Greg Sigworth

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  1. Are you talking about the horse or about people?
  2. You should also address the cause of the crack. In dry weather, the winter the top will shrink transversely more than the ebony saddle resulting in the saddle pushing at the ends outward. This causes the top to crack at the location here. The saddle needs to be free at the ends with no glue and a space there on both sides about a business card width. Make sure this is do when finished repairing the crack.
  3. Not on violins but on other things smooth peanut butter was quite useful , peanut oil and fine peanut pulp?
  4. No experience here but I have some on old leather cases I have resurrected. Probably either the top, bottom or both is warped. Figure out which, and after the insides removed apply some light moisture/little heat , straighten and dry. The inside would look great in new plush material of a bright color. Outside? Up to you, but why not refinish after straightened. The brass fixtures as what gives this box a future.
  5. Maybe he wanted the scraper to be more stiff and put a wood back on it.
  6. Thank you for this. I just made my first shooting board and will use it to join the plates on the next violin.
  7. Worked in a lab which had this very thing. If I remember correctly the exhaust motor was special to ensure that there would not be ignition of combustible fumes. Just something that might be of concern. Oil and turpentine may not be too much of a concern but alcohol might be.
  8. When I worked in a Met Lab we made samples from gear teeth that had been surfaced hardened and tempered to around 62 HRC. We cut them with a huge 14" carborundum blade flooding it with water as we cut. Still the heat generated tempered the sample neat the cut. After mounting in thermal-plastic mounts we hand ground the surface to get below the tempered area. No more that two seconds hand grinding before putting the sample in a can of water. Repeat this at least about 15 times. It the sample tested too low in hardness then do some more hand grinding to see if the tempered area had not been removed. You could do this on a tool that had been tempered in grinding and also do this always to avoid the problem.
  9. Thank you all for sharing ideas. Question: would the arc connecting the inflection points be at the same height from the plane of the plates as one moves around the violin or would it differ? I assume the same height would be a good choice, but possibly not true in reality.
  10. Thank you for the comments on Dominant strings and especially the e string. This information is very helpful for me. Thanks again.
  11. Sorry. I should have checked the dimensions on small instruments first. Change 3/4 violin to 7/8 violin in the above text.
  12. If this has already been mentioned just disregard. Would it be a good idea to have the potential client try a 3/4 violin just to see how the neck feels, not to sell? If that felt good then try to give the neck the desired length on the new violin. You could leave the string spacing of the bridge alone and space the strings of the nut closer together. Thinking outside the box here.
  13. The mechanism of a sharp edge becoming dull would be the same for a knife, gouge, plane blade or shaving razor if the material and process of hardening is the same. Martensite is formed when high carbon steel is quenched from high temperature fast enough to prevent soft ferrite forming. The carbon gets trapped within the structure stressing it and making it hard. Razors are martensite and brittle so the dulling is from pieces of the edge being broken off, not worn off. Knives, blades etc. that are softer metal and not martensite will not dull this way. Martensite has hardness usually of RC 56 and higher, depending on the tempering temperature. The comparison only applies when dealing with a martensite edge. Things to do to prolong the sharp edge longer during use: 1. Avoid cracks in the cutting edge by a too aggressive honing process. These cracks will be stress raisers in cutting and be sites for fracture. Be a little patient and use less pressure in honing, 2. Eliminate as much of the brittleness without sacrificing hardness or as little lost hardness as possible. This is done thru tempering. A blade tempered to a slightly lower hardness, say HRC 56 instead of HRC 64, will keep its sharpness longer, less brittle. Another thing which can make a big difference. After tempering and slow cool to room temperature repeat the temper again at the same temperature. The reason for this, and this may not make sense to you, is after the first temper there is some retained austenite in the structure which has not transformed to martensite which under use will transform to martensite, untempered martensite and be very brittle. The second temper will cause much of this to transform to martensite at the tempering temperature and become tempered martensite. This is especially true for the more exotic steel such as PM, A2, O1 etc. 3. Uniform structure gives better microstructure uniformity and the PMs are the best for this. They bypass the normal liquid solidification process and the resulting segregation of material and structural non-uniformity caused by solidification of liquid steel.
  14. I just re-read the original note: I think the reference to 100% turpentine only indicates that the turpentine is pure and not to the final percentage of the turpentine in the varnish. Also if my memory is correct when reaching the final temperature for each of the three batches it was not necessary to hold at temperature long to get the desired state of turpen resin. I can find my original recipe and produce it is you wish, but I believe it was as Fulton gave it. When I use the varnish I add turpentine to thin it to the desired thickness and brush on, thin coats and put in UV box. It dries quite well and quickly. I have added small amounts of Windsor Newton Permanent Alizarin Crimson to give a red hue to the varnish.