bionut Posted January 24, 2014 Share Posted January 24, 2014 Hello, I want to make a romanian caval (http://www.eliznik.org.uk/RomaniaMusic/cavals.htm) from plum wood. I have read that those kind of gimlets are the best chioice for that because they follow the grain of the wood. I have a old one, but the diameter is too small, i need a bore diameter of about 17 mm. Does any of you have a ideea about how could i make such a gimlet? I can't figure out how i need to form the metal before turning it in a spiral. If some of you have experience with those kind of thing and can explain it to me that would be great. Some images would be great also. Thanks! Quote Link to comment Share on other sites More sharing options...
VaughnT Posted January 24, 2014 Share Posted January 24, 2014 The end is just flattened out and then twisted. You might experiment with the shape of the flattened part to get the width and length right, but it should be, basically, like a leaf preform. I'd point, flatten, maybe peen wide a little bit, then sharpen the point/edge and twist. The cupping will occur as you round it out on the anvil after twisting. Quote Link to comment Share on other sites More sharing options...
bionut Posted January 24, 2014 Author Share Posted January 24, 2014 So the cupping is made after twisting... I thought that i need to make it before the twist. The tip is "screw like" to enter the wood just from rotating, without too much presure, do you think that i could make that threads with a file or something similar? Quote Link to comment Share on other sites More sharing options...
Wayne Posted January 24, 2014 Share Posted January 24, 2014 I would only sharpen the end of the gimlet and leave the rest of the head blunt, if the full length of the head is sharpened then any runout as you turn the gimlet is going to cause it to cut the hole over size. If the sides are left blunt then they should guide and steady the head. A little trial end error should guide you as to how much to sharpen. Wayne Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 24, 2014 Share Posted January 24, 2014 Yes tapered screw threads were often filed in place back in the old days. Experiment with doing the cupping beforehand with a swage, afterwards by rolling the twisted section on the anvil lightly tapping it to shape, using needle nose pliers, etc Whatever gets closest to the shape you want to end up with is the *right* method. Note I would not sharpen until after the shaping/twisting/rolling and the heat treat is done; then clean up the surfaces and sharpen. Quote Link to comment Share on other sites More sharing options...
bigfootnampa Posted January 24, 2014 Share Posted January 24, 2014 The usual method for making such flutes from hardwoods is to drill the hole undersized and then ream it with a long tapered reamer. Otherwise they were made from materials that naturally were easy to hollow in the centers. Professional flute turners will usually have more than one reamer of slightly different tapers. They generally treasure these reamers and consider them the key tools in their tool boxes! Quote Link to comment Share on other sites More sharing options...
bigfootnampa Posted January 25, 2014 Share Posted January 25, 2014 The lead screw, while likely useful, is probably NOT essential. Most modern tools for long hole boring on the lathe have a much simpler lead. The natural action of the spinning wood tends to correct a wandering bit unless it has enough directional stability to resist these forces! Thus a bit with a long spike lead or a very rigid shaft would be a poor choice! I have bored fairly long holes using just small bowl turning gouges with a long fingernail grind! The key is that the lead should ride to the center of the vortex of the spinning wood... easier done than you might think... still, NOT a slam dunk proposition! IME you can put plenty of feed pressure on the bit without the need for a screw lead! Depending on the size of the bore and strength of the bit you could easily over stress your bit and snap it off with a strong screw lead! Quote Link to comment Share on other sites More sharing options...
Stephen Olivo Posted January 25, 2014 Share Posted January 25, 2014 Quote Link to comment Share on other sites More sharing options...
bionut Posted January 25, 2014 Author Share Posted January 25, 2014 Quote Link to comment Share on other sites More sharing options...
Stefflus Posted January 26, 2014 Share Posted January 26, 2014 Yeah I would check out Håvard Bergland's book, an english edition exists. In this book there is a small chapter on Norwegian gimlets (navar). These are cupped and the cutting edge thinned, most often in a die, prior to twisting. Then they are straightened and over-cupping hammered out, before sharpening. Grinding on the outside, filing the inside. They are regarded as the most difficult item to do well in this country however. Anyone can make one, but few can make them well. One needs to be finicky about getting the point absolutely in the right spot, and the heat treat has to be spot on so it doesn't break. In the old days they were laminated, and with appreciably harder edges. For your use I would consider a spoon bit, unless you like the challenge. Or you could get Håvard or some other smith to make one. According to the norwegian book "Navarsmeden", a smith named Trond Gaustad apprenticed with legend Edvin Odland, he might be availabe? Quote Link to comment Share on other sites More sharing options...
bionut Posted January 26, 2014 Author Share Posted January 26, 2014 Would a spoon bit work without a lathe? Those gimlets work by hand, maybe in a slow speed drill too... Quote Link to comment Share on other sites More sharing options...
Stefflus Posted January 26, 2014 Share Posted January 26, 2014 Even if you use a norwegian navar my guess is you would need supports to guide the tool, somewhat like a lathe. This is essentially a scaled down version of the water pipes we've been making with the navar for centuries, it is still turned by hand even if the diameter is 3", but with the tool and workpiece clamped down (with the tool in wooden greased bearings). And by the way, my school has been affiliated with a number of flute makers, one of them (from your approximate area if I remember correctly) made flutes out of very snaked branches. He burnt them hollow. Yet another, but less cool way is obviously to make it in two halves. I'll ask around tomorrow or tuesday. Quote Link to comment Share on other sites More sharing options...
bionut Posted January 27, 2014 Author Share Posted January 27, 2014 I am intrigued by the burning method. I would like to know more about that. Thanks! Quote Link to comment Share on other sites More sharing options...
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