Fiberglass, plywood, Woodworker & Building Tips
Boat Articles, Guides, Commentary and archival articles & helpful information,care of gear and sails
Shop, Woodworker & Building Tips
By David N. G.
How to Cleaning Your Saw Blades
If you do a lot of ripping of resinous woods such as Yellow Pine as I do (I used it for my deck on Toad Hall) you will soon build up a thick yellow pitch layer on your saw blade. The drag it creates makes ripping an even more tedious job than it is already.
In any woodworker's catalogue you can find many high-priced products which purport to remove this pitch. You spray 'em on and wipe 'em off! In your own kitchen however you probably already have a product which is just as good; it's Easy Off™ Oven Cleaner!
You use it just as you would the high-priced sprays. Spray it on,
let it sit for about 15 minutes and wipe it off. For really thick
build-ups I find its easiest to wipe it off with a little steel
wool, and sometimes it takes two applications, but no matter how
thick the pitch is on the blade, a generous application of Easy
Off™ (or similar) and a little patience in waiting for it to work
will result in a sparklingly clean
Curved Cuts from STRAIGHT BLADES
When you need to cut a long and curved shape from plywood or any other material, a good tool to use is your portable circular saw. This can cut a surprisingly tight radius if you take it easy and the cut is generally less "wandering" than that which you often get from a saber-saw when trying to guide it around a very long outline.
The tightness of the radius that you can cut depends on really two considerations; the thickness of the material and the diameter of the blade in the saw. Thin material can be cut to a tighter radius and the smaller the blade obviously, the tighter the radius which can be negotiated. A little practice will make perfect!
How To make...
I usually sail alone, and even though the little 8' pram dinghy I built a few years ago is relatively small it still weighs enough to make it a little awkward to handle on my own. Especially if the launching ramp is a good distance away from the car park.
To make it a lot easier to manhandle the dinghy around and to launch it, I made a single-strut landing gear. It's simply a plywood/yellow pine construction with the yellow pine acting as the cheeks to the plywood. As can just be seen in the sketch below, the cheeks are shaped to match the rocker of the boat. In use, the gear is simply inserted into the dagger board slot, the boat turned right side up and trundled away! A piece of cake.
One other useful advantage is in launching the boat. You can move it to the launching ramp like a wheelbarrow, roll it down the ramp and into the water and leap in. If you have attached a lanyard to the bottom of the landing gear (which you certainly should!) and carried it around the topsides and secured it to one of the rowlocks or any other convenient attachment point, you can push the gear out of the dagger board slot with the dagger board and retrieve it with the lanyard. Another piece of cake!
The wheel is any wheel you might happen to have lying around or you can do as I did, buy a cheapie from your local home center. Don't bother with fancy hardware, any kind of bolt axle will do. You're not going to the Hebrides with this thing, just to the local lake.
LINE THEM HOLES
I had the need to make a sump cover for the rope locker on board TOAD HALL. I wanted to use plywood and I knew that it would need a liberal coating of epoxy
to seal it from the water, especially on the endgrain.
The piece of plywood that formed the cover over the sump was pierced with a large number of holes of course to provide the drainage to the sump but prevent small parts from falling in. I was at a loss for a while to figure out how I was going to effectively seal the end grain exposed by the holes with the epoxy. The holes were only about 5/8" diameter and getting a brush in there was problematic. I was sure that the end grain in the holes would not be completely sealed and before long I would be faced with delamination.
...and the solution:
The plywood was 3/4". I cut off a number of pieces of copper
pipe to about 3/4"
each. I wasn't too fussy about the length, just approximate. This was 1/2" copper pipe and the O/D of that pipe was just about 5/8". They made a nice snug fit in each of the holes. I coated the inside of each hole with epoxy as best I could pressed into each hole a piece of the copper pipe. When it all cured up, the pipe was irretrievably inserted into each hole and effectively sealed it. I then took a belt sander with a course grit and ground down each piece of pipe to a flush fit to the surface of the plywood cover.
A couple of coats of epoxy on the plywood (paying special attention to the side end grains) and the job was finished.
I am confident that these holes at least will not be the source of water ingress to the plys and the cause of delamination.
My first thought in making the blocks for TOAD was to use rope-stropped blocks as pictured in Hervey Garrett Smith's The Marlinspike Sailor. His drawings are reproduced below.
I made a couple of attempts to reproduce this type of block with reasonable success. However, I decided that I much preferred a metal strap in place of a rope strop, and it was clear that these would be much faster to produce than the mortised type. An example is shown below.
