Thickness / Drum Sander

Drum sander (also known as a “Thickness Sander”)

A large sander that uses a rotating sanding drum. The sanding drum is a horizontal metal cylinder with an interchangeable strip of sanding cloth wrapped around it. The cylinder is motorized and is mounted in a metal housing which is vertically adjustable in relation to a conveyor table beneath it.  The operator adjusts the height of the drum housing and conveyor speed to feed the wood into the machine. The sander smooths the top surface of the wood and sends it out the other side. The machine in the SOA is good for finishing surfaces, and is only to be used for wood products within the following parameters:

• Maximum board width ........................... single pass – 22 in. (559 mm); two passes – 44 in. (1188 mm)
• Maximum board thickness ............................................................................................... 4 in. (102 mm)
• Minimum board length ............................................................................................... 2-3/8 in. (60 mm)
• Minimum board thickness .......................................................................................... 1/32 in. (0.8 mm)

Basic Safety

There is a PPE tag mounted to the top of the Thickness Sanding machine, which indicates that the operator must wear safety glasses, contain loose clothing and jewelry, remove any extraneous materials from the work area, and that hearing protection is recommended especially when using the Sander for long durations. Also indicated, are the following restrictions and precautions: Wood products only!  Materials must be free of any stray hardware, price stickers or finishes.

Additional Safety Precautions:

• ALWAYS PROVIDE ADEQUATE INFEED AND OUTFEED SPACE WHEN OPERATING THE SANDER.
• KEEP THE WORK AREA CLEAR OF ALL EXTRANEOUS MATERIALS, TOOLS AND TRIP HAZARDS.
• ALWAYS STAND TO THE SIDE OF THE SANDER WHILE FEEDING THE WORKPIECE.
• DO NOT FEED MATERIALS INTO THE MACHINE FROM THE OUTFEED SIDE!!!
• DO NOT REMOVE MORE THAN 1⁄32" FROM THE SURFACE OF THE WOOD STOCK IN ONE PASS.
• INSPECT YOUR STOCK BEFORE SANDING. Never sand stock with nails, staples or other foreign objects, which may be embedded in the surface. Do not sand lumber with loose knots or knots that may become loose during sanding.
• DO NOT ATTEMPT TO REMOVE JAMS UNTIL POWER IS DISCONNECTED.
• DO NOT SAND WORKPIECES BEYOND THE PARAMETERS LISTED IN THE DESCRIPTION.
• GIVE THE WORK YOU ARE DOING YOUR UNDIVIDED ATTENTION.
• KEEP HANDS OUTSIDE THE MACHINE. NEVER REACH UNDER THE GUARDS TO TRY TO CLEAR STOCK THAT STOPS FEEDING. DO NOT CLEAR CHIPS AND SAWDUST WITH HANDS; USE A BRUSH.
• DO NOT USE THIS SANDER AS A WORK TABLE.
• ALWAYS USE THE DUST COLLECTOR WHEN OPERATING THIS MACHINE.

Basic Operating Procedure

1. Establish depth of cut.
2. Start dust collection system.
3. Start sanding drum.
4. Start conveyor and select feed rate.
5. Feed stock through machine.

Controls and LED display

Figure 1

• A – Main power switch 
• B – Drum motor switch 
• C – Conveyor speed dial 
• D – Emergency stop (E-stop) 
• E – Unit selector 
• F – Zero depth reset 
• G – Conveyor speed indicator 
• H – Load indicator 
• I – Feed Logic ON indicator 
• J – Drum motor circle/ON indicator 
• K – Drum height 
• L – Drum height units

Dust collection

The Dust Collector MUST be used when operating this machine. Typically, the dust collector hose is connected to the Thickness Planer Machine, but can simply be transferred to the top dust port of the Thickness Sander when in use. The Dust collector is near the wall by the Thickness sander. It has a large, round RED button switch on the left side of the motor housing. To turn on the Dust Collector, pull outward on the RED “button”…to turn it off, push the button in.

