FullCircle
Well-Known Member
Need to buy about 2.5 metres of 75mm diameter stainless tube to fabricate my Cruising Chute bowsprit in Essex.
Any ideas for a supplier?
Any ideas for a supplier?
75mm diameter Stainless tube for a bowsprit?
- Thread starter FullCircle
- Start date
Talbot
Well-Known Member
not just tube diameter that is important, but also wall thickness!
FullCircle
Well-Known Member
and has to be 316, etc etc....
Anything around 1mm wall would do it.
Anything around 1mm wall would do it.
Rowana
Two steps lower than the ships' cat
1mm is a bit thin, is it not?
10mm more like.
10mm more like.
FullCircle
Well-Known Member
10mm??
thats thicker than a North Sea oil pipe!!!
No, I think 1mm will be about minimum, going to 2mm max.
After all the current load is taken by a size 2 Barton turning block with a shackle to the bow roller, and that copes fine.
thats thicker than a North Sea oil pipe!!!
No, I think 1mm will be about minimum, going to 2mm max.
After all the current load is taken by a size 2 Barton turning block with a shackle to the bow roller, and that copes fine.
Twister_Ken
Well-Known Member
Why not an ali spinny pole section? Or a bit of carbon windsurfer mast? Much less weight on the bow.
FullCircle
Well-Known Member
So true Ken, but it will look less of a lash up in SS....... and it will match the bow roller frame.
Besides, there is about 4km of chain in the locker underneath it, so Ho Hum.
Besides, there is about 4km of chain in the locker underneath it, so Ho Hum.
fireball
Well-Known Member
Erm - are you putting a downhaul on the end of this bowsprit? If not I think you need to look at your bending moments ...
1mm is not very thick and will bend very easily - especially with a nice big kite on the end of it...
I'm looking at a bowsprit too, no downhaul - but I haven't specc'ed the pole thickness yet ... going to look into that once I've got the length sorted.
1mm is not very thick and will bend very easily - especially with a nice big kite on the end of it...
I'm looking at a bowsprit too, no downhaul - but I haven't specc'ed the pole thickness yet ... going to look into that once I've got the length sorted.
Graham_Wright
Well-Known Member
In my experience tube does not bend;- it kinks and that's the end of it-finished!
2mm is still a joke. What's the size of the boat?
2mm is still a joke. What's the size of the boat?
BAtoo
Well-Known Member
Thinking about this too!! Friend with a Dehler 35 has a set-up the uses his spinny pole (conventional ali pole w piston fitting either end) going thro a s/s ring over his 2nd bow roller. In board end fixes onto a standard fold-down pad-eye. Thinking of copying this but my spinny pole isnt double ended so will need another pole specifically for this.
I dont anticipate alot of probs with bending/kinking as there wont be too much sticking out - maybe 2-3' to clear the pulpit?
Not thinking of using anything more then 3mm walled spinny pole -certainly not 10mms/s ??
I dont anticipate alot of probs with bending/kinking as there wont be too much sticking out - maybe 2-3' to clear the pulpit?
Not thinking of using anything more then 3mm walled spinny pole -certainly not 10mms/s ??
FullCircle
Well-Known Member
Oh dear, I have excited the design community here , what?
All I asked for was a supplier of 75mm tube, which actually no one has come up with yet!
I did not disclose my design intentions, or mention lengths, restraining bracketry, triangulation of forces,end fittings etc etc. Suffice to say, I used to design bits of aircraft, and now design bits for cars, and am slightly conversant with light weight high strength lumps.
I will post the results after fabrication installation and testing.
Provided someone tells me where to buy the material of course. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
All I asked for was a supplier of 75mm tube, which actually no one has come up with yet!
I did not disclose my design intentions, or mention lengths, restraining bracketry, triangulation of forces,end fittings etc etc. Suffice to say, I used to design bits of aircraft, and now design bits for cars, and am slightly conversant with light weight high strength lumps.
I will post the results after fabrication installation and testing.
Provided someone tells me where to buy the material of course. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
FullCircle
Well-Known Member
<<In my experience tube does not bend;- it kinks and that's the end of it-finished!
2mm is still a joke.>>
You mention being an Engineering Director. Are you sure? /forums/images/graemlins/grin.gif
Of course tube bends, unless you have a lead on something with infinite flexular modulus. After all, your mast bends, doesn't it? And you should see the angle I can get my radar tower to deflect. Quite astounding.
Why is 2mm a joke? Can you send me your base calculations for the force vectors?
2mm is still a joke.>>
You mention being an Engineering Director. Are you sure? /forums/images/graemlins/grin.gif
Of course tube bends, unless you have a lead on something with infinite flexular modulus. After all, your mast bends, doesn't it? And you should see the angle I can get my radar tower to deflect. Quite astounding.
Why is 2mm a joke? Can you send me your base calculations for the force vectors?
BAtoo
Well-Known Member
Found this on google - http://www.orionalloys.co.uk/section-2.aspx?item_id=3.
Hope it helps.
What are you going to use for the end fittings??
Hope it helps.
What are you going to use for the end fittings??
