Formulae and Tables - Wood / textbooks for vocational training (GTZ, 122 p.) 8. Wood Working Machines 8.1. Sawing Machines (introduction...) 8.1.1. Circular Saw Benches 8.1.2. Parallel Rocking Circular Sawing Machine 8.1.3. Table Band Sawing Machine 8.2. Milling Machines (introduction...) 8.2.1. Smooth Miller 8.2.2. Thicknessing Miller 8.2.3. Shaping Machine 8.2.4. Slot Milling Machine 8.3. Lathe 8.4. Drilling Machines (introduction...) 8.4.1. Box-Column Drilling Machine 8.4.2. Hand Drilling Machine 8.5. Sanding Machines (introduction...) 8.5.1. Horizontal Belt Sanding Machine 8.5.2. Column-Type Disk Sanding Machine 8.6. Presses 8.7. Sharpening Machines 8.7.1. Ripping Chisel and Plate Iron Sharpening Machine 8.7.2 Sharpening Machine for Circular and Band Saw Blades 8.7.3 Milling Cutter Sharpening Machine 8.7.4. Blade Sharpening Machine

Formulae and Tables - Wood / textbooks for vocational training (GTZ, 122 p.)

8. Wood Working Machines

8.1. Sawing Machines

Sawing machines are used mainly for parting materials made of wood.

8.1.1. Circular Saw Benches

The machine serves for making straight longitudinal, cross, angular and mitre cuts.

Construction

Figure 12 Circular saw bench

Information on labour safety

The splitting wedge has a clearance of 10 mm; blade thickness < splitting wedge thickness < setting width; the splitting wedge is secured against removal. The protective hood is fixed to the splitting wedge and must cover unused parts of the saw blade above the workpiece. It must project 20 mm beyond the entrance of the cutting circle in the machine table. In case of hand feed the stop rail should project 1/4 of the saw blade diameter beyond the centre of the blade in cutting direction. In principle, gauges or work guides are to be used when sawing. Sliding and rolling tables must firmly be connected with the machine and secured against lifting. The table edges adjacent to the saw blade consist of cuttable material and are replaceable. The spacing between saw blade and table is £ 3 mm.

Recommendations for maintenance

Remove chips, wood residues and dust before using the machine. Regularly lubricate bearings and other movable parts according to the lubrication instructions. Protect bare parts against corrosion.

Specification

tool diameter	250...600 mm
tool speed	1500...4500 min-1
dimensions of the main table	1000 mm × 1200 mm
dimensions of the sliding table	750 mm × 350 mm
input power	2.5...5.6 kW

8.1.2. Parallel Rocking Circular Sawing Machine

The machine is used for rough cross cuts in solid wood.

Construction

Figure 13 Parallel rocking circular sawing machine

A round column supports the revolving and vertically adjustable upper part of the machine. A swivel arm carries the saw motor the feeding movement of which is effected in a straight line and in parallel to the surface of the supporting table by means of a parallel linkage. The tool is mounted on the motor shaft.

Information on labour safety

After the cut the saw blade must automatically return to the position of rest and be held in place. In doing so, the saw blade must run into a safety guard. The locking device must be disengageable by the handle. The spacing between work stop and lower edge of the protective hood must be < 8 mm in position of rest. The work supporting table must have rolls or rollers. Slots are not permitted on both sides of the saw blade at a distance of 400 mm. See also circular saw benches.

Recommendations for maintenance

Regularly check the function of the feeding rolls or rollers. Lubricate all moving parts according to plan. See also recommendations for circular saw benches.

Specification

tool diameter	300...600 mm
tool speed	» 3000 min-1
swiveling angle of the saw blade	£ 45°
width of the cut	£ 600 mm
height of the cut	£ 150 mm
input power	2.0...5.5. kW

8.1.3. Table Band Sawing Machine

The machine is used for straight longitudinal, cross and angular cuts as well as for chamfering and rounding.

Construction

Figure 14 Table band sawing machine

Figure 15 Roller guide of the band saw blade

The machine consists of frame of the machine, upper and lower band saw guide rollers and machine table. The upper band saw guide roller serves as stretcher for the saw blade the deflection of which under stress is prevented by saw blade guides. The upper band saw guide roller is tillable for adjustment of the blade run (saw tilt).

Information on labour safety

Adjustment of the upper saw blade guide must be possible without any danger while the machine is running. Cover those parts of the saw blade which are not required for sawing as well as the saw blade after the sawing process up to the table surface. When cross-cutting round wood or similar, work with holding means. The saw blade passage in the machine table must not be broader than 3 mm. An emergency circuit breaker for quickly braking the motor must be available.

