This is sheer genius!!! I can replace the nine blocks that took me three days to make with something that I can put together in an hour or so. Not only that but it is more or less infinitely adjustable.If you make long wedges with a scale printed on them you should be able to reproduce sails accurately.One drawback is trying to get that first layer of D.S. tape off, that could be tricky with thin Trispi. I wonder if there is a low tack D.S. tape? Maybe glue a strip of masking tape face-up on the aluminum strip. Another drawback would be the flexibility of the strip, different strips would cause different shapes so a set of numbers would probably not transfer from one sailmaker to another. You may get an interesting shape using a tapered aluminum strip. Put the thin end towards the luff for a flatter leach.
I’m pumped and headed to the shop
Don
It is in fact somewhat triky to remove de 1st layer of adhesive. I trained myself by stiking some strips on a polyester film of 50microns often used for my sails, and then scraped away as shown in the last photo. A friend got some more difficulties to remove a 3M layer. I have once used an alchool base solvant, it was a disaster !!
Low tack spray could be used but I have no experience about yet, it should be a good idea, if you try first let me knows.
The Aluminium bar bending angle is so small that no deformations are expected. As said before a Plexiglass should be better but more expensive. Here in Nice, I payed 85 euros/100$ for two bars (specially laser cut and polished) of 120cm long and 2 x1.2 cm of section. In Italy it is suggested to use plexiglass drawing rules of 1.5x1.5 cm of 50/60 cm long . I can’t find it in Nice.
Start making one tool and you will be surprised as easy to use.
Ciao
Claudio
I just tried it using an oak strip and it seems O.K. but might lack in precision. A caution for the inept(me). Make sure that the first panel goes on the strip side of the gaget(as shown in the instructions) or you end up with reverse curve. Thats something you can’t do with blocks! The first stip of tape is a problem. I used mylar panels and Scotch D.S. tape and it will not come off, it just smears. Maybe if I don’t stick it down so hard. I’ll try that and report back.
Don
O.K. If I don’t stick it down too hard I can get it off, but that means that the permanent layer of tape is also not stuck too well and this opens up the possibility of slippage when you are lifting the sail off the gadget(we need a name for this thing). I’m out of spray on tacky stuff so I will go get some and try that. I also think that this gadget should be attached to a larger sail making board so index marks can be used to keep everything lined up.(I have shakey hands)
I’m off to town to get some tacky stuff
Don
Don,
first : you stiks the adhesive on the flexible bar
second : you bend the flexible bar
third : you fix the milar panel or whatever material on the bent bar.
fourth : you return the bar back to the base and the tissu/fabric material will vrap and the flexible bar shall be retained back to the base either with clamps or with rubbers rings. (see photos)
The above sequence shall be strictly followed before continue with the second sail panel assembly.
For good precision, flexible bar and main base bloc shall have high accuracy cuts ant straight edges over the full lenght.
Yes it happen to my friend to smear the scotch. Actually he has changed the brand and the problem is solved.
Ciao
Claudio
Dan,
Where are you sourcing the frosted mylar? I can only find clear domestically.
-Todd
Todd,
I got my mylar/polester film from http://www.plasticsuppliers.com/ about 5 years ago. They have a large selection, but the minimum order is like $250 USD if I remember correctly. I purchased the ?Opaque White?.
I tried some spray on gasket cement that stays tacky and it didn’t work. Everthing seemed O.K. but I got no draft-I think the sail slipped when I pulled the wedges. So I put some D.S. tape on the strip and put some 1/4 "masking tape sticky side up on the D.S. tape. That meant that the sail sticks to the masking tape. That worked! I also positioned the second panel and taped it down with masking tape then removed the D.S. tape backing, pulled the wedges and stuck the second panel down kind of all in one motion. That gives the bottom tape less time to slip. As Claudio says I think hunting around for a slightly less tacky D.S. tape would be the better solution but if you knew the trouble I went to to get what I’ve got you would understand my motives. All this said, even though I can now make a nice seam I’m still a long way from making a good sail. But this will make it easier to practice. As I fiddle with this I will post any more revelations I have. Thanks Claudio for bringing this method to my attention.
Todd
I have a bunch of old company maps that I use. They have a graph pattern on them that is not nice but they work for experimenting.
Don
Happy you start managing the affair. Pitty that a tack spray does not work.
Claudio
Here the secuence to remove the adhesive; start rubbing at midle way, once broken start rolling up with the finger up to the end.
here some exemples of seams - cord 25 cm draft 12%
Claudio
Dan,
If you had to buy that much . . . do you have some to share or re-sell? Drop me a line. brownt@alum.rpi.edu
My enthusiasim is waning. Has anyone else tried to use the graph to determine the thickness of the wedges? I don’t seem to end up with anywhere near the draft that I want. For example the top seam on the trial US1M main I am playing with is 100mm and I want an 11% draft. The graph says 100/100x0.35. This I can do in my head. The wedges should be .35mm thick.So I put the .35 mm wedges 100mm apart and make my seam. It comes out practically flat. 11% draft on a 100mm seam should be about 11mm. I get maybe 2 mm and thats being optomistic. If the wedges were 3.5 mm it might be close but I couldn’t bend my plexiglass strip that much. Is there maybe a decimal point in the wrong place?
