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Everything posted by Dr PR
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Be careful using super glue on cloth or cords! It releases a lot of heat when it cures. I once used it to treat the unravelled ends of 1/8" drawstrings on a sleeping bag - mistake! They soaked up a lot of glue. After a minute or so the cords became very hot and started to smoke. I dunked them into a glass of water to avoid a fire.
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If a mast is broken out at sea, what do you do?
Dr PR replied to Devin Camary's topic in Masting, rigging and sails
The Young Sea Officer's Sheet Anchor describes how to raise masts. Page 17 tells how to step a mast. You need two poles (spars) longer than half the length of the mast. The poles are secured to the deck on either side of the mast hole and tied at the top to form a triangular "crane" (shears). This is then lifted and hoisted vertical over the mast hole and secured with lines. Blocks are attached to the top of the crane to be used to lift the mast using tackle attached to the mast above the center of the mast length. When the mast is vertical the foot is lowered into the mast hole and then stepped on the keel. After that the stays and other rigging are attached in the normal ways. This could be done underway with fairly calm seas, but it would be a lot easier in port! The lower mast is used to hoist (swaying up) the topmast. This is shown on page 26. A lifting line is run through the fid hole at the foot of the topmast (small masts) or is run through a sheave near the foot (larger masts) and then back up to the top. The topmast is lashed to the lifting line with ropes. The running end of the lifting line is passed through a block at the top of the lower mast and then back down to tackle. Then the lifting line is used to haul the topmast up through the crosstrees and the hole in the top cap. When the foot is clear above the crosstrees the foot is stepped in place in the top and secured with the fid. Hoisting new spars on the mast is trivial by comparison. -
Exploring FreeCAD for ship modeling
Dr PR replied to TonyM's topic in CAD and 3D Modelling/Drafting Plans with Software
See post #4 in this link for an excellent animation of the process for using contour/waterlines for detecting imperfections in hull surfaces. -
Beck, Thanks for posting your animation! It does a much better job illustrating what I was talking about than my words. Now remember my caution - you can spend a great deal of time trying to get everything perfect (I speak from experience). Personally, I am a frustrated perfectionist because I know perfection isn't possible. At some point you just have to stop and say it's good enough! If you are planning to build a real model you will probably end up using filler, files and sandpaper to eliminate the last imperfections.
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Cutting brass sheet
Dr PR replied to Landlocked123's topic in Metal Work, Soldering and Metal Fittings
Like Wefalk, I have used the back side of the saw teeth on occasion with thin brass and aluminum. Another trick is to angle the saw blade very low near the surface of the metal. This way you will have several teeth cutting at the same time and the saw behaves a bit better. But when you get near the end of the cut you have to angle the blade perpendicular to the cut and it might not cut as smoothly. I have also used the broken tip of a #11 blade, dragging the back side (not the sharp edge) against brass tubing to "worry" a cut lengthwise along one side. Surprisingly, this worked pretty well for short cuts! -
Look at post #9 for ideas about how to get a smooth hull surface. You are right that you don't get a perfect hull shape from lines drawings, and even working from a Table of Offsets can produce some significant errors. One problem you seem to be seeing is that sudden/drastic changes in the hull surface may result in "wrinkles" around the transition points. It is OK to use multiple surfaces for the hull, keel, stem post, stern post, etc. This can also be a problem at "knuckles" in the hull surface - these are places with sharp bends or "kinks" in the surface. With a fairly coarse grid mesh the grid facets cannot bend over the knuckle. A solution is to create two separate surfaces above and below the knuckle. This all depends upon how much control your program allows for these sorts of things.
