Affordable benchtop mortisers have changed the way many woodworkers produce joinery for a variety of projects. By being able to conveniently make one of the strongest woodworking joints — the mortise-and-tenon joint — we can produce more durable projects.

That said, a benchtop mortiser has limitations. Primarily, the table, fence and how the workpiece is held in place all can be improved.

The Problem: The Holddown

All mortisers have a fence running from left to right behind the bit. The fence can be adjusted forward and back to orient the mortise location directly under the mortising chisel. Then the fence is locked down.

To keep your work held in place while mortising, you can clamp it to the fence. Or you can secure it using the holddown, which keeps the work from lifting off the table when you pull the tooling out of the cut. After each plunge, you need to shift the work left or right to make the next hole.

Having to unclamp, move and reclamp the workpiece before drilling each hole takes a long time. And many holddowns on mortisers have design shortcomings that cause them to slip during use, ruining your work.

The Solution: An X/Y Vise

Enter the cross-sliding (or sometimes called X/Y) vise: this nifty device allows you to hold the workpiece firmly in place but still be able to easily move it under the mortising chisel.

Originally designed for work on metal milling machines, cross-sliding vises allow the operator to clamp a workpiece tightly below the spindle (or, in our case, the chisel) then smoothly move the piece forward and back, as well as side-to-side, without having to release the work from the clamp.

Many floor-model mortisers have these vises built in, but these big machines can cost $800 or more. But we've found a $50 upgrade that can be added to almost any benchtop mortiser. If you don't have a mortiser, you can also use it to upgrade your drill press and use overlapping holes to effortlessly create your mortises.

Is it too good to be true? Well, almost. There are some technical difficulties to overcome before you decide if this vise belongs in your shop.

Problems with the Solution

First, as you'll note in the picture below left, there are three operational handles on the cross-sliding vise (X-axis, Y-axis and clamping handle) located on three of the four sides. The non-handled side is the one facing the column of the machine. This keeps the clamping vise oriented front-to-back so that if it is holding a table leg, for example, the leg will jut straight out from the mortiser. This orientation, which is at a 90° angle from the way a mortiser is usually used, puts the part in an awkward location during mortising. But that's only one problem.

The next hurdle is height. As shown in the photo below right, benchtop mortisers come in a variety of heights. The Shop Fox is designed to allow the motor to raise 12" above the table. This allows 8" below the chisel for the cross-sliding vise (shown attached). The Fisch mortiser (on the right) and most other benchtop mortisers available on the market today allow only 4" of space between the table and the tip of the chisel, leaving no room for the vise.

Combo Solutions

We've come up with a couple of options to solve both of these problems. First, by buying two separate metalworking accessories and combining them, the right-angle orientation problem can be solved. The photo on page 61 shows a compound slide table (Grizzly #G5757, $90) mounted directly to a drill press table. That provides the X- and Y-axis movement we're looking for, but doesn't give us a way to hold the work.

Mounted on top of the slide table is a 6" drill press vise (Grizzly #G5753, $22.50) that allows the workpiece to be oriented in the traditional left-to-right orientation. You need just a couple of bolts and you're ready to drill.

Fortunately, our floor-model drill press, which we have the two accessories mounted on, easily accommodates the extra 7" in added height. Unfortunately, a benchtop mortiser isn't quite so accommodating, but we'll get to that in a minute.

Machining Solution

You may have remembered that we threw out a $50 price tag earlier in this article. And if you're paying attention, you may have noticed that the slide table and vise combined cost more than $110. Well, there is another option that will put us back in the $50 range.

A single cross-sliding vise (Grizzly #G1064) costs only $40, but still has the workpiece orientation problem. But by moving a few of the pieces around on the vise and tapping two new bolt holes, it's easily rearranged to work just the way we want.

The end result has the vise handle and the front-to-back slide handle closer to each other than we'd like, but ultimately it's worth the little bit of metalwork to improve your mortiser's performance. We've included step-by-step photos to retrofit the cross-sliding vise for mortising work on pages 64 and 65.

Gaining Height

Even with our sleight of hand on the cross-sliding vise, there is still a height issue to deal with if you own a benchtop mortiser. While the cross-sliding vise adds only 51/2" above the table (compared to 7" with the combo solution), that 51/2" is still too high for most mortising machines.

To fix this, we need to build a riser, but building just a box (which is all most risers are) isn't good enough. Most benchtop mortiser columns can be unbolted from their base. The base is no longer necessary with the cross-sliding vise, but the column must still be firmly supported in proper orientation to the vise. Plus, when used, a mortiser exerts a fairly high amount of pressure against the column mount. Any flex in that connection will cause problems with your mortise.

So we came up with the riser box shown above. The "L" shape and torsion-box design make a riser and stand that's sturdy enough to park a car on and won't flex under the strain of mortising.

While the dimensions given worked for our mortiser, you may need to customize them to fit your situation. Make sure that when the chisel is plunged to full mortising depth, the tip of the chisel will reach the inside bottom of the vise opening. Everything else will then fall in place.

Also, the center supports (F) on the riser should be located directly under the mounting holes on the mortiser column. This allows the bolts holding the column in place to extend through the top (A) and into the supports for lots of strength.

As an added bonus, the spaces below the cross-sliding vise make clamping easy, and provide bit and tool storage.