Phoenix of Hamble
Well-Known Member
Tee Hee..... I was waiting for that.... /forums/images/graemlins/grin.gif
PuffTheMagicDragon
Well-Known Member
[ QUOTE ]
Of course tube bends, unless you have a lead on something with infinite flexular modulus.
Why is 2mm a joke? Can you send me your base calculations for the force vectors?
[/ QUOTE ]
I'd look at it from a simpler angle. Would the kite lift me up (76kilos). In my case it does not. If I hang onto the end of a horizontal pipe, 75mm diameter, even if it is only 1mm diameter and there's a full 2 metres of it 'free', it wouldn't even give me the time of day! My weight would be, for all intents and purposes, not even worth considering.
Just make sure that the 'part' that holds it down to the deck is more like a sleeve with a slightly flared end rather than a 'U-bolt' type of arrangement; this to avoid having point loads that could induce a kink in the tube, leading to catastrophic failure.
Personally, I'd go for 3mm aluminium tube - if I were determined for a metal solution. Otherwise wood or, if weight is an issue, I'd make my own pole by laminating fibreglass rovings around a plastic drainpipe of the correct diameter. I have made stern tubes using this system.
Of course tube bends, unless you have a lead on something with infinite flexular modulus.
Why is 2mm a joke? Can you send me your base calculations for the force vectors?
[/ QUOTE ]
I'd look at it from a simpler angle. Would the kite lift me up (76kilos). In my case it does not. If I hang onto the end of a horizontal pipe, 75mm diameter, even if it is only 1mm diameter and there's a full 2 metres of it 'free', it wouldn't even give me the time of day! My weight would be, for all intents and purposes, not even worth considering.
Just make sure that the 'part' that holds it down to the deck is more like a sleeve with a slightly flared end rather than a 'U-bolt' type of arrangement; this to avoid having point loads that could induce a kink in the tube, leading to catastrophic failure.
Personally, I'd go for 3mm aluminium tube - if I were determined for a metal solution. Otherwise wood or, if weight is an issue, I'd make my own pole by laminating fibreglass rovings around a plastic drainpipe of the correct diameter. I have made stern tubes using this system.
Twister_Ken
Well-Known Member
Very possible a chute would lift a lightweight such as yergoodself into low earth orbit, given sufficient wind strength.
OK, I know you don't plan to fly the thing in strong winds, but along comes this squall, see, and the next thing...
PS to Fullcircle - how about titanium? Expensive, good looking, lightweight. Bit of a challenge to weld, but for a man of your infinite wisdom, nae bother. Used in some of the very best bicycle frames, which stainless never is.
OK, I know you don't plan to fly the thing in strong winds, but along comes this squall, see, and the next thing...
PS to Fullcircle - how about titanium? Expensive, good looking, lightweight. Bit of a challenge to weld, but for a man of your infinite wisdom, nae bother. Used in some of the very best bicycle frames, which stainless never is.
DJE
Well-Known Member
Thin walled tube will buckle locally before it develops its maximum theoretical bending resistance. The ratio of outside diameter to wall thickness (D/t) is critical. D/t of 80 or more (roughly 1mm thick 75 dia tube) is generally considered to be "slender" and likely to suffer from local buckling. D/t of 40 or less (roughly 2mm thick 75 diameter tube) is generally considered to be a "fully plastic" section and unaffected by local buckling.
But I bet you knew that already.
But I bet you knew that already.
PuffTheMagicDragon
Well-Known Member
[ QUOTE ]
OK, I know you don't plan to fly the thing in strong winds, but along comes this squall, see, and the next thing...
[/ QUOTE ]
Very true. I guess it also depends on the size of the sail, no? In my case I only use an assymmetric, and that is only to F4. (At the moment there's 7kts of 'wind' with a temperature of 38 Celsius /forums/images/graemlins/frown.gif )
OK, I know you don't plan to fly the thing in strong winds, but along comes this squall, see, and the next thing...
[/ QUOTE ]
Very true. I guess it also depends on the size of the sail, no? In my case I only use an assymmetric, and that is only to F4. (At the moment there's 7kts of 'wind' with a temperature of 38 Celsius /forums/images/graemlins/frown.gif )
FullCircle
Well-Known Member
You are all assuming an unsupported bowsprit.
And no one has given me a supplier yet.
You are all fired.
And no one has given me a supplier yet.
You are all fired.
VicS
Well-Known Member
[ QUOTE ]
All I asked for was a supplier of 75mm tube, which actually no one has come up with yet!
[/ QUOTE ] [ QUOTE ]
And no one has given me a supplier yet.
You are all fired.
[/ QUOTE ] Perhaps you should start a new thread and ask the question again!
Have you looked under "metal stockholders" and "stainless steel" stockholders in Yellow Pages or Yell.com
All I asked for was a supplier of 75mm tube, which actually no one has come up with yet!
[/ QUOTE ] [ QUOTE ]
And no one has given me a supplier yet.
You are all fired.
[/ QUOTE ] Perhaps you should start a new thread and ask the question again!
Have you looked under "metal stockholders" and "stainless steel" stockholders in Yellow Pages or Yell.com