How to Mill Using a Slitting Saw

Slitting blades have teeth very similar to circular saw blades, but are often much smaller.

Milling slits into metal is done with a slitting saw. You can use one or more blades on a tool holder to cut slits into any type of material, including aluminum, steel or brass. The saw blades have teeth and must be positioned on the holder with a key slot as if they are loose, or they will not cut properly. The key slot keeps them from spinning loosely, and allows them to grip the material and cut. Slitting requires coolant and very low speeds and feeds.

Things You'll Need

• Slitting blades
• Slitting saw holder
• Wrenches
• Vise
• T-bolts
• Dial indicator
• Coolant

Instructions

1. Set up the slitting saw in the tool holder for cutting. Place the number of saw blades you will need for the job on the saw blade shaft. Calculate the slot size you will need and the pattern of slits to cut for the job to choose the correct saw blades. Line each saw blade up matching the key slot with the key way on the shaft of the slitting saw holder. Place them all on the shaft and tighten the retention bolt to hold them in place.

2. Place the tool holder in the milling machine spindle. Slide it into a collet and slide the collet into the spindle hole and tighten the draw bar. Tighten it by hand first and then use a wrench to tighten it further so that it does not come loose while cutting. Move the spindle out of the way to place the vise on the work table.

3. Clean the table and the bottom of the vise and place it on the work table near the middle. This will allow you to cut in either direction without hitting the travel limit. Slide one T-bolt on each side of the vise to hold it down and place a dial indicator on the spindle. Move the spindle into place above the vise and set the indicator needle on the front face of the vise. Move the work table in the negative Y-axis direction to apply pressure to the tip of the indicator.

4. Readjust the bezel of the dial indicator to zero and move the work table along the X-axis, left to right, to measure the straightness of the vise. Tap it on either side to make it straight, which would entail a zero reading on the indicator across the entire front of the vise. Tighten the T-bolts with a wrench and check the vise once again for straightness. make any adjustments necessary, including loosening the T-bolts to tap it straight again.

5. Place the raw material to cut in the vise and tighten it. Bring the slitting saw to the outside of the material, on the cutting side, just to the left or right of the material. Look at the direction of the teeth to decide which side to choose. The cutter must spin clockwise and the teeth must cut into the material against the grain. Start the spindle and adjust the speed to about 250 rpm as the slitting saw must be run slowly to prevent teeth breakage.

6. Make small cuts to prevent too much load from breaking the blades and use ample coolant to prevent heat damage. Take passes of 0.01 of an inch to prolong the life of the tool and material. Check the state of the blades and the measure the material after every pass.

References

• Sherline: Use of a Slitting Saw