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Cutty Sark by Cuda1949
Dr PR replied to Cuda1949's topic in - Build logs for subjects built 1851 - 1900
Nice build. The clippers were beautiful ships! You mentioned the "Underhill book." Did you get "Masting and rigging the Clipper Ship and Ocean Carrier" by Harold A. Underhill? It has very detailed descriptions of the masting and rigging of clippers. However, one thing about it really bothers me. He has excellent drawings, but the publisher has scattered them more or less randomly through the text. And the references in the text refer to "Plate ??" and do not give the page numbers! It does have a list of plates after the contents, so you can jump back and forth and eventually find the drawing the text is referring to. -
Exploring FreeCAD for ship modeling
Dr PR replied to TonyM's topic in CAD and 3D Modelling/Drafting Plans with Software
Vaddoc is certainly right about one thing. If your intention is to make a real model just getting close to the right frame/station outlines is good enough. When you plank the model hull (assuming you plank it with wood) you will end up sanding it to get a suitably smooth surface. You can fiddle with a CAD drawing forever trying to get it perfect. You need to decide what is good enough. -
Exploring FreeCAD for ship modeling
Dr PR replied to TonyM's topic in CAD and 3D Modelling/Drafting Plans with Software
Tony, The first time I tried to create a hull I used cross sections (frames/station lines) and discovered the port and starboard sides weren't perfectly symmetrical. Now I create half hulls and mirror the finished piece, with assured symmetry. I tried to follow Kris' procedure and I have to say is seems to be about 10 times as much work as I do with DesignCAD! Once you have a station/frame curve why do you need to start over with all the many points and splines? In DesignCAD any line/curve can be used as the template line for creating surface grids. From my experience fewer points is better than a whole lot of points. I use only the minimum necessary to cause the curve to fit. The reason is that when you start refining the frame/station curves using the method I described above, lots of closely spaced points make it difficult to reshape the curve. Phil -
Exploring FreeCAD for ship modeling
Dr PR replied to TonyM's topic in CAD and 3D Modelling/Drafting Plans with Software
Working on the half hull will likely be a lot easier. Once you get the station/frame lines done and start adding the skin you may discover some irregularities in the hull surface. Even when working from a Table of Offsets this can happen. Adjusting only one side to get the properly faired surface is much easier than trying to correct two sides. After the correct lines are created it is simple to mirror them to get the other half. You can examine the hull surface in a shaded view by rotating the view point and lighting to show up any irregularities (high or low areas). But after you discover these (and you will probably have a few in your first hull surface) it can be frustrating trying to adjust the frames/stations to eliminate the problems. Here is an example: The hull appears to be pretty smooth, but you can see a bit of irregularity in the highlights. So how do you fix this? One trick I use to get a smooth surface is to create contour/waterlines at regular elevations on the hull surface. Your CAD program may have a function to do this. Or you can create a horizontal plane, position it at a desired elevation and generate the intersect line between the plane and hull surface. Create these intersection/contour lines on a separate layer and hide the hull surface. Then rotate the view to look down the length of the hull. If there are any irregularities in the hull surface they will show up as wavy contour lines. Even the slightest irregularity will be pretty obvious. You can clearly see this in the lowest waterline in the image above. The fifth and seventh frames are too low where the lowest waterline crosses them, creating "waves" or "wiggles" in the water line (frames are blue and waterlines are red). To correct these problems I draw a separate curve/spline along the contour/waterline by snapping to the line at the frames where the curve is correct, and allow the curve to shape itself over the irregularities. Then I reposition points on the relevant station/frames to snap to the new curve. After the station/frame curves have been corrected I delete the old hull surface, the contour/waterlines and temporary curve. Then I generate a hew hull surface and repeat the process, over and over until the contour/waterlines all come out to smooth curves. In the image above you can see the frames have been corrected so the lowest waterline comes out smooth. Still a bit of work needed on the 3rd and 4th waterlines farther aft. With all of this in mind you can see why it is much easier to just work on a half hull until you have a good hull surface. Phil -
Back in the mid 20th century many (most, all?) kits supplied sheets of wood with the part outlines printed on them. You had to cut out the pieces one by one. Looks like someone started cutting out the center/keel part.
