HOW TO REPAIR your "High Speed Steel" bur => 37 photos

 I know that every gemstone setter uses these remarkable burs. But what happens when they get well-worn? In this interesting essay, I'll explain (with photos) how to repair and recut them, at your bench.

 After many days or months of continual cutting, these teeth get badly worn and become almost smooth.

 The well-used term for HSS means "HIGH SPEED STEEL", which basically refers to the high tensile strength of the steel bur.

 I prefer to initiate the bur cutting by using a bud-shaped bur to prepare where the HSS will start its cutting. If I don't use a 'bud-bur', the HSS bur will wrap itself around the whole claw and render it nearly useless.

  The optimum level of bearings is 1/3 off from the claw tip. 

 This is the maximum height (or depth) from the tip of the claw. This is EXACTLY where the gemstone should be sitting.

 This bur is not an 'HSS' bur, but only a 156C, which means 'Carbide'; these can be used primarily in Channel Setting.

 In this close-up of a well-worn HSS bur, you can see the well-worn rounded edges of the teeth.

 

 These HSS burs come in a variety of sizes. I won't discuss the sizes in this essay; one of my photos shows the box of these HSS burs.

  Under closer examination, you can see that the teeth are starting to get badly worn. 

 When you are using these HSS burs in Tube settings, it is important to have the teeth cutting the inner tube metal as sharp as possible. Using a sharp bur leads to improved accuracy.

 The size of the bur does not reflect the shape of the gemstone. Many setters name this bur, as a 'bearing cutter', as it only cuts the bearing for the Girdle of the stone, but not the Pavilion Facets.

   This is the correct angle of the gemstone to the shape of the bur.

 In the technique of repairing the teeth, all that matters is to have the 'outside edges' of the teeth repaired. There is no need to refurbish the whole bur.

 We've now covered the 'angles and shapes' of the burs; now, let's work on repairing the 'HSS' teeth. 

  These teeth are in desperate need of being fully repaired above and below the widest section of the bur. This is where the Girdle Facets will be situated.

 How did I know that this bur needs to be repaired? By looking at the edge of the teeth, you can see a shiny surface. This is about useless and must not be used, as many future setting projects using this one bur, will be damaged. 

 Each tooth on this bur must be handled with absolute care. If not, the edges of each refurbished tooth slot will cause an improper cutting process.

  

 This is my box of 'medium-sized' HSS burs. I keep these within close proximity to my working area on my bench.

 When the HSS bur is starting to cut into the claw, there will be a large flange of metal being extruded. This normally occurs, and before the stone is set, this flange must be removed.

 I would use a Pumice Wheel of  #2/0 grit. If you use a file, there will be stirations and this will lead to refurbishing all along the claw.

   You can observe that some of the HSS burs need to be repaired ...NOW.

  If some of the HSS burs are too small, then it won't be advisable to start the repair. Then the teeth are too close together, and attempting the repair will ruin the final outcome.

 Now, honestly, how is it possible to navigate your rotating bur to initiate the metal cutting if the teeth are totally worn down????

 This is where a series of sharp rows of bur teeth have only one chance of metal cutting.

 To execute this high precision of cutting, your burs MUST BE IN PRISTINE CONDITION at all times.

 You can now observe the shallow angle given to this 'bearing-cutter'. There are NO gemstones shaped at 45 degrees.

 

 

  When I require absolute quality in my diamond setting, I need a full range of HSS sizes. Even in this selection, you can see a few of these burs that were 'gently modified'.

 Which tooth needs to be repaired? I apply ink to the many teeth of the bur. Why would I do this?

 When the cleaning has started, I can instantly see which tooth has been 'repaired'. I use a 'Separating Wheel' to cut into the HSS bur.

   In my vast collection of burs, the total cost is not an issue. How can anyone justify precision stone setting if any burs are missing?

 There is only one opportunity to create a seat inside this 'Tube setting'. If you have a mediocre range of burs, the only recourse is to re-evaluate your collection of tools, agree?

  You can easily see that a few of these larger burs have been 'painted'. This is important in seeing which tooth has been touched for repair.

 There is no need to recut the full length of each tooth. The cleaning process is only where the metal contact has taken place.

 This is exactly where the repair work is now taking place.

The measurements of the "Separating Disk" are 0.64mm by 22.21mm. or 3/4's of an inch in diameter.

 This repairing is GREAT on large HSS burs, but not for the smaller sizes.

There is no need to recut any further than what is shown in these 3 photos.

 If your HSS bur has gotten badly worn and is just sliding without cutting. REMEMBER that your reading on this extensive essay will now guide you in repairing that well-worn bur.