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Tools, Jigs and Tricks


Howard

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Curious what most are doing about drawing curves.

 

In most plans, I find three versions of curves. One is the long sweeping curves that form the edges of long panels, such as topsides, bottom panels, etc. These are typically, drawn from plans on full sheets of plywood or several sheets joined together with scarfs. The series of points are platted out, then a finish nail is set at each point. Then long battens are used to connect the points, the natural curve of the batten forming the curving sweeping lines of the edges. Key is a good, stiff batten that will throw a fair curve, but that is eased some by how close the points are to each other. Such a long, fair batten is a valuable boat building tool that can be tough to find. Again, if there are two identical panels, such as sides or bottoms, stack and cut them both at the same time. Cut outside the line, then finish them together with a plane, bringing the edges right to the line.

 

Second curve type is sometimes found along the edges of bulkheads, etc. Instead of a straight line, the plans may show a straight line, with a small bump out in the middle. Perhaps a 3' edge segment, with a point shown in the middle that is 3/8" or so out from the edge. Process is the same as long panels, Set a finish nail at the midpoint bumpout and ends, then bend the batten over these to form the curve. When the topsides are later stitched to this edge, they will form a similar curve. Aside from the visual of a finished panel with a slight curve to it (vs. table top flat), a curved panel is many times stronger than the flat one. As a general rule, plywood (or even a sheet of paper) will easily bend in one direction, or rather in one plane, but does not like to bend in two planes at the same time. (Tortured ply forces a twist in the panel, ergo the term "tortured". If it survives the bend, it will be incredibly strong and stiff). Take an otherwise floppy sheet of plywood, put any bend in it from any direction, and it stiffens up a remarkable amount. Even a thin sheet of plywood, with a bend in it, is quite stiff and strong, firmly resisting any further attempts to bend it in a different direction.

 

Third curve type, and the one I'm thinking of here, is what happens at the top of some panels, such as the transom or some bulkheads. Plans generally show how wide the panel is (chord), and the height of the curve, but that is it. Plans typically do not show how to plat or draw this curve. I can think of four different ways a person might approach drawing this curve.  The simplest would be to simply set nails at these three points and bend a batten over them, similar to the other curves. Since these are often wide curves, with substantial bends, I have not found this to work for me. The batten has to have a consistent bend, and even if one of those is found, I have found my curves inconsistent, with irregular flat spots. In short, the end result for me is not a reliably fair curve.

 

The other ideas would be to calculate the radius of the circle formed by the three points and plat it as a segment of a circle.

 

I am platting them as parabolas, calculating at least three points along the curve, in addition to the ends, then forming the battens over those. That provides me with consistent curves that can be achieved with less than perfect battens.

 

Again, curious what others are doing or what others recommend?

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Most of us are  doing stitch and glue boats. How do you cut the wires ahead of time, and get them the same length.

 

Here's how  I do it, or PI is your friend :)

 

To make 3 inch (roughly) long wires, wrap the wire around a 1 inch dowel or hunk of PVC pipe, slide the wraps off, and cut down one side with tin snips. Now you have wires all the same length and it takes just a minute or two

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Howard, check this out. this is a traditional way I learned when working in the design department of Morgan yachts years ago. I've used it for several boats since then. click on the picture on the right and it will show an enlarged view.  http://www.lackeysailing.com/daysailor/rebuilding/deckframe1.htm

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Chick:

 

That is the same method I'm using. Good to hear........as I've always hoped mine would end up looking like yours.

 

The sidebar with details is found here:

 

http://www.lackeysailing.com/daysailor/sidebars/beams.htm

 

As I understand it, the end result is a curve that is parabolic in shape, which is a good choice for this purpose.

 

Howard

 

(Edited)

 

Forgot to mention, the method Chick referenced works for bulkheads, etc, and also for deck beams. But when laminating deck beams, the amount of crown height has to be modified slightly to account for spring back, or a slight amount of relaxation of the laminated beam when the clamps come off.

 

This article describes the method and formula to use, which appears to be well tested and accepted:

 

http://forum.woodenboat.com/showthread.php?141333-Laminating-deck-beams-Spring-back

 

I laminated a beam to mate to my #1 bulkhead, and according to the formula, I should have expected 1/16th" spring back, and that is what I got. So for a laminated beam, probably a good idea to work through the formula, then add the amount of spring back to the crown height indicated on the plans. In addition to finishing where you want it, you may get a structural benefit similar to a pre-stressed I-beam.

 

The attached photo shows the laminated beam relative to the finish nails that were used to form it. If you have plastic or clear packing tape, etc. under the nails, you can clamp directly to them. As shown, this is a screw up. To make this beam, I clamped to the outside of the nails, which threw the curve off by enlarging the radius of the curve the height of my laminated beam. In short, it flattened it above and beyond the amount of springback. Since it is the top of the beam that mates up to the crown, put your lamination to the inside so the top of the beam will be where it belongs.

