Crimson0087 Posted March 22 Report Share Posted March 22 So my first attempt I had a purfling channel that was too wide. This time out of fear I made it too thin. I don't think I have the skill to move the ibex purfling cutter around and make it wider while following the same path..I know I'll deviate one way or another. What would be the best way to widen the channel? Should I just get a narrow file and try to widen it? It's probably about 1mm wide and I can't get the purfling to fit down in it. I admit the walls are not perfect vertical it tapers to a narrower bottom. I can post pictures later if needed. Any suggestions? Also thanks again to all who have given me advice on this forum. I have enjoyed this challenging yet rewarding task. Quote Link to comment Share on other sites More sharing options...
FiddleMkr Posted March 22 Report Share Posted March 22 2 minutes ago, Crimson0087 said: So my first attempt I had a purfling channel that was too wide. This time out of fear I made it too thin. I don't think I have the skill to move the ibex purfling cutter around and make it wider while following the same path..I know I'll deviate one way or another. What would be the best way to widen the channel? Should I just get a narrow file and try to widen it? It's probably about 1mm wide and I can't get the purfling to fit down in it. I admit the walls are not perfect vertical it tapers to a narrower bottom. I can post pictures later if needed. Any suggestions? Also thanks again to all who have given me advice on this forum. I have enjoyed this challenging yet rewarding task. I assume that you set the width of the channel using both cutters at the same time? If so, remove one of the cutters and move the other one in or out as needed. Also I suggest you grind another bevel on the cutter so you can cut both ways. Quote Link to comment Share on other sites More sharing options...
nathan slobodkin Posted March 22 Report Share Posted March 22 You may do better to scrape the purfling a bit thinner rather then widening the channel but either way the consistent width of the channel is paramount. Are you trying your purfling on a test piece beforehand? If it fits when you do that then you need to go back over the groove and look for bumps along the inside of the channel which must be shaved off. I also recommend either tilting your knife as you deepen the groove so the wall of the channel is perpendicular to the surface of the plate or using knifes sharpened on one side only in which case you would need both right and left hand knifes so the unground side was always on the outer ide of the channel. If you look carefully (and honestly!) at your channel as you work you can see the bumps, kinks and tight spots and fix them as you go. There are several discussions of purfling technique on the forum already and reading them should be helpful. It does occur to me to ask if you are working the knife cuts deeper all at once and removing the center only after you have gone around the whole plate or trying to advance the full depth channel as you go. The second method invariably leads to more inconsistent purfling in both channel width and smoothness of the lines. I generally scribe the lines with my marker, deepen the lines carefully but not too deep while establishing the corner points and button area then one pass all around to deepen the the lines as far as I can press the knife and one more pass with a slightly narrower ground knife to final depth before picking out the whole channel all around. Quote Link to comment Share on other sites More sharing options...
Crimson0087 Posted March 22 Author Report Share Posted March 22 Did not try on a test piece. I think the channel is too thin. I have a pic before I removed wood I'll add that. Quote Link to comment Share on other sites More sharing options...
Don Noon Posted March 22 Report Share Posted March 22 1 hour ago, nathan slobodkin said: You may do better to scrape the purfling a bit thinner rather then widening the channel but either way the consistent width of the channel is paramount. It might also be possible to compress the purfling so it fits. Quote Link to comment Share on other sites More sharing options...
iburkard Posted March 22 Report Share Posted March 22 Any chance you could swap a blade with a guide? Quote Link to comment Share on other sites More sharing options...
Crimson0087 Posted March 22 Author Report Share Posted March 22 You mean like the purfling cutters? Like this? Quote Link to comment Share on other sites More sharing options...
FiddleMkr Posted March 22 Report Share Posted March 22 (edited) 32 minutes ago, Crimson0087 said: You mean like the purfling cutters? Like this? Yes, and use the cutters mainly for marking. Use your knife (mainly) to cut the channel. And I suggest using your scrap pieces of spruce to practice on. That will get you used to going across the hard and soft growth rings. Edited March 22 by FiddleMkr Needed to add a comment. Quote Link to comment Share on other sites More sharing options...
Wood Butcher Posted March 22 Report Share Posted March 22 What are all the dots on the outside of the belly? Quote Link to comment Share on other sites More sharing options...
MikeC Posted March 22 Report Share Posted March 22 How tight a fit is it? In the picture it doesn't look extremely narrow. You may be able to scrape the purfling thinner. I always round over the bottom edge of the purfling where it goes into the channel so there are no square edges there, not perfectly round, just scrape off the square edges, it goes in easier or at least I think it does. Quote Link to comment Share on other sites More sharing options...
Davide Sora Posted March 22 Report Share Posted March 22 1 minute ago, MikeC said: I always round over the bottom edge of the purfling where it goes into the channel so there are no square edges there, not perfectly round, just scrape off the square edges, it goes in easier or at least I think it does. It does, I also remove the sharp edges from the bottom side to get the purfling in and out more freely and to avoid surprises when gluing. Quote Link to comment Share on other sites More sharing options...
