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20170627_210550_New Quay Court

Finished posts, coated with tung oil

Well progress is definitely happening.

20170622_185235I cut out my blanks for the samson posts on the bandsaw.

20170625_184644_New Quay CourtThe time consuming part was shaping the top of the post. I had made a pattern for this.

There are a variety of ways of cutting a concave curve. The method I chose is essentially the same as making a housing, but using a gouge rather than a chisel.

20170626_170958_New Quay CourtHaving marked the pattern all round, I cut down to the lines with a tenon saw. Then I cut out the waste, trimming carefuly down to the line. Having down this on two opposite faces, it was simply a matter of removing the waste between the finished lines.

The second pair of curves were effectively marked with the saw cuts. So I just drew in the curve and repeated the exercise.

The rest of the process was the same basic technique as spar making. You turn the square octagonal, then 16 sides, then sand smooth with 60 grit paper.

Of course it all takes time, and care, smoothing out bumps and getting curves that feel good. But really, like so many things, the path is simple if it is done in the right order.

Finishing off I used my favourite tool the cabinet scraper, which saves hours of sanding.

I had to glue an extra piece on the flare at the back, because the timber stock I had available was not quite wide enough. This was only a thin taper. But it is worth mentioning that when this kind of thing happens, the extra piece should be kept chunky and oversize. It is much easier to glue on a decent thickness of wood, because it remains stiff. If I had shaped the thin taper first, it would be very hard to glue it on and would bend all over the place. Glued on oversize, it was just a matter of planing flush, band sawing off the excess, and planing the taper.

The finished posts look well. I have oiled them, and tomorrow I will dry fit them. Then they will be varnished before going in place.

20170627_210550_New Quay Court

Finished posts, coated with tung oil

Eeek!

20170618_164409_New Quay Court20170618_164405_New Quay CourtFor years my lovely gaff cutter has been hanging around next to our massive houseboat project, sadly neglected.  Time to find out what is going on.

I knew that the starboard side deck and after deck had rot, so off they have come, revealing the bones beneath.  It is a painful thing running a circular saw across your boat’s deck.

Well, it’s not too bad.  The eyebrows had to shoot up at the timber selection of some of the deck beams.  My goodness, some serious grain run out, to the point where a couple of the half dovetails have parted.  Still these will be fairly simple to replace.

A bit more thought will have to go into a section of the carline, which is certainly rotten at the top edge.  I’m not yet clear how far it goes, but it may be a case of scarfing in a repair.  I certainly want to avoid replacing sections of it.

The samson posts on the aft deck have decayed sufficiently to weaken them at deck level,  One problem was insufficient clearance between them and the transom, so water has been trapped.  I’ve made a new design that gives me  a bit more clearance.

20170622_181754

The timber I have to hand does not quite fit the new pattern, but I’ve found some that’s close enough and I can get away with a small shim to make up the extra width.

It’s always fun searching around for timber that fits a shape, and then revealing the inside.   This piece is a 5″ thick board of oak I have had hanging around for about twenty years, and the grain matches quite well to the angle between the sloped transom and the more vertical post.  My lovely Sedgewick planer and bandsaw will do the rough work…20170622_185235The worst rot revealed by lifting the decks was unexpectedly in the port quarter block, a sizeable chunk of timber that connects the beam shelf to the transom, provides corner strength and holds one of the large iroko davits.  This is sufficiently decayed to merit complete replacement, so I’m fishing around in the wood pile for something that works.

Deck plywood has arrived from Robbins, and bronze nails, so I’m really looking forward to quick progress!

We’ll see…

So having half lapped the rubbing post stock, shaped it and tidied it up a bit, it was time to bore some holes.

The posts were to be bored through the width (about 6”) with a 13 mm hole to take a length of 12mm stainless studding. The outboard edge needed to be counterbored so the nut and washer were below the surface.

Jig showing guide plate and 'legs', screwed together

Jig showing guide plate and ‘legs’, screwed together

The procedure I used for boring the holes is very familiar to boatbuilders, but with a couple of refinements.

Having set out the locations of the holes, I squared a line across the face and both edges. I found the centres of the edges, and punched the hole location on both sides. I almost always punch holes I’m going to drill. It ensures that the hole is spot on.

The principle of drilling a hole that is perfectly square to the edge and parallel to the face is to construct a guide jig that will support the drill some distance above the hole. This guide is a small piece of wood drilled to the same size at the hole. By positioning it exactly over the punched location of the hole, it will guide the drill along exactly the right path.

To construct this jig, I took a small offcut of 18mm plywood and ripped it to the thickness of the post. By sliding the post up to the circular saw blade, and the fence up the post, the exact thickness was captured on the saw. The offcut was ripped to this width.

Then I found the centreline on this guide piece, and then punched a mark in the middle on that centreline.

This I drilled out with a 13m drill.

I found two more long offcuts and screwed these to the edged of the drilled guidepiece. The jig is pretty obvious from the photographs.

The other requirement was two spacers, made from another offcut about 5 inches wide, with parallel sides, which I cut in two.

Jig initial set up

Jig initial set up

To align the jig, I lightly clamped it in place and slid the 13mm auger bit I was planning to use, through the hole, with the tip resting in the punched mark.

Spacers set up. The idea is that, because the spacer edges are parallel, the squareness of the square is 'transmitted' to the drill bit.

Spacers set up. The idea is that, because the spacer edges are parallel, the squareness of the square is ‘transmitted’ to the drill bit.

