- Twist drill bit for wood
- Single-tape twist drill or wood drill
- Expanding drill (center bore)
- How to choose a wood drill for different operations
- Work and sharpening
In this article, we will show you how to choose the right drill bit for wood and how to handle it so that it will last for many years. You will find out which drills are optimal for different operations, what they look like and how much they cost. The article also contains a table of the dependence of revolutions on the diameter of the drill.
The drill is essentially an end mill, and comes in many varieties. When working, a force acts on the drill in two directions – rotation and pressure. Moreover, rotation accounts for 90% of the efforts, and 10% is enough for pressing. Mechanization of labor made it possible to “give” the lion’s share of the loads to the tool, leaving only directive responsibilities for the operator – precise direction, tool retention and pressure adjustment. There are several basic types of drills for hammerless drilling in wood..
There are special wood drills, the common feature of which is a guide pin. It is needed to accurately position the drill at the mark before starting the operation. Given the relative softness of wood compared to metal, holes in it do not require preliminary drilling with a smaller diameter.
All wood drills, common among craftsmen, are divided into four types.
Flat end mill with horizontal cutting edges on straight hex bar. Has a guide spike. Diameter from 12 to 38 mm with a total length of up to 250 mm. It is used for holes (through and non-through) up to 60 mm deep (working part of the “pen”).
Nuance of work – tendency to jam when skewing at high drill speeds. The cutting force is concentrated on the short edge – almost all the torque from the drill is transmitted to it. The hexagon holds well in the chuck, therefore, with a wedge, the tool can be pulled out of the hands. Pen does not deflect chips.
Twist drill bit for wood
Drill on a spiral rod with a spiral cutting edge and a center spike. Round shank. Has cutting edges sharpened at a flat angle. That is, the length of the edge is the minimum possible. Diameter from 3 to 12 mm. The length of these drills can reach 800 mm.
It is used for small holes in furniture production and construction, as well as for blind holes (leaves an even “bottom”). Optimum hole depth (drilling layer thickness) – 50-100 mm.
Nuance of work – poor chip evacuation, when deep drilling requires several dives.
Single-tape twist drill or wood drill
Helical spiral with one horizontal cutting edge. The guide pin is threaded and the drill itself looks like a regular steel band. About 50% of the rotational cylinder volume of the drill is the chip evacuation groove. Hex shank. The length of the drill can reach 1.2 m with a diameter of 6 to 40 mm. It is used for through holes in a tree of considerable depth (length), when joining logs or timber masonry walls.
Nuance of work – drilling speed should not exceed 800 rpm at Ø 30 mm.
Expanding drill (center bore)
A bar with a variable section shape – flat at the end, round middle, hex shank. It has special fasteners for installing a movable knife, which extends under the required diameter from 15 to 40 mm. Used for shallow holes (up to 30 mm).
Nuance of work – a relatively small resource, it breaks down during intensive work (due to moving parts). Not subject to repair. Convenient for auxiliary periodic operations and for substitution (“on the catch”). The design is prone to seizure at high speeds.
How to choose a wood drill for different operations
From the above analysis, it can be seen that the pen and expanding drill have the largest range of operations. At the same time, they have a limitation on the minimum diameter – 10 mm.
It is good to have a centrobore as a backup and not use it too often, or use it in case of frequent diameters change, if there is only one drill available – you can change the diameter without removing the drill from the chuck.
Sliding drill prices
|Name||Manufacturer||Diameter range, mm||Price, cu e.|
|BAHCO (2 knives)||USA||15-45 / 22-76||18|
For small to medium diameters (4–25 mm) holes in hardwood, it is best to choose a conventional twist drill. It is also convenient to use when working with hand tools – the round shank insures the chuck against overload in the event of a wedge. For household periodic work, it is more profitable to purchase sets that are produced by many companies – ERMAK, Enkor, Sparta, BIBER and others. A set usually contains from 6 to 18 pieces. drills of different diameters. The cost of a set is from 3 to 8 USD. e.
The pen is best used in construction, when it is necessary to drill many through holes of medium diameter (20–40 mm) at a shallow depth. The main advantage is that it is easy to sharpen it with an improvised tool, grinder or file.
Prices for feather drills using the example of Ø 12 mm
|Name||Manufacturer||Length mm||Price, cu e.|
Wood drill is mainly used by professionals in the construction of log cabins and houses from a bar for driving crowns and then fastening with a chop. The power of the tool is at least 1300 W.
Example of prices for wood drills
|Name||Manufacturer||Diameter / length, mm||Price, cu e.|
Work and sharpening
There are several important points to pay attention to when working with drills. They refer to tips for careful use of the tool and safety:
- Before drilling (especially with a “pen”), make sure that the body of the tree in the future hole does not contain foreign inclusions – nails, screws, staples. Metal can not only spoil or even break the drill, but also cause a wedge and jerk of the tool from the operator’s hands.
- Choose a soft-start tool. The sensitive button of a conventional revolving drill will cause sharp jerks, which will affect the quality of work.
- The wood drill has a self-guiding design – the threaded spike itself pulls the edges to the surface, so make sure the drill is installed correctly before drilling.
- Optimum speed for woodworking:
- If it so happens that you have to drill wood with a drill for metal, sharpen the edges at an angle close to the horizontal sweep – the edge heating when drilling wood is minimal.
- The sharper the angle of the cutting edge, the more efficiently it cuts into wood. But at the same time, it is erased and dull faster. The optimal edge angle is selected empirically in each case.
- If you need a high-quality hole without tearing at the outlet, press the material (board, slab) to a flat, flat surface (which you do not mind) and drill the hole to the end. The clamp will prevent the fibers from breaking out at the exit. Or wait until the drill appears and drill from the back.
Subject to the rules of work, the drills will serve you for a long time, and the ability to restore and sharpen them will save on purchase. In the next article we will talk about drills for metal and plastic.