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JET JFM-5 Hollow Chisel Mortiser
Great design + great manufacturing = one cool tool
Text, photos & video by Tom Hintz
Posted - 11-23-2007
For many woodworkers, cutting mortises - particularly lots of them - is not high on their fun things to do list until a cool mortising machine finds its way into their shop. The JET JFM-5 Hollow Chisel Mortiser is hereby ordained as such a cool tool.
Construction and Power
The JET JFM-5 Hollow Chisel Mortiser is built from several well-made iron castings, each of which has been precisely machined. The powerhead and table slide on dovetail-shaped keyways that are more time consuming to make but known to be very accurate. All of these slides have gib screw adjusters that allow you to create the feel you like and compensate for wear should that actually occur a decade or two down the road.
Even the 14"-wide, 16"-deep, 23 1/2"-tall base cabinet is all steel, fully welded and structurally heavy duty. A padded shelf has been added to its interior behind a surprisingly heavy door with a positive latch. The base cabinet puts the material able at a comfortable 32 " height above the floor.
The base cabinet does not have wheels but does fit nicely into a JET universal mobile base that allows this 240-some pound machine to roll around the shop easily.
The JET JFM-5 Hollow Chisel Mortiser is powered by a real 1 hp TEFC (totally enclosed fan cooled) motor, rated by JET using a continuous duty cycle rather than the "Max developed" or "peak" hocus pocus that some other manufacturers think we still believe. The motor turns the chuck at a very consistent 1725 rpm which seems to be just right for this kind of drilling/chiseling operation. A heavy-duty industrial style pushbutton On/Off switch is mounted next to the motor where it is easy to reach and see.
Chuck and Bushings
A pair of hinged doors, one on either side of the powerhead encloses the high quality, 1/2" capacity, key-operated, 3-jaw chuck. An extended chuck key is included that helps keep your knuckles out of harms way when installing or removing the auger bits. As mounted from the factory the chuck is compatible with the popular long-shank auger bits. However, a chuck extender is included that when installed between the chuck and spindle allows using short shanked auger bits.
The powerhead housing below the chuck is bored for a set of three bushings that accommodate chisels with 5/8", 3/4" and 1 1/8"-diameter shanks. These bushings are compatible with JET auger/chisel sets in 1/4", 5/16", 3/8", 1/2", and 3/4" sizes. The bushings are included with the JET JFM-5 Hollow Chisel Mortiser - the bits are not.
Not packing a set of bits with the JET JFM-5 Hollow Chisel Mortiser is an increasingly common way to reduce the selling price. Frankly, it makes sense because few woodworkers use more than one or two chisel sizes for the work they do. Buying the chisel sets you really need saves money up front and down the road.
Stuff That Moves
The up and down motion of the powerhead is driven by a rack and pinion system. What is different about the JET JFM-5 Hollow Chisel Mortiser is how well that rack and pinion is made and the 24"-long all-steel handle that operates it.
The handle is mounted to a spring-loaded cast iron hub that can be pulled out and repositioned on the splined pinion shaft. That enables the operator to use the most comfortable stroke for the job. That may seem like a small thing but it makes cutting mortises way easier and safer.
The JET JFM-5 Hollow Chisel Mortiser has a basic-looking stop rod arrangement for controlling the depth of cut. However, in place of the thumbscrew or bolt so common on other mortisers, JET added a repositionable handle that is very easy to use.
Not so common is that the depth rod is located just behind the line of force on the main column. This position helps prevent deflection of the bit when the stop rod hits its base. This helps the JET JFM-5 Hollow Chisel Mortiser to cut exceptionally clean mortises and reduces side loads and wear on the chisels and auger bits.
What is very different about the JET JFM-5 Hollow Chisel Mortiser is the X/Y table movement. Many woodworkers bought a separate X/Y vise to add to their mortising machines and often had to deal with clashes between the vise and the mortiser table. JET saves you that trouble by building X/Y movement in as a standard feature.