I started out by making the classic block, with the cheeks separated by spacers and a hooped strap which would be attached to a tang by a shackle. I purchased a Delrin sheave for the line and made the cheeks from oak flooring scraps which I happened to have available. When I put it all together though, several things troubled me. The flooring scraps were a little narrow when the tongue-and-groove was trimmed off and the sheave therefore projected slightly more than I wished. I also did not like the resulting elongated shape. It was clear that I would need some other material for the cheeks.
I thought about this for a while, and in cogitas I realised that the hardwood cheeks on the $45.00 blocks we see advertised in the yachting press were really an anachronism, albeit a beautiful one. I believe the development was as follows. Originally, all blocks were mortised in very hard woods and rope-stropped, as were Smith's versions shown above. Subsequently metal-strapped blocks appeared, and the wood was mainly relegated to the function of cheeks, and this function is primarly that of fairing. In fact, it would be very possible to make a block with just the straps and the sheave were it not for the possibility of snagging them on lines and fittings. It was apparent to me therefore that the cheeks could be made of almost any material which would serve this function. All of the strain would be taken by the straps. I then thought to use plywood. This has worked out superbly, and I can use the odd-shaped scraps of 3/4" plywood left over from bulkhead and central-girder making. I made a set of sample cheeks from this material, and tried a coat of epoxy and spar varnish on them. They came up beautifully.
I was still unhappy with the sheaves however, because I had to buy them for $3.00 apiece. I planned to make up about 60 blocks for use and for spares, and this would be $180.00 just for sheaves. Not good!
I decided to try plywood!
I had already tried making up sheaves from the oak flooring scraps and this had worked out fairly well, but the use of plywood offered me several further advantages. The oak would have its grain oriented in only one direction and thus would take the strain in the wrong direction at least 50% of the time. The plywood, because of its cross-grain plys, would have its grain oriented in a useful direction for the vast majority of the time. I made up a couple and tested them satisfactorily.
At this point I had a hooped strap with plywood sheaves and cheeks. I was progressing nicely I thought. Then I went shopping for shackles. When I finally found one that was appropriate, it cost six dollars! That would be $360.00 just for shackles if my inventory of 60 was to be maintained. Even less good!
By using plywood for cheeks and sheaves, and a piece of scrap steel from the back of a set of steel shelves for the strap and a couple of brass bolts and nuts, I had got the cost of making the prototype block down to about 20 cents! I wasn't about to spend six bucks for a shackle to fasten a 20 cent block to a fitting or a line. It just didn't make sense.
Cogitas ergo explicatum!
I looked at the shackle and how it joined the block and realized that if I eliminated the hoop and instead terminated each side of the strap in a rounded end with a hole in each, I could join the two with the pin of the shackle, with a clevis pin, or (with thanks to John Marples) with the shank of a bolt with the threaded end shortened.
I could get clevis pins from the marine store for just $2.00 each. By eliminating the $3.00 sheave and the $6.00 shackle I had already saved $9.00, or a total of $540.00. I was rich! Better still, I knew I could get galvanized clevis pins from an auto supply store for even less.
Now I come to the final innovation in this block-making effort. While making up the first prototype of this final design (Block; Toad, Mark V, Mod 1), it occurred to me that I really did not need the spacers, (the filler pieces at the top and bottom of the block). If I held the block apart by the use of steel tubing, I could get the same effect as the spacers and enjoy faster and easier construction. A schematic of the final assembly is shown above.
The two straps lie in dadoes cut into the inside face of each cheek. The sheave axle runs through the cheeks and the straps in traditional fashion. The cheeks and straps are held together by two round head machine screws which run through two pieces of steel tubing. Tightening these two screws fastens the block together tightly and completely. The clevis pin functions both as a pin and a shackle.
One big advantage of this method of construction lies in the convenience of being able to make up the block inventory as parts only, and then put them together as needed. Since all that has to be done to make up a block is to insert the axle through the sheave and the straps, insert and tighten the bolts and fasten in the axle retainers, assembly is simple in the extreme. But an even greater advantage is that by making just three different strap types, and stocking a few bolts of different lengths, I can make up a very large variety of blocks, with and without beckets.
I will say however, that after I had come up with this idea, I was reminded of the old BlocKits from the early 70's. These were similar arrangements of cheeks, straps and sheaves, which the buyer could purchase in individual pieces and thus make up finished blocks from the parts. (They weren't as pretty as mine though!).