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Exploring FreeCAD for ship modeling
Dr PR replied to TonyM's topic in CAD and 3D Modelling/Drafting Plans with Software
I'll be following this to see what tools you use and how they work. -
Mike, The kit I am working from is #771, but I bought it in the early 1980s. There is no scale given on the plans or "instructions" (such as they are). As you can see, I am not following the instructions or the plans that came with the ship - although I am using them for reference for some things. After looking through a number of books I have decided the deck plan in the kit is pretty good for a Baltimore clipper privateer of the Revolutionary War or War of 1812 period. It is similar to the American Lynx, which was captured by the British and renamed Mosquidobit. But I wanted to build the model as a revenue cutter. The hull shape is good for just about any Baltimore clipper of the late 1700s to mid 1800s, so I decided to build it at 1:48 scale where 1 foot = 0.25". O scale trains are also 1:48 and I thought this might make it easier to find some parts. At 1:40 scale 1 foot = 0.3 inch, as you have determined. And yes, you are right that some of the dimensions in the kit are pretty strange. I suspect many of the parts are just stock items that they put into many different kits, regardless of whatever scale the kit was supposed to be. On the plans I have the length between perpendiculars (the waterline length) is about 15.3" and the length on deck is 17". This gives the following hull lengths and deck lengths at the various scales, and the length of a scale foot: Scale Deck length Hull length Scale foot 1:40 56.7' 51' 0.3" 1:48 68' 61.2' 0.25" 1:64 90.67' 81.6' 0.1875" 1:72 102' 91.8' 0.1667" 1:96 136' 122.4' 0.125" As it happens a French fellow (Marestier) visited the US in the early 1800s and was interested in the Baltimore clippers. He recorded the dimensions of many of them. Howard Chapelle's "The Baltimore Clipper" published dimensions for 18 vessels Mariester recorded (page 112), along with many more. The length of these ships ranged from 54' to 115' length. The smaller vessels were pilot schooners or revenue cutters. For comparison the Lynx/Mosquidobit was 95' length on deck. It had a deck plan similar to the kit and carried six cannons like the small ones in the kit. It was common for privateers to carry an extra long gun, like the kit. At 1:40 scale the model would make a very small ship, more like a pilot schooner or small revenue cutter. These ships did not have bulwarks like the kit. The small cannons supplied with the kit would be 3 pounders, or smaller! 6 pounders were about the smallest guns the Baltimore clippers carried, and 12 pounders were common on the larger vessels. Even at 1:48 it is small for a privateer or cargo ship. To me it makes more sense for the kit to be 1:64 or 1:72 scale. At 1:64 the tiller handle would be 22" above deck, the distance between tiller and binnacle would be 2.7 feet and the capstan bars would be about 3 feet above the deck. The important thing to remember is that the dimensions of these ships was pretty much determined by formula, based upon the length between perpendiculars. So all Baltimore clippers had about the same relative dimensions, regardless of the actual size of the ship. The British and French copied the original American design because they made fast ships (but that may have been influenced by an earlier French design). There were variations, especially in the more radical sail plans of the later American vessels. But all in all, a Baltimore clipper looked like a Baltimore clipper no matter when or where it was built. So I suggest you do what I did. Ignore the scale suggested in the kit plans, and build it to whatever scale you think best. It will come out looking about the same no matter what scale you choose.
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Drill presses are intended for vertical motion of the tool. As mentioned above, the bearings are designed for this. You can do simple milling with a drill press if you have a moveable X-Y table, but only for very light work. Horizontal movement of the work piece will stress the bearings, and eventually they will wear and the centering of the tool will become sloppy. A milling machine is just a more sophisticated drill press that is designed for cutting in the horizontal and vertical directions. But milling machines have much higher precision than drill presses. Some mills have motorized tables to achieve a very constant rate of movement for fine finishes. They have variable speed motors to allow matching tool speed with the type of material being machined. The tables usually have provision for lubricant collection. They have more precise horizontal controls, often with digital readouts for very precise cutting. And there are accessories that allow an amazing variety of operations - often at an amazing additional cost! So what do you want to do? Drilling, or drilling and milling? Select the proper tool for the job.
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I have used Pacific madrone (Arbutus menziesii) and it is very nice for carving. No pores, polishes very smooth, and finishes with True Oil (purified linseed oil) in a beautiful color that looks like honey you could dip your finger into. It does have annual growth rings that are quite apparent. It doesn't chip or fuzz when carving it. It has been compared to European pear, and is possibly superior. However, as said above, it is very difficult to dry. Large pieces split radially along the grain the full length. I have never tried working with long thin strips so I don't know if it is brittle and prone to splitting. It has a few distinctive features. The bark is very smooth and thin, like deep red paper, and it peels off every year, leaving pale green limbs and trunks that start a new growth of bark every spring. It produces many pale whitish-green flowers at the very top - you usually can't see them from the ground, but from a distance a hillside with many madrones may look white as if it was covered with snow. It also produces a lot of bright red seed pods. I got my pieces out of clearcuts in nearby forests. Foresters/loggers try to eliminate the madrone because it is a non-commercial "weed" species. Some of it is cut for firewood but most is burned on site or left to rot. Fortunately, the US Forest Service has a practice of trying to maintain a viable population of all native species so it probably won't become extinct. There are a few giant madrones (5 feet/1.5 meters diameter) in some natural reserves near my home, but most of what we have now is 1 foot/0.3 meters or less diameter. Consequently, there aren't many commercial sources and it is relatively expensive - $30 to $40 per board foot (12x12x1 inch/30.48x30.48x2.54 cm).
