Powermatic DDS-225 Abrasives, Edge Sanding, Sanding Imperfect Stock, Reversing Conveyor Direction

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 24

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. 25). 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 25

Abrasives

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 Powermatic and are listed on page 39.

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 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 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. In general, premium quality abrasives will produce a better finish with a less noticeable scratch pattern.

Grits that are too fine can sometimes burnish the wood and leave a glossy surface which will not accept stains evenly.

This will vary by type of wood. Oak, for example, is susceptible to burnishing because of its open pores.

Cleaning abrasive strips. Regularly clean the abrasive strips on the drums with commercially available cleaning sticks, following the manufacturer’s directions.

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