2 sticky fingers.

My post ‘sticky fingers’ got more feedback than any other post in a long time so i thought that rather than try to answer individual responses i would quickly write a follow-up post, and, while i’m at it learn some new tricks and techniques with glue.

Both father Ted and Stephen Mundane mentioned cascophen glue and that’s definitely one of the glues that i have no practical experience of myself.   I did know of cascophen glue from my boatyard days and may even have seen it being used.  Resorcinol glue also got a mention and that one i definitely saw in use at Dickies yard back in the late 1970’s. In those days i am pretty sure that nobody at that yard had ever heard of epoxy resin , in fact it was so long ago that they were probably boiling up bits of dead animal in a big pot out the back to make ‘natural’ glue…..must tell you that story some time !

Anyway, lets bring up one of the recent comments and chew on that one a bit.

If you don’t mind, I’d like to comment on your post. It’s based on 40 experience working on wood boats.

In this internet age, with too much information available, and people looking for quick and easy answers, it is easy to get bamboozled. Epoxy is not the only solution and West System is not the only supplier.
The best, absolutely best glue or oak is Resorcinol. It’s the only glue to work for underwater joints. Epoxy doesn’t.
Polyester resin works just as well and costs about 1/4 as much.”
(Barry Thompson)

Me…

What i want to point out immediately, and as i said in the post is that i’m not an expert at all, merely a back-boatyard bodger and certainly not a crafted boatbuilder or even a competent woodworker.

First though with regard to the internet and my own posts.

I try to work to a simple set of rules as a content creator on the internet myself.         Those rules are : if it’s something i have done myself then i will usually start off with ‘in my experience’ even when that experience is limited, secondly i might say ‘i have seen’ because i have seen more things done than i have done directly myself, going down a layer i might then say ‘in my opinion’ when something isn’t quite fact but where i simply have a personal opinion….i do try to back up my opinions though.          Lastly i do use the internet a lot and that can be a problem, it is a veritable sea of information and occasionally i will refer to something that seems to make coherent sense but, once again , try to refer to whoever that is has said what.   If i can refer to someone who seems to me to be a competent source then i will do and i will say who that is.     Where possible i try to refer to a much better opinion or knowledge source that my own….thus in this case i mentioned Nick Gates as he really does seem competent and i may have referred to Larry Pardey who had some strong opinions about epoxy but had at least built 2 wooden boats himself.

With regards to Barry’s response i have no personal experience with resorcinol glue and the only thing i have heard about is that it needs high clamping pressures and very accurate/close joints.  With polyester resin and plywood my actual experience is that it only bonds very poorly in the sense of GRP cloth to a plywood hull and have i personally peeled set GRP cloth/polyester straight off a plywood hull by hand.  I think that the concensus is that epoxy resin is the only effective glue for bonding GRP cloth to a plywood substrate and also for bonding veneer laminates or plywood laminates.

Anyway lets move this on.

PVC ‘Gorilla’ glue now has a place on my workbench but i also wanted to follow up some things that boatbuilder Nick Gates said to me when i spoke with him.  The glues that he had in his workshop were clear PVC and he had different ones with shorter and longer cure/working times and they weren’t ‘Gorilla’ brand.  I just can’t remember what brand Nick uses although ‘Titebond’ is a possible.  I initially checked but couldn’t find a clear PVC glue under their label and then did find it on Axminster tools website.  So far i have only found one cure time/working time clear PVC glue of theirs and the price does seem better than ‘Gorilla’ glue.

What i have found in the Axminster catalogue online is Titebond clear PVC in a 335 ml bottle at just over £13 which is cheaper than my local source of ‘Gorilla’ brand which costs me around £12 for 250 mls at the local Screwfix store and quite a lot more at the local hardware store although it’s also a lot more expensive in smaller bottles.

What i haven’t found so far are any examples of very fast and very slow working time PVC woodworking glues.

https://www.axminster.co.uk/titebond-polyurethane-glue-ax22585

At the same time as i started this post i was also working on the next woodworking projects for my Hunter Liberty and continuing to research some longer term potential ones.    The current projects ‘on the bench’ are sprits 3 and 4.  Sprit 3 is to be a slightly longer sprit-boom for the mains’l and i will cover that in part 2 of the sprits and booms project post.   Sprit 4 that i am working on right now is a short bowsprit, the main purpose of which is for anchoring although there is a small possibility that i might also play around with a small jib….some HLMOA members saying that a small jib improves the windward performance of the boat.  When i started that project i thought i might have to make a laminated bowsprit….essentially a stack of thinner timbers and that was to be my first cascophen or resorcinol project .  That should have been relatively easy to clamp and glue several layers but as it happened i found a really nice single piece of old pine to work with.

