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wrkempson

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Everything posted by wrkempson

  1. See above post #22. Does Solidworks have something called a Style Spline and is that the same thing as a Bezier? I can spell Solidworks and that exhausts my knowledge of the program. I may be confusing you by using the names given to spline tools in TurboCAD. At this point, it seems to me that splines and their control points all use the same equations, but differ in how one manipulates the control points. To be sure, I am not the person to opine here in that my acquaintance with mathematics falls in the interested hobbyist category. There are videos on YouTube that explain Beziers and the history thereof using basic algebra. That and a series of Google searches constitute the foundation of my awareness of the math involved. Wayne
  2. I am with Druxey on this. Take a look at this part of EdT's log on the Naiad (a vessel of similar size and construction). This is page two of his log, Find post #57 and begin reading. You will find many helpful photographs of how the internal planking might be done. As a further caveat, Steel says that the limber strake is drawn on the inboard profile plan as a line parallel to the cutting down line (which amounts to the bottom of the keelson). On Steel's plates this line for the limber strake runs the length of the keelson, although as Druxey ponts out it is fairly impossible to place a single plank this entire length and so the channel ends much sooner The original plan from RMG shows the limber strake line the full length of the keelson. I did not build Euryalus. Perhaps Allan can give us some better insight here. Wayne
  3. You ready for this bit of wisdom? It depends. I used something that TurboCAD calls Beziers which is fit points plus control handles for every point. I have more trouble with the other versions of the spline (by control or by fit points). I find "fit points" easier to use than "control points" and Bezier easiest among the three. So I would say use what makes the most sense to you. I would expect there to be a learning curve on using splines. rtwpsom2 says he prefers the control point splines to Beziers, I have the opposite preference, mostly on the basis of what I am most accustomed to using. I like Beziers but have seen some lines drawn with fit points and control points that were just as good. Use what falls most easily under your mouse. There are folks on this forum who do CAD for a living, and I would greatly appreciate reading their insights on this. My CAD work and knowledge is purely that of the interested amateur. Lately, however, I have been trying to use arcs rather than splines. Sometimes that works out, sometimes it may be more trouble than it's worth. I hope this helps. Wayne
  4. I am not a mathematician nor do I play one on TV, but I find the visual explanation of Bezier curves to be quite interesting. The math behind it is barely in my range of comprehension. This link gives a picture of how linear, quadratic, cubic and quartic curves are generated. This is a very amateur understanding, but it takes something of the mystery out of how the spline is drawn and what is happening as it is adjusted. https://www.jasondavies.com/animated-bezier/ Also, the Wikipedia article on Beziers has some interesting animations about two thirds of the way down in the article. https://en.wikipedia.org/wiki/Bézier_curve#Constructing_B.C3.A9zier_curves There are some other basic articles explaining Beziers curves and thus indicating how splines are generated. As far as I can tell, a spline by control points and a Bezier are generated with the same equations. None of this changes how we do things, but I thought it useful to visualize how the computer is doing things. Wayne
  5. Both the drawing and your procedures are works of art. Thanks for sharing. I did not understand how the offset of the splines was used to center the traced working line. This may be because I do not have access to Solidworks. Still, I couldn't get my head around the theory of it, but it sounds like a useful thing to know in general (unless this is Solidworks specific). It seems you have a very good original plan. Even at that, I take it you did a bit of work to straighten some lines out prior to use in CAD. I find all this very interesting. The tools available to you for curvature analysis are fascinating. In TurboCAD I rotate the drawing and eyeball down the line, a method similar to the actual method on the lofting floor. I like the more accurate tools in Solidworks. I believe similar tools are available in Fusion 360 and Onshape. This looks to be a very interesting project. Wayne
  6. Good observation, Rick. When you speak of splines are you including Bezier curves in that category? Frankly, while I use Beziers quite often, I cannot think of a time when I have used a traditional spline. The control handles on Beziers make them a very powerful way to create a curve. With that said, and with my completely amateur status noted: The "arc or spline" question might have the age old answer: it depends. For earlier plans arcs reflect the original practice; so if you want to mimic the old ways then an arc is your friend. On the other hand, later plans I suspect made more use of ship's curves for which Beziers are a good substitute (vis-a-vis a collection of tangent arcs). Using arcs is not as well adapted to 3D modeling since they complicate the need for uniform node counts, etc. Beziers, as pointed out, can produce all kinds of accurate curves. There is something satisfying to me in drawing out lines with just arcs and a straight edge. But for actually getting the work done splines (Beziers for me) are great. So, as one who started out using Beziers (splines, if you will), and then learned to use acrs, I suggest we have both in the tool box. Wayne
  7. If your program has this tool, construct a circle from three points along the curve of the stem. I would use a portion of the curve that does not intersect the base line since if there is more than the one arc, the second arc will be found at the base line. The center of the circle will of course be the center of the arc. The same end is accomplished geometrically by placing three points on the stem arc. Join the bottom and middle points with a line. Draw a perpendicular line to this line that bisects the line. Repeat the process for the middle and upper points. The intersection of the two bisecting perpendiculars will give you the center of the stem arc. If your heart is pure you will find the artist's pin prick nearby. It may not be useful, however. I have yet to find a table of scantlings helpful in drawing the stem curve. I have always had to find the center myself. By and by, I am thinking we are talking about the arc of the rabbet which often is the after face of the stem. Be careful when then drawing the forward face of the stem since that arc does not necessarily share the same center. The forward face arc center may have to be found separately. Also, the stem arc can be two (as per Druxey) or as many as three arcs. This is known by observation. I don't know if this helps, or even if I am on topic. In my defense I will say I enjoy drawing out the stem arc(s). Of course, the curvature of the cutwater is even more a thing of beauty. Wayne
  8. It seems to me that a measurement taken from the plans should trump one taken from elsewhere. A contract measurement might trump the plan but only if the contract is for the specific vessel at hand (ie, not from a sister ship). My observation indicates that the lines on the plans are about 1/4" wide or so, so a variance of 1/2" is understandable in this case. I love the zebra analysis. The curvature of the rabbet in the area of the fore foot seems to be off, but that is due to the program, not your work. Wayne
  9. wrkempson

