33 replies to this topic

[gorn]

Hi Guys

Just wanted to post a progress report on my Shad build

 

Im using a clam shell style strongback, as listed in the Kudzu book.

All frames have been cut, and strongback mounts attached.

 

Today I cut my first scarf joints with a basic jig on my table saw.

 

The Paulownia wood is very light, and cuts easily, though the knots in it drive me insane.

Ive actually had to buy Western Red Cedar for the Gunwales, as I would be short on Paulownia due to the amount of knots present.

Very annoying, but seeing as the wood is provided to order, I cant just go along to a lumber yard and sort through shelf stock.

Next time I will state that I wont accept c graded wood (Im guessing here on grade, but thats my opinion on what I was supplied)

When I picked it up, the 10 lengths were strapped together, with the best boards on the outside  grrrrrr.

A bit like buying a punnet of strawberries, only to find inedible ones in the bottom.

 

One other thing that has me a bit miffed, the strongback frames for either end of the kayak will have the bow and stern plywood forms sitting in them, which is all fine, except on the paper plans I cut out, the slots are larger to suit the actual keel sized wood which is larger by 3mm.

So now I will have to fill those gaps somehow, so that it doesnt just wobble around by itself.

Annoying yes, but Im not posting this to tell Jeff off, rather to bring it to his attention for future reference.

 

Im hoping by the end of the week to have the frames fitted to the keel and gunwales at the least.

Im moving a bit slow at the moment, as I nearly broke my ankle this week, and am hobbling around like an idiot now lol

 

So far its been quite the challenge  (though enjoyable) for me, being my first build, and also my first time really working with wood.

 

For the most part, the plans and the instructions, coupled with the first book, has been very good.

 

The only other thing I really was not sure on, and could not find anywhere, that wasnt covered in the manual, is the orientation of the scarf joints.

What I mean is, as an example, looking at the side of the keel stringer, is the scarf meant to be cut across the side or the top of the stringer.

Looking from the side I am looking at the scarf joint. If I did it the other way, I would only see the join if looking from the top.

 

Im not sure if it matters or not, and hope Im going the right way

 

Some pics of my scarf jig, my garage/man cave, and the strongback.

 

 

Cheers

Aaron

[Hirilonde]

I have no experience with Paulownia, but I bet buying all lower grades of wood to cull for clear stringers is the same.  You really have to go pick it up and cull it at the yard.  They have to sell all of their stock to make money and they won't send you all the best pieces.

 

BTW, where are the pictures? 

[Kudzu]

One other thing that has me a bit miffed, the strongback frames for either end of the kayak will have the bow and stern plywood forms sitting in them, which is all fine, except on the paper plans I cut out, the slots are larger to suit the actual keel sized wood which is larger by 3mm.

So now I will have to fill those gaps somehow, so that it doesnt just wobble around by itself.

Annoying yes, but Im not posting this to tell Jeff off, rather to bring it to his attention for future reference.

 

On ever other boat, the bracket is located so that the stringer fits in the slot. This is the exception.  I can't remember why, but there is an issue with the bracket going behind the frames. 

 

Problem is, if I make the slot the width of the plywood, you are going to have a hard time fitting the keel stringer in place. There would be no room to put the stringer and then mark and trim it. It would have to be slightly longer than the space between brackets because of the curve in it. Most people would up with the stringer being to short. So this is the best way I saw to  handle it. 

 

Besides, If you have your slots cut accurately and your frame clamped tight to the bracket it isn't going to move much once it is in place on the keel strip. Most boats the bow and stern are just hanging out in the air because the brackets are not located at the ends like this one.

 

 

 

The only other thing I really was not sure on, and could not find anywhere, that wasnt covered in the manual, is the orientation of the scarf joints.

 

 

 

That has come up a couple of times and i will be adding that in the manual.  I don't think it is going to matter as long as the angle cut on the scarf is right. I cut mine  so the scarf face  is parrallel with the outside of the boat.

[gorn]

Hi Jeff

Ok that makes sense about the bracket   , and the scarf joints too , thanks for the fast reply.

 

Hirilonde

The problem with the Paulownia, they dont have a stock yard.

The have the mill with no public access, and then they have an upstairs office in the city.

You place your order, someone from the mill delivers to the office, and joe public goes to pick up what they left.