Drum motor operation

1. Connect power supply to machine. – Display remains dark.
2. Turn on main power switch (A). – Display will illuminate. Racetrack (G) may flash continuously, indicating that emergency stop is still engaged.
3. Rotate emergency stop (D) clockwise to disengage stop.
4. Turn on drum motor by firmly pressing switch (B) – Illuminated circle (J) will run, and “ON” will illuminate.
   Note: If drum motor does not start, make sure conveyor speed dial (C) is set to OFF.
5. Load indicator (H) may illuminate. – When motor is running without load, one bar may illuminate. More bars are illuminated as load increases
6. Turn off drum motor switch (B). – “ON” will go dark. Circle (J) will continue running for 5 seconds while drum slows to a stop. Then circle (J) will stop running.

Feed Logic activation

If load on the sanding drum becomes excessive and motor is overloaded or exceeds specified current, “FEED LOGIC” (I) flashes and “ON” (I) lights up. Conveyor will be automatically slowed to highest efficient speed.

Conveyor motor operation

Rotate conveyor speed dial (C, Figure 15) clockwise  to start and increase speed of conveyor. – Racetrack (G) will illuminate and run. Conveyor speed will show inside racetrack.

IMPORTANT: If sander is shut off or E-stop is engaged, conveyor speed dial must be returned to OFF position in order to restart sander.

Unit conversion

Toggle unit selector button (E) to select imperial or metric units. Units for drum height and conveyor speed will change accordingly on the display. When power is turned off, units default to imperial.

Drum height setting

Lower drum until it just contacts workpiece, then push zero depth reset button (F, Figure 16) to zero the setting of drum height from workpiece. The handwheel is then used to lower the drum in exact increments for each pass, by viewing the depth on the control display (K). When handwheel is rotated to move drum downward below zero point, a negative sign will appear before the depth number (K).

Emergency stop

Press E-stop button (D, Figure 16) to shut down all machine operations. When E-stop is pressed, drum motor stops and “ON” (J) goes dark on display. Conveyor motor also stops, and racetrack (G) flashes.

Setting depth of cut

Adjusting the drum sander for proper contact between abrasive and stock determines the depth of cut. The depth of cut is controlled by the height adjustment handwheel. (located on the top right of machine)

It may take some experimentation to determine the proper depth of cut, given the variables of abrasive grit, type of wood, and feed rate. For best results, use scrap wood to practice sanding and to develop skill and familiarity with the machine before doing finish work. A combination of several variables will determine proper depth of cut to use, including the following:

1. Abrasive type and grit size.
2. Width of piece being processed.
3. Hardness of piece.
4. Feed rate of conveyor belt.

Establishing drum height

A good rule of thumb when sanding with grits finer than 80 is to place the stock to be sanded under the drum and lower drum until it contacts the stock. Drum should still rotate by hand. Without changing drum height, finish feeding the stock under the sander with the machine OFF. Start sanding drum and sand the stock at that same position. Do not start drum while in contact with stock.

For sanding with grits coarser than 80, you can lower the drum slightly. Always maintain control of stock. Through practice you will learn the proper depth of cut considering the variables above.

Selecting conveyor rate

A faster feed rate allows faster sanding but fewer revolutions of the drum per inch of sanding. A slower feed rate provides more revolutions of the drum per inch of sanding to allow a greater depth of cut and smooth sanding. Begin experimenting with feed rate set to about 40% to 50% of maximum. The best feed rate will depend on a number of factors, including type of stock, grit and depth of cut used, and whether the stock is fed directly in line with the conveyor bed or at an angle. If the drum motor is lugging down, if the conveyor belt is slipping, or if you observe a ripple effect on the stock, slow the feed rate. If the finish is smooth and the machine is not overworking, you can experiment using a faster feed rate.

The Feed Logic control continuously monitors the load on the drum motor, and automatically regulates the speed of the conveyor motor to maintain highest feed rate without overload. When “Feed Logic” flashes and “ON” illuminates on the display, the Feed Logic control has detected too great a depth of cut and/or too fast a feed rate. If load on the drum motor increases, Feed Logic will decrease the conveyor feed rate and will stop the conveyor under extreme conditions. If load on the drum motor decreases, Feed Logic will increase the feed rate but will not increase it faster than the speed the user has preset on the dial. The best and most consistent finish will be achieved if the conveyor does not change speed during operation. A change in conveyor speed may affect the finish surface. If the finish is affected, make another sanding pass without changing any settings.  If the finish is still affected, make adjustments by slowing the conveyor and/or decreasing the depth of cut and run the stock through again. Also try a faster feed rate or less depth of cut if the stock you are working begins to show burn marks. With cherry, hard maple or other hardwoods, using a shallower depth of cut and a faster feed rate will help minimize burn marks.