To actually make up the blocks all I needed now were materials. I hate buying anything at the marine store for this boat if I can avoid it. I would much rather make it up from something else. Accordingly, I went to my favorite steel scrap yard and bought about 80' of 1" x 1/16" steel bar for the straps. and 12' of 3/8" chrome molybdenum steel rod for the axles. The latter was a real find. The twelve feet of chrome steel rod cost me two bucks! The 80' of 1" steel strap cost me .25 cents per pound., or $4.00!
Now all I needed was the tubing for the fastening bolts. At my local auto supply store for $2.48, I bought 48" of electro-galvanized steel tubing which would just slip snugly over the bolts. Enough for 24 single blocks.What was this? Why it was brake line! It's perfect for this use. Final cost was about 21 cents per block. That's acceptable!
The first thing I did was to rip some scrap plywood to the width of the cheeks, plus a little extra. Following this, I dadoed the 1" valley for the straps into the rectangular pieces. I then traced out the shape of the cheeks and cut them out on the band saw. I located the three holes that would pass through the straps, (the axle and the two fastening bolts), and made up a Master Strap of each type to be used for all subsequent measuring. I then borrowed a "chop saw" with a Carborundum cut-off disc and sliced off all the straps to the three lengths necessary to make up the block parts. I used the Master Strap to mark out the locations of the three holes to go through each strap and drilled these. Then I rounded over the tops and bottoms of the straps to match the contours of the cheeks.
I also used the Master Strap to locate the three holes in the cheeks, drilled these out and then sanded the cheeks to their final shape. By turning the cheeks over so that the face was up, I had the locations for making the counterbores for the nuts and the heads of the fastening bolts and for the axle covers. I used Forstner bits to cut these counterbores.
The only thing that remained to make were the sheaves. I had previously experimented with using the lathe to make these but abandoned this quickly as it proved too clumsy. The method I ended up using was simple, and utilized the drill press. I first cut out the circles with a simple hole saw of a little larger diameter than my finished 2" sheave size. I used a machine screw and two nuts and washers to chuck the sheave blank into the drill press, and set the machine to its highest RPM.
I first used a small round shaping tool from the lathe to rough cut the valley, then made up a smaller but similar tool from an old screwdriver. This enabled me to turn a small, deep valley of the right size for 3/8" line into the sheave. I finished it up with sandpaper while still turning in the drill press. I enlarged the axle hole to take a piece of 7/16" I.D. nylon tubing (it is self-lubricating) to use as a bushing, pressed this in using the drill press and ended up with a very nice sheave made from plywood. I then used the band saw with a metal-cutting blade to cut the axles to length and to cut off the brake line to the right length for the stand-off tubes.
The only thing left were axle covers to go on the outside of the cheeks and retain the axles.
In a fine British publication, (and aren't they all), called Classic Boat, I had previously seen English pre-decimal pennies used for this purpose. Since I had quite a few on hand, I planned to use them.
Test assembly was simple. I laid the straps into the strap-valleys, pushed the axle through the cheeks, straps and sheave, then put the fastening bolts through the cheeks, straps and stand-off tubing and tightened the nuts. I had previously drilled two holes through the sides of each of the pennies, and I fastened the axle covers into the counterbores with #4 round head brass wood screws. Finally I inserted the clevis pin at the top of the straps. The block was assembled!
I finished the blocks while disassembled. I coated the cheeks inside with one coat of Epoxy and two coats of Polyurethane. I did the same with the sheaves. On the outside of the cheeks I used two coats of Epoxy, two of Polyurethane, and two coats of Spar for gloss and UV protection. I put the straps in the pile to go to the galvanizers. Finally, I wire brushed and buffed the pennies until they shone brightly with their natural copper sheen, and then sprayed them with three coats of a good clear lacquer.
NOTE: There have been some changes since I wrote this article and I have now decided to go back to rope stropped blocks after all. I came up with some good ways of making these two and I will post that article in a few days. Also, I will have some results of the tests I ran for load-bearing on the steel-strapped blocks described above.
Cutting and Ripping Heavy Gauge Steel with Woodworking Tools
A Guide for Woodworking - Tools, Tested Methods, Tips, Techniques and the most fundamental parts of good woodworking.
Steel is a very useful boat building material, even in wooden boats. All of TOAD HALL's iron work is made from common mild steel, most of it scrounged! The mast step and the rotating tabernacle cuff are made from a piece of 1/4" X 4" steel pipe that I found in a dumpster. The same pipe makes the gooseneck bands, the spider bands and the hounds band. One quarter inch X 3" steel angle from a scrap metal yard made up the Mizzen mast step and the stem-head. Black iron pipe fittings made up the gammon iron which was welded to the steel-angle stem-head. Black iron pipe also formed the cranse iron and the Mizzen Mast hounds band. Three-quarter inch black iron pipe made up the gooseneck and 1 1/2" X 1/8" steel made up the cabin fore structure and all of the companionway frames.
