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During the weekend I ripped and notched the strips for the gaffs and managed to glue one of them. Tapering the staves with a hand plane was nice work, I always prefer making shavings to making dust  ;D


For staves this small it would have been a better idea to taper them first and make the notch last. Or even tapering the board before ripping it. It was quite challenging to clamp the staves when the one side had the birds mouth with  one edge longer than the other. Four was max I could manage at a time.

This will be the first item that is going to be part of the actual boat! So far  everything has been preparation like lofting or some temporary stuff like the moulds. It was a nice fit when dry fitting it.


But when glueing there were gaps between some of the staves no matter how much pressure I applied with the hose clamps. I wonder if the unsymmetrical notch had too little wood on the inside edge to align the staves properly.

I will have to see when the epoxy has set tomorrow. If that is the case I think I will use symmetrical staves and just plane off the extra material. It is not that bad with spars this small, they are just two meters long and 50 to 40 millimetrers in diameter.

Even if the result wasn´t so encouraging it feels good to be back in business with the boat.

I've found alignment issues are almost always twist that has gotten into the staves. I use rubber straps from old bicycle inner tubes and wrap the mast every 170 mm or so, just to insure I'm not applying too much pressure and forcing the staves to align with it's neighbor.

I know a fellow in Maine that uses shrink wrap, again spaced about as I do. He quickly wraps up the mast, then a few passes with a heat gun tighten it down neatly.

Greetings all,

I remember an article from Wooden Boat, or Yacht Designer, or some other boat building magazine, where they were using heat-shrink tape to wrap the part along its entire length to act as a clamp.  You might want to poke around on this web site for a while ... http://www.shrinktape.com/hishrink/release/  The literature says clamping forces of 2500 psi are possible using this kind of stuff.

Cheers,
Tom

Something like that might be a good idea with the gaffs where the staves are so thin and flexy. You would like to have the clamps, whatever they are, touching each other tp apply the pressure to the length of the spar.

I expect this problem to go away when I move into the masts or even to the bowsprit with a little thicker and more rigid staves.

Btw I checked the results of the first glue up. Not as bad as I suspected. There were some gaps but the staves held nicely together and I will just fill the gaps when gluing the halves together. I also made some fillings to enforce the fittings and turned the knob to the peak.

Spent some time rounding and smoothing the first gaff. It looks quite nice.


Filled the gaps while gluing the second one


The second gaff was a better fit between the staves but it is not as straight as the first one, which is absolutely straight to the millimeter. The second is bent, maybe 10-15mm off in the middle. I don´t think I will let it matter but it was a nuisance to notice it when I took the halves apart. I think I should have been more careful flipping every second stave when making them.

Before starting the build I knew I was going to hate the "goo-part" of the process but I had no idea how much! Especially the first attempts when I had not figured out a decent procedure with the mixing, spreading, cleaning and clamping. At times I was wondering whether I am making things out of wood that is glued together or if I was casting pieces of wood into plastic!

Fortunately I am starting to get a grip of it but it is still a PITA. I am so happy to have the design with the lowest goo factor  ;D

Good morning Timo. I'm up having just watched the space shuttle take off in the morning mist. Quite a sight as we had two sun rises, the real one that followed the manmade one. We take these events for granted (okay maybe some of us), but it's an awesome sight. I'm close enough to see the "bird", the smoke trail, the fire coming off it's butt, though can't really hear it.

Yea, goo sucks, but you'll get better at it. Developing procedures (and sticking to them, once you establish what works) are the key to successful epoxy use. The biggest mistakes are usually traced back to bad prep, improper setup, bad mixing ratios, etc. All these things can be "fixed" with a set of procedures that you always stick to.

Most that do a fair bit of epoxy, work find they need an "epoxy station". This is an area where they keep their goo stuff, epoxy supplies, clean up supplies, epoxy specific tools (these are the ones covered in clumps of dried goo) such as clamps, putty knives, plastic spreaders, scrapers, gloves, solvents, mixing trays, paper towels, etc.

