Shop Area: Woodshop
Tool: Drum Sander
Requires in-person training: Yes
UG 110-10, Rev. 2
The drum sander is used to give a smooth and consistent finish, and can be used with parts too delicate for the planer.
- Always wear approved safety glasses or face shield while operating the equipment.
- Before operating equipment, remove tie, rings, watches and other jewelry, and roll sleeves up past the elbows. Remove all loose clothing and confine long hair.
- Closed toe shoes are required when working in a shop area.
- Do not wear gloves while operating the equipment.
- Always feed stock against the drum rotation.
- Never place hands or fingers under the drum or dust cover.
- Keep hands and clothing away from operating drums.
- Never operate the sander without its dust cover or drum and belt guarding in place.
- Always maintain control of boards to avoid kickback.
- Always disconnect electrical power before doing any servicing or adjusting of the machine.
- Check for alignment of moving parts, binding of moving parts, breakage of parts, mounting, and any other conditions that may affect its operation.
CAUTION: There are 2 lock bolts on the bed adjustment bolts to keep the current setting. Please DO NOT change these settings. There are guides lines on the front showing where the belt should run so it's obvious if it starts to track to the right and curl under which will grind the right roller and bed. If this happens please STOP since the belt is just a large sheet of sandpaper and it will grind out the entire roller support and permanently damage the machine.
Typically a coarse grain sandpaper is placed on the front drum and a fine grain sandpaper is placed on the rear drum so that both rough and fine finishing can occur in one pass, but different configurations are possible.
The adjustment knobs inside the top cover of the drum sander allow for a variety of front and rear drum configurations:
1. When at "0" the rear and front drums are at the same height. Both drums will remove the same amount of material.
2. To lower the rear drum the knobs are BOTH turned so that the guides read in the "+" or positive direction. To raise the drum the knob are BOTH turned so the guides read in the "-" or negative direction. It may help to think of it as the "+" or positive number moving toward or "into" the material and the "-" or negative number moving away or "out of" the material.
3. These knobs should be adjusted so they are the same value though one could have a reason for tilting the rear drum so it's not parallel. This does not seem like a good idea though. The right spring on the adjustment knob sticks a bit so make sure that the value actually changes when you turn it. Just tap or flick the spring a bit.
4. The adjustment setting allows 4 positions for a variety of possible finishes:
A. "0" SETTING - The rear drum will be even with the front drum and will provide a double pass with the front and rear drums using both grits at the same height.
B. "-” NEGATIVE SETTING - The rear drum will be HIGHER than the front drum and will provide one pass with the front drum ONLY.
C. "+" POSITIVE) SETTING - The rear drum will be LOWER than the front drum and will allow 2 options:
a. If the bed depth (using the height crank on the right) is set so that the material DOES engage the front drum, the front drum will remove material and the rear roller will remove more material (unlike A above which will remove the same amount of material with each drum).
b. If the bed depth (using the height crank on the right) is set LOWER so that the material DOES NOT engage the front drum, the front drum will be bypassed and ONLY the rear roller will remove material.
Belt Tension. To adjust the tension of the conveyor belt, first adjust the take-up screw nut (see Fig. 10) on both sides of the conveyor to obtain approximately equal tension on both sides of the belt when taut. Insufficient belt tension will cause slippage of conveyor belt on the drive roller during sanding operation. The conveyor belt is too loose if it can be stopped by hand pressure applied directly to the top of the conveyor belt. Excessive belt tension can result in bent rollers, premature wearing of the bronze bushings or belt.
Belt Tracking. Belt tracking adjustments are made while the conveyor belt is running. After the proper belt tension is obtained, turn the conveyor unit on and set it at the fastest speed setting. Watch for a tendency of the conveyor belt to drift to one side of the conveyor. To adjust the belt tracking, tighten the take-up screw nut (see Fig. 10) on the side the belt is drifting toward, and loosen the take-up screw nut on the opposite side. Adjusting the take-up screw nuts on either side of the conveyor allows belt tracking adjustments to be made without affecting belt tension. NOTE: Adjust the take-up screw nuts only 1/4 turn at a time. Then allow time for the belt to react to the adjustments before proceeding further. Try to avoid over-adjustments. Make sure wrench is below surface when sanding.
CHECKING TABLE HEIGHT CONTROLS - The table height and depth of cut is controlled by the height adjustment handle (see Fig. 11). Turning the handle raises or lowers both sides of the table simultaneously by transferring the handle rotation through the miter gear and cross bar assembly. Important: Before using the height adjustment, be sure to loosen both the set screws located on the front of both table support castings to allow the table support to slide on both column tubes. Readjust the set screws just so they eliminate free-play between the table support casting and the column tube. To properly adjust, tighten the set screws only finger tight so they lightly touch the column tubes. Then hold each set screw in position with an Allen wrench and tighten the hex nut. Check the operation of the height adjustment mechanism. If it does not operate smoothly or easily, further adjustments may be necessary.
BASIC OPERATING PROCEDURES
1. Set depth of cut. 2. Start drums. 3. Start conveyor and select feed rate. 4. Start dust collector system. 5. Feed stock through unit.
To feed stock, rest and hold the board to be sanded on the conveyor table, allowing the conveyor belt to carry the board into the drums. Once the stock is halfway through, reposition yourself to the outfeed side of the machine to receive and control the board as it exits the unit.