Something or somebody had to cut and fabricate all this steel before it was ready to be welded! A hacksaw was out of the question and I don't own any welding torches; (a friend does all my welding but to ask him to do all the cutting and fabricating would be an imposition.) Something else was needed!
I had borrowed my friend's 14" Hitachi chop saw on occasion but I needed something of my own so that I didn't have to be constantly running the chop saw back and forth, and also to have the tool on hand for immediate use when I needed it. I knew that the carborundum discs used in the chop saw were readily available and that I could get them in the 10" size which would fit both my radial-arm saw and my table saw. I went to an abrasives company and bought one to try it out. It worked perfectly and I have cut and fabricated all my heavy steel with these discs ever since.
Here's how to go about it.
Here's how to go about it.
Once you find a supplier for the discs (look in the Business-to-Business Telephone Directory under Abrasives) buy one or two which will fit your saws. Note that the arbor hole comes in various sizes. If they don't have one to fit your particular arbor, they will almost certainly have little adapters which size down the larger holes to fit smaller arbors.
You might be tempted to buy a larger disc than is designed for your radial; after all there is really no limit to the size of the blade that it can swing, just the size of the guard. Do not do this! I tried it and found that the larger (14") blade actually cut slower than the 10". The friction at the cutting surface is such that it can slow down the larger blade quite dramatically. Stick with the right size blade and use the guard. The photographs which accompany this article show the guard removed but that is only for photographic convenience.
Once you are ready to cut your first piece of steel, perform a little housekeeping. You are going to be making a LOT of sparks, so get out the shop-vac and clean up the surroundings of the saws to get rid of all the sawdust. Be diligent. Get out the sawdust from underneath the table of the radial and underneath the bench saw if you are going to use that. These sparks are hot and can cause a fire! Another precaution that I take is that I never leave the house after cutting steel until after at least a couple of hours have passed so that I can take a look at the surroundings and make sure that some errant spark isn't smoldering in some overlooked sawdust.
After all that is taken care of you are ready to start cutting! You will of course wear eye protection! A spark is just as uncomfortable as a sharp stick in the eye! Let's look at the technique for each saw in turn since they are quite different.
THE RADIAL-ARM SAW
The big thing to remember about cutting heavy steel with the radial is to LOCK the traveler. You DO NOT want to try pulling the motor and blade through the work as you would do with wood. This will immediately bog down the blade! Instead, lock the blade over the work and raise and lower the arm with the crank on the front of the machine. This gives you much more control over the speed of cut which in turn eliminates almost all of the binding.
It is also important to always cut down an edge. That is, if you have a steel angle such as in the first photograph here, you will NOT try to start the cut on the wide surface of the angle. This will also bog down the blade. Start the cut on the edge of the angle and move it down as shown in the photograph. Do the same with flat plate steel as well. The motor just can't handle a lot of extra friction.
Crank the arm down until the disc just contacts the material and starts to cut. You will soon see how quickly you can move the arm up and down to make the cut. Start out slowly at first until you get the hang of it.
As the disc wears away, (it will take quite a while; these discs last a long time and can cut a lot of material), you will start to encounter a problem with the body of the motor which can contact the work and stop all progress. Just turn the work over then and cut from the other side. If it is a large angle such as shown in the photograph, my procedure would be as follows:
As far down one side as possible until the motor housing restricts it.
Turn the angle over and do the same on the other side.
Turn the angle over until it forms an upside down "V" and cut down through the web.
A word about disc position. Always try to position the disc so that it is cutting from the bottom of the disc and not the side, and when cutting the web, take it a little more slowly; there's a lot of material there. The photographs show the procedure.
THE BENCH SAW
This is simplicity itself. You handle it just as you would if you were ripping a 2 X 4. You will be astonished at how easily the disc marches through the 1/4" steel angle which is being cut in the photographs.
With the bench saw it will not be possible to get the material positioned at the apex of the disc because of the nature of the machine. Elevate the disc as high as you can and it will be fine!
You can use your rip fence, your mitre gauge etc., to do everything with steel that you do with wood; just a little more slowly!
Fill Gaps with Fiberglass Insulation
STRONG STRUCTURAL FILLETING MATERIAL
While building TOAD HALL, I occasionally found that I had to fill a gap where I had not beveled a fit. I found what I think is the ideal material for this purpose; ordinary household insulation fiberglass.
