samson all the facts on the
Bolger described hollow mast, in excruciating details, for the rest
of us Chebacco builders? I'm sort of sure Bill would want to publish
them as well as discuss Fraser's problems in an upcoming Chebacco
Newsletter.
Woah. I've been thinking about a birdsmouth mast.
Dick Burnham
I think I sent this off to the older, now-defunct BolgerList, so I'm
re-sending it. Apologies if it comes up twice.
Fraser, sorry to hear about your mast breaking. My books support the
comments already made that a hollow, unstayed mast needs to have solid, or
at least thick, reinforcing plugs at the partners. Still, at the rate you
get things done, that shouldn't hold you up long!
At the other end of the speed scale, this weekend I eight-sided my Chebacco
mast. This is made as shown in the Bobcat plans, I think the same way that
Col Mooney is suggesting for his Martha Jane. My mast so far is shaped, and
eight-sided, and weighs exactly forty pounds. I don't think this will
change much more in the final rounding. (Length is about 20 feet, diameter
4 inches except for a taper to 2 1/2 inches over the top 8 feet, and a taper
to 3 1/2 inches over the bottom 3 feet -- which are square.) There is an
inch square hole running up the centre, with about the top sixteen inches
plugged. (The length of the final plug will be less when the top is cut off
a bit.) I didn't plug at the partners, because the walls are one and a half
inches thick and should be strong enough. PCB suggested this construction
when I wrote to him to check on wall thickness for a conventional hollow
mast.
I stopped the side pieces from slipping when glued by using hardwood dowels
as sold for furniture joints. If you've shopped at Ikea, you know the ones.
I cut these down to about one half inch long, and they locked everything
nicely while the glue (epoxy) cured. Getting all these set up took quite a
while, but it made the gluing a simple operation. I glued all the pieces at
once.
Jamie Orr
re-sending it. Apologies if it comes up twice.
Fraser, sorry to hear about your mast breaking. My books support the
comments already made that a hollow, unstayed mast needs to have solid, or
at least thick, reinforcing plugs at the partners. Still, at the rate you
get things done, that shouldn't hold you up long!
At the other end of the speed scale, this weekend I eight-sided my Chebacco
mast. This is made as shown in the Bobcat plans, I think the same way that
Col Mooney is suggesting for his Martha Jane. My mast so far is shaped, and
eight-sided, and weighs exactly forty pounds. I don't think this will
change much more in the final rounding. (Length is about 20 feet, diameter
4 inches except for a taper to 2 1/2 inches over the top 8 feet, and a taper
to 3 1/2 inches over the bottom 3 feet -- which are square.) There is an
inch square hole running up the centre, with about the top sixteen inches
plugged. (The length of the final plug will be less when the top is cut off
a bit.) I didn't plug at the partners, because the walls are one and a half
inches thick and should be strong enough. PCB suggested this construction
when I wrote to him to check on wall thickness for a conventional hollow
mast.
I stopped the side pieces from slipping when glued by using hardwood dowels
as sold for furniture joints. If you've shopped at Ikea, you know the ones.
I cut these down to about one half inch long, and they locked everything
nicely while the glue (epoxy) cured. Getting all these set up took quite a
while, but it made the gluing a simple operation. I glued all the pieces at
once.
Jamie Orr