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Question on aluminum soldering
Dr PR replied to BlueOcean's topic in Metal Work, Soldering and Metal Fittings
Brass is much easier to work with than aluminum! It is easy to solder and machine. If you want a "silvery" metallic look you can always use a relatively inexpensive electroplating kit to put chrome or nickle plating over the brass. Note: I have never used the electroplating method, so I don't know what effect tin/lead solder will have. The plating instructions say it works on tin and brass, but I don't know how well it will work on areas where the tin/lead solder has dissolved into the brass (soldering works in part because the tin dissolves into the brass). -
Need CAD type program
Dr PR replied to Sambini's topic in CAD and 3D Modelling/Drafting Plans with Software
DesignCAD V25 is a good solid version with a minimum of problems. It is the version I use most often, and I have them all from the latest beta versions back to V15. For the last few years they have been adding new features to position the program as an inexpensive 3D printer driver program. They have also added a lot of file format input/output features to allow files to be transferred to other programs. So, when the new programmers come up to speed (the beta testers are helping them with this) it should be a very nice program. DesignCAD has far and away the best user interface I have seen in any program, and I have been programming and using computers for 43 years! I have used TurboCAD - a "light" version. But because I was already very familiar with DesignCAD I found it very hard to use. It seemed to me that everything worked backwards from DesignCAD and it was harder to use. TurboCAD is more expensive, and upgrades can become very expensive. You can get a 30 day free trial version of DesignCAD and play with it a bit. The user Forum is free and open to anyone, and you can ask all the questions you want. You don't have to register and you appear as "guest." But registration is free and easy and allows you to create a unique "handle" to distinguish yourself from other guests. Rick is correct, however, if you really don't plan to use the program regularly. Learning any CAD program is a time sink that could be used for modeling. On the other hand, you might become addicted to CAD modelling (it's fun, and the models don't need more shelf space)! See my USS Oklahoma City CLG-5 thread listed below to see what you could be getting into! You have been warned!! -
I have also had problems with kits that have too wide spacing between bulkheads. You can get flat areas in the hull surface between these widely spaced bulkheads. I usually make extra bulkheads from sheet plywood and add them as needed. Then the edges are sanded down to conform with the hull shape before I start planking. You can also just fill in the spaces with blocks of balsa and sand them into shape. But it is much easier to make corrections at this point than it is after you have started planking. Another thing I do to prevent cracks between planks and uneven edges between planks a few years down the road is to paint the inside of the planked hull with clear two-part epoxy paint - just very thin epoxy cement. This soaks into the planks and bulkheads, and after it cures the hull will be very solid. I have single layer planking hulls 35+ years old that show no signs of cracks. You can see both of these techniques in my Albatros thread listed below.
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Need CAD type program
Dr PR replied to Sambini's topic in CAD and 3D Modelling/Drafting Plans with Software
Ron, I have been using DesignCAD (ProDesign) since 1988 in my work and for hobbies. I have also used about half a dozen other CAD programs, and they all have a steep learning curve for someone who has never done computer aided drawing. Check either of the links below to see how I use CAD in ship modeling. The best thing going for DesignCAD (or any CAD program) is the free user forum. It is monitored by users all around the world and there are a number of us that check it daily. New users can post any question and get quick responses from very experienced users. And if the question stumps the users technical support will chime in. I would advise anyone thinking of getting a CAD program to first look for the user forum and see how good the advise is and how fast it is forth coming. Are bug fixes and upgrades available free of charge, or do they cost as much as the initial program? Avoid any program that requires an annual fee for you to be able to communicate with other users on a forum or to get tech support (some programs charge thousands of dollars a year for forum access, tech support and updates to fix bugs). **** Having said this, I must give a warning about DesignCAD right now. I am a beta tester for the program, and it is having problems. The best version in my opinion is the 2016 version (V26). The parent company fired almost all of the US programmers and developers a few years back and hired programmers in Russia! About the time those guys became familiar with the program they were fired and now the programmers are in Elbonia or somewhere. They are introducing bugs faster than they fix them, so the latest version (2019 or V29) really isn't useable. -