Thanks
Don
Don,
what you have done is correct, but the tissu is not a solid material that can keep the shape. Is not easy to observe but escluding others problems the 11% draft exist . I suggest to adds others panels of 100mm with the same 0.35% coeficient and than keep with two fingers in vertical position, you should notice a bent. Observe the panel’s photo in my posts and you’ll see the bending.
Actually, 0.35mm wedge on each side and positioned close to 100 mm , does produce a very litle angle, any imperfection of the tool (straightness) of parts and surfaces finish irregularities could ruin the process.
Assume a dective surface of 0.15 mm that is almost nothing, jour draft of 11% will drop to 5.5% .
If after having connected some additional panels to help visual bending if you still do not see any effects , then is time to verify the tool precision and/or the manual sequence. I will do tomorrow (actually midnight here) the same work as you did with polyester film of 50 microns and I let you knows. Probably with photos.
Ciao
Claudio
PS: actually the panel photo presented on the previous page , the cord is of 250 mm and the draft was supposed to be 12% - you will observe a small curve , on your panel that is less than half witdh , the curve will be difficult to observe. Only with the full sail assembled under wind pressure or gravity will be possible to appreciate the draft.
A full panel without any seams does exibit a draft and I believe that small boats like MM use the sails in that way.
Claudio
Thanks for the response. I finished the sail anyway and its not that bad. I’m going to hang it up and take pictures and run them through the Accumeasure program and see what I get. The sail I made is just an experiment so it has seven seams with (supposedly) 5,6,7,8,9,10 and 11 percent draft from bottom to top. Just with rough measure the middle seam is 7% so thats pretty good.
Don
happy to hear see you later
Claudio
This is by far one of the best threads I’ve see since I started visiting this forum earlier this year. This one is worth making a Digest out of it…
Marino nice to hear
How is going the tooling ?
Claudio
Pretty much complete, all I need to completely finish it is the flaps for the clamps. I’ll do a test set of sails for the RG-65 I’m currently sailing, hopefully by the end of the week, using 60 micron mylar (could be kind of heavy, but is what I have now - and I’m not going to compete in the America’s Cup anyway), just for practice.
The goal is to eventually use the method with a set of sails for a couple of 1/20 Luna Rossas being currently built by a friend and I…
I was wondering about the table published in minicoque (which I printed and placed in a binder, toghether with other sailmaking articles I’v found), and, while waiting for Don’s analysis, under the light of his comments about not getting enough draft for shorter chords, if there might be other factors affecting the drafts for shorter chords… any ideas?
Some more thoughts. After running the sail through Accumeasure I am happier.As I said I had seven seams going from five to eleven percent.Accumeasure says top, middle and bottom are all about 7%. This is with the outhaul pulled tight and very little twist. Draft position came out at 40,44 and 37% from top to bottom which suprized me because I centered the sail which should give 50% draft. These measurements are done on the building board so the luff curve may not be right.(that brings up a whole different subject).
The building of the Gadjet Mark I (what is this thing called anyway?). As Claudio says accuracy counts. I made mine with a piece of aluminum door frame glued to a piece of hardwood and a piece of 1/2" x 1" plexiglass for the bendy part. The plexi is dead flat but the aluminum is out by a couple of thousands of an inch. I’m going to get a better piece of aluminum for Mark II. I think 1/4" plexi would do, the 1/2" is really stiff on the short chords. To get more draft on the short chords I think you need more flex. As for the 1st layer of tape problem I ended up using a sticky-side-up piece of 1/4" masking tape attached with DS tape. It stays with the strip and is re-usable at least 10 times. It dosen’t seem to slip but I’m going to try some extreme bends just to make sure. As for the wedges I’m going to get a couple of sets of feeler guages today. I think that will be better than messing with sheets of paper. I was using stacks of mylar which is less compressible than paper but I think the feeler guages is the way to go.
I would highly recommend getting the Accumeasure from UKSails. Its a neat program and seems easy to use. I did have a bit of a problem getting the same results as Dan did on the picture that he posted. Dan, if you are there and willing maybe we could post another picture (higher res) and compare results. I’v only used the program a few times so I may improve with practice. The trouble is mostly with the top stripe, things get kind of vague.
Thats all for this time
Don
For Don & Marino
As you have remarked the Conversion Table is a wide band and not a single line. This is because the band shall cover for assembly inacuracies , type of tissu and number of patches. My experience is that the bending of each panel is affected by the bent of near panels.
Precautions should be taken not to increase the wedge thickness because that will cause more draft than required. In the past I used on a Class M ? factor of 0.4% to obtain 10% draft and finally I ended up with ? sail having almost 13/14 %. with 4 panels all placed on the upper half of the sails.
I did the test today with 3 panels (polyester film 50 microns/85g/m? )100 mm wide. Hanging freely the assembly, a draft close to 10% is visible. I used a small plexiglass ruler (0.5x0.5 cm) and also drawn some red lines to show that the bending exist. One should also consider that while we produce an horizontal draft a vertical one is created to. In the photos below, the gravity tend to reduce momentarely the horizontal one.
Claudio
PS: have you tried on the RG65 a single panel sails ? the outhaul adjust should be sufficient !
next two photos
Claudio
