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lehmann

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About lehmann

  • Birthday 07/21/1960

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  • Gender
    Male
  • Location
    Surrey, BC, Canada
  • Interests
    USS Constitution: Scratch build solid hull 1:96 scale

    Member Nautical Research Society

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  1. Draftsight is a free, fully functional 2D drafting program from the same company that produces SolidWorks (3D cad). Basically, a similar program to AutoCad or TurboCad. I've run it on both Windows and Linux systems
  2. I recently pickup this pickling chemical from a local jewelry supplier. Pro-Craft Pickling compound (No. 45.122): Sodium Bisulfate. 10 oz bottle makes 1 quart. Solution works well at room temperature, but faster at about 125 F.
  3. Pre-bend planking: looks like a feature you should have paid more for. I would just wet the areas with the hardest bends/twists to avoid creating fuzzy grain and water stain. Maybe heat with hot iron. The longer, slower bends should straighten out as needed, although if you're planning to rip into strips, they could be awkward. What is the intended use?
  4. I have two of these sleeveless drums from Lee Valley Sleeveless sanding drums. The picture on the web page doesn't show the method for holding the sheet of sandpaper, but it works very well. There is a slot in the drum to insert the two ends of the sheet and a simple, but effective locking method. No problem getting the sheet tight around the drum. I see that they are also sold at https://woodworker.com/1x3-w-14-shaft-sander-sleeveless-drum-mssu-815-895.asp. The picture there gives some idea of the slot and design.
  5. There are a lot of features that don't make sense for this to be a regular block. The top lateral through-hole would not be able to take much load as the end-grain would easily pull out. For this to take a tension load there would have to be an iron band around the block. This is a large block, so it's not for small rope or small loads. Also, if the outer corners are relatively square, so chaffing would soon cut the rope. To me, this means a pin, wooden or metal, went through the through-hole. The tops of the pulley mortises appear to intersect with the bottom of the lateral through-hole. The pulley pin is not centered in the block. It's more towards the left in the side view. It's too far off to think it wasn't made that way This may indicate that the back of the block is against a surface. However, the rounded ends of the rope mortises indicates that the rope should only go over the top of the pulleys. Based on the location of the pulley hole and the diameter of the pulley, the rope just run down across the "front" face, but could not run down the "back" face. This means the rope turned through and angle of, say 90 degrees, certainly not 180. The large opening above the pulley will also make it easier to run the rope through the pulley, which may indicate that the block was used frequently, but the rigging was temporary or changed often. Since these blocks were made by hand, no one is going to dig out a mortise larger than necessary, Based on the tight opening around the bottom of the pulley, it doesn't look like the pulley was worn down. There is more asymmetries: in the side view, the top right corner is relatively sharp, the top is sloped and the left corner is very rounded. in the side view, the shoulder for the tenon seems to be only on the back side. I don't know how a shoulder on the front side can be justified. To me it looks like a rabbet on the "back" side only. the top of the mortise for the middle pulley is slightly higher, and appears to intersect with the bottom of the lateral through-hole. Overall, I think the block is intended for the corner of a deck or railing where ropes need to turn roughly 90 degrees. The flat back and the rabbet take the horizontal and vertical compression sload, and the three holes on the bottom are possibly for trunnels to hold the block in place and take the tension load that would develop there. Consider that the block may mounted horizontally, not vertically. I realize that this doesn't explain the lateral through-hole, but I suspect a pin or bar went there, not a rope.
  6. Greg, The source of almost all published properties for North American woods is from the USDA book "Wood Handbook: Wood as an Engineering Material" based on tests done at the Forest Products Lab in Madison WI, and similar facilities in Canada. Click on the link to go to a page to download the book. (It's free, paid for by US tax payers) Boxwood isn't listed in the USDA book, probably because the volumes of commercial harvest are so small and it's not used for structures. I haven't been able to find a source for the Wood Database numbers. The listed properties on the Wood Database are extremely high, which leads me to think it's closer to ironwood or purple heart (very dense and doesn't float!). Definitely not the wood used for planking, but excellent for carving details. Keep in mind that the published values are averages and that the range is typically at least 15% either way, mainly dependent on growing conditions. For instance, second growth (re-planted after a forest has been logged) is generally less dense with larger annual rings than old growth because the growing trees are not shaped by mature trees around them so they grow very fast. While not strictly true, it is often said that there is more variation in a wood property within a single tree of any species than there is between species.
  7. This doesn't sound like the the yellow cedar I'm used to, which has a hardness similar to black walnut. It's a slow growing species, so generally has very fine grain with faint annual rings. No way I can indent it with a finger nail without really trying, especially after it has seasoned for a while. Excellent wood for holding detail in carvings. Maybe the source is a second growth stand in open sun light, which will grow quickly and has a lower density.