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This is absolutely delicious reading!!

I don't know that this will add much to the reading pleasure, but there were post about table saw sleds. I made on and use it often, pictured below.

For normal everyday cross cuts, the chop saw is preferred, but when I am doing repetitive cuts on not large stock this sled is very useful. I use it on things like cutting two inch dowels, epoxy stir sticks, glue clamps where it help to have the cut pieces stay in the "box".

A simple c clamp holds a stop.post-3404-0-93344500-1388683432_thumb.jpg

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Howard, check this out. this is a traditional way I learned when working in the design department of Morgan yachts years ago. I've used it for several boats since then. click on the picture on the right and it will show an enlarged view.  http://www.lackeysailing.com/daysailor/rebuilding/deckframe1.htm

Wow, haven't seen a reference to Tim in ages.  The Plastic Classic Forum is a perfect example of what happens when the great admin running the forum leaves.  Don't ever stop appreciating Frank.  He and this forum are a great tool or jig.

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I don't think it was all about Tim leaving, although that certainly didn't help.

 

A very nice guy, who LIVES on a classic Plastic boat ( a Pearson Ariel), and is running several other forums about boats, building and sailing picked it up and is running it.

 

But they chased away several very knowledgeable folks with nastiness and some of the folks seemed to have the idea that if something was just "good enough" it was fine. And seemed to heap scorn on those who didn't agree

 

Personally, I still visit, but I'm not involved in restoring a plastic Classic anymore- I'm sailing her, so don't have much to say.

 

I do totally agree about Frank- a jewel of a site, which I don't frequent as much as I used to anymore either- busy USING the boat-Grin

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Third curve type, and the one I'm thinking of here, is what happens at the top of some panels, such as the transom or some bulkheads. Plans generally show how wide the panel is (chord), and the height of the curve, but that is it. Plans typically do not show how to plat or draw this curve. I can think of four different ways a person might approach drawing this curve.  The simplest would be to simply set nails at these three points and bend a batten over them, similar to the other curves. Since these are often wide curves, with substantial bends, I have not found this to work for me. The batten has to have a consistent bend, and even if one of those is found, I have found my curves inconsistent, with irregular flat spots. In short, the end result for me is not a reliably fair curve.

 

 

I use the two-stick method to make big arcs. The height of the crown determines the angle of the sticks:

 

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I don't think it was all about Tim leaving, although that certainly didn't help.

 

A very nice guy, who LIVES on a classic Plastic boat ( a Pearson Ariel), and is running several other forums about boats, building and sailing picked it up and is running it.

Well, I can't prove, nor do I even necessarily believe that Tim leaving is the only cause, but I have no doubt it is the primary cause.  Being a nice guy doesn't make one a good admin.  And being distracted by other forums can make one less.  And the "good enough" standard now prevalent would never exist under Tim.  He always squashed those posts like a bug!  He never let tact interfere with honesty and knowledge.  Here we have quite a few professionals and a much more knowledgeable bunch of amateurs.  The skills of the people here may vary, but the technical discussions are always based on best practices.  And people aren't afraid to link resources to back up opinion.

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  • 1 month later...

Another tool I've recently added to the stable is a moisture meter. I got the basic Wagner pinless version. Assuming the readings are correct, and I have no reason to think they are not, this is a handy gadget to have.

 

Going back to the West Systems epoxy book, plus other sources, they recommend that the dimension lumber used in these type boats be dried to at least 10% and less in the range of 8% to 9% would be better. At that point, the lumber is considered dry and dimensionally stable. Most purchased lumber is no where near that. Some yellow pine I purchased was only dried to 17%. Picked up some scrap stuff today for a project and it is 14%. If I were to cut it up and use it today, I could probably expect cracks and other stresses and it continues to shrink as it dries out.

 

On the yellow pine, I let it dry for over 2 months in the house, then marked up some pieces. That was about 6 to 8 months ago and it has continued to dry over the winter. I remeasured yesterday and found some of my marks to be off as much as 1/16th an inch in less than 4 feet of span. No worries as is, but if that had been glued, I suspect the joint would have been stressed and either wood or joint could have cracked. Without a meter, you are left to guess as to when it is dry enough to use.

 

The only issue I have found that is never mentioned in the reviews is that moisture meters are not accurate when working with pressure treated wood. The meters work by measuring conductivity, which is a function of the moisture content in the wood. The chemicals used in treated wood (mainly copper) throw those results off as they also are conductive.

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  • 4 months later...