    Fusion 360

    So I took the Fusion 360 challenge. Having used Turbocad for years, I found F360 to be fairly straight forward. The hardest part is finding the tool you want and learning the peculiarities of the program. I have done some work in Onshape and found it comparable. It seems to me that anyone willing to put in a bit of time, willing to look at training videos and willing to persevere can learn both F360 and Onshape in a reasonably short time frame. The work flow details differ, but not so much as to make difficult the adapting previous of methods to each program. Both Onshape and F360 are free cloud based programs. Onshape's free version is fully functional but limits the number of files one can store to 10. Fusion 360 offers the fully functional version for free to hobbyists. You do have to sign up and indicate that you are either a hobbyist or a start up business. The guidelines for signing up are very clear. I choose to model a 29' Launch in TC and F360 just to compare the two. I was learning F360 from scratch and have done a fair amount or work in TC. The results are appended. Do not get too excited about comparing the renderings since my skills in rendering are quite crude. The point is that each program produces an interesting model. Perhaps I will test out converting the models to 2D drawings at some future date. I should mention that launches were still whole moulded, so there was very little employment of Beziers in these models. This the the Launch from Fusion 360: And the same plan in Turbocad v. 19: Wayne
  10. In theory this arrangement keeps the planks for sliding alongside one another resulting in a stiffer longitudinal structure. In the hold of USS Constellation the ceiling planking has square cutouts across the seams into which a square block is inserted in order to stiffen the hull as well. The attached photo shows these openings, some of which have had the blocks fall out. Indicated in red are examples of an empty and a filled opening. Other instances are apparent as well. Wayne
  11. The area indicated by your arrow is one of the more difficult parts of the hull to plank. This is true even on the best of kits. Getting that plank to take the severe bend is quite a challenge and there are a few ways to do it. Some actually carve a thicker plank to shape. Aggressive steaming and bending might work. It may be possible to laminate thinner planks to shape. Anyway, don't think Mamoli has overlooked a problem here. It is endemic to the kind of hull and the era of Victory. The above is offered by one who has never quite succeeded at getting a plank to take this turn. But look at it this way, now you have something to think about when life is lazily drifting by. Wayne
  12. My advice is based more on what not to do (because I did it) than anything else. I notice you have not cut the rabbet on the keel plate. I don't know when Mamoli asks you to do this, but now is going to be a better time than later. Actually, before assembling the bulkheads would have been better still. Particularly at the stern, the rabbet is cut so that the planking (both layers if you go that route) will sit flush with the stern post area. It will never be easier than at the present to cut in the rabbet. Attaching the false decks will give the hull some rigidity for the work needed to get ready for the external planking. A lot of this (or any) model is thinking ahead. Now is a good time to educate yourself on the external planking process since all your good work on the bulkheads leads to the planking. Knowing what's coming will help you do the preparatory work now. Wayne
  13. She won a contest with Model Expo, and now sits in my office.
  14. You are on your way to a great model. I built this kit some 30 years ago, enjoyed the experience, learned a lot, and made a plethora of mistakes. Might I suggest you brace the bow and stern on your building board. I found the keel plate and bulkheads could easily twist out of alignment, so perhaps bracing fore and aft would help to obviate this problem. Check the run of the decks fore and aft from time to time. I discovered a slight twist very late in building and had to make cosmetic adjustments. You are right to be very careful now to get everything into proper position. Wayne
  15. TurboCad 2017 Pro allows pdf files to be inserted as underlay objects, more or less as raster images. The resolution is not the greatest but it does allow it. You can also load your pdf in Acrobat, take a screen capture and convert in Paint to a jpg. The resolution is a little better that way. Actually, you may want to search the web with "pdf to jpg" and you will find several apps that convert pdf's to jpg's. I am under the impression that Acrobat Pro has a utility for converting to jpg's. I have no need for such, but they are there for your consideration. Wayne
  16. Trying to muscle the errant middle into place sounds like something I would try to do. That should warn you that it may be a questionable move. It seems to me that a buckle in the middle indicates a snying of the ends. This happens to me (all the time when I was laying on the hull planking) due to poor spiling of the plank. Before you apply the force, maybe one more time with a careful spiling might be interesting. I say this as one whose skill falls far below yours, so I offer this more as a question than as advice. Wayne
  17. wrkempson

