UK-Cherub Forum
Cherub Chat => Calendar Events => Topic started by: simon_jones on September 12, 2011, 08:20:27 PM
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This years sticky weekend will take place on the 26th and 27th of November at Pauls workshop (Weston Super Mare). For those new to the class it's an opportunity to see the more experienced Cherubers playing with carbon. If you have a project that you would like some help with or just wish to come and join in with other's projects and learn what goes on, this is what you've been waiting for.
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Events like this are great for newbies like me - looking forward to coming along, not just to make new shiny things but to get to learn from the experienced pros.
Look forward to more details in due course :)
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We will be around during the day for some sticky action, but we have plans and guests on the Saturday night, otherwise I would have suggested open house at ours for those who didn't fancy the workshop floor. If people are coming from a distance and want somewhere to stay on the Friday night, that can probably be arranged.
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Would anyone be offended if i bring a kayak?
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Depends what you plan to do with it ;D
Having seen you play, I wouldn't be surprised if it needs patching. You people are vicious. What's the damage?
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I want to make a carbon seat, and replace the foam spine with something remotely structural! I don't like the way the bottom skin flexes as i paddle along..
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I have discussed extending Banshee Ambulance's rudder with Paul as well as the possibility of a T-Foil.
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Sounds like we have a foil theme starting. It would make sense to co-ordinate these together and share ideas.
If you are starting from scratch it will be necessary to identify the planform and section that you want to use for each foil and put this information into a form that will allow you to rout the contors out of a sheet of foam. (Routing the shape from a plot of contors is the most popular method at present).
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I have an alternative foil making idea I would be keen to try over the weekend.
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Has anyone got any experience in fixing sails?
my jib has a couple of bits that are looking slightly tatty (batten poking out etc.) so it would be good to try and get them fixed at the sticky weekend (or before if I can get some pointers.)
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If you ask nicely i'm sure born slippy will bring his sewing machine and some offcuts.
If the batten is broken it can be repaired quite easily. Jib battens seam to have a habit of breaking when the wind gets up and we start to loose control.
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cheers Phil, the batten is still okay, it has just worn through the end of the pocket. I have some kevlar tape somewhere that I think I can stick over then sew on to hold it in place. If Born Slippy would bring his machine along, that would be very much appreciated :)
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Are you now bringing Atum along as well to fix the shroud point back on as well or do you have this covered?
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I'll be there to watch people make foils which will keep a strong trailing edge after at least one sqil, none of my attempts have :/
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At the moment the plan is to try and find time to fix her before the sticky weekend as I would like to get some sailing in before then. The only problem is, my carbon skills are less than adequate. I am going to stick with the same sort of system as it seemed to last a good few years and it was probably just the extra stress from capsizing a lot recently that did it.
I would really appreciate it if someone could run through a bit of an explanation as to how i might go about attaching a stainless ring to the rack tube. In the technical section of the website, there is actually a picture of Atums shroud point being bound on with something, but I am really not sure what this something is.
I will bring Atum to the sticky weekend anyway as i would like to address and bit of a water ingress problem and I would like to try and re-enforce the end of the rack where rolling the boat has caused the tube to crack.
Thanks in advance.
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there is actually a picture of Atums shroud point being bound on with something, but I am really not sure what this something is.
Unidirectional carbon fibre. Can't find a photo, but its a carbon "cloth" which isn't actually a cloth put just filaments all run parallell to each other.
Basically you cut strips the appropriate length, wet them out with epoxy and wrap them round ring and tube. It seems pretty crude at first but works well. The tricky part is working out how much to put on! You could think of it as lashing the ring on to the spar with carbon fibres...
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Hi Ben,
Are you in SW London? This is a job much better done with help. It's not a big job but it is rather important. I would also like to see the failure.
The ring is a seasure one I think. You want a small overall diameter and a big rod thickness. I think it was 20mm od and 4mm rod. Measure the other one.
The ring was bogged on to the rack, and then in a single mix more bog is put over so there are minimal/no hollows. Then individual strands from carbon cloth are wound round and round, having been wet out already. It is not that important to put on loads of fibres because they are very strong, but it is important that they are spread out as they go round the tube. The other thing that is important is that the strength in the art which goes through the rig is good right up to the edge of the strands. If it tapers down then slight flex in the rig can cause the carbon to break one strand at a time.