Recommendation for maintenance

Regularly check the guide rollers for proper setting. Regularly check the rubber coating of the band rollers for cleanliness, wear and damage. Untension the saw blade of machines which will not be in operation for a long time.

Specification

saw-blade length	3000...5500 mm
saw-blade width	5...60 mm
speed of the band saw guide rollers	650...950 mm-1
roller diameter	300...850 mm
depth of throat (cutting width)	350...900 mm
workpiece thickness	£ 500 mm
input power	1.0...5.5 kW

8.2. Milling Machines

Milling machines are used for dressing, levelling and shaping of materials made of wood.

8.2.1. Smooth Miller

The machine serves for making plane surfaces.

Construction

Figure 16 Smooth miller

The box-like cast column supports the two vertically adjustable machine tables and the housings of the antifriction bearings for the blade shaft. The electric motor in the column drives the blade shaft via a belt drive. An adjustable stop rail serves for guiding the workpiece. The feeding table is set to be lower then the unloading table by the amount of the cutting depth. That part of the blade shaft which is not required is covered by a safety guard which is firmly connected to the machine.

Information on labour safety

The spacing between the table lips and the cutting circle is a 3 mm. The table lips must not be damaged, when feeding by hand they must not be recessed. Adjust the table only when the blade shaft is at rest. Workpiece with a length of less than 400 mm and a thickness of less than 25 mm and workpieces with a length of 400...800 mm and a thickness of less than 10 mm must not be machined. Machine such work-pieces only with the help of a feeding device.

Recommendations for maintenance

Clean the table surface and stop rail from resin residues and other impurities after use. Regularly check the table lips for damage. Regularly check the stop rail for ease of motion. Lubricate it according to the lubrication chart.

Specification

diameter of the blade shaft	100... 125 mm
speed of the blade shaft	4500...6000 min-1
number of blades	2; 4
length of the feeding table	1100...1600 mm
length of the unloading table	1100...1500 mm
working width	400...600 mm
input power	3.0...6.0 kW

8.2.2. Thicknessing Miller

With this machine parallel broad surfaces and - in case of strip-like thicker workpieces - also narrow surfaces are produced.

Construction

Figure 17 Thicknessing miller

The box-like frame of the machine (cast or welded construction) supports the vertically adjustable machine table and the functional elements of the machine. A heavy driving motor (mostly outside the machine) drives the higher blade shaft via a belt drive. Feeding is effected by higher feed rollers and lower table rollers which are driven by the blade shaft. A motor provides for the table height adjustment (rapid adjustment).

Information on labour safety

Rebound protections must be available. The feeding devices must be constructed in such a way that the workpiece is safely supported and cannot be thrown out. Workpieces having a thickness of less than 5 mm must be machined with a base. Open protective hoods of blade shafts only when the machine is at rest. Workpieces which are thinner than 25 mm require elements of rebound protection which are half as wide as the workpiece. It must be possible to stop the feeding device independently of the tool.

Recommendations for maintenance

Regularly check the vee belt belt between motor and blade shaft for proper tension. Make sure that the chips are properly removed. Lubricate according to the lubrication chart.

Specification

diameter of the blade shaft	100...125 mm
speed of the blade shaft	4500...5500 min-1
number of blades	2; 4
feeding speed	4...30 m/min
workpiece length ³ 200 mm
workpiece width	5...800 mm
workpiece thickness	3...300 mm
input power	4...7.5 kW

8.2.3. Shaping Machine

With this machine profiles, groove and tongue joints, overlap joints, mortise and tenon joints etc. can be produced.

Construction

Figure 18 Shaping machine

Figure 19 Tool carrier of the shaping machine

The frame of the machine supports the work-rest table which has a round opening for the tool carrier. An electric motor drives over a belt drive the cutter spindle on the extension of which, i.e. the cutter arbor, the tool is mounted. During operations where the cutter arbor is heavily loaded the latter can be guided in an upper bearing. For vertical adjustment either the spindle or the rest table is adjusted.

Information on labour safety

The following fixtures must be available: stop rail with stop block; fence ring and fence strip of extended template; clamp carriage and feeding slide; steel band hand guard and guard bow; upper cover for chip suction; guard bow and protective ring with ball bearings; protective box or protective bell; pressure racks, rebound gripper; rebound-proof guide box with stop block. The distance from the cutting circle to the halves of the stop rails may be £ 3 mm.

