WARNING Use MILWAUKEE core bits. Do not use LHS (Large Hole System) Com- ponents with these rotary hammers. The bits could fail, breaking apart at the threaded stud and causing injury and property damage.

Using Rotary Percussion Core Bits

Core bits are useful for drilling larger holes for conduit and pipe. MILWAUKEE Heavy-Duty Core Bits have heat-treated steel bodies with durable carbide tips. These core bits are specially designed for fast, accurate drilling with combined hammering and rotary action.

1.Clean and lubricate the threads on the adapter and core bit to make later removal easier. Screw the threaded end of the adapter into the rear of the core bit.

2.Push the guide plate onto the pointed end of the center pin. Insert the center pin and guide plate assembly into the core bit. Be sure the small end of the center pin is securely placed into the hole in the center of the core bit (Fig. 5).

5.After drilling to about the depth of the core bit teeth, remove the center pin and guide plate from the core bit. Resume drilling.

6.To change the core bit, hold the tool upwards, pointing it away from your body, and run the tool allowing rotation and impacting for about five seconds to loosen the core bit from the adapter shank.

NOTE: To make deeper holes, remove the core bit, break and remove the core. Resume drilling. When drilling long or deep holes, after each inch of penetration pull the bit partially out of the hole while the tool is running, to help clear dust from the bit flutes. Dust can clog the bit flutes and can make the bit bind in the hole. If this occurs, stop the tool, free the bit and begin again.

Drilling Large Diameter Holes with Core Bits

When drilling holes with large diameter core bits, dust may build up in the cut and can cause the tool to stall, bind, or cut slowly. By creating an opening for the dust to escape, drilling time, bit stress, and tool stress can be reduced.

6.Reinstall the core bit and continue drilling (Fig. 9 & 10) . Dust and debris will fall through the hole and optimize the cutting ability of the bit.

NOTE: If unable to drill a hole in the kerf, pull back on the bit with the hammer run- ning (Fig. 11). This will remove some of the dust and debris from the cut. Repeat this for every inch of drilling. If necessary, vacuum dust and de- bris from the cut and surrounding area.

Fig. 10

Side view of slab

Fig. 11

Pull bit out as

far as possible

 

once or twice

 

per inch drilled.

MAINTENANCE

WARNING To reduce the risk of injury, always unplug your tool before performing any maintenance. Never disas- semble the tool or try to do any rewiring on the tool’s electrical system. Contact a MILWAUKEE service facility for ALL repairs.

Maintaining Tools

Keep your tool in good repair by adopting a regular maintenance program. Before use, examine the general condition of your tool. Inspect guards, switches, tool cord set and extension cord for damage. Check for loose screws, misalignment, binding of moving parts, improper mounting, bro- ken parts and any other condition that may affect its safe operation. If abnormal noise or vibration occurs, turn the tool off immediately and have the problem corrected before further use. Do not use a damaged tool. Tag damaged tools “DO NOT USE” until repaired (see “Repairs”).

Under normal conditions, relubrication is not neces-

Fig. 5

3.Insert the adapter into the nose of the tool. Set the action selector to the hammering with rotation setting.

4.Press the center pin firmly against your center mark, hold the tool firmly and pull the trigger.

NOTE: If a center pin and guide plate are not available, use a template or notched board to start the hole (Fig. 6).

Fig. 6

1.Start the cut as normal.

2.Once the bit is firmly Fig. 7 established in the cut (about 1/4" deep), re- move the bit from the

cut (Fig. 7).

Cut approximately

3. Remove the bit from the

1/4" deep with a

tool.

core bit.

4.Install a standard fluted bit, approximately 7/8" in diameter, onto the tool. Fig. 8

5.Drill a perpendicular hole through the kerf of

the large hole (Fig. 8).

Drill a hole

• Depending on the loca-

through the work.

tion of the work, the

 

 

hole should either break

 

 

through the other side of

 

 

the hole/floor or extend

 

 

4"-5" past the end of

 

 

 

 

the workpiece (such

Fig. 9

Top view

as into the dirt below

 

 

a concrete slab).

 

 

• If dust builds up in the

 

 

hole, vacuum it out and

 

 

continue drilling.

Dust and debris

• If drilling through a

wall, the hole for dust

will fall through

should be drilled on the

the hole.

lowest part of the large

 

 

hole kerf (Fig. 9) as the dust will fall there when drilling and can be evacuated more easily.

7.For core bits, once the maximum core bit depth is drilled, the core must be broken and removed (Fig. 12).

Install a chisel bit.

Place the chisel into the hole kerf.

Chisel down into the kerf at several points until the core is loose or broken.

Remove the core and vacuum/remove any remaining dust and debris.

Install the core bit and continue the cut.

Fig. 12

sary until the motor brushes need to be replaced. After six months to one year, depending on use, return your tool to the nearest MILWAUKEE service facility for the following:

Lubrication

Brush inspection and replacement

Mechanical inspection and cleaning (gears, spindles, bearings, housing, etc.)

Electrical inspection (switch, cord, armature, etc.)

Testing to assure proper mechanical and electri- cal operation

WARNING To reduce the risk of injury, electric shock and damage to the tool, never immerse your tool in liquid or allow a liquid to flow inside the tool.

Cleaning

Clean dust and debris from vents. Keep the tool handles clean, dry and free of oil or grease. Use only mild soap and a damp cloth to clean your tool since certain cleaning agents and solvents are harmful to plastics and other insulated parts. Some of these include: gasoline, turpentine, lacquer thin- ner, paint thinner, chlorinated cleaning solvents, ammonia and household detergents containing ammonia. Never use flammable or combustible solvents around tools.

Repairs

If your tool is damaged, return the entire tool to the nearest service center.

8

9

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Milwaukee 5426-21, 5446-21 manual Maintenance