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JET JBM-5 Benchtop Mortiser
Durable power for the home shop
Text, photos and video by Tom Hintz
Posted - 6-1-2010
The JET JBM-5 Benchtop Mortiser may have been designed with the home woodshop in mind but a load of cast iron and steel formed into a tough, user-friendly machine gives it industrial-like properties. The common sense design and simple function of this machine translates into easy mortising. JET's attention to quality means the JET JBM-5 Benchtop Mortiser will continue performing for many years to come.
Iron and Steel
The JET JBM-5 Benchtop Mortiser is built using real cast iron and steel. No nonsense castings and quality machining make this a stable, smooth operating machine. The heavy-walled steel column can even be installed on the base 180-degrees from normal to provide lots of room for oversized pieces by working "off the bench".
The JET JBM-5 Benchtop Mortiser is stabilized by the 7-1/2" by 12-1/4" cast iron base. This base serves as a mount for the worktable and fence but also has cast-in holes for bolting the JET JBM-5 Benchtop Mortiser firmly to a suitable surface. It should be noted that if you reverse the column and powerhead the base MUST BE bolted to a secure surface to prevent the JET JBM-5 Benchtop Mortiser from tipping over. This is one of those things that should be a no-brainer but you just know someone will reverse the powerhead off of the base, watch it fall over and then blame everyone else for the crash.
A 13-5/8"-long by 6"-deep MDF table comes predrilled for two screws that secure it to the base. While there should be little wear on this table in normal use, it would be easy to use this one as a template to cut one yourself should that become necessary.
Mounted on a shaft through the main column is a cast iron fence with a 13-3/4"-long by 1-9/16"-tall milled face. The fence position (front to back) is adjusted with a single lever bolt at the column. The fence face has holes pre-drilled for mounting auxiliary wooden fences for taller jobs.
At the center of the fence is an iron hold-down that can be adjusted vertically on its steel shaft with a simple finger-operated lever bolt. This hold-down has a maximum height of 4".
The JET JBM-5 Benchtop Mortiser is powered by a 1/2HP, 1Ph, 115V TEFC (totally enclosed fan cooled) motor with a heavily finned steel case. That case design dissipates heat far better than smooth sheet steel versions found on cheaper motors. That extra cooling translates into increased efficiency and a very long life for the JET JBM-5 Benchtop Mortiser motor.
The motor power is rated using the continuous duty cycle rather than the "peak" or "max developed" verbal camouflage some others use attempting to inflate your opinion of lesser motors. JET motors are more powerful on purpose so they can handle the demands of even a busy shop. That extra power means that the motor can turn the bits at a very consistent 1725 RPM for maximum efficiency with all of the compatible chisel sizes.
A heavy-duty On/Off switch is mounted right on the motor where it is easily accessible by the operator. To keep the shop safer when you are not around the switch has a removable "key" that disables the On/Off switch when it is removed.
Chuck & Chisels
The JET JBM-5 Benchtop Mortiser comes fitted with a 3/8"-capacity chuck mounted directly to the motor shaft. A shaft extension is included to configure this mortiser to use short-shanked chisels.
Hinged doors on both sides of the powerhead provide easy access to the chuck for bit/chisel changes. An extended chuck key is included with the JET JBM-5 Benchtop Mortiser that makes changing bits much easier with fewer bruised knuckles. A spring clip on the side of the power head stores the chuck key where you can find it, assuming you put it away in the first place.
The JET JBM-5 Benchtop Mortiser is compatible with chisels up to 1/2 by 1/2" with shanks of 5/8" and 3/4" diameters. Bushings are included for both shank sizes. This JET JBM-5 Benchtop Mortiser comes with 1/4", 3/8" and 1/2" chisel/auger sets that will cover a huge range of mortising work in the average shop.
The JET JBM-5 Benchtop Mortiser has a total vertical head stroke of 4-3/4" to accommodate most material sizes and chisel lengths. The head moves on a rigid, 1-7/8"-diameter ground tubular steel support column. The column is secured to the base by three machine screws through a flange on the end of the column. Additional holes are provided so that the entire column can be turned and remounted 180-degrees to work "off the table" if very big project pieces come along.
The head is moved vertically by a tough rack and pinion drive that is easy to use, smooth-operating and virtually wobble free. A 16-1/2"-long all steel handle provides plenty of leverage for mortising even tough woods. The boss into which the handle mounts can be pulled out and repositioned on the shafts' splines so the operator always has a full, comfortable stroke when mortising.
The powerhead action is steadied by a "shock absorber" on the side. Though not obvious when using the JET JBM-5 Benchtop Mortiser, this "shock" does make this a smoother operating, more predictable machine.
An easy-to-use depth stop rod is mounted on the let side of the head. A single lever locking screw is used to set the stop rod at the depth needed for the job. This is a very simple but very effective depth stop system that makes it easy to produce mortises with consistent depth whether you are making one or a hundred mortises.
In the Shop
The JET JBM-5 Benchtop Mortiser arrives mostly assembled from the factory. To ready it for use you have to install the operating handle, table, dampener assembly and fence. There really are no alignments necessary during the setup process so in ten minutes or so, you are ready to make mortises.
The only cautions I have on the JET JBM-5 Benchtop Mortiser is that the chisels actually are very sharp so using a heavy glove or scrap of wood to hold the business end when installing the chisels should make sense to you. The other is that while the JET JBM-5 Benchtop Mortiser seems reasonably stable when just placed on a flat, solid surface, it always is a much better idea to bolt (or clamp) the base to a suitable surface. Be smart first, look cool (or dumb) second.
The instruction manual explains installing and adjusting the chisel sets that come with the JET JBM-5 Benchtop Mortiser. This one setting can make or break the performance of an otherwise perfectly good mortiser. Take your time learning to install the bits/chisels and your mortising life thereafter will be far easier. I also have a dedicated story on this setup procedure as it can mystify some folks until they have done it a few times. Click Here to see that story.
Setting the fence is a simple task as is adjusting the depth stop. The one thing that seems to fake out people is setting the operating arm to get the most comfortable stroke. First, you just pull the arm mount outwards, turn the arm to where you want it and let it slip back over the splines on the shaft. The idea is to position the arm so that you can make clean, one-motion strokes to cut the mortise. This is a very simple feature but one you will come to appreciate.
Overall the JET JBM-5 Benchtop Mortiser simply works very well. It is not a fancy machine with bogus bells and whistles but rather a well designed one for cutting mortises. No frills just solid materials and design that offers a long lasting machine that enhances your woodworking. I hated mortise and tenon joints until I brought the first mortising machine into my shop. Now I will never be without one. If you enjoy cutting mortises by hand, great. If you want a machine some of or all of the time, the