    Color of ratlines

    Also for what it is worth, colors do not behave on small models the same way as on full size ships. Here we are getting into the area of scale colors. I would observe that a very light colored ratline on a black (maybe) shroud will pop out to the eye on the model. An even worse mistake that I have committed is to use a line that is too large. The scale size of the ratline should not be exceeded, but may be lessened if anything. When I look at photos of full rigged ships, the ratlines are barely visible unless one makes the effort to see them. I don't think the ratline should call attention to itself. As always, the usual disclaimer. Wayne
  18. I presume you are building the Model Shipways kit. If so, I found the manual at http://modelexpo-online.com/assets/images/documents/MS2018-Flying_Fish-Instructions-Complete.pdf . On page 24 Figure 36B there is a good illustration. The knightheads are the two timbers on either side of the opening for the bowsprit and each one receives an eyebolt. The Figure gives a profile and top view of the piece you are asked to make. The exact shape will be determined by your own model so the process is to cut and fit, sand, fit, shape again, fit, etc. until the timbers are in place. I do not have the plans, but the manual points you in the right direction. On the actual vessel, the knightheads extend from the rail level down along the side of the stem to a place well below the water line. On your model they are represented with only the visible portion above the deck. When you install them make sure they are secure as they will have quite a bit of strain on them from the fore stay that attaches to the eyebolts. It is unclear to me what your exact question might be, but maybe the above helps. Wayne
  19. Very nice. Getting the right entry and run can be quite a challenge. Wayne
  20. This is new to me as well. According to the Online Etymology Dictionary the term "staircase" appears in the 1620's in reference to the enclosure of the stairs. I know we are looking at a contracts 150 years later, but it seems to me the nautical "staircase" or "stair case" or "stair-case" might refer to iron railings, hand rails, etc. that might surround (encase) the ladders. So my vote goes to staircase=handrails. In support I note that this section of the contract comes far distant from where the storage rooms would be described, lying between the office cabins and the pantries. Thus, the use of iron for casing the ladders would be of a more ornamental nature. This is pure speculation. Wayne
  21. Dropping perpendiculars from the half breadth plan to the sheer plan identifies the darkest lines as the rail line, as you surmised. A few waterlines run outside this line because of the slight tumblehome. The diagonals generally run wider. The confusion at the bow seems (to me) to be the result of careless drawing. I'm not sure about the confusion at the stern. At least, this is my less than expert take on things. Wayne
  22. To wit: below is the forecastle of a 70 gun ship c. 1715
  23. Ed, I'm pretty sure that renegade eye bolt came from my work table. It was lost some time ago. I thought it had vanished into thin air, but now I know it fell through a space warp into your CAD program. Wayne
  24. Astounding model. Thank you for the renderings. May I ask what software is being used and, if not too personal, what are the specs on the computer employed? Wayne
  25. I look forward to your progress. It looks like an exciting project. One very small thing. The box shows two pins at the ends of the spokes set into the felloes. I don't believe these are at all right. There are no pins or fasteners in the wheel. Everything was held together by the iron tyre (rim). If you consult photographs you should see there are no such pins. I feel like I am being more dogmatic than I should, so I am open to correction and reproof. Thanks for letting us look over your shoulder while building. Wayne

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