Abrasives

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.

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 pressure rollers. Try to only process multiple pieces of similar thickness. If there is a significant thickness difference, the thinner pieces may slip on the conveyor belt if they do not contact the pressure rollers.

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 small stock, clamp several pieces together to prevent them from slipping 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.

Figure 20

Face Frames & Raised Panel Doors

It is 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 of the stiles.

Reversing Conveyor Direction

If a board becomes jammed under the rollers, back it out by reversing the conveyor direction, using the switch (Fig. 21). Do not perform sanding operations in reverse mode, as the drums rotate in one direction only.

Allow the conveyor belt to come to a complete stop before reversing direction.

Figure 21

The abrasive material you choose will have a substantial effect on the performance of your sander. Variations in paper type, weight, coating and durability all contribute to achieving your desired finish. Ready-To-Cut strips are available from WMH Tool Group and are listed on page 38.

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. This means if you are using two different grits on your DDS-225 dual drum sander, the coarser grit should always be placed on the front drum.

The amount of stock to be removed is a major consideration when choosing the grit grade to start with. Grits 36 and 60 are primarily designed for stock removal; grits over 100 are primarily finishing grits designed to remove the scratch pattern from the previous grit used. For best

DDS-225, DDS-237 specifications

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