The individual strands are called 'tow', pronounced "tau" or "toe" variously.
People do use strips of uni, but we used tow. With regard to how much to put on, in section carbon is stronger than steel (which is what the shroud is made from ), so as long as there is more than that in cross section, (taking into account mechanical disadvantages etc), then you'll be fine.
I think we used huge tow from a roll of 'mega-weave' which is quite good for making formula 1 cars, but is too heavy for making cherubs from. There is probably some still around. It was a gift to the class from a formula 1 team and has been used for all kings of funny jobs, like rudder stocks, shroud points, fronting plates, etc.
We can get together to fix this at some point.
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I am plannig a mass purchase from Wiz. If anyone wants small qunaitites of resin,fibres etc it may be worth asking me to decant some (at cost)...
For those wanting to make rudders/poles/booms this is almost certainly the cheapest way of getting the materials.
I can happily post or bring some tow - although not sure if I have any of the mega I have a load of slightly smaller diameters (or you can peel some from a sheet of uni and use in the way Will describes). PM an address?
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Thanks guys, I am currently in west London but the boat is based in Hampshire at my parents due to not having anywhere to store it yet. It would be great to get some assistance on fixing this but I am not sure when I am going to have time. I will get back to you when I have a better idea.
In the mean time I will order a new loop. What sort of epoxy should I use? I have some sp systems stuff but I would have to check.
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When i have attached rings and shackles to things I have used strips of uni as it is a bit quicker and a bit easier to handle. The ring for the kicker on my boom is held on with 3 strips of uni each about a cm wide.
What I have found is that once you have wound all the fibres on round the rack and through the ring as a lashing it helps if you wind some fibres round the lashing between the rack and the ring. This just holds everything together and appears to stop the fibres pealing from the rack or the ring and thus avoiding chafing of the ring on the lashing. As will says avoid any voids.
We all use an epoxy resin. SP is fine for smaller jobs such as this but tends to cure quite quickly. For larger jobs we generally use a slower curing epoxy which delivers the highest mechanical strength. We then usually use this for every job because it is easier to have 1 type of resin.
The important thing is to follow the instructions. Resin is sensitive to temperature, moisture and the ratio of resin to hardener. The SICOMIN 5550 is a general purpose epoxy and is a bit more temperature tollerant. The Sicomin 8200 gives higher strength and is easier to use on on larger laminating jobs. This can be post cured to achive maximum strength. The sicomin resins can be purchased from MCM in bristol. prices get cheaper the more you buy so I would ask born slippy for a bit of his.
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So to summarise the fixing job in newbie terms:
I need to:
- take the old shroud point off
- sand down to the tube
- mix up some filler and epoxy
- stick the new ring to the tube with the mixture
- while it is wet, wind round some 12k tow (or similar) until the cross section of tow is more than that of the steel it is holding
- wet the area thoroughly with more epoxy
- keep the temperature correct while curing (will a beer making element do?)
- have a cup of tea or 2
- sand and fare it
- laquer it (optional i'm sure)
- rig
- sail
I will pm Born Slippy about carbon bits. I need to get a move on with this fix before it gets too cold and also the bonfire night blast sounds like fun :)
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Sounds about right.
As a rough guide the resin we use will set if kept above the temperature you can survive in Shorts and a jumper. But it really is happier if it is hotter (hence BMG use a tea urn and central heating pump).
For the shroud point I'd recommend placing a plastic sheet over the finished job and placing a hairdryer or better still an oil filled electric rad in the bottom for the first couple of hours.
R
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It can be difficult getting the ring to stay sanding up, the big doesn't hold it very well. I suggest tacking it on with a hot glue gun, then bogging it really well to give the carbon as smooth a path as possible with no voids behind or sharp corners.
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I'm only too aware of Mr Tinner's previous ring problems.
5 minute Epoxy and some firm clamping to tack the ring in can have very pleasurable results.
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The tow or uni fibres go on better if wet out before being applied. with the latex gloves on it is easier to do this with a small bit of resin and fingers. The fibres will then stick together. Doing the fibres dry will be a night mare.