Davide Sora Posted March 22 Report Share Posted March 22 5 hours ago, Crimson0087 said: Did not try on a test piece. I think the channel is too thin. Fatal error. Widening a channel that is too narrow is a very difficult and tedious undertaking, probably the best way would be to cut one of the walls a little at a time with just the knife, a tool with a guide and a blade would not be stiff and firm enough to cut a very thin strip accurately, unless it is a computer-controlled (CNC) cutter. My advice is to leave the channel as is and thin down the purfling if the blacks are wide enough, or replace it with a thinner one (thinner white). Thin purfling is by no means uncommon among antique instruments, see some Amati. Quote Link to comment Share on other sites More sharing options...
Crimson0087 Posted March 22 Author Report Share Posted March 22 What about a thin file and just slide it around in there? For future reference how wide should the channel be? Quote Link to comment Share on other sites More sharing options...
HoGo Posted March 22 Report Share Posted March 22 Not for purists but you can fold a 5x1cm strip of 100 to 150 grit stiff sandpaper into 2.5x1 cm so that it will be same thickness as your purfling and will cut on both sides. You may insert a piece of paper to reach desired thickness if the sandpaper alone is too thin. You can glue the layers together with white glue or just hold it as you folded it. If you insert this sanding strip into the channel and smoothly move it along it should follow the curvature nicely and remove some bumps or thinner places in just few passes. Quote Link to comment Share on other sites More sharing options...
FiddleMkr Posted March 22 Report Share Posted March 22 1 hour ago, Crimson0087 said: What about a thin file and just slide it around in there? For future reference how wide should the channel be? About 0.1 mm wider than the purfling. You want an easy drop in fit. The glue will swell it tight. It is better to cut a new side than trying to widen the slot with file or sandpaper, assuming the outside of the plate is a smooth curve. If you only have to widen a very small amount, it is easier to reduce the purfling width. Quote Link to comment Share on other sites More sharing options...
iburkard Posted March 22 Report Share Posted March 22 10 hours ago, Crimson0087 said: You mean like the purfling cutters? Like this? I just meant swapping one of the blades with a piece of metal instead of a sharp blade, and it could ride the existing channel that you've cut, while cutting/widening with the other blade (spaced to whatever width you've determined will work). Since you'll be cutting in different directions, it would be tricky. I'm not so sure about just thinning the purfling. There's basically no black left, it looks weak from a design point of view. Instead of thinning away both black strips, maybe just kill one dark strip instead of thinning both down to nothing? Quote Link to comment Share on other sites More sharing options...
iburkard Posted March 22 Report Share Posted March 22 5 hours ago, Wood Butcher said: What are all the dots on the outside of the belly? I would assume arching plans/reference? The plate isn't fished. Quote Link to comment Share on other sites More sharing options...
Crimson0087 Posted March 23 Author Report Share Posted March 23 Correct on the holes...but looks like I'm scrapping another. Davide was right fatal error...I think I need to try the Dremel again......also I realize my cuts were not perpendicular they were very angled.... Quote Link to comment Share on other sites More sharing options...
Davide Sora Posted March 23 Report Share Posted March 23 7 hours ago, Crimson0087 said: also I realize my cuts were not perpendicular they were very angled.... Like this? Apparently, Girolamo also had a similar problem, but it didn't seem to bother him too much. Quote Link to comment Share on other sites More sharing options...
nathan slobodkin Posted March 23 Report Share Posted March 23 1 hour ago, Davide Sora said: Like this? Apparently, Girolamo also had a similar problem, but it didn't seem to bother him too much. The issue is not really whether the channel is perpendicular to the plate as much as whether the sides of the channel are parallel to each other. If the channel narrows very much toward the bottom then he won't be able to push the purfling down to the bottom of the channel. Quote Link to comment Share on other sites More sharing options...
FiddleMkr Posted March 23 Report Share Posted March 23 9 hours ago, Crimson0087 said: Correct on the holes...but looks like I'm scrapping another. Davide was right fatal error...I think I need to try the Dremel again......also I realize my cuts were not perpendicular they were very angled.... Go to Lowe’s and buy a 2x10 sawn through the center of the tree and make a top out of that. That is what I made my first one from. Save the tone wood for those who are experienced. Quote Link to comment Share on other sites More sharing options...
Dave Slight Posted March 23 Report Share Posted March 23 3 hours ago, Davide Sora said: Like this? Apparently, Girolamo also had a similar problem, but it didn't seem to bother him too much. Interesting that the cuts were made at approximately 90° to the fluting. Quote Link to comment Share on other sites More sharing options...
iburkard Posted March 23 Report Share Posted March 23 The best artists are good at recovering from mistakes. I wouldn't scrap this. 1 hour ago, FiddleMkr said: Save the tone wood for those who are experienced. A little harsh, but I understand the sentiment. Quote Link to comment Share on other sites More sharing options...
Evan Smith Posted March 23 Report Share Posted March 23 . Quote Link to comment Share on other sites More sharing options...
FiddleMkr Posted March 23 Report Share Posted March 23 37 minutes ago, iburkard said: The best artists are good at recovering from mistakes. I wouldn't scrap this. A little harsh, but I understand the sentiment. 11 hours ago, Crimson0087 said: Correct on the holes...but looks like I'm scrapping another. Davide was right fatal error...I think I need to try the Dremel again......also I realize my cuts were not perpendicular they were very angled.... Don’t scrap it. Use (wider) viola purfling, and chello after that, if needed. And use lumber at first as I said before, wisdom from the book I learned from. And the author said it a little less harsh than I did earlier. “Leave the tone wood until YOU are experienced.” Quote Link to comment Share on other sites More sharing options...
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