Some Useful Machines

I was in the shed with the camera and it occured to me that some one might be interested in the wood working machines I use so I took some photos.

This is my new bandsaw, well new to me anyway (it was made about 20 years ago). It replaces my old bandsaw which was underpowered and would not cut timber more tha 25 mm thick. I haven't been able to stop this one yet! In the photo it had just arrived and I was setting it up and making a wheeled base for it prior to moving it into a space at teh back of the shed.

Boatbuilding needs timber that is finished to unusual sizes and often in long lengths. These can be ordered from a timber merchant (expensive and involves delays) or cut from larger planks as needed. I use the Triton workbench to rip the lengths about 3 mm oversize. The longer and sometimes heavy planks are supported on roller stands as the go over the saw bench. The planer in the background is moved to one side and the sawn timber is supported by pieces of pipe on the workbench. When the sawing is done the planer is moved to the saw bench and the sawn timber is run through it supported by the rollwer stands and workbench. This system seems to work well enough and saves money and time.

This is another "new" acquisition. It keep the shavings from the planer under control and helps with the floor cleaning - the floor is often covered in sawdust and shavings which is OK but if you drop something small it can be lost forever.

Last photo shows my Tormek grinder. This has greatly reduced the time I spend sharpening plane blades, chisels and knives. It is a magic piece of equipment. Previously I used oilstones and Japanese water stones but it took a long time to restore a edge that had been damaged by a nail or similar. I still use the water stones (kept in the bucket in the sink) to put the final edge on.

More on the Stems

I shaped the inner stem using the template mentioned in the previous post. When it was done I used the inner stem to laminate the outer stem. The outer stem laminations were 5.5 mm thick and would not bend around the curve of the inner stem. I put them to soak in cold water for about 3 hours and this made them pliable enough to take the curve. Here they are clamped to the inner stem sitting in the sunshine to aid the drying out process.

After several days to allow the laminations to dry out they were glued together with epoxy. Both sides of each of the 12 laminations (only one side of the outermost laminations) were coated with unthicked epoxy as a primer and then one side of each was coated with thickened epoxy to fill any voids in the joints. All 12 pieces are put together and clamped around the inner stem. There is plastic sheet to prevent the two stems sticking to each other. Here's a photo taken with clamps in place and after I had removed my rubber gloves and cleaned up a bit.

This next photo shows the two stems separated. Inner stem in front and outer behind with temporary braces to minimise springback.

Here is the inner stem in place in the building frame. There will be considerable sideways force on the inner stem as the planks are pulled into place hence the bracing. The white sheet sticking up between the back of the stem and the mould is plastic to keep the glue under control when the keelson is glued in place. The photo on the cupboard door provides inspiration as I work away at this long project, it shows John Sharpe's Able sailing (more photos of his boat at links on right).

Inner Stem, Keelson and Transom

The photo below shows my template for the inner stem. It is made from scrap plywood and is shown here in position after a bit of fine tuning. The actual inner stem can be either laminated from thin strips bent around a former or fabricated from larger pieces of timber. I have chosen the second approach because I wasn't keen on the idea of bending the laminations around the sharp radius in the stem. I will laminate the outer stem but even with its larger radius the laminations will have to be soaked or steamed before they can be bent to shape (more on that later).

Here is the fabricated inner stem with the last of the 6 pieces being glued in place. There are 2 layers each 35 mm thick with 3 pieces in each layer arranged so that none of the joints fall on top of another joint.  The finished stem will be 65 mm thick x 75 mm wide.

The transom is in place on the building jig. It is made from 2 pieces of 9 mm plywood glued together and then cut to shape. Fitting it was quite tricky because it is at an angle with its upper edge (lower edge because the boat is upsaide down) lined up with the end of the building frame. It also has to positioned vertically relative to the datum line (string line stretched horizontally above the frames, visible in the previous post). The final shape of the transom is a bit smaller than in the photo as shown by the line (click on the photo to enlarge it). The edge of the transom is bevelled to fit the planks that come down onto it at an angle.

The datum line (string) is important at the moment because everthing is positioned relative to it; the frames are vertical and therefore at right angles to it, they are all at right angles to it in the horizontal plane and are set below it by specified measurements. Once the stem, keelson and centre board case are in place the string line will be removed.

There is a rare thing in the photo, sunlight and shadow through the window of the shed! Brisbane has been very wet and dark in recent days.

Last of today's photos shows the parts of the keelson being prepared. The keelson is 30 mm x 75 mm and a bit over 4.5 metres long. It is laminated from two 15 mm thick pieces to make it easier to bend over the frames. Because I didn't have any timber long enough  the two laminations have to be scarph jointed. The photo below shows the tapered ends of the scraph joints. The 4 pieces, each 18 mm thick, are arranged stepwise on the end of the bench. Each step is 150 mm long (the length of a scarph joint should be at least 8 times the thickness of the material). Once they are accurately positioned and clamped in place the steps are planed away to form a ramp. Having made the ramp, I ran the belt sander (coarse belt) over it to scratch the planed surface up providing a key for the glue.

Temporary Moulds in Place

I have spent the last couple of days marking out the temporary moulds onto the sheets of laminated plywood, cutting them out with a jigsaw and then cleaning up the edges with a hand plane. The moulds have been positioned on the building frame and can be seen in the photos below.

This boat is bigger than the last one I built in this shed. while it is only 300mm longer it is 820mm wider in the beam and it fills the workspace. It will be difficult to take photos as the work progresses!

The Building Frame

I had a building frame left over from my Acorn 15 build but for the Able it needed to be wider and longer. I replaced the crossmembers with some longer ones and added a box shaped section on one end to increase the length. When this was done I positioned the frame in the shed and marked the position of the legs on the floor with chalk. Then I carefully levelled the top of the frame by putting wedges under the legs. Once leveled I drew a line around each leg the same distance from the floor, tipped the whole frame on its side and cut off the legs to the line. I put a good sized dollop of thickened epoxy on the floor where each leg would land and then tipped the frame back onto its legs. When the epoxy sets the top of the frame will be levelled with a plane. Here's a photo of the result (the temporary braces on the legs will be removed when the glue sets).

Starting on the Moulds

I worked out that I would need 5 sheets of material (2.4 x 1.2 metres) to make the temporary moulds that the boat will be built over. Looking around for inexpensive ply I found some smoke damaged 7mm thick plywood and bought 10 sheets for $30. At 7mm these sheets of ply are too thin so I glued them together in pairs to make sheets 14mm thick.

To do this I laid a sheet on the floor of the shed, spread a thin layer of glue on it with a rubber squeegee and then laid the second sheet on top. To apply pressure while the glue set I laid a sheet of polythene over the plywood sandwich sealing all around with some cheap gap filling goo and then sucked all the air out with a vacuum pump. This gave me close to 15 pounds per square inch over the whole surface of the sheet. This is approximately the same as putting a 30 ton weight on top of the sandwich!

Here are a couple of photos. First the whole setup. The vacuum pump (at the top left of the black sheet) was home made using a 1 HP electric motor (blue) and a very old compressor (pinkish).

Below is a corner of the sheets where the vacuum tube enters. It was a bit tricky getting a seal where the tube went under the sheet but I succeeded by adding more of the gap filler. The sharp fold over the edge of the ply and the very small radius where the sheet hits the floor give some idea of the vacuum achieved.

I used a glue called Purbond which has a drying time of 2 hours at 20 degrees C and ran the pump for about 5 hours for each pair of sheets.