Grind drill - instructions

Grind drill - instructions: drill

Handle the drill properly
  • Drill with little pressure and only move the drill in the borehole while turning.
  • Avoid overheating. Drill slowly and with breaks. Also applies to the grinding.
  • When drilling metals, use drilling and cutting oil.
  • Repeatedly put the drill into the boxes or the like. Fold back after use, so that they do not repel each other.
  • Never use a drill bit for the wrong material, it will ruin it and / or the workpiece.

A blunt drill is not just a nuisance. He also carries various risks. Starting with the overheated drill, which leaves traces of burn on the wood, over the broken drill in the borehole up to the risk of injury.

If there is no substitute at hand and can not be worried about the quick, only helps: Grind drill! Metal drills (twist drills) can be sanded particularly well, also stone drills can be reground a few times. It will be difficult with the wood drill, but that too is possible within limits.

How to grind your drills, what tools you can use and what you should be aware of is explained in this guide. It makes economic sense in any case with the larger versions, which have their price in the purchase and their durability is significantly longer, if you sharpen the drill, as soon as they become dull.

Grinding tools and tools for the drill (cost overview)

  • Grinder drill - Device Grinder from approx. 20,00 EUR
  • Cooling during metal drilling - drilling and cutting oil approx. 7.50 EUR
  • Drill Grind Angle - Drill gauge about 3,50 EUR
  • Special device - drill grinder from approx. 40,00 EUR
  • Universal device grinding station from approx. 25,00 EUR
  • Double grinder (grinding block) from approx. 38,00 EUR
  • Grind the drill by hand - needle files / key filesapprox. 13,00 EUR
  • or diamond files about 11,00 EUR
  • Safety glasses - Safety goggles approx. 12,00 EUR

Grind manually or by machine?

[img uuid = "7576b572-2a4a-4a60-b94d-b19daa3d3edc" alt = "Westfalia sharpening station on lets-rebuild.com in the test." height = "251" width = "335"]
Westfalia sharpening station on lets-rebuild.com in the test.

Grinding by hand requires more practice, but often results in more accurate results and reduces the risk of overheating the drill.

Wood drills can be grinded practically only by hand, unless you get yourself a professional grinding machine for this type of drill, which, however, costs around 1,500 euros and is unlikely ever to be amortized in private use.

By hand with needle or key files

When grinding by hand, clamp the workpiece between two woods in a vise - leaving only two to three centimeters of the drill out. Always grind away from the body. Always try to keep the angle in which you are holding the file the same.

For HSS drills, diamond files are required because this particular alloy is too hard for normal needle or key files.

Use grinding block for grinding drills

Always wear safety goggles when grinding with a bench grinder, but never wear gloves (can cause very bad injuries if the disc picks up a glove). With a drill sharpening device, the angles succeed exactly. In any case, the grinding wheel must be straight. Do not let the drill get too hot when sanding. For wood drills, a thin grinding wheel must be used.

By hand with needle or key files

When grinding by hand, clamp the workpiece between two woods in a vise - leaving only two to three centimeters of the drill out. Always grind away from the body. Always try to keep the angle in which you are holding the file the same.

For HSS drills, diamond files are required because this particular alloy is too hard for normal needle or key files.

Drill a drill - machine specifically for certain types of drill

When grinding with a drill sharpener, carefully follow the manufacturer's instructions - especially for which drills the machine is suitable, which is very different. The settings are specified for the respective drill types. When buying such a machine, look for comparisons and / or ratings. Good equipment is not cheap and often only useful for craftsmen. However, you can rent some devices also.

Grind drill - instructions: instructions

The point angle should be 118 degrees - during the grinding measure again and again.

Grind metal or twist drills

Regardless of whether you are grinding by hand or whether you are working on your drills on the trestle or in the drill grinder - you should definitely know how to grind the drill how many degrees the grind must have.

Grind drill - instructions: instructions

The clearance angle falls off the outside of the cutting slightly, with 3 to 5 to max. 8 degrees.

The apex angle should be 118 degrees, at the so-called clearance angle, it is 3 to 5 (maximum 8) degrees, the transverse cutting edge has an angle of 55 degrees to the central axis of the two main cutting edges and is arcuate.

Grind drill - instructions: grind

The chisel edge describes a slight arc and has an angle of 55 degrees.

Attach to the bottom of one of the two main cutting edges and pull your file without exerting much pressure, following the rotation upwards to the point when grinding manually. When grinding on the trestle, place the drill on one or two fingers, turn it clockwise with the other hand, following the cutting edge to the tip. You pull the drill at the rear end down.

Check the angles again and again and grind the other side as well. If everything is done correctly, the transverse cutting edge results from the grinding of the point angle almost automatically, it should describe a slight arc.

With a little practice, it is always easier and faster to grind drills.

Grind wood drills

Wood drills are much harder to grind than metal drills. The profile is more complicated and smaller and the centering tip is often in the way during grinding. As a handyman, sanding wood drills is best done with fine files by hand. With a thin grinding wheel, it may also be partially mechanical in larger wood drills.

Important: The centering point (especially if it has a thread) must remain completely unaffected by grinding on all wood drills and flat milling drills, otherwise the tool will no longer work exactly.

The point angle of a wood drill should have 180 degrees, the clearance angle falling between 1 and 2 degrees. Due to the top profile testing is not easy. To record a corresponding angle (eg with a geodetic triangle) can be helpful. When checking, place the tip on the drawing to detect and correct deviant tendencies.

An exception among the wood drills are the so-called flat milling drills, which have a much simpler profile and can be reground relatively easily. For this example, diamond files or the grinding block are suitable. Only the two sheaths need to be ground. The angle should be about 10 degrees and the two cutting edges at the end must lie horizontally exactly at a height.

Grind stone or mineral drills

Fortunately, drills of this type rarely need to be reground. It is also limited. The tip of the drill is made of carbide. This also means that the material breaks more easily when sanding.

For many stone drills there is a small mark indicating from which material wear the drill should be exchanged. If this is already achieved, regrinding also makes no sense.

When grinding on a trestle, a carbide grinding wheel must be used, paying particular attention to overheating. An advantage is in the case, if one has a Nasschleifmaschine. Otherwise take a lot of time to cool down and spray with drilling and cutting oil.

The tips of stone drills can have two or more blades, the tip angle is usually either 118 degrees or 130 degrees - this can be tested on an unused drill of the same series. Mostly, they are quite simple and regrinding is self-explanatory.

Grinding drills - mistakes that happen frequently

  • Workpiece has annealed and has turned blue> better replace> avoid in the future
  • Cutting unequal length - drill drills too large> rework shorter cutting edge
  • Point angle unequal - only one edge cuts and will dull quickly> rework
  • Clearance angle too small - feed too large, drill breaks easier> rework
  • Clearance angle too large - cutting edge breaks easily and / or the drill hooks> rebuild the ground joint

Author: Christiane Baldwin - Online Editor and Handyman

Photo Credits:
  • Page Image: Christiane Baldwin
  • Cover picture: Christiane Baldwin
  • Drill grinding machine: Riccardo Düring
  • Pictures Grinding a drill: Christiane Baldwin

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Video Board: How to Hand Sharpen a Twist Drill