With the combination square resting on the edge, I placed the two spacers in position, one sitting in the edge and the other on the top of the jig. By pushing the jig towards the combination square (a light hammer tap maybe), the whole thing aligned perfectly.

A big gap - the jig and square are pushed together to square up the drill bit.

A big gap – the jig and square are pushed together to square up the drill bit.

A hammer can be used gently to tap it together

A hammer can be used gently to tap it together (terrible photo!)

The drill bit is now aligned to the spacer

The drill bit is now aligned to the spacer

The spacers press against the side of the auger bit and the edge of the square, the jig swivelling until everything is touching. Clamp up hard in two places.

Checking to ensure that the guide is on centre. As it was ripped to the same thickness as the stock, the straight edge should align with the the face of the stock and the edge of the guide.

Checking to ensure that the guide is on centre. As it was ripped to the same thickness as the stock, the straight edge should align with the the face of the stock and the edge of the guide.

To ensure that the guide plate was directly on centre, I set the straight edge against the face of the stock, which just touched the guide plate. If it hadn’t, I would have slackened the clamp and pushed it sideways slightly.

Rather than risk moving anything, I removed the bit from the jig to fit it to the drill, and then re-inserted it carefully. Then it was simply a matter of squeezing the trigger and letting the drill do the work.

Right through the hole...

Right through the hole…

I actually bored from both sides, first counterboring the outside with a forstner bit. But I probably didn’t have to because the holes were so accurate that you couldn’t see any join where they met.

This method is pretty good. For boring really long holes there are better ways, as any bit will tend to wander off course, diverted by the grain of the wood. A good way is to use a boring bar rather like you would bore out a cylinder on a metal lathe. This is often used for boring the stern tube hole in a boat, which has to be very accurate over a long thickness of timber.

Traditional rig fans w20150613_180956ill recognise this immediately.  No, not some strange Aleutian Islands carving of a marine Beast, but a jaw for our sailing dinghy Tiny Tim’s new boom.

The last boom for Tiny Tim had no gooseneck or jaw, and it always blew away from the mast on port tack.  So I thought the two hours that this project would take would be be worth it  For land lubbers, and those strange people who like bermudan rigs, the jaw is fastened by the straight edge to the boom.  The jaw and the protruding boom then form a collar that fits aft of the mast, creating a kind of universal swivel joint.  A slightly fancier vesion has a string of parrel beads around the forward curve of the mast to complete the circle.

I designed this to cut out of a piece of keruing.  Ideally the grain should be chosen to follow the curve, but I didn’t have the right shape.  I do however have loads of keruing, a tough, dense tropical harwood, so I used that and cut it on the diagonal.  For a small spar it should easily be strong enough.

The fun thing about making bits for boats is that you can to some extent make up some of the lines, and here patterns become fun things to make.

For repeat items, plywood patterns are worth making, but for one offs, a paper pattern can be quick and very useful.

In this case, the diameter of the mast is a fixed factor, as is the curvature of the boom.  But the rest is up for grabs.  On a piece of paper a compass gave me the circular space for the mast, plus quarter inch clearance all round.  The curve was drawn freehand until it felt good. So now I had my paper pattern.

The principle I have found most useful in turning an idea into a physical object is a simple one, which involves the gradual transformation of a conceptual line into a physical one.  The way this is done depends upon the tools used.  Ideally each tool rides on the surface left by the previous one.  So working out the strategy backwards is a good idea.

The finished jaw, before final shaping with abrasive paper, would be routed with round overs running on a bearing.  The router would run on a square cut ‘blank’ already satisfactorily curved.  The circle is cut with a hole saw in a drill press.  The curve will be cut roughly with a bandsaw and smoothed with a spoke shave.    The straight edge will be band sawn or cut carefully freehand with a circular saw, and then planed to the lines.

So how to transfer the lines from the paper pattern?  Easy.  Glue it on with a stick glue like Pritt.

This gluing on strategy is brilliant.  You can also use PVA glue, although Pritt dries fast and doesn’t cockle the paper much.  If you use PVA, paste the paper and let it expand before stucking it on the timber.

For a job like this, simply line up the sticky pattern with the desired grain direction and rub it on.

First I drilled the big hole on the drill press.  Then I then sawed the straight edge on the circular saw and planed to the line.  I bandsawed off the waste around the curves and tickled then up with a pair of spokeshaves.  A stationary sanding disc or clamped belt sander also does a good job of the convex curves.

The pattern is now redundant, so can be pulled off.  A light rubbing with sandpaper gets rid of most of it, the rest will come off in finishing.

I thought of routing the roundovers on the router table, but it just felt too small to work with safely, so I clamped it to a bench and used a laminate trimmer with a 3/8th roundover to get the curves on the edges.  Here I made a slight error of judgement, as I predrilled the fastening holes when it was square, thinking it would be easier and more accurate (which it was).  But of course the roundover bit bearing dipped slightly into the drilled holes.  It’s a tiny wobble in the curve, but a good reminder for the future.

Then I used 40 grit abrasive really to round out everything.  Don’t muck around with anything finer.  80 grit to rub out the marks, and 120 pre-finishing.

The straight section had to be hollowed to take the curvature of the spar.  I do have a set of hollows and rounds sitting up in my workshop loft.  But I used my handy rasp, which for such a small job was just as easy and avoided climbing a ladder.

The hole drilled in the face has a double purpose.  It serves as a fastening point for a downhaul; and whilst I am experimenting with where it fits on the boom (before permanently fastening it with copper nails and roves), I will lash it through this hole.

A coat of oil rubbed in with wet and dry, more to come.

An enjoyable little project, which I am looking forward to using.