I have used Aero Gloss sanding sealer - it is basically a clear lacquer with a suspended filler. I think I read somewhere that the filler is talcum powder, but that was a long time ago! It does an excellent job of filling wood grain. Apply a coat, let it soak in and dry. I wait over night. Then sand with a very fine grit sandpaper. Apply another coat and repeat until the wood surface is glossy. I normally rub down the last coat with #0000 steel wool. Be sure to brush/wipe off any steel wool fragments as Wefalck says. The result is a very smooth and grainless surface. The instructions on the bottle say to wait at least 72 hours after the last coat before applying paint over it. I let it dry several weeks while I was applying smaller details to the hull. I second what Wefalck said about never gluing anything to paint. Attach all of the wood parts to the surfaces to be painted before applying the sanding sealer and paint. This will give you much stronger glue joints, and when you apply the sanding sealer it will fill any cracks between parts and give you a much nicer painted finish. One word of CAUTION: I would not use lacquers on any plastic parts. The solvents may craze the surface, causing it to blister and wrinkle! When in doubt, test it first on a scrap piece of the plastic. If you are planning to leave the wood unpainted you should try applying the sanding sealer to a test piece and see what the resulting grain looks like. The sanding sealer makes the wood a bit lighter. You can also create your own sealer by using clear lacquer and adding fine wood dust from sanding. This will have the same color as the wood. Or just paint the wood with clear lacquer, sand it, repaint, etc. like you would with sanding sealer. This will also leave you with a nice smooth finish after several coats, with the natural wood color and grain. I used acrylics over the sanding sealer. Unfortunately, I used "craft store" paints and they were very bad. Most experienced modelers recommend using artists acrylics. However, the acrylic paint did go on in a very smooth coat, even though I brushed it on. But it took weeks for the acrylic paints to harden enough that it didn't scratch off easily when handling - even with my fingernails - or be suitable for masking over with painter's tape. After a couple of months I still am not comfortable with masking over the acrylic for fear that the paint will lift off with the tape! So the Aero Gloss sanding sealer is compatible with acrylics - even cheap acrylics. But I would much rather have used lacquer paints on the model!
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Before planking the deck you might think about sealing the inside of the hull with liquid epoxy or resin. I had problems with some of the first planked hulls I built with cracks appearing between the planks after a few years of heat and humidity cycles. The edges of some of the planks rose above the neighboring planks. Looks pretty nasty! Then I used a thin two part epoxy paint that aircraft modelers use to seal balsa motor mounts. It is applied like a paint with a brush, and it soaks into the wood of the planking and bulkheads. After it sets the hull is very solid. After three decades there are no hints of cracks.
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I have about 65 years experience with artists oil paints and modeling lacquers and enamels. Recently I tried acrylics for the first time on a ship model. I decided to use acrylics because the water solvent doesn't have an odor (I was working indoors in the winter) and I can use water to clean the brushes. First I applied a lacquer sanding sealer to areas to be painted (or clear lacquer to parts where I wanted to see the wood grain). After this dried I applied the acrylic paints over the sanding sealer. The paint did not bleed into the wood. I used the "small bottle" hobby acrylics from a craft store. I never got the paint to apply evenly with my air brush and the mechanism clogged every time (even when highly diluted), so I gave up on that. Then I applied the paint with brushes. It dried slowly enough that I didn't have runs of streaks. I had to apply two or three coats to get a good color. Do not use these paints on a ship model! They appear to dry fairly quickly, but days later they were still about as hard as butter! The paint was easily scratched by my finger nails. It was impossible to use masking tape over the paint. All of the paint lifted off with the tape. This was the worst experience I have ever had with any type of paint! I will never use acrylics again! I have read several opinions about diluting acrylics with isopropanol (rubbing alcohol) or another alcohol solvent, or a water/alcohol mixture. But there does not seem to be a consensus about how to do this, so it remains conjecture in my opinion. Polyscale used to make the best paint for modeling I have ever used - especially for airbrushing. The solvent was isobutanol. It had a slight peculiar odor but it wasn't objectionable (to me). Unfortunately, like everything else, it was known to cause cancer in California and is no longer on the market. I have had much better results with lacquers and enamels. Artist oils dry very slowly - it takes weeks for an oil painting to dry enough to be handled. If you dilute them with a fast drying solvent you may get a dull finish. But I guess you could finish by applying a thin clear overcoat to give the finish you desire.
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