Re: [bolger] Re: dangerous math
Thanks, that posting needed a response. I know that not everyone on this
board is an amateur but I sure am and I found you analysis interesting.
Maybe not accurate to perfection, but it proved the point. I hope nobody
gets shy about putting such information on the board as we post to discuss,
not for disgust! It's all about learning!
Jeff
board is an amateur but I sure am and I found you analysis interesting.
Maybe not accurate to perfection, but it proved the point. I hope nobody
gets shy about putting such information on the board as we post to discuss,
not for disgust! It's all about learning!
Jeff
----- Original Message -----
From: <richard@...>
To: <bolger@yahoogroups.com>
Sent: Thursday, August 23, 2001 11:38 AM
Subject: [bolger] Re: dangerous math
> --- In bolger@y..., Richard <rocwandrer@p...> wrote:
> > I just don't get how all of this "theory" helps someone trying to
> decide on a material for a rudder
> > post. 5 feet of 2" x 0.120 wall ss tubing is exactly $24 plus
> freight from the nearest catalogue i
> > have (aircraft spruce) you could get it in your local (if
> available) for probably $35 or so.
> >
> > Richard
> Very simple. Use the theory to determine if your proposed material
> and configuration make any sense.
>
> It's not that simple Richard. Sure, I could get the SS post for about
> $35. Then, I need the bottle of Ar and the MIG kit for the welder.
> Another $250. Plus, I would still need to be able to weld carbon
> steel, so I would need the AR/CO2 tank for the welder, another $150.
>
> Sure, there are other ways. Farm it out. Use fasteners, etc, but I
> would want to be able to weld it.
>
> BTW, does "aircraft spruce" have a webpage? That is a pretty good
> price for SS.
>
>
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - pls take "personals" off-list, stay on topic, and punctuate
> - add your comments at the TOP and SIGN your posts, snip all you like
> - To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA,
01930, Fax: (978) 282-1349
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>
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>
>
--- In bolger@y..., richard@s... wrote:
it for a bit more than what normal flux-core wire sells for. Well,
shit. If I had know that! I can buy a 2lb spool, enough to weld all
the SS on the boat, for $18.13...
>about
> It's not that simple Richard. Sure, I could get the SS post for
> $35. Then, I need the bottle of Ar and the MIG kit for the welder.On a hunch, I googled "stainless flux-core wire". McMaster Carr sell
> Another $250. Plus, I would still need to be able to weld carbon
> steel, so I would need the AR/CO2 tank for the welder, another $150.
>
> Sure, there are other ways. Farm it out. Use fasteners, etc, but I
> would want to be able to weld it.
>
> BTW, does "aircraft spruce" have a webpage? That is a pretty good
> price for SS.
it for a bit more than what normal flux-core wire sells for. Well,
shit. If I had know that! I can buy a 2lb spool, enough to weld all
the SS on the boat, for $18.13...
--- In bolger@y..., Richard <rocwandrer@p...> wrote:
and configuration make any sense.
It's not that simple Richard. Sure, I could get the SS post for about
$35. Then, I need the bottle of Ar and the MIG kit for the welder.
Another $250. Plus, I would still need to be able to weld carbon
steel, so I would need the AR/CO2 tank for the welder, another $150.
Sure, there are other ways. Farm it out. Use fasteners, etc, but I
would want to be able to weld it.
BTW, does "aircraft spruce" have a webpage? That is a pretty good
price for SS.
> I just don't get how all of this "theory" helps someone trying todecide on a material for a rudder
> post. 5 feet of 2" x 0.120 wall ss tubing is exactly $24 plusfreight from the nearest catalogue i
> have (aircraft spruce) you could get it in your local (ifavailable) for probably $35 or so.
>Very simple. Use the theory to determine if your proposed material
> Richard
and configuration make any sense.
It's not that simple Richard. Sure, I could get the SS post for about
$35. Then, I need the bottle of Ar and the MIG kit for the welder.
Another $250. Plus, I would still need to be able to weld carbon
steel, so I would need the AR/CO2 tank for the welder, another $150.
Sure, there are other ways. Farm it out. Use fasteners, etc, but I
would want to be able to weld it.
BTW, does "aircraft spruce" have a webpage? That is a pretty good
price for SS.
IMHO
Dismissing Richard Spelling's post as "wrong in basic fundamental ways"
without at least a brief explanation as to why he is wrong is itself
"fundamentally wrong". Such a post does a disservice to RS and the
group; particularly those of us who are physics, math, and theory
impaired.
hal
rudder posts are done that way?!
