Repairing your “High Speed Steel” burs!
The size for your recutting bur should not be smaller than 4.00 mm in diameter.
As the price of Diamond Setting tools are always increasing, I have found a method to cut some of the costs of the HSS burs.
The only tools you need to do this repair, is a Corundum (Separating) Disk. This rather unique method will save you many dollars in the future.
BTW, the down-side to this process, is that every time you repair that bur, you are slowly reducing that size of the bur by almost 1/10th of mm. That is just why I usually have many burs in my collection. If one bur is slightly made smaller over a period of time, I have another bur at the “original size!”
“On the Difficulty Scale, this procedure is a mere 3 out of 10!”
The first indication of ‘teeth getting worn down’ is you will see a little bright & shinny surface on the edge of the teeth. These teeth will noticeable be on the widest cutting section, where the bearings are being created. Basically, “no sharp teeth…no metal cutting!”
When I have a bur selected, I will ‘paint the teeth’ with a black marking pen. Why so? This will make the “untouched teeth” distinguishable to the ‘repaired teeth’, simple as that!
Once the teeth are totally blackened on the top and the bottom of the bearing-cut sections, you may now proceed! This bur now being shown hit some steel by accident and needs a total recutting of the teeth. This photograph was taken at 175x power magnification.
I will hold the bur steady in one hand & use your stronger 5x, or 7x power lens on your ‘Opti-Visor’ then you can see exactly where you are cutting. The ‘separating wheel’ must cut just one tooth at a time, just follow the same angle as on the bur. The size of the cutting wheel is 7/8” inch and have the width of .035mm’s the disk must now rotate at a relatively slow speed.
This process is very delicate with little or no mistakes are allowed, why so? You are dealing with a new and repaired bur!! If some of the teeth are missed or ruined, therefore the numerous cutting teeth will not cut as you expected!
Please watch every tooth that you are now delicately ‘fixing’!! Make very sure your Corundum, separating disk is properly aligned to the teeth!!
After some months of using your favourite bur, you will find the HSS-teeth are just not cutting, but they are still not worn down. Under closer examination, you will see the teeth are just crumbling. Another great reason to again totally ‘Recut’ them, agree?
This complete process should take no longer than 5 minutes. My saying is “Out of this negative, you now have a nice cutting bur!”
This specific action will not be for 156C (Carbide, Under-Cutting) burs, as the teeth are too close together & not originally cut deep into the metal.
When you start, align up the separating disk with the first tooth. This is so important!!!
Start the rotating disk and observe if you are actually repairing one tooth and not two at a time. Start half-way (Pavilion) down the HSS bur and finish at the widest section a.k.a. bearing-cut section. Invert your bur and start at the section nearest to the bur shaft! From that point…finish at the 'bearing-cutting teeth!'
Please view the many photographs showing this delicate procedure. If you read this and you find this process too convoluted. Remember, it’s still a rather easy method and saving you money at the end of the day
This photograph looks like a duplicate, but it was taken at 220x power magnification. The size of this little bur was only only 3.5 mm’s
Remember if you ‘cut two teeth at a time’, this isn’t going to work!!
I would suggest “trying to align your disk to the bur-cutting angles first” but not to start your bench-motor. Even I do this myself. Once you feel comfortable with the preparation, you’re on your way successfully…Over the period of one year, imagine your dollars being saved in buying newer burs…have fun!