Slightly angling the stock as it is fed into the machine will also help prevent burning the stock.

Because of the wide range of variables, it is important to experiment with your specific conditions and make adjustments to achieve optimum feed rate. If problems occur, first inspect and adjust feed rate.

Maximum performance tips

The versatility designed into the PM22-44 drum sander allows it to be used for a variety of tasks that will boost return on your investment. For example, it will speed up fine sanding work often done with slower, dust-generating hand sanders, and will achieve fine thickness adjustments not possible on some sanders. It can be used to surface figured woods – bird’s eye or curly maple, for example – which can be damaged if fed through a planer. Learning how to use its adjustments and controls will allow you to fine-tune the machine for maximum results. The best results come from experimenting with different abrasive grits and machine adjustments to fit the job at hand. Following is a list of useful tips which can help you improve performance of your sander.

Multiple-piece sanding runs

When abrasive planing (or thickness sanding) a run of similar pieces that you want to have the same thickness, it is best to determine the thickness of the thinnest piece and process all pieces to that same thickness in one session. Be aware that the sander will remove cups and crowns in the workpiece; consider this when measuring and processing stock to the same thickness.

Simultaneous multiple pieces

When sanding multiple pieces simultaneously, make sure to stagger (step) the pieces across the width of the conveyor belt. This provides better contact with the tension rollers. Try to process only multiple pieces of similar thickness. If there is a significant thickness difference, the thinner pieces can slip on the conveyor belt if they do not contact the tension rollers. Also note that pieces thicker than 3/4” should be  longer than the minimum normally recommended to prevent tipping of the stock.

Edge sanding

When edge sanding, the sander will mimic the opposite edge of the stock which is lying on the conveyor belt. Because of this, it is important for the stock edge to have been ripped at the proper angle to the face before the sanding process. When edge sanding stock that is less than 3/4” wide or more than 2” high, it is good procedure to stack and clamp several pieces together to prevent them from slipping or tipping on the conveyor belt.

Sanding imperfect stock

When sanding stock with a cup or crown, place the crown up. This will stabilize the stock to help prevent tipping or rocking during sanding. After the crown has been removed and the top is flat, turn the stock over and sand the opposite side. To avoid personal injury, take special care when sanding stock that is twisted, bowed, or otherwise varies in thickness from end to end. If possible, support such stock as it is being sanded to keep it from slipping or tipping. Use extra roller stands, help from another person, or hand pressure on the stock, to minimize potentially hazardous situations.

Face frames and raised panel doors

It is very important to have the proper abrasive contact when doing this type of sanding. If the machine is set to take an excessive depth of cut, the result can be a gouge or dip as the drum goes from sanding the rails at full width to sanding just a few inches of width on the stiles. To prevent this make sure, when using abrasives finer than 80 grit, that the drum is in contact with the wood but can still be spun by hand. If there is room, angling the stock on the conveyor belt can also help. Slowing the conveyor feed when coming to a rail in the stock can help prevent a dip or gouge. This allows the abrasive to work the wider width with less effort, and to achieve better consistency of the finished surface.

Stock feeding angle

Some pieces, because of their dimensions, will need to be fed into the machine at a 90° angle (perpendicular to drum). However, even a slight offset angle of stock will provide for more effective stock removal. The optimum feeding angle for stock removal is about 60°. Angling the workpiece for stock removal provides other advantages, such as less loading of certain areas of the drum due to glue lines or mineral streaks in the stock, more even wear of abrasive strips, potentially faster feed rates, and lighter loads on the motor. Note that to get the best final finish, however, the stock should be fed through the machine so it will be sanded in line with the grain of the wood on the final one or two passes.

Clean-up

When you are finished working at any machine or workbench, please be aware that there are 4 Trash barrels in this room, and that each one has a broom, bench brush and dust pan attached. You must use these items to clean up your work areas at each machine, when you are finished working there.