By Simon Watts

Tedswoodworking Plans

Ted's Woodworking Plans

Get Instant Access

and then I'll describe the various machines that do the same job.

Any machine involves some setup time. If you have only a few mortises to deal with, it's often quicker to mark them out individuallv, drill out the

waste, and chisel to the lines. If you don't have a drill press, a self-centering doweling jig speeds the work and keeps holes square to the surface.

Hollow-Chisel Mortising

If you already own a drill press, consider buying a hollow-chisel mortising attachment to go with it. This attach-

mcnt consists of a sturdy cast-iron frame, or yoke, which clamps to the quill of the drill press. (See photo.) Into this yoke fits a square hollow chisel that's pushed down into the work while a rotating hit inside removes the waste. You can cut mortises up to H in. across. 3 in. deep, and any length you want.

A hollow-chisel mortiser cuts square-ended mortises that need minimal cleanup with a chisel. However, this method is relatively slow, and the hollow chisels are expensive, tricky to sharpen, and take time to set up. An even bigger consideration for a busy shop, tiie mortising attachment tics up the drill press.

If you go the hollow-chisel route, make sure that the mortising attachment you select tits your drill press—it's the diameter of the quill that matters. Along with the attachment itself, you'll need to order hollow chisels and bits. Mike sure that the shanks of these cliis-

cls also fit the vokc—usuallv a > » in. dia. * •

Large chisels take considerable effort to withdraw—especially from hardwood. If the chisel remains embedded in the wood, the cast-iron yoke is likely to slip down the quill. If tills happens, the rotating bit is pulled up iaside the chisel, causing severe damage to both bit and chisel—even splitting the steel, as shown in the photo.

Slippage occurs when the bolt that clamps the yoke to the quill has not been sufficiently tightened. I've found that the standard bolts supplied with mortising attachments arc often inadequate and shear off when threatened with even moderate torque. Hie solution is to replace them with a stronger bolt before they fail. Stainless-steel bolts are an option, but high-tensile bolts are better. You want at least a grade three (Ux)k for five ridges on the head of the bolt) or, better yet, grade eight with six or seven ridge*».

All of the hollow-chisel mortising attachments come with a hold-down, a fence, and two adjustable curved retaining Ixtrs that keep the work against the fence. For heavy cuts. I've found these ready-made devices wanting, so I improvise my own. *

What works best Is to have a fence and counterfence clamped securely to the drill-press table. (See photo, previous page.) A third block, slightly offset.

Wood Being Chisled
This hollow cliiiel split when lli«» rotating hit was pulled up inside the chisel as the chisel was being withdrawn from the wood.

acts as a hold-down. A shop vacuum (reversed) blows the chips away to reveal the guide marks. The air flow also helps cool the chisel.

Hollow chisels (with matching bits) are available in widths from '/« in. to V. in. However, I'd limit the larger chisels to a substantial drill press. I've found the siirin, and Vin. sizes lo lx- the most useful. Two parallel, narrow mortises make a stronger joint than one wide mortise.

Unless the hollow chisel is supported on all four sides, it will wander oft" the vertical. This is especially important at the ends of the mortise, so cut these first, and then remove the wood in between.

The limits of the mortise can either Ik* set with stop blocks clamped to a fence or marked with a couple of pencil lines or knife cuts. The depth-of-cut is

Drill Attachment Dove Tails
This I-(--in. drill press is fitt«Ml with a c«inveiitional hollow-chisel mortising attachment.

Tilt* Kuuter.Mmtcr is a sturdy mount-

in«: carriage for a heavy-duty router.

Tilt* Kuuter.Mmtcr is a sturdy mount-

in«: carriage for a heavy-duty router.

Mortise And Tenon Drill Press
Thi* lieuehtop hollow-chisel mortis-cr i> iui|H)rtc<l from England by Dclta. It taken chisel* from '/« in. lo '/2 in.
Mortise And Tenon Drill Press

The Joitilmastcr Joinery System cuts dovetail;* as well as mortises and tenons.

The Mulli-ltouler in a versatile machine that cuts a variety of woodworking joints widi precision.

The Joitilmastcr Joinery System cuts dovetail;* as well as mortises and tenons.

set with the depth stop that's provided on most drill presses. For a haunchcd mortise, simply slip a wood spacer block under the depth stop when making the shallower cuts.

A benchtop mortiser is a good alternative to a hollow-chisel mortising attachment. This is a portable hollow-chisel mortiser that takes up little space, docs an excellent job. and doesn't tie up the drill press. It is less tiring to operate than a drill press is because the lever arm Is longer and the action smoother. It also comes with a sturdy hold-down tliat needs no modification. A further advantage is that it readily converts to a small drill press should the need arise.

The one drawback is the 3.400-rpm motor that direct I v drives the cutter.

Was this article helpful?

0 0
Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

Get My Free Ebook

Post a comment