Below is the bow well, when i mention the ‘bridge’ in the post the best way of thinking about is spanning either the mast slot or crossing the mast just below the edge of the well.  It has to me removeable so that the mast can rotate out through the mast slot.

004

I originally thought that i would have to make the bowsprit as a laminate, at least out of 2 lengths of timber so my first thought was to try a different glue and learn about that as part of the job.   Cascamite was the obvious first choice but then i started researching resorcinol resin glues and decided to give that a go.  That work, not work exactly, of reading up on resorcinol glue came about partially when i entered a search term (aerodux) as i seemed to remember that on a tin way back in my boatyard days.

That search quickly took me into structural timber construction, for example in the making of glue-laminate beams, and then into aircraft construction.  Now, i did know that the famous ‘Mosquito, fighter/bomber of our own RAF was basically built out of wood and i even found a website covering the building of one (link below)….hey-presto another night gone on the internet !

As it worked out with the bowsprit i haven’t, so far, had to glue-up lengths of timber as i spent a while down at the local reclamation yard and found an ideal length of very dense old softwood.  It feels and looks like a slow-growth pine or maybe Douglas fir but whatever it’s got at least twice or  times the growth-ring count of modern commercial whitewood.  That piece  only needed a few nails pulling out and then cutting down a bit and lots of planing.  I was sort-of regretting spending last month’s tool budget on a power planer and not on a pillar drill…..well the planer saved the day on this project in that it saved me hours of difficult hand sawing and planing.

What i did initially do though is work out a couple of different ways of mounting the butt end of the sprit : the outer end just sits in the groove where the anchor roller would normally go and where i have just removed the pilot boat style closed fairlead from.  My first attempt at building a mounting for the butt end was a total failure in that i tried to pattern and then make a pads and bridge structure that would attach to the aft face of the bow well but where the ‘bridge’ would be de-mountable to allow me to swing the mast down.  My problem is that the aft faces of the bow well either side of the mast are angled in 2 planes, in fact they are actually angled in all 3 planes if we consider the deck crown as well.

In this picture the outboard (working) end is on the left : the blue box represents where the bow of the boat is.  The anchor warp is likely to be going down through the timber about 2/3rds of the way along the left hand sloped section.  The ‘tail’ is the problem part.

001

I first made 2 patterns, essentially one in plan and one a vertical section and then transferred those onto a a useful chunk of scrap timber.  Lots of planing later and i had something that looked as though it was right…..down at the boat though it was a long way out and as soon as i started to correct my sins the whole thing got worse and worse.  As it happens i think the 2 face pieces of the bow well might be slightly asymetric but whatever, it was a mess and a failure.

For simplicity i then made a pair of raised blocks and ‘bridge’ to do the same thing but to be mounted on the base of the bow well.  It worked although the eventual structure is heavy and clunky.  The first look at that as a build it and then try and improve it would have been a good project for a first try with cascamite but as i hadn’t ordered any i did it with the old epoxy that i spilled most of last month…..means i can get rid of the old tins as well.

The mounting blocks for the ‘bridge’ and a temporary bridge to show how it all works, the ‘bridge’ spans the mast slot and has to be removeable.  The blocks are functional but heavy and clunky.

004

One of this month’s more delicate builds : a pattern for a stainless steel mizzen mast mount spacer.  Ply-epoxy construction and using fillets which mimic the weld lines.

003

And this one utilises 5 minute epoxy (Gorilla brand) to make quick fillet joints.

003

Ok so….

I hadn’t intended such a long segue into my ongoing projects given that i came here today to talk about glue.  What i feel i have done is some useful research about resorcinol resin glue (in my case Aerodux) and i re-read a lot of the Gougeon brothers manual of epoxy boatbuilding.