Cutter arbors with upper bearing journal are to be used with upper bearing also for test work. For clockwise and anti-clockwise rotation the holding nut must be secured by a lock nut. The time lag of the tool after switching-off of the machine is £ 10 seconds.

Recommendations for maintenance

Clean seatings and bearing surfaces as well as guide slots daily. Regularly clean the air intake side of the motor and facilities of vertical and stop adjustment from chips and dust. Regularly check the spacers and fence rings for cleanliness and intactness. Regularly check the seat of the Morse taper.

Specification

length of the machine table	800... 1200 mm
width of the machine table	500...1000 mm
height of the machine table	850...900 mm
cutter arbor diameter	30; 40 mm
spindle speed	1200...12,000 min-1
input power	1.0...12.0 kW

8.2.4. Slot Milling Machine

With this machine round holes and longitudinal slots can be produced.

Construction

Figure 20 Slot milling machine

A cast frame carries the tool box, the motor and, on the front side, the machine table with the mechanisms for movement. The axial feed (drilling) is carried out by the tool box or the machine table with mounted workpiece. The cross feed (milling) is performed either by the machine table or by a floating movement of the tool with the table being motionless. For angular recesses the table can be adjusted (tilted), the work can be set up with eccentric gripping lever, screws or pneumatic clamping elements. The drive is effected by a belt drive.

Information on labour safety

A bonnet is necessary. Check the tool clamping devices regularly for their operational reliability.

Recommendations for maintenance

Keep clamping shanks and chuck clean. Always keep the surface of the machine table and work stop clean. Lubricate according to the lubrication chart.

Specification

tool diameter	4...25 mm
spindle speed	1400...10,000 min-1
drilling depth	£ 100 mm
length of the longitudinal slot	£ 200 mm
input power	1.5...5 kW

8.3. Lathe

This machine serves for turning between centres and face turning and is suited for chucking work. Construction

Figure 21 Lathe

The machine bed made of cast iron carries the headstock, tailstock, hand rest and spindle drive. The electric motor for the spindle drive is located in the left base. Tailstock and rest are adjusted along the bed by hand and arrested by an eccentric. The gap makes machining of short workpieces with large diameter possible.

Information on labour safety

Chucks with protecting chuck jaws, clamp or locking screws are to be provided with a smooth all-round cover. Never leave the key in the chuck. Do not check the workpieces while they are rotating. Do not remove the chips while the machine is running. Do not slow down workpieces by hand during the run-out. The hand rest should be as close to the workpiece as possible. Do not lay down tools on the machine bed. Wear tightly fitting clothing.

Recommendations for maintenance

Slightly grease all bare parts regularly with acid-free grease. Regularly check the function of the cam-lock. Keep the machine bed clean. Make sure that the tailstock is in perfect condition. Clean the faceplate, chuck and tailstock centre regularly from adhering dirt, resin and similar.

Specification

centre distance	1000...2000 mm
centre height	200...400 mm
work diameter above gap	£ 750 mm
length of the workpiece to	£ 225 mm
be turned in the gap spindle speed	250...2500 min-1
speed increments of the spindle	» 9
input power	1.5...2.5 kW

8.4. Drilling Machines

Drilling machines are used for making rotationally symmetrical bore holes.

8.4.1. Box-Column Drilling Machine

The machine serves for drilling round holes.

Construction

Figure 22 Box-column drilling machine

The base plate carries the column with the vertically adjustable work supporting table and the drill head with motor, belt drive and tool spindle. The drilling feed is produced by a hand or foot lever or automatically (transferred from the spindle drive).

Information on labour safety

Locking screws on toolholders must be covered or countersunk. Clamping fixtures have to provide for proper seating of the tool and workpiece. All safety guards must be adjustable to the various height and depth settings of the drills.

Recommendation for maintenance

Keep drill chucks and tool shanks clean. Clean the work support and the work stops regularly. Lubricate according to the lubrication chart.

Specification

tool diameter	£ 40 mm
speed of the tool spindle	150...4500 min-1
travel of the tool spindle £ 150 mm
length of the support table	250...450 mm
width of the support table	200...350 mm
input power	0.7...2.5 kW

8.4.2. Hand Drilling Machine

The hand drilling machine serves for drilling round holes and is mainly used on building sites and for erection work.

Construction

Figure 23 Hand drilling machine

In most cases the driving element is a universal motor which can be used for direct and alternating currents. The prolonged motor shaft is simultaneously the carrier and is provided with a chuck. The motor is enclosed by a light-metal casing with handle.