To squeeze it all together use a strip of cling film and wrap it tightly around the join. If you have some peal ply this is better.
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Here is a pic of the damage. I have measured the other ring and it is a 5x30mm one. inspecting the break, it looks as if the weld in the ring did not penetrate to the middle of the metal. I assume that the excess capsizing and probably excess weight of myself, led to the failure.
In order to get the boat back on the water as quickly as possible, I am going to order a ring, and some tow and attempt a fix myself. You will all be able to mock my handiwork at the sticky weekend and I can put it right with some guidance then.
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Excellent breakage!
It looks like the carbon is fine (phew!). You might want to send a pic of the break and your analysis to Seasure as some feedback.
Here is my advice to save yourself some hassle.
1) Get the ring out somehow. If it will unthread all the better. If not, then cut down from the top to release it.
2) Sand down all around, but leave the impression of the bottom of the ring so the new ring can it in there and not fall out.
3) Also try to limit your sanding so there are no hollows when you put the new ring in.
4) Lots of tow/uni/both.
5) Go sailing.
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Interesting breakage indeed!
I use D-rings for this - the weld is then in the middle of the flat part, and the fibres cam spread out along the flat part, and also you can put more fibre towards the ends.
I would use carbon 'string' that makes up maybe 1.5 x the stainless ring diameter.
The flatness means that you can alternatively use strips of ud tape.
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I have just checked and they are rated to 1600kg. It must have been stress over the years.
I will see what seasure have to say about it.
The D rings look like they might be a bit easier to hold on straight but I have just bought a circular one so I'll have to make do.
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I started off using D rings but found that they deformed at the top under rig loads. I then started using Triangular rings, which seem more solid, and you can use Uni tape.
The thing about tying rings on is that the load transfer area from the ring to the carbon is small so you need layers where the ring is but can do with less around the tube.
I always put short layers through the ring first and then tie this load transfer patch down to the tube with longer strips that go around the tube.
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Hi All, my order of carbon tow has not arrived (supplier not using registered mail most probably) and I was really hoping to fix Atum this weekend. Does anyone in the Hampshire/Sussex area have some Tow or uni or similar that I can purchase?
Thanks
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You'll have to come to E1, but its yours.
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Thanks Will but I found a guy who could sell me some at short notice in Tooting. Very helpful chap who makes catamaran masts. even threw in some peel ply for free as well.
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So Ben how did it go is Atum back up and sailing
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Atum is now fixed and ready to sail ;D. I put enough tow for over 3 tons so the ring should go before the carbon does. Tried to finish it with a bit of epoxy and microfibres this morning but it hasn't come out as smooth as desired even after quite a bit of sanding. I don't want to take the filler down too far from fear of getting down to the carbon so I am going to wait until the sticky weekend to re fare and paint it. I'm not going to get a chance to sail until the fireworks do at netley so I guess I am going to have to wait until then to test it :P
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Any Ideas on the best course of action for these little problems? I'm unsure if I can make the sticky weekend.
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For the bow sprit:
The outer diameter and taper need to stay the same so the break needs to be sleaved. The damaged area needs to be removed and the ends of each bit needs to be chamfered over about 10cm through the tube's wall thickness. This allows new cloths to layed over a sleave and overlap the chamfer with each new layer being a bit longer than the previous one. i currently have Paul Croote's Pole mandrel so at worst we can make a new pole.
The spreader can be fixed in a similar way however it is not critical to keep the outer dimensions the same. Once the break has been splinted. this could be wrapped with 2-3 layers of weave.
If you can't make the sticky weekend let us know when you are free and we can arrange something.
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What happened? :-(
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Not sure! We were bombing along at Mach 3, there as a crunching noise and the pole gave way. Helm fell out the back in the process!
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Oh dear! Could have been far worse.
If you come to the sticky weekend you will go home with both of those repairs done. They are both quite easy jobs when there are lots of people around.
The pole failed at the point where it exits the launch tube, right?
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sadley not going to make it this year, due to house selling. A bit gutted really, was looking forward to it, but hopefully will get the house rubbish out of the way before sailing starts again next year.