SETTING THE DEPTH OF CUT Adjusting the sander for the proper contact between the abrasive and the stock determines the mechanical depth of cut. Determining the depth of cut is the most important set-up procedure before operating the sander. It may take some experimentation to determine the proper depth of cut, given the variables of abrasive grit, type of wood, and feed rate. A good rule of thumb when sanding with grits finer than 80 is to raise the conveyor table so the drums contacts the workpiece but still can be rotated by hand. When using grits coarser than 80 grit, you can raise the conveyor table slightly more. However, a combination of several variables will determine the proper depth of cut to use, including the following: 1. Abrasive type and grit size. 2. Width of the piece being processed. 3. Hardness of the piece. 4. Feed rate of the conveyor belt.
On dual drum units, the depth of cut of the secondary drum is controlled by the two adjustment knobs (analog indicators) located on both sides of the drum. The drum adjustment knobs allow proper depth of cut with virtually any abrasive grit combinations on the drums. The two drums are normally both used during sanding operations, but either the primary or secondary drum can be used alone.
On dual drum models, sanding with a different abrasive grit on each drum is possible in a single pass. The coarser abrasive is wrapped on the primary (front) drum for dimensioning and surfacing of the wood, while the finer abrasive is wrapped on the secondary (rear) drum. When used in this way, the secondary drum generally is positioned just slightly lower than the primary drum so it removes the scratches left by the coarser grit on the primary drum. However, the exact depth of cut of the secondary drum will depend on the specific abrasive grits on each of the drums. See chart below that shows grit combinations and rear drum settings, can also be found under the dust cover of your machine. When adjusting the secondary drum, turn both adjustment knobs so that the indicator needles move to the desired setting at the plus (+) end of the scale. The depth of cut of the secondary drum should be rechecked each time a different grit combination is used.
Fine-Tuning the rear drum settings can help improve performance. Raise the rear drum so it is higher than the front drum, with the indicators showing a -3 setting. Place the stock to be sanded under the front drum. Then raise the conveyor table so the front drum contacts the wood, but still can be rotated by hand. Sand the piece with the front drum and stop the machine. Then insert the stock in from the back so it is under the rear drum only. Turn down the rear drum using the adjustment knobs on each side. Lower the rear drum until it contacts the stock but still can be rotated by hand. Use this setting.
DISENGAGING THE DRUMS - On dual drum models, either the primary (front) or secondary (rear) drum may be disengaged so that the other drum can be used alone. To use the primary drum as a single-drum sander, disengage the secondary drum by raising it to the -2 setting on the indicators on both sides. To use the secondary drum alone, lower it to the +4 setting on both sides. In this mode, the table height adjustment handle is used to determine the depth of cut, which will be limited to about 1/32 of an inch before the primary drum starts contacting the work piece.
SELECTING FEED RATES Selecting the proper feed rate is essential to proper finish sanding. The variable feed rate control of the conveyor belt adjusts the load on the machine; it can be infinitely adjusted for maximum operating performance. A faster feed rate allows faster sanding but fewer revolutions of the drums 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 smoother sanding.
The Intellisand control (See Fig. 15) continuously monitors the load on the drum motor and automatically regulates the speed of the conveyor motor to maintain the highest feed rate without overload. If the load on the drum motor increases, the Intellisand control will decrease the conveyor feed rate and will stop the conveyor under extreme conditions. If the load on the drum decreases, the SandSmart control will increase the feed rate but WILL NOT increase it faster than the manual setting on the switch dial. For abrasive planing and thicknessing, the feed rate can be set at any speed after adjusting for the proper depth of cut. If the load on the drum motor approaches its optimum due to inconsistent stock, the feed rate will automatically slow down. As the load on the drum motor decreases, the feed rate will automatically increase to its original setting.
When finish sanding with grits finer than 80, the best finish will be achieved if the conveyor does not change speeds during operation. While the Intellisand control will slow the feed rate when the main motor reaches its optimum, it is advisable to operate below the regulation point. When the red indicator light comes on, the Intellisand control has detected too great a depth of cut and/or too fast a feed rate. This change in conveyor speed may leave a detectable mark on finish surfaces. If a mark is visible, make adjustments by slowing conveyor and/or lessening the depth of cut and run the stock through again.
Begin experimenting with the feed rate set at 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 feed directly in line with the conveyor bed or at an angle. If you observe a ripple effect on the stock, slow down the feed rate. If the finish is smooth and the machine is not overworking, you can experiment with using a faster feed rate. Also try a faster feed rate if the stock you are working begins to show burn marks. With cherry, hard maple and some 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 may also help pre vent burning the stock. Because of the wide range of variables, it is important to experiment with your specific conditions and make adjustments to achieve the optimum feed rate. If problems occur, first check the depth of cut and/or adjust the feed rate. Refer to Troubleshooting.
SELECTING DRUM ABRASIVES It is important to select the proper grit of abrasives for the type of sanding being performed to achieve maximum sanding results. As with any sanding operation, first begin sanding with a coarser grit, depending on the roughness of the stock or the amount of stock to be removed. Then progressively work toward finer grits. The chart below shows the general uses for the various grits.
Selecting Abrasive Grits. The amount of stock to be removed is a major consideration when choosing the grit grade to start with. Grits 24, 36, 50, and 60 are primarily designed for stock removal. Grits 24 and 36 will remove the most material in one pass, whether you are doing abrasive planing, cleaning up glued panels, or flattening stock. Grits from 100 through 220 are primarily finishing grits designed to remove the scratch pattern from the previous grit used. For best results, never skip more than one grit grade when progressing through a sanding sequence.
For fine work, such as furniture, try not to skip any grit grades during the sanding process.
END OF THE PROCEDURE