Zip Slot Mortise Mill - Fine Woodworking Tool Review
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Zip Slot Mortise Mill

JessEm - Zip Slot Mortise Mill

The Zip Slot Mortise Mill lets you cut mortises with a special bit driven by any drill-corded or cordless.

$250 (As of 3/1/2009)

(4 user reviews) Write a Review

Editor's Review: Choose the Right Drill Bit for the Job

by Jeff Miller

review date: March 1, 2009

Jessem Tool Company recently introduced a unique jig called the Zip Slot Mortise Mill that lets you cut mortises with a special bit driven by any drill-corded or cordless.

After clamping on a workpiece, you just slip the bit into a bearing-guided bushing that's part of a sliding carriage. Then you start the drill and move the carriage back and forth while pushing the bit incrementally deeper with each pass. The jig is nicely machined and well made. Even after a lot of practice with the jig, however, it was easy to end up with slightly stepped side walls, evidence of each back-and-forth pass. That said, the variation was less than 0.005 in. total, and the mortises produced by the jig were generally better than I can drill and chop with a chisel.

Zip Slot Mortise Mill

The jig cuts mortises up to 3-3/8 in. long, located up to 1-7/8 in. from a board edge. The standard bit cuts a 3/8-in-wide mortise; accessory bit and bearing sets that cut 1/4-in.- and 1/2-in.-wide mortises are available. Changing from one set to another was quick and easy.

The jig sells for $250 at; they sell several sizes of loose tenons, too. For information, go to

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Editor Test Results:

Runout N/A

Manufacturer Specifications

Manufacturer JessEm
Manufacturer's Web Site
Manufacturer's Phone Number 866-272-7492
Chuck Capacity N/A

No comments.

Looks like a waste of money. Why not buy a regular mortiser?

I purchased my zip slot mortise mill about 6 months ago for $170 CAN. I have found it very easy to use and no more difficult to setup then another other style of mortising machine. The results have been very satisfying. As with any Jessem product the quality is first class. The only fault I have found to this point is having to fumble with a clamp while trying to secure the work-piece. I spoke with a Jessem company rep at a recent trade show and he advised me they were coming out with more accessories i.e. a clamping system in the near future. I purchased the ¼” and ½” bit and bearing sets for less than $50 at the last show which I didn’t find unreasonable considering you’re getting the bearing assembly and special bits. Overall I’m very pleased with the tool it’s just another option in the shop. Bruce Ontario

Like all jigs, setup is critical and not nearly as straight foward as the manufacturer would have you believe. While JessEm certainly makes a number of high quality tools most of their items are overly complex IMO. While greater versitility requires greater complexity, so does it invite greater variance the enemy of all woodworking joinery. All that is excepting one, the loose tenon which at its core it tends to be much more forgiving. For the professional speed and accuracy are paramount. In terms of speed this unit ranks below average. Its accuracy is for the job type consistent and accurate within the bounds of the machine doing the cutting. Cuts are consistently cleaner than I can do as quickly with my hand drill and chisels. The downside here is that this thing is EXPENSIVE! Unlike a stationary dedicated mortiser (which it is) does not come with everything you need. By the time you've paid for this kit you could easily have purchased a quality bench top mortiser and all the HMC bits you'll need. I've toyed with purchasing a bench top unit many times (I cut my mortises by hand) but have always decided that a Forstner bit and a good chisel is more than adequate and much more versatile. But for those for whom its cost is not an issue (about $250 for the basic unit and much closer to $400 with everything you'll need to optimize its usefulness) it is an interesting space saving alternative.

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