  8. Filling all the gaps is probably not a good idea, although tempting. On another post (Drazen), someone had filled all the spaces between frames with solid wood. The problem is that wood will move with humidity, and he ended up with cracks in the planking, especially at points where the filler piece wanted to move and the plywood bulk head didn't. The lessons from that, at least for me, were: leave a gap between the filler and the bulkhead. If not a gap, put a soft layer of cardboard that can flex and shear as the wood moves align the grain of the filler with the grain of the planking. Wood doesn't change length much with humidity, but it does change length. Over-constraining wood structures is never a good thing. There was also a discussion that the change in width of a plank with humidity for flat grain boards is almost twice that of edge grain. Overall, I would add more bulkheads: fit them in as best as possible then fair them. This is how "real" ships are built and it eliminates the flat spots when the bulkhead spacing is large and gives more points to tie to when bending around hard curves.
  9. In doing your tests, be aware that the blade may flex when you push against it during your measurements. If you want to verify this, put a dial indicator on the back side of the blade. Also, the fence will flex a little as well as it may not always register square each time. When you're trying to work in the range of 0.001" you need to watch for these things even when using large metal working machines. I do some work at 0.0001" and have to be hyper vigilant. If you want to just test the accuracy of the IGaging system, I suggest zeroing on a block of wood clamped solidly to the table right next to the rail that the fence runs on. I seriously doubt the iGaging system itself is not going to be repeatable within 0.001" as it's basically the same technology as your digital calipers. The 0.004" accuracy is probably over the length of the travel.
  10. The main concern here is whether the fence is parallel to the saw. If the back of the saw is closer to the fence than the front, then the saw will be pushed sideways, That's the only way I can imagine getting 0.090" thicker.
  11. I'll send you to the Wood Handbook. Wood Handbook CH 4 - Effect of Moisture See page 4.5 Figure 4.3 shows how wood from various places in the tree shrinks and warps Tangential - parallel to the grain rings Radial - 90 degrees to the grain rings or in a line from the center of the tree Flat grain (or flat sawn) - the grain rings are somewhat parallel the wide side of the board Edge grain - the grain rings are parallel to the narrow side of the board Another term you'll see for edge grain is quarter-sawn. I hope that helps
  12. Drazen, By the pictures of the deck planks it looks like you used flat grain boards (maple). The effect of moisture on wood shrinkage/expansion in the tangential direction is about twice that of the radial direction. In other words, edge grain boards will move only half as much. That is why wood floors and wide door sills are usually edge grain (that, and the wear resistance is higher). A few numbers: Relative humidity Equilibrium Moisture content 20% 5% 70% 13% Difference 8% Flat grain maple shrinks 11 % from green (28% to oven-dry (0%). So, your flat grain planks, over a width of 250 mm will want to shrink (250 mm) x (11%) x(8%)/(28%) = 7.9 mm The shrinkage for edge grain maple is only about 4.5%, which results in a width change of 3.2 mm. Either, way, since the plywood bulkheads/frames will have negligible shrinkage, a lot of stress will be generated. In looking at the shrinkage data for various species, I can see why pine was often used for decking. While is is much softer than oak, the edge grain shrinkage is Eastern White Pine (North America) is only 2.1%. As is teak, at the other end of the price scale. My second point, is that the cracks in the picture seem to be near transitions in how the deck is supported. In other words, near openings. The deck parallel to an opening can shrink with little constraint, but the deck at the ends of the opening is probably attached to a bulkhead and can not move. The difference in constraint creates the stresses and cracks you are seeing. I also suspect that since maple is so strong it does not crush like a softer wood, which would have relieved the stresses before a crack formed. So how to fix, or avoid in other large models? Edge grain decking is an obvious must do. Use a wood with a low radial shrinkage. Avoid gluing the edges of the boards together so that the shrinkage can occur at each join rather than finding one place to fail. Either no glue, or a glue that never hardens, so that it acts like tar - fills the gap, but does not restrain movement. Many narrow planks means the gaps that appear will be smaller, assuming the gaps are uniformly distribute across the width of the deck. Install the boards when they are bone dry (dry in an oven, or a small box with a light bulb inside (not LED light!)). That way, even at 20% humidity, the boards will swell. Full size ships rely on the planking swelling when the ship is put in the water to achieve water tight seams. However, I would firmly attach the water channels to ensure that railings are not pushed out when the deck expands. Last thought: I wonder if Admiralty models at 1:48 scale are often left half planked to avoid these issues.
  13. From what I can see they are still available from several sources. These are a few that I found quite quickly. https://mdiwoodcarvers.com/t/dockyard-micro-tools https://www.treelineusa.com/micro-gouge-carving-set.html http://www.chippingaway.com/cat/hand-woodcarving-tools-accessories/dockyard-micro-carving-tools/
  14. I have a set of micro-chisels made by DockYard tools that were, but no longer, sold by Lee Valley. However, I see that they are available from other suppliers. These are the smallest chisels and knives I have seen as the blanks are more of a wire than a bar or rod. Definitely, not tools for roughing. However, the steel is good in that I can get a razor edge on them. I also have a set of small chisels that Lee Valley sells (part 81D40.01 ). I thought they would be just good for scraping, but the steel is remarkably good so I got very sharp edges. The set included two fish-tails, which are difficult to find in such a small size. I've made a few small knives/chisels from broken (or sacrificed) drill bits. This is probably the cheapest source of tool steel available.

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