Was installing some cleats to bulkheads today and recalled another trick I like to use. To anyone who has glued these up, you may have experienced the case where a piece being clamped on tends to slip and slide all over the place when you put the screws to the clamps? Worse, you have it aligned perfect, then go off to do something else while waiting for the epoxy to kick, only to return and find the piece moved sometime between when you last saw it and when it stuck?

 

What I do when I'm dry fitting is once I get it aligned I'll use either a drywall screw or finish nail to hold it in place. I prefer small finish nails if I'm clamping. Drive the nail in until the tip just starts to break through, then when the piece is aligned, give it one more gentle tap to drive it no more than one or two ply layers deep into the plywood, Not enough to even stick the nail, but enough to dent the plywood with it. Then when you have everything buttered up, align the nail tips to the nail holes and the piece will be locked in place. It won't move around no matter how much clamping pressure you apply. And when you come back to check on it later on, it will be right where you left it.

 

One of the reasons I like the small finish nails is later on after the epoxy has kicked, nails pull easy enough with a hammer and do not break off like screws can. The hole they leave is smaller too.

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  • 2 months later...

Had intended to include reference to this jig before, but somehow overlooked it. For those who are now using things like hand planes, etc. this is used in sharpening your blade, which is not a one time thing, but an ongoing process. Trick to keeping it sharp and working well is frequent sharpening.......you don't let them get too far out of shape. My guess is there are folks on this forum who do this daily. I'm not that bad, but I do hit them pretty often. A touch up being easier than taking something that has been abused and bringing that back to life.

 

Anyway, part of the problem with sharpening is repeating the bevel angle. There are folks good enough to do this freehand (Charlie Jones comes to mind), and can feel the blade register on the stone or paper. I'm not one of those. Maybe with a chisel, but not a plane blade. So I use a sharpening roller. Mine is a General. The trick with these is you have to mount them the same way everytime, or the angle of the bevel changes. Do that often enough and your edge becomes rounded vs. dead flat and coming to a sharped edged point.

 

To use this jig, the tip of the blade is set against the stop, then the jig is attached and also pushed forward until it stops, where it is clamped into place. That sets the same bevel angle every time. There are two blocks, 25 and 30 degrees, depending on use.

 

Next problem is what to sharpen with. I like my wet stones, but keeping them dead flat gets to be a problem, not to mention if you don't already have one, good stones are hard to find and expensive if you do. Scary Sharp is a good temporary alternative and works well with larger plane blades and these rolling jigs. I usually quit when they are sharp enough to shave hair on my arm. Do that and they will work well enough on the softwoods and plywood we usually need them for.

 

The best solution I have found with Scary Sharp is to use high quality wet/dry paper. I get mine from an auto parts store that sells automotive painting supplies. Their paper holds up. The hardware store stuff.........not so much. A one foot square piece of marble floor tile from the box stores seems to work OK for the base.

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I'm using a Wagner 205 pin-less..........

 

http://www.wagnermeters.com/moisture-meters-woodworking/

 

I think I got mine off Amazon.

 

The pin-less versions somehow set up an electrical field, that is affected by the moisture level in the wood. You have to calibrate it for the type of wood you have, as natural density affects it. For example, a different setting for western red cedar vs. doug fir or yellow pine, oak, etc. Only in the very depths of the owner's manual does it mention these do not work well with treated wood, as the treatment throws them off. However, I have found they do work well enough.

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 Only in the very depths of the owner's manual does it mention these do not work well with treated wood, as the treatment throws them off. However, I have found they do work well enough.

One of the biggest problems with PT is that it is so often fresh out of the tank.  It is like starting with green wood again. (pun intended)  I would suggest anyone/everyone  buying your PT way early so that it can air dry.

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I agree on normal pressure treated lumber. I have seen stuff come straight from a bundle that was so wet the sawdust off it was more like saw slush. If that was the case, best plan is to store that under cover and for a long, long time. Several months at the least. And sticker the pile so air can get to and around all of it.

 

The 5/4 pressure treated deck lumber is indicated to be kiln dried after treatment, but still is not totally dry. More like 17% or so. It too has to dry down.......but that takes several weeks......not months.

 

Storing it indoors in the winter will help all that along.

 

So overall, I think it would be good advice to get all the structural wooded needed for a project well in advance of when you actually expect to use it.

 

BTW, a lot of folks will suggest that epoxy and pressure treated lumber do not work well. My tests show otherwise. They do just fine and like most other woods, the wood will blow apart before the joint does. BUT, it has to first be dry, and in the case of 5/4 deck lumber, DO NOT get the kind that has had a preservative treatment (read wax) put on it. It might say something like "weather shield". Those won't glue up at all. You can almost bust those apart by hand.

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