Front-mounted 5"-diameter handwheels with spinner knobs control each movement. Both axis move smoothly on dovetailed keyways fitted with gib screws that make adjusting wear out fast and simple. Below the front edge of the tabled is a pair of collars that can be set to limit table travel to the left and right. This is very handy when cutting multiple mortises, speeding that process while insuring consistent length. Many people when they have time, always trying to play gamed. Especially because these friv games are good tools for relieving stress and different kinds of depression. And good thing is that there are actually many available games, that you can choose.
The built in table movement is not only cool, it is necessary because JET made the table from cast iron, including the fence. At 20 1/4" long, 7"-deep and a cast-on 3 1/2"-tall fence, this table could be a handful to adjust manually. A pre-cut and drilled, full-size MDF table cover board is included.
Stop and Hold
A fully adjustable, rod-based material stop is included with the JET JFM-5 Hollow Chisel Mortiser that makes repetitive cuts very accurate. The stop device mounts to bosses cast into the fence that allow it to be used on either end of the table. All of the stop adjustments are done with easy to use set screws equipped with paddle-type handles.
To secure the wood to the table JET added an exceptionally versatile clamping system. Special "Quick-Adjust threads let you slide the wide cast iron clamp face (pre drilled for attaching an auxiliary face or jig) against the wood and then turn the handle to apply pressure. The threads don't "catch" until you begin turning the handle to apply pressure. Very nice, very fast and no, I don't know how it does that. It does and that's all I am concerned with!
The mount for the clamp is also out of the ordinary. A pair of hex head bolts secures the clamp mount to the table but one of those bolts passes through an arched slot that lets you pivot the clamp. Securing odd shaped or angled material has never been easier.
In the Shop
Like many of you I have owned different versions of the same machine along the way, usually progressing from a benchtop model to the floor or stationary version with predictable results. The floor models are generally more robust, have larger capacities and are frequently more accurate. The JET JFM-5 Hollow Chisel Mortiser abides by all of those observations but adds the promise of long-term durability thrown in as well. This is a well made machine with a load of user friendly features that make cutting mortises easier, more accurate and safer.
I like moving parts that slide on dovetail-shaped keyways, especially when they have gib screw adjusters. This kind of slide is always very accurate, seldom wears very much, but the gib screws mean you can compensate for wear - if wear ever happens. The quality of the materials and construction make it unlikely you will need to use this adjustment anytime soon. Note: You do have to set the gib screws initially because they are tightened down at the factory to prevent unwanted movement during shipping.
The rack and pinion drive system for the powerhead is nice and the 24"-long operating arm goes a long way towards reducing operator effort, something you really appreciate when making lots of mortises.
The X/Y table movement turns out to be the headline feature. Combined with the table travel stops, the adjustable work stop and the very trick clamping system, the table movement feature completes a system that makes cutting mortises on the JET JFM-5 Hollow Chisel Mortiser very accurate and very easy. Cutting large numbers of similar mortises is even faster and just as accurate.
Throughout the evaluation the JET JFM-5 Hollow Chisel Mortiser did everything as expected, often better than I anticipated. The motor is more than strong enough for the toughest woods I could find and the JET chisel sets used for these tests performed perfectly. Even the instruction manual is easy to use and clearly shows important information regarding the setup and use of the JET JFM-5 Hollow Chisel Mortiser.
If you need a mortiser, the JET JFM-5 Hollow Chisel Mortiser would be a good choice. It's heavy-duty construction, smooth operation and full set of features make the JET JFM-5 Hollow Chisel Mortiser very productive, very tough and very easy to use.
With a street price of around $900 (11-23-2007) for the JET JFM-5 Hollow Chisel Mortiser with the enclosed stand, this is an investment with long term implications. Mortises will not go out of style and the durability of the JET JFM-5 Hollow Chisel Mortiser insure it will continue to make your woodworking more productive and more fun for a very long time.
JET auger/chisel sets carry a street price of around $27 each for most sizes with the 3/4" version running about $42.
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