Information on labour safety

Plug the machine only into a socket with earthing contact. Never use damaged cables.

Recommendations for maintenance

Regularly check the condition of the lead-in cable. Always keep the chuck and tool shanks clean.

Specification

tool diameter	£ 40 mm
tool speed	350...2000 min-1
input power	0.2...0.8 kW
weight	1.4...6.0 kg

8.5. Sanding Machines

Sanding machines are used for making smooth and flat surfaces on wood-based materials.

8.5.1. Horizontal Belt Sanding Machine

This machine is required mainly for smoothing of broad surfaces, but it can also be used for lacquer sanding.

Construction

Figure 24 Horizontal belt sanding machine

Between the columns of a cast upright standard the vertically adjustable work supporting table is running on round bars or guide rails. The drive is capable of being switched over (clockwise or anticlockwise rotation), the driven belt roller is designed in most cases as face sanding disk. For sanding on the sliding table which is provided with an adjustable stop a pressure shoe is used on which felt is glued on. For lacquer sanding the pressure shoe must be provided with hard bristles instead of the felt. This helps to reduce the frictional heat. (Reduce sanding belt speed to 12...14 m/s).

Information on labour safety

The sanding belt at the belt rollers and the upper part of the rotating belt at the front edge must be completely covered. The pressure shoe must automatically lift itself when not being used. The hand guiding the table must not get within reach of the sanding belt. Collecting grids are to be attached to the exhaust openings. Strictly observe the regulations on exhausting the sanding dust and storing it. Lacquer and wood sanding dust must be exhausted and kept seperatly. When sanding lacquer, connect all conductive parts to earth to prevent electrostatic charges and increase the relative air humidity to 70 %. Use antistatic polishing agents.

Recommendations for maintenance

Protect bare parts against corrosion. The pressure shoe must be movable to slightly reciprocate and to adapt itself to the work surface. The pressure shoe must be in an impeccable condition.

Specification

sanding belt width	150...500 mm
sanding belt speed	15...30 m/s
belt roller diameter	» 300 mm
distance between belt roller centres	» 3000 mm
belt roller speed	» 1500 min-1
length of the supporting table	1000...2500 mm
width of the supporting table	300... 1000 mm
input power	3...10 kW

8.5.2. Column-Type Disk Sanding Machine

This machine serves for smoothing small and thin as well as curved parts.

Construction

Figure 25 Column-type disk sanding machine

A box-like cast column accommodates the driving motor. Over a vee-belt the motor drives the machine parts on which the sanding disks are mounted. The work supporting table is inclinable in most cases.

Information on labour safety

Distance between disk and table s 3 mm; the sanding tool must be fixed by means of a locking ring (at least 6 fastening screws). With the exception of the working surface the disk must be covered on all sides. When working on the upwards running portion of the disk, secure the workpiece against being torn upwards. Regularly check disks made of grey cast iron for cracks.

Recommendations for maintenance

Lubricate the machine according to the lubrication chart. Protect all bare parts against corrosion. Regularly check the vee-belt for serviceability.

Specification

sanding disk diameter	600...1300 mm
speed of the sanding disk	750... 1500 min-1
input power	3.0...7.5 kW

8.6. Presses

Presses are used for compressing flat workpieces during solidification of the glue.

Hand Screw Press

This press serves for coating flat workpieces and for similar operations.

Construction

The frame made of sectional steel is bolted. Cross members on the bottom beams cary the press table (sometimes the press table is retractile).

Figure 26 Hand screw press

Figure 27 Mode of action of the hand screw

Between the upper beams there are flanged cross bars with threads for transmitting motions for the screws. At the lower end of the screw the pressure shoe is supported. By means of the press plate forming the lower end of the pressure shoe a uniform force transmission is obtained.

Information on labour safety

The pressure elements require a safety guard, they are to be secured against unintended lowering.

Recommendations for maintenance

Make sure that the points of support are regularly lubricated. Immediately remove impurities, especially those of the press plates. Regularly apply parting compounds on the press plate to prevent sticking of glue residues.

Specification

press length	2500...3000 mm
press width	1000...1100 mm

8.7. Sharpening Machines

8.7.1. Ripping Chisel and Plate Iron Sharpening Machine

This machine serves for sharpening mortising, cutting and plane irons and certain drilling tools.