I will just have to tell them staright out that crappy would will not be paid for, as its useless.

Its looking like I have enough wood for the keel, the mid side stringers, and all the deck stringers (with lots of scarf joints)

Im hoping I only have to use the WRC for the gunwales.

 

I will have some pics later today or tomorrow

 

Thanks guys
Aaron

[Kudzu]

I am anxious to try Paulownia, but have yet to find any locally. But I do understand about knots. The cedar I use can be full of knots. That is why I created my scarf jig, because I too have to cut a lot of scarfs.

 

BTW, if you have not please read up on how I build mine. I messed up a thumb really bad because my first scarf jig. What seems like a good idea, the way most people want to build one will get you trouble.

[gorn]

Hi Jeff

I did experience a few "flung" pieces of wood initially lol.

I swear I could hear you telling me off

And yes I keep to the side, out of the firing line, just in case.

Pics Ive added to the initial post show how Im cutting now. The offcut cant get into the blade, and just jangles on the side of it until I push it away with a plastic tool.

I line the tip of the pine block up with the very edge of the saw blade tips, then the stringer gets clamped with its end flush at the front of the pine.

I wanted a 10;1 cut ratio, which would be about 160mm, I think I about 165 or 170, either way is ok.

 

The strongback is 20ft, even though the boat is 17'5. Reason being, I also need new shelving in the garage, so their doing double duty

I have the ends marked so I know where Im at.

 

Ive glued some stringers today, and I gotta tell ya, I was nervous as hell!

Mostly just second guessing my own abilities, which is stupid I know.

 

I wish the Paulownia was straight too

Every one of the boards I bought, had mutiple warps in them, and of course when cut to size, they keep that trait.

Im curious to see how they pull together when the frames are added, hopefully on Saturday.

Im Im not happy, then I will get the heat gun out and add some pressure, until it behaves the way I need it too.

 

I still cant settle on the idea that a scarf joint with the titebond 3 is going to be stronger than the initial wood.

So this weekend is destruction test for one poor piece of Paulownia

 

Tomorrow I will have gunwales glued, the keel is already done, and the side stringers each only have 1 more joint to glue.

 

I do have enough Paulownia to do all of the deck beams, so Im very pleased about that, as I really wanted the Paulownia, light, available, not really expensive, easy to work with.

Just the knots and warping are a PITA.

 

Once I have the inital frames attached with keel at gunwales, I will post more pics and an update

 

Jeff, I will phone the mill that sells Paulownia here, and see what I can find out as far as lumber in USA is concerned.

You might check companies that do Paulownia Longboard surfboard kits, they may not sell you the wood, but you can find out where and who from.

 

 

Cheers guys

Aaron

[labrat]

You might check companies that do Paulownia Longboard surfboard kits, they may not sell you the wood, but you can find out where and who from.

.....and then again they might - the bloke I bought mine from on the gold coast is a board maker and there is another board maker in Vic that sells timber as boards or as glued up blanks.

Aaron, I am concerned that you used Titebond for glueing your scarf joints. The standard for these is a good quality epoxy and I don't know of any experienced builders who would use anything else. Epoxy will fill small voids but unless the surfaces are perfect the Titebond is likely to leave some areas of the surface unconnected. See what other feedback you get here as someone may have found that Titebond works for them but in the absence of any supporting posts I would be remaking those joints with epoxy.

[Kudzu]

 

Aaron, I am concerned that you used Titebond for glueing your scarf joints. The standard for these is a good quality epoxy and I don't know of any experienced builders who would use anything else. 

 

Sure you do, ME! I don't use epoxy in my  boats at all. I use Titebond 3 on my all my scarf joints and most boats have several of them. I have not had one fail yet.

 

You make a good point about the needing good mating surfaces or it will not hold. But a good saw cut will work. I cut mine with my jig on the table saw and most times I don't even have to sand them, just glue them straight off the saw. 

 

If you do it right the wood will break before the glue joint fails. This is typical with most PVA glues. 

[Hirilonde]

I use only epoxy for scarfs, but that is in part due to habit.  Most of my work requiring scarfs in the past has been of teak or plywood and left exposed to the weather and water for months at a time.  For softwoods I am sure Titebond is stronger than the wood as Jeff says.  For hardwoods I don't think this is so.  Epoxy is definitely more waterproof, but that does not seem to matter for these kayaks.  I would never use Titebond on a boat that spends serious time wet.