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I will be attending. with Madge.
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We will be bringing "This Way Up". Sadly after pulling a few bits (not too hard) she is in need of a new transom. The plan is that Jason and Andrew will fit the new back bar (including a flappy panel and hinge as long as I finish it before Saturday...). This will result in a stronger rear end that is ready for a T-foil.
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I have a single skin gantry from the E5 Mould which just needs drilling and finishing if that will help speed up the process as I'm not sure I will need it any time soon. It may also stop me staring at the gantry on Numb and reaching for my angle grinder... I will let it go for the cost of the carbon, or actually for some carbon which you would use to make it to replenish my stocks!
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me and digby will be making an appearance fairly late on sat, as we have a rugby match at clifton college first, any chance of sharing a car to get to the curry??? ( i assume there may be one) and any floorspace available paul?
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Yes, plenty of floor space and the curry house is booked
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The train from Bristol toWSM is fast -call and we'll pick you up form the station...
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Does anyone want any Wiz supplies for making things this weekend? I can happily arrange to buy and collect. Use the message service on this site to contact me, but please send your phone number so we can arrange payment parameters.
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Does anyone know how I might sure up the bolt through my mast that holds the trapeze lines? It has become a bit wobbly of late. I was going to figure of eight some tow around it and the spreaders to hold it in place but I am not sure if this is the right course of action. I am bringing her this weekend so hopefully get this fixed then.
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Is this Atum? We just used two bits of vectran tied in a figure 8 around the spreaders. First we used tow but one side kept breaking.
The two bits of vectran is so that there is a spare when the first one breaks! That bit of vectran also held the ring for the desprangler shock chord.
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Lets have a look at it on the weekend.
The trapeezes normally meet the mast close to where the shrouds do. You don't want to many holes next to each other. Our trapeeze lines are attached in a similar way to how Will describes. It may be worth reverting to Will's method and covering the holes with a few layers of carbon to reduce stress concentrations.
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I changed the attachment point of the trapeze lines after my crew took a trip around the forestay and ripped the spreaders of the mast. The kite then did its best to snap the mast but was lucky. The bolt goes through a fibreglass tube that is bonded into the mast. If the bolt has worn the hole larger in the tube we can replace it or if the tube has come loose we can re bond it.
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Sounds like a plan. I have some new smooth shackles as opposed to the current folded ones as they seem to be chopping through the trapeze lines at a fairly alarming rate. (Charlie decided to leave Sam sailing solo at the Bonfire Blast)
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So last weekend there was no wind. This weekend we're getting sticky.
And Born Slippy is sitting at Thornbury http://www.windguru.cz/int/index.php?sc=47859
Dammit.
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The tide is out at thornbury and chew this weekend so unless we travelled then sailing would be off the menu anyway, let's hope for next weekend
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Unfortunately I'm not going to be able to make the Sticky weekend, even though I've been looking forward to it for months :( A combination of lost income from a holiday, a dip in turnover and an expensive MoT means that I am going to have to work this weekend instead of palming off the jobs to a subbie as I'd planned.
Hope those attending have a great weekend of stickiness :)
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Thanks to Paul for use of his fantastic workshop and to everyone who popped in over the weekend.
From the weekend's fun it looks like the '97 revival will result in some serious competition amongst the single wire boats this year. It would be good to set up a bit of a guide/micro site on the wiki as to which events we should be trying to get Born Slippy along to.
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Yes indeed - many thanks to Paul. Have added a few pics to Latest News.
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Thanks to Paul for once again hosting such a great weekend. Also, big thanks to everyone for my surprise birthday cake!
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Thanks Paul...and thanks to all for the help.
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Thanks Paul. . . and thanks to all for the help.
here-here thank you Paul, Roland, Andrew and everyone for getting 'this-way-up' back on track, i can't wait to try her out one-day, but in the meantime Andrew please look on her as your own
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Again; Many thanks to Paul for lending us his (awesome) workshop. Interesting to see various repairs being done the right way :-)
Also many thanks to Jason for his help, and Mr and Mrs Trim for their time and materials, great to see This Way Up looking structurally sound again. :-)
With any luck, she will hit the water again in the next few weeks, possibly days!