Construction

Figure 28 Ripping chisel and plane iron sharpening machine

A pedestal of steel or cast steel carries the motor the shaft of which directly drives the sharpening tools. If the machines are designed for wet grinding, the sharpening wheels run through a tray filled with cooling liquid. In most cases the adjustable tool support is provided with a clamping fixture.

Information on labour safety

Take care to ensure that the proper grinding tool is selected. Observe the specified speed of the sharpening tool. Do a test run of the sharpening wheel. Use the safety guards specified.

Recommendations for maintenance

The tool carriers must be clean. Make sure that there is sufficient cooling liquid available. Check the safety guards for functioning. Regularly clean the machine.

Specification

diameter of the sharpening wheel	£ 200 mm
speed of the sharpening wheel	» 3400 min-1
grinding speed	» 35 m/s
motor power	0.5 kW

8.7.2 Sharpening Machine for Circular and Band Saw Blades

This machine serves for sharpening circular and band saw blades by dry grinding.

Construction

The machine consists of the machine frame and the grinding wheel head which is mounted on the front side of the machine frame and arranged to swivel. Lifting and lowering of the grinding whell head is effected by means of a cam which corresponds to the tooth shape of the saw blade. Swivelling of the grinding wheel head during angular grinding takes place from a special cam via toothed segment, toothed gear, slider-crank mechanism and lever system. The saw blade is fed by a pushing pawl.

Information on labour safety

Select the appropriate grinding tool and make sure that it is in good condition. Do a test run of the grinding tool. Check whether the safety guards are intact. Wear protective glasses. When grinding dry, exhaust the grinding dust.

Figure 29 Sharpening machine for circular and band saw blades

Recommendations for maintenance

Clean the tool carriers regularly. Check the oil level regularly. Lubricate and clean the machine regularly.

Specification

diameter of the circular saw blade	160...1200 mm
width of the band saw blade	³ 10 mm
saw pitch	5...60 mm
tooth height	3...30 mm
tool orthogonal rake g	15...30°
tool cutting edge inclination a	8...15º
diameter of the grinding wheel	£ 200 mm
speed of the grinding wheel	2800 mm-1

8.7.3 Milling Cutter Sharpening Machine

This machine serves for sharpening all kinds of milling cutters by wet grinding.

Construction

Figure 30 Milling cutter sharpening machine

The machine consists of the machine frame which carries the grinding tray with the guideways for the longitudinal slide rest. The longitudinal slide rest is running on rollers. The sharpening wheels are inserted into a chuck and will be replaced with this chuck. So they will always have the same seating in the spindle. The tool clamping fixture can be replaced with another one according to the tool to be sharpened. The machine is equipped with a cooling system and a water splash guard for the operator.

Information on labour safety

Make sure that the proper abrasive tool is selected. Test the abrasive tool in a test run. Exhaust the grinding dust in case of dry grinding. Use a sight screen. The sight screen should be coupled with the switching-off mechanism. Make sure that safety guards are intact.

Recommendations for maintenance

Like sharpening machine for circular and band saw blades; check the coolant cleaning system regularly for reliability in operation.

Specification

cutter diameter	£ 200 mm
grinding length	£ 150 mm
speed of the sharpening wheel	1400; 2800; 3500 min-1
input power for sharpening wheel motor	0.6 kW
input power for feeding motor	0.25 kW
input power for coolant pump	0.13 kW

8.7.4. Blade Sharpening Machine

This machine serves for sharpening machine blades by wet grinding.

Construction

Figure 31 Blade sharpening machine

A heavy column of cast steel carries the guide rails for the mobile grinding unit and encloses the cooling tray with the grinding bed. The blades to be sharpened are fixed on the clamping plate mechanically or electromagnetically. The cooling liquid is supplied through the hollow shaft of the grinding motor. The sharpening wheel is fed automatically and steplessly.

Information on labour safety

Select the appropriate grinding tool carefully. Do a test run of the grinding tool. Observe the operating instructions strictly.

Recommendations for maintenance

Clean the clamping plate each time before a blade is to be mounted. Make sure that the guide rails for the sharpening unit are absolutely clean. Check the coolant cleaning system for operational reliability. Regularly lubricate and clean the machine.

Specification

grinding length	800...4500 mm
blade width	£ 250 mm
feeding speed of the grinding unit	8...16 m/min
grinding speed	» 30m/s
diameter of the sharpening wheel	175...200 mm
grinding infeed	0.002...0.3 mm
input power for the sharpening wheel motor	3.0...5.0 kW
input power for the travelling drive	» 0.75 kW
input power for the coolant pump	» 0.1 kW