Activity-2.pptx

Honing and stropping

1. Activity 2 Honing and Stropping Lorna G. Amoranto , RMT, RN, MD, DPPS

2. Honing and Stropping I NTRODUCTION The degree of sharpness of the m icrotome knife is proportional to the fineness of the abrasives used in sharpening . The final sharpening m a t e r i al used must have a grain smaller than the p ermmi s a ble st ri ations remaining in the edge . Sharpening may either be done by hand of machine

3. Why do we h one mic r otome knive s? 1.Re-texturing the ground edge. The coarse abrasives used in a grinding wheel are necessary for the fast and cool removal of metal . Fine abrasives would be U nproductively slow cutting would rub more than they removed causing heat bud-up that ruins the tempered hardness of a blade The large particles serrate the tool's working edge into a weak (microscopic) s a w tooth texture the strongest possible sharp edge would be un if ied l inear and continuous), not chopped into separate teeth unsupported by adjacent substance. We strengthen the sharp edge by honing the bevel / edge entity on a series of ultra fine-abrasive oil s to n es Good honing reduces the peaks and valleys to a virtual straight line, even viewed under very high, magnification.

4. Why do we h one mic r otome knive s? 2. Removal of burr. As metal is ground to thin cross-section (ie., sharpness) it does not form a neat triangular profile the tissue-thin edge and attached debris curl over into what is called the "burr or wire" We must abrade or fatigue this microscopic "steel wool," to expose the underlying solid edge via the honing process. This also straightens, burnishes and polishes the edge's component front and back faces, hence the edge itself

5. Why do we h one mic r otome knive s? 3. Second bevel Honing at a raised angle (5 degrees or so) consolidates, and strengthens the edge by forming a second (more obluse) bevel. This is an option

6. Why do we h one mic r otome knive s? 4. The final probably commonest reason for honing is simply to restore an edge moderately dulled by normal use NOTE: Grinding is for or alteration of edge and bevel. Honing is for everyday finessing

7. The purpose of stropping is not to abrade more metal, but rather to continue bending, flexing fatiguing, and bu rn ishing off the miniscule metal strands still clinging to the edge of the bla de after the burr breaks off. If you sharpen with waterstones a n d use a "gold" 8000 grit stone as a final step, stropping is not necessary.

8. Strop the bevel and back of the tool using a smooth firm piece of leather (very hard machin e- belt leather is not good). Do not use abrasiv e dressings on leather - they are coarser than t he Arkansas stone and will remove its effects. Wipe honing oil off the tool before stropping. Str op on clean, undressed leather only.

9. A good size for a strop is around 14" long by 3 wide. A single thickness of leather, held down on the bench with the left hand as you strop with the right, is satisfactory. However, it is worth the extra effort to tack two layers of leather onto a 1 1/2 inch thick piece of dressed wood, 12 x 3 “ A 1/16 ” layer of hard felt between leather and wood makes an ideally mellow but firm strop th at is less prone to bend the micro-thin cutting edge at the end of a stroke. The 1 1/2 " thickness of the wood allows it to be held in a vise, 3/4” proud of the surrounding surface, or to be comfortably elevated above the bench, gripped by the left hand.

10. PROCEDURE To hone: 1. The hone is first wiped clean with a soft cloth, occasionally, it should be wiped clean with a soft cloth moistened with xylene so as to remove loose particles of stone and metal. 2. Cover the h o ne with a thin film of lubricant 3. Fit the knife in its own back and lay obliquely on the stone edge forward 4. Apply gentle pressure on the knife with the thumbs or forefingers and draw the knive obliquely to the stone in a stead y motion

11. To hone: 5. "Heel" (handle end), until the other end of the stone has reached the "toe" 6. Rotate the knife on its back so that the other cutting facet rests on the stone 7. Draw the knife towards you, again from heel to toe

12. To hone: 8. Repeat the action approximately 20-30 times 9. Wipe the knife with a clean cloth moistened with xylene 10. If warranted, inspect with a magnifying glass 11. Prepare to strop

13. To strop: 1. Technically, stropping is the inverse of honing 2. Fit the knife with its back 3. Lay obliquely on a strop 4. With the cutting edge behind (edge last) push backward and forwards in a "toe to heel" direction.

14. https://www.youtube.com/watch?v=lAb-x6sau8g

15. Activity 2 Honing and Stropping NAME _____________________________________SECTION___ What is honing? Differentiate it from stropping What are the types of hones used in histopathology lab? What arethe grades of honing? What are the types of abrasives used in honing of the knife? What are the lubricants used for honing of knife? What are the disadvantages of excessive honing? How is stropping leather maintained and taken care of