Academy Notes and Tips - Clean Cuts

Academy Notes and Tips

NOV/DEC 2003
Volume 46/Issue 6

IN THIS ISSUE
Project Articles
• California Dream Toys
• The Mantel Clock
• Christmas Tree Ornaments

DEPARTMENTS
• Ask Smitty
• Owner’s Gallery
• Letters from Owners

Academy Notes
Clean Cuts - Pt. 3 - All About Router Bits

Service Pointers
MARK V Saw Guards

Safety Tips
Proper Workshop Lighting

What's New
When accuracy counts Incra Rules

EDUCATION
• Find A Shopsmith Woodworking Academy Near You
• National Woodworking Academy in Dayton, OH

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From the Shopsmith Woodworking Academy
Clean Cuts -- Part 3--All About Router Bits
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Fig. 2. Honing face of router bit on benchstone.

Honing almost all router bits is based on the principle that the whole face of the cutting flute is on one plane. If that flat plane is large enough, you can find and hone it. Touch-up sharpening is always done on the face of the flute and never on its contoured profile (See Fig. 2).

Unlike honing large chisels on a benchstone, the action of the stone on these small tools is limited to very, very small movements: 1/4" of total back-and-forth movement, or even less.

Fig. 3. Drill chuck mounted on tailstock chuck arbor to hold router bits while sharpening.

You might choose to mount the bit securely in a vise and move the stone instead of the bit during sharpening. You can put together a very handy device for doing this job by mounting your MARK V's Drill Chuck in the Tailstock Chuck Arbor, slipping it into your MARK V's Tailstock and using it as shown in Figure 3.

Squirt a drop or two of oil on the bit itself and position the stone on the major portion of the flat of the bit. Avoid rubbing the pilot of the bit (on solid pilot bits), as this will ruin it. When the oil on the bit darkens with swarf (little flakes of metal), you'll know that you're on your way to a sharp edge.

If you're having trouble getting the feel of the flat, you can check just how well you're doing by using a dark color, felt-tipped marker to coat the bit's face. By checking to see how much of the color is removed, you can tell whether you're honing the entire surface. It helps to use a good, concentrated light and a magnifying glass.

If a burr forms on the profile of the bit, remove it very carefully with a Hard Arkansas Stone.

To check for sharpness, run the cutting edge over your thumbnail: it should “grab” the nail and leave a slight “track” rather than slip over it easily.

The shaft: don't overwork it.
A small shank coupled with a large cutting edge can weaken a bit. The larger the shank, the stronger the bit. This is one reason why Shopsmith offers a selection of bits made with 1/2" shanks for those tough straight or dovetail-cutting jobs.

Don't overwork the shank or the cutting edge by “hogging” into stock at high speeds and fast feed rates. This will stress the bit and the router motor...overheating both. Whenever practical, take a series of light cuts in smooth passes.

When mounting a bit in the Router's chuck or collet, push it in until the shaft bottoms-out, then retract it about 1/16" to 1/8". This will prevent the transfer of heat and vibrations directly to the motor armature of your hand-held router.

General routing tips
Always try to feed your stock into the router against the rotation of the router bit. This keeps the speeding bit from “grabbing” the workpiece and forcing it past the bit's cutting edges too quickly.

Clean router bits always work better. Pitch and resin build-up can seriously affect the performance of even a sharp router bit, causing burning and unsightly marks. If you notice a build-up of pitch or resin, remove it immediately with a commercial sawblade cleaner.

CAUTION: Remove the ball bearing pilots before performing this cleaning operation...as these cleaners can remove all lubrication from these bearings, rendering them useless.

When used to trim laminate material, a router bit with a ball bearing pilot can really get gummed-up. Clean the outer collar of the bearing with the tip of a rag soaked in a solvent that will dissolve the type of glue used. Once cleaned, use a bearing lubricant to re-lubricate the bearing pilots before going back to work.

If you're using your MARK V for routing with either the 1/2" shank bits or with 1/4" shank bits and our special 1/4" Router Chuck, you should rev the machine up to its maximum speed of 5200 rpm's.

For even smoother cuts, add the Shopsmith Speed Increaser to boost your routing speeds to 10,000 rpm's. But just remember...although higher speeds can produce better results...so can slowing down your feed rates and taking a series of lighter cuts.

Coming up in the January/February issue -- PART FOUR - Oriental Waterstones