Dremel 398 owner manual Operating Speeds for Accessories, Electronic Feedback Circuitry EFC, Tool

Operating Speeds for Accessories

Electronic Feedback Circuitry (EFC)

Your tool is equipped with a internal electronic feedback system that provides a "soft start", which will reduce the stresses that occur from a high torque start. The system also helps to keep the pre- selected rotating speed virtually constant between no-load and load conditions.

Set the speed indicator to fit the job; to achieve the best job results when working with different mate- rials, the speed of the Rotary Tool should be regu- lated. Model 398 Rotary Tool has an integral speed control.

!An external speed control CAUTION should never be used with this

tool.

To select the right speed for each job, use a practice piece of material. Vary speed to find the best speed for the accessory you are using and the job to be done.

NOTE: Speed is affected by voltage changes. A reduced incoming voltage will slow the RPM of the tool, especially at the lowest setting. If your tool appears to be running slowly increase the speed setting accordingly.

Digital Speed Selector Switch

Your rotary tool features a digital speed selector switch which displays an L.C.D. reading of the tool’s RPM. The speed can be selected from 5,000 RPM to 35,000 RPM in 1,000 RPM increments by simply depressing the positive or negative buttons on the switch.

TO TURN TOOL "ON": slide ON/OFF switch to the "ON" position.

TO TURN TOOL "OFF": slide ON/OFF switch to the "OFF" position.

TO INCREASE SPEED: depress button with + sign.

TO DECREASE SPEED: depress button with - sign.

Needs for Slower Speeds

Certain materials, however, (some plastics, for ex- ample) require a relatively slow speed because at high speed the friction of the accessory generates heat and causes the plastic to melt.

Slow speeds (15,000 RPM or less) usually are best for polishing operations employing the felt polishing accessories. They may also be best for working on delicate projects as “eggery” work, delicate wood carving and fragile model parts. All brushing applications require lower speeds to avoid wire discharge from the holder.

Higher speeds are better for carving, cutting, routing, shaping, cutting dadoes or rabbets in wood.

Hardwoods, metals and glass require high speed operation, and drilling should also be done at high speeds.

The point to remember is this: You can do the great majority of work at its regular speed of 35,000 RPM. But for certain materials and types of work, you need slower speeds — which is the reason the variable speed models were developed.

To aid you in determining the optimum operational speed for different materials and different accessories, we have constructed a series of tables that appear on page 13, 14, and 15. By referring to these tables, you can discover the recommended speeds for each type of accessory. Look these tables over and become familiar with them.

Ultimately, the best way to determine the correct speed for work on any material is to practice for a few minutes on a piece of scrap, even after referring to the chart. You can quickly learn that a slower or faster speed is more effective just by observing what happens as you make a pass or two at different speeds. When working with plastic, for example, start at a slow rate of speed and increase the speed until you observe that the plastic is melting at the point of contact. Then reduce the speed slightly to get the optimum working speed.

Some rules of thumb in regard to speed:

1.Plastic and materials that melt at low temperatures should be cut at low speeds.

2.Polishing, buffing and cleaning with a wire brush must be done at speeds below 15,000 RPM to prevent damage to the brush.

3.Wood should be cut at high speed.

4.Iron or steel should be cut at top speed if using tungsten carbide accessory, but at slower speeds if using high speed steel cutters. If a high speed steel cutter starts to chatter — this normally means it is running too slow.

5.Aluminum, copper alloys, lead alloys, zinc alloys and tin may be cut at various speeds, depending on the type of cutting being done. Use paraffin or other suitable lubricant on the cutter to prevent the cut material from adhering to the cutter teeth.

Increasing the pressure on the tool is not the answer when it is not cutting as you think it should. Perhaps you should be using a different cutter, and perhaps an adjustment in speed would solve the problem. But leaning on the tool seldom helps.

Use only Dremel Tested, High Performance Accessories.

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