Popular Woodworking 2005-10 № 150, страница 96

STEPS FOR SETTING PLANER KNIVES

■ Unplug the machine!

■ Before you start, measure from the bed to the cutterhead to determine if they are parallel.

■ Then measure from the bed to the knife at bottom dead center at both ends of the cutterhead.

■ If the bed and cutterhead are parallel, you want to set the knives a consistent distance from the cutterhead. If they are out of parallel by a few thousandths, you can compensate by setting one end of the knife out by the difference. However, if they are out more than that, you will need to adjust the bed of the machine.

■ Change one knife at a time. Set your jig the correct distance from the cutterhead based on existing knife placement or using the manufacturer's specifications.

■ Tighten the knives just enough to hold them in place without falling while you set them in place. If you have springs, let the jig push against the knives to set the correct distance. If you have jackscrews, adjust the screws to set the knives against the jig.

■ Tighten the knife like you would tighten the lug nuts on a car wheel. Alternate nuts, get them snug, then go around a second time.

■ Make sure that tightening doesn't move the position of the knife. The turn of the wrench can move it a few thousandths of an inch.

■ Double-check your work by measuring the bed-to-knife distance at each end of each knife. - RL

The easiest way to set the knife at the proper distance is to use a magnetic jig. Leave yourself room for the wrench when you position the jig.

results. Tightening the knives in our planer's head pushed the jig out of place by about .005"".

Jointer Pal

This device, which holds jointer knives with magnets, comes in two versions, one with a plastic base, and a more expensive one with a metal base. The plastic one seemed to grip a little better than the metal. Like the Planer Pal, these work very well if you can get (and hold) the cutterhead in the right place.

The key to using the Jointer Pal is getting the cutterhead exactly at top dead center, and then making reference marks on the jointer fence and the outfeed

The magnet holding the knife in the Planer Pal is adjustable to set the knife the correct distance from the cutterhead.

table to get the jig positioned correctly for each knife.

Making the Right Choice

There are two steps to changing knives. The first, and the only really necessary one, is setting the knives in the right position. The second step is accurately measuring where the knives are. If you use the measuring tools for setting, you will go insane watching the needle on the dial indicator bounce up and down a few thousandths as you position and tighten the knives. We like the magnetic holding jigs, but aren't so sure about the value of the measuring tools we tested.

All were well made and quite

The Magnetic Planer Setting Jig also has an adjustable knife magnet, but its small size made the jig less reliable.

Tightening the knives can cause them to move away slightly from the cutterhead. Use a jig to hold them while tightening and always double-check your work afterwards.

92

Popular Woodworking October 2005