Dismissing Richard Spelling's post as "wrong in basic fundamental ways"
without at least a brief explanation as to why he is wrong is itself
"fundamentally wrong". Such a post does a disservice to RS and the
group; particularly those of us who are physics, math, and theory
impaired.
hal
>It bugs me that people use simple physics and math to stateSome stuff deleted
>something that is obviously wrong. Right
>now i am picking on Richard, but i have seen some problems with a
>lot of posts to this list. I don't
>have the time or expertise to get into it all. don't misunderstand
>me, i am not professing to be an
>expert, but the post below is wrong in basic fundamental ways that
>the poster know, just wasn't
>thinking about. see example below:
>What are his rules? You seem to imply that there is more to it. What?
>Theoreticaly, with a 5ft tiller, I should be able to break the 1-1/8"
>solid 6061-T6 rod with about 135lb of force on the tiller end.
>
>in a system where only the rules you took into account apply, this is true.
>Bill's 1" solid steel rod (assuming 1018 cold rolled) would break atI admit that I'm not the sharpest knife in the drawer but I don't think
>85 lb of force.
>
>sure, same thing. in reality it would start ot bend at well over
>100 lb. of force on the end of it, if
>it was rigidly held at the oposite end, 5 feet away, with no
>intermediary support.
rudder posts are done that way?!
>As designed, using a 2" 304 SS tube with 1/8" walls, it would takeWhy is it silly?
>792 lb of force on the tiller end to break the rudder post.
>
>not even going to get into this one!!!!! sillyness....
>I just don't get how all of this "theory" helps someone trying toMore stuff deleted
>decide on a material for a rudder
>post. 5 feet of 2" x 0.120 wall ss tubing is exactly $24 plus
>freight from the nearest catalogue i
>have (aircraft spruce) you could get it in your local (if
>available) for probably $35 or so.
>
It bugs me that people use simple physics and math to state something that is obviously wrong. Right
now i am picking on Richard, but i have seen some problems with a lot of posts to this list. I don't
have the time or expertise to get into it all. don't misunderstand me, i am not professing to be an
expert, but the post below is wrong in basic fundamental ways that the poster know, just wasn't
thinking about. see example below:
Message: 13
Date: Wed, 22 Aug 2001 20:26:22 -0000
From:richard@...
Subject: Chebacco tiller stock
Incidently, just had a long thread on the math of shear and torque on
the 7x10 mini-lathe group.
Theoreticaly, with a 5ft tiller, I should be able to break the 1-1/8"
solid 6061-T6 rod with about 135lb of force on the tiller end.
in a system where only the rules you took into account apply, this is true.
Bill's 1" solid steel rod (assuming 1018 cold rolled) would break at
85 lb of force.
sure, same thing. in reality it would start ot bend at well over 100 lb. of force on the end of it, if
it was rigidly held at the oposite end, 5 feet away, with no intermediary support.
As designed, using a 2" 304 SS tube with 1/8" walls, it would take
792 lb of force on the tiller end to break the rudder post.
not even going to get into this one!!!!! sillyness....
I just don't get how all of this "theory" helps someone trying to decide on a material for a rudder
post. 5 feet of 2" x 0.120 wall ss tubing is exactly $24 plus freight from the nearest catalogue i
have (aircraft spruce) you could get it in your local (if available) for probably $35 or so.
Richard
now i am picking on Richard, but i have seen some problems with a lot of posts to this list. I don't
have the time or expertise to get into it all. don't misunderstand me, i am not professing to be an
expert, but the post below is wrong in basic fundamental ways that the poster know, just wasn't
thinking about. see example below:
Message: 13
Date: Wed, 22 Aug 2001 20:26:22 -0000
From:richard@...
Subject: Chebacco tiller stock
Incidently, just had a long thread on the math of shear and torque on
the 7x10 mini-lathe group.
Theoreticaly, with a 5ft tiller, I should be able to break the 1-1/8"
solid 6061-T6 rod with about 135lb of force on the tiller end.
in a system where only the rules you took into account apply, this is true.
Bill's 1" solid steel rod (assuming 1018 cold rolled) would break at
85 lb of force.
sure, same thing. in reality it would start ot bend at well over 100 lb. of force on the end of it, if
it was rigidly held at the oposite end, 5 feet away, with no intermediary support.
As designed, using a 2" 304 SS tube with 1/8" walls, it would take
792 lb of force on the tiller end to break the rudder post.
not even going to get into this one!!!!! sillyness....
I just don't get how all of this "theory" helps someone trying to decide on a material for a rudder
post. 5 feet of 2" x 0.120 wall ss tubing is exactly $24 plus freight from the nearest catalogue i
have (aircraft spruce) you could get it in your local (if available) for probably $35 or so.
Richard