You'll get in the habit of doing the same tasks and having everything you need in one spot makes sticking to a known procedure much easier. Yes, you'll get better at it.

I wouldn't get too upset about a 1/2" deviation in the gaff. If you have the option, place the "bow" up, away from the sail attachment edge. This way wind pressure will align the gaff.

I had read so much about epoxy that I started with a specific epoxy workstation. It was also dictated by the fact that I wanted it just below the ventilation that is sucking air out of the room because I want the fumes out asap. Whenever I need to do more than just a drop of goo I am using a respirator which makes working inconvenient but on the other hand it removes the smell completely, which is a good sign of its efficiency.

Mixing and the ratios and all that is not a problem, I am used to working to a specification that needs to be followed. My main issue is with the sticking and dropping googe that messes up the place and the items being glued. I am the cabinetry kind of guy who wants to minimize the squeeze out to avoid the cleaning afterwards and that seems next to impossible with epoxy  >

All the stuff you learned with glue and cabinetry, must be forgotten with epoxy.

You want ooze out, you want slightly sloppy joint fits, etc. Epoxy requires some bulk present to work, so less then perfect joints are then norm, not the exception. Ooze out all around a joint insures the joint isn't glue starved and also provides a handy supply for starting a fillet (if necessary).

Epoxy itself doesn't smell much. A slight ammonia odor maybe when you first open the container, but it's high vapor pressure will dissipate it quickly. Of course solvents like acetone do smell (hell my other half wouldn't know it was me, without some acetone smell involved). For most cleaning you can use white vinegar, especially on people. It cuts the goo fairly well, but more importantly stops the chemical reaction in the resin. I use acetone as a final rinse on tools and stuff, but vinegar as the bulk cleaner. So, you go home smelling like a barrel of pickles fell over on you, get used to it.

Much of the difficulty some people have with epoxy is just their physical make up. Those that have bad reactions to alkaline substances, or glycols may have issues with epoxy. Most people don't unless they start bathing in it, where it can accumulate in the system until toxic levels are reached. The use of solvents, such as acetone will expedite the mitigation of these chemicals into the blood stream so don't use them to clean skin, use vinegar.

As a general rule of thumb, assume epoxy will get on everything you don't want it to. Cover everything, it's magical ability to get on things that were not remotely close the actual site where epoxy was used is well documented. Cover tools with plastic bags or tape. Paper  or plastic sheeting on floors, tables etc. are normal if you don't want a glossy, hard plastic sheen in a few hours.

I was involved in a company using two part glue (not epoxy) to assemble aluminium structures and we used acetone to clean before applying the glue. I have had enough experience with the stuff to know that I don´t want it anywhere near my skin. I think prevention is the key, I want to keep the goo out of my skin so there is no need to clean other than sweep some minor things. Work tidy and wear gloves, plan ahead so you are never in a hurry. That is, if the world were perfect 8) We all know it ain´t.

Is there a filler that would make thye epoxy more tixotropic? I have use talc but no matter how thick I make my goo it seems to keep running 

(04-06-2010, 02:13 AM)Timo Knuuttila link Wrote: [ -> ]I was involved in a company using two part glue (not epoxy) to assemble aluminium structures and we used acetone to clean before applying the glue. I have had enough experience with the stuff to know that I don´t want it anywhere near my skin. I think prevention is the key, I want to keep the goo out of my skin so there is no need to clean other than sweep some minor things. Work tidy and wear gloves, plan ahead so you are never in a hurry. That is, if the world were perfect 8) We all know it ain´t.

Is there a filler that would make thye epoxy more tixotropic? I have use talc but no matter how thick I make my goo it seems to keep running 

Silica will stiffen it up.  for fillets I use a mixture of wood flour and silica.  It holds its shape nicely. About equal volumes of each.  One thing you can do with the spooge is to go back after it has cured a bit but is not yet hard as a rock and use a scrapper.  You get rid of the runs and minimize the sanding.