[labrat]

Well that sounds like good news for Aaron - and it goes to show you learn something new every day!

[andy00]

All the discussion on scarfs inspired me to make a pitch for butt blocks. I've made scarfs in plywood and in dimensional lumber on other boats, but thought of butt blocks as a good joint for longitudinals on a skin-on-frame boat (a Ravenswood in the current case) because 1) they are easier and quicker than scarfs, 2) you can't see them from the outside (and the inside looks like a bunch of sticks anyway), and 3) I was working with 10-foot sticks so I had latitude in locating the butt blocks out of the way between frames. The construction worked out fine. Has anybody else out there used butt blocks?

Fair winds, Andy

[Hirilonde]

Unless you put a butt block on both sides and make them over lap enough they are not as strong as a scarf, and.........................

 

1. The stringer will never bend as fair as a scarf joint

2.  Scarfs are so ridiculously easy I just see no point.

 

Once you have a good jig and have made a few, I can't imagine wanting to avoid making scarfs.

[gorn]

Labrat

Thanks for your concern.

yes I'm using the Titebond due to Jeff's success with it.

I hate epoxy, messy, stinks etc etc.

Titebond is stupidly easy to work with, and cheap too.

Even though I'm a newby, if my joint doesn't line up properly, I re-cut it and start again.

As I said before, I will be doing some of my own testing over the weekend, just to put my mind at ease about scarf joints, not so much the glue.

Its one of those things, unless Ive seen it, its hard to believe.

But everyone uses them, so it must be right, I just have to see it myself is all

[Kudzu]

If your joints fail the problem typically is one of two things. 1) You didn't have good mating surfaces. Got to be smooth and flat. Unlike epoxy it is not gap filling  2) Not enough clamp pressure. Not talking about crushing the wood, but you have to pull the joints tight and you want see a glue squeeze out.

[Hirilonde]

Titebond shrinks as it dries/cures.  Epoxy just cures.  This is a big part of why making scarfs with epoxy is easier to do well.  This and that by using the proper fillers epoxy can bridge quite large gaps as Jeff has mentioned.  I have heard that people don't like epoxy because it is messy, but not that it stinks?  Regardless of what glue you use one of the best techniques for gluing is to wet out both mating surfaces before clamping, wait a couple minutes, then clamp.  This allows the glue to do what ever saturating it will do before mating the pieces and reduce the chance of starving the joint of glue.  It also reduces the chances of a bubble and hence a void in the glue.

[andy00]

Dave:

To continue our discussion of butt blocks...As to your first point, an epoxied butt block is as strong as the stick. I don't think a scarf is stronger than that. You're right that a butt block will be stiffer than a scarf, but in the middle of a 16-foot stick, I don't think that the difference in curvature would be discernible. Regarding the ease of constructing a scarf, I assume that you are using a jig on a table saw. If one does not have a table saw, the comparison of the joining methods is seen in a different light.

Fair winds and a calm sea, Andy

[Hirilonde]

I used to make scarfs free hand using a band saw and belt sander.  With a little practice they can be made with a hand saw and block plane if need be.  I just don't see any reason to do anything else.

[woodman]

All my scarf joints are cut on my arm saw.....Tight bond 3 glue.....In the cabinet industry have used tight bond 1 for decades....a good but joint on solid 3/4'' lumber is typically stronger than the wood itself...Just work the glue into both surfaces using a finger before clamping...do a break test and see which is stronger..the grain of the wood or the joint.. I have done a lot of epoxy and cedar strip boats..just don't see the need on SOF....

[gorn]

With my own scarf joints, I have good glue squeeze on both sides of the join, no gaps, and am using spring clamps at either end, and a quick clamp in the middle.

No silly pressures, but enough for a tight join.

So far so good

[Kudzu]

I would love to use my radial arm saw for the  scarfs but since I am often cutting in the middle of a 12' foot board it won't work. I have often wondered if one of the Delta .... can't remember the model number, but the dual armed ones would twist around to where you could make the cut on the table. If so, that would be the one thing that would make me give up my DeWalt I restored.

 

 

Gorn, your clamps sound good to me. I use some strong spring clamps on mine most of the time.