I still have an impression, most likely mistaken, that resorcinol resin glue is hard to work with or at least more demanding to work with.  That’s most likely unfair given how difficult epoxy is to work with : temperature and humidity conditions for example.  I think i have always had a concern with resorcinol resin that my basic jointing work might be too sloppy and that resorcinol might have more ‘tight’ timings to work to : ‘open’ time for example and temperature/humidity conditions although the main problem i have in mind is adequate clamping pressure.  I spent quite a while reading through ‘Aerodux’s‘ downloads, they do define what clamping pressures are needed although quite how i would measure them i have no idea.  It does seem acceptable to thicken the basic resin mix and i note that they suggest wood flour as a filler. I am surprised that they haven’t looked at the epoxy fillers such as the cotton microfibres that the Gougeon brothers recommend as a glue mix.

What i had in mind this month was either an actual project that needed doing in wood and could have been used as a viable experiment with one of the 2 glues i want to try out.   My second idea was to continue the rig project into building an actual section of a hollow birdsmouth mast and where i did some scarph joints of the staves and then worked out a method of clamping the whole thing with enough pressure and keeping the pressure on while the glue set.  With having a lot of jobs to do that are of immediate priority i didn’t get around to finding timber for the mast model project.  I did realise that i would have to find a way of machining the birdsmouth staves and that i would have to make a scarphing jig .  This is also an ongoing aim of mine to gradually improve my skills and knowledge with wooden boatbuilding.

Where this could be going, and yes there is a long term direction, is that i am still working on design and planning for hollow wooden masts on the Liberty.  I am covering that in a long post about Canoe Yawls and still thinking about converting WABI”‘ from cat-ketch to cat-yawl and possibly using a gunter or very high-peaked gaff configuration for the main mast.  That of course is going to be in the same place as the existing alloy stick and would have to be at the limit for weight and strength.  Carbon fibre would be the absolute ideal but hollow wood comes in close and is potentially do-able at my level of skill…..but only just and then only if i am super careful.

I am working out the basic mast design myself and it’s likely to be either birdsmouth or hollow stave construction.  A major consideration is the glue i would use to build the mast, the yard and the boom which is why i am putting the work in now.  I had planned a completely different post as i wanted to get into some technical talk about adhesive sealants such as Sikaflex 291 which i seem to use a lot, i thought about that because i have been using it and a similar sealant (CT1) recently.  Guess that will have to wait….in the meantime i’m working on workshop infrastructure and organisation again.  As i write today it’s an absolute minger out there so i spent the morning tidying and sweeping the workshop.  Once again i have run up against the problem of a difficult drilling job…..this time making the angled slot in the sprit and drilling for the sheave spindles.  Open in a second window here is Axminster tools catalogue and i am thinking hard about buying that pillar drill.

Next time….

To finish the post this time i thought i would quickly list the glues and other adhesives that i keep aboard in the bosun’s locker.

PVC Gorilla glue, small bottle

Gorilla brand 5 minute epoxy, 2 syringe type.

Sikaflex 291, ‘toothpaste’ sized tubes…several

Loctite thread ‘glue’ one tube (needs replacing)

Epoxy repair pack (SP systems) various mixing pots, gloves etc.

Large rolls gaffer tape and Gorilla brand repair tape (very good)

 

The Mosquito.

I think the fuselage shells must be cold-moulded.

5 Comments

  1. Yep, very useful stuff. The film about the wooden wonder was also a worthy background addition to the other info, and illustrated that with the right materials what can be achieved. I know this is slightly left field, but I have had a very long time interest in Fred Miles and his Miles Aircraft designs, all built of wood – I was fortunate to have learnt to fly in the Miles Magister, post war. The Miles designs and construction were extremely good, but as most never intended for a long life, so sadly few have survived, with glue failure the main cause.

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    1. Wasn’t the Moth a miles design ? The dinghy that i bought as a project to do the EC in literally peeled apart in my hands as i stripped it down…..didn’t get a mention as i have no idea what the glue was. I spent a bit of time on a couple of modern kit airplane building sites and that was useful for glue practices.

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  2. Hi Steve. Still left field – the Moth was from the De Havilland stable, same as the later Mosquito. It had a wooden box and skeleton frame but fabric covered. The Miles types were all wood including ply covering of the flying surfaces. Now I come to think of it I believe the glues used were resorcinol. It was a good product, but where used the finished article needed to be well protected from the weather, and wet.

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  3. I think Geoffrey de Havilland designed the Tiger Moth Steve. Great documentary on the Wooden Wonder. Good luck in your search for the one glue to rule them all — great information you’re putting out here.

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