I use the pink stuff because I found that it changed colour with the addition of the resin and I was able to discern exactly when it was fully saturated by this change in colour. I tear off whatever I need from the batt and stuff it into the gap, then pour in the epoxy. The fiberglass soaks it up quite quickly. It starts out changing to a slightly darker pink then, as the epoxy soaks in and you add more, it will turn a very dark red. That's enough! It is fully saturated. The multitude of thin fibers in the fiberglass I feel, add significant structural strength to what would normally only be filler. One thing to be aware of though; the epoxy/fiberglass insulation mixture has considerable density and this means the the set-up time will be much faster than with just ordinary epoxy coatings. Be aware!
The finished fillet will be a little rough, (all those little fibres sticking up), but you can sand it smooth and add a little smooth filler on the top to even things up. The photograph shows the fillet between the cabin sole and the hull sides of TOAD HALL. I did NOT try to fillet this 1 1/2" of plywood sole but instead left the sides straight. Then I filled it with the structural fibreglass insulation and smoothed it off with the smooth filler.
If you don't have enough room on the outside stern - if i can mount a external transducer inside the boat and expoxy it to the inside bottom of the boat ?
That anything that is in front of the transducer would greatly affect the accuracy and would make it useless. They make a through hull transducer that I believe may be a better option.. Think they are $60 and up depending on manufacturer. You can buy an 'In-Hull' transducer that comes with a mounting plate at an angle to match your hull. No drilling through your boat is required. I don't think they work going through foam though. West Marine sells them for around $140.
DRILLING WITH ANTIFREEZE
There's a lot of iron work in TOAD HALL and it all needs a certain amount of machining. The cutting of the metal I have covered in another article on this page. Once fabricated however, all of this metal needs to be drilled.
I don't know if you habitually use oil when drilling metal now, but you should certainly use a lubricant of some sort. It saves the bit, lets the drilling go a little easier and produces a really nice curl.
That's how you know you are getting good cutting; when the metal curls out in long spirals instead of coming out in thousands of little chips.
I used oil for this for a long time. Then I read a tip somewhere, (I don't remember where, but this tip is not original with me), that antifreeze would do as good a job.
I think it does a better job!
It lubricates the bit and produces an excellent curl; every bit as good as oil.
It is a lot less messy. It doesn't collect in a sticky, oily, metallic mess on the drill press table or on the floor, and it is a lot easier to clean up, especially because it is soluble in water.
It's cheaper. A gallon will last for years. I use a French's mustard squeeze bottle I got from my neighborhood deli to apply it. Just squeeze a little stream onto the bit and keep doing it by raising the bit and squirting a little more into the cavity formed by the drill bit.
A SCREW BIT
Toad Hall's rudder tube runs up at an angle from below the counter stern to the deck. I had installed the tube itself when I built the Central Girder and that was fine. But when I put the king plank down and epoxied it to the sub-deck I forgot to mark the location of the tube at the deck surface and the king plank completely obscured the position. I didn't want to spoil my king plank by guessing at the location. I knew that if I had a long enough drill bit I could just insert it into the tube from below and drill a small hole through the king plank which could then be enlarged quite easily.
Electricians use long flexible drill bits to get through rafters when running wiring, and my friend (who is an electrician) has a couple of these. But I wanted to drill the hole NOW!
Here's what I did.
The distance from the bottom of the hull to the top of the deck measured out to 27". I have a couple of long bits but they were not long enough to reach this. I didn't want to fiddle around making up some extension either. I did however have some 3/8" threaded rod that I found behind a business one day and put away until I needed it.
I never throw anything away, remember?
I ground a simple "bit" on the end of the threaded rod which measured about 36" in total length. The profile is as shown.
Note that I ground the bit so that it had a flat on the tip rather than a point. In this configuration it scraped the wood to penetrate it. Since it is not possible to grind a true twist into the end with a simple grinder, it is important that you (if you try this at home) grind a profile which will quickly "scrape" away material in order to penetrate it.
It didn't have to be very precise because I was only trying to get through about 5/16" of material in the king plank.
I chucked it in my right-angle drill, pushed it up the rudder tube until it contacted the bottom of the king plank and pressed the button. With a little push the drill entered into the wood and to my surprise, climbed right through in double-quick time with no effort. In fact, I could not remove the "bit" without switching the drill to reverse and backing it out!
What had happened was that the point of the "bit", being smaller than the outside diameter of the rod, had allowed the threads of the rod to bite into the wood and pull the bit right through. It made drilling very easy.
If you ever have need of a long bit, use a bit of threaded rod like I did; it will make the job easier.
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