aarongreen -> RE: Rosette Designer (Jun. 11 2006 13:39:48)
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When you build the rosette log that the tiles are cut from, you make it with a taper, so the bottom is wider than the top. This is what allows the tiles to fit together as they go around. The closer you get to the ideal taper, the better. In mosaic rosettes you have some wiggle room as the glue softens everything and to some degree the tiles will conform. In a wooden side grain rosette, like the braid I do, you have 0 wiggle room, either those tiles fit perfectly or they don't. That kind of tolerance is in the 100th of a millimeter. The way to figure out your taper is to take the inner and outer diameter of the rosette channel. Let's say your inner channel measures 95mm across and your outer channel is 107mm across (which gives you a 6 mm wide channel). You mulitple those numbers by pi (3.14) to get the circumfrence (I think that is the correct word) so for inner channel that comes to 298.3. Let's say your rosette tile will be 7 mm wide at the top, so you then divide 298.3 by 7 which is 42.6. That is the number of tiles you will need to completely finish the circle. Now you need to figure out the width of the bottom of your rosette tile to come up with the needed taper. Your outer diameter as you recall is 107mm, muliplied by 3.14 gives you 335.98. You know you need 42.6 tiles so you divide 335.98 by 42.6, which is 7.88 which is the width of the bottom of your rosette tile. So now you have a rosette tile that is 7 mm wide at the top and 7.9 mm wide at the bottom and your taper is .9 mm. You would think I actually did good in school, wouldn't you? When making a mosaic rosette you glue up strips of veneers that correspond to one vertical line of your design. Normally I would make them 30 mm wide and 150 mm long, so I can make more than one rosette. You make up as many of these as you need to complete the pattern and then with a very fine saw you cut off a strip that is a bit thicker than you need, using a set scraper you then thickness that strip to exactly the correct thickness (if your veneers were.5 thick then you should make the strip .5 thick) but you make the top a little thinner than the bottom so you are building in the taper as you go along. Once you done with all the stips and you now glue up your log. The maintain your taper you use tapered wooden clamping cauls. This last part can get very tricky but once you got it down, the results can be very good. I realise this is probably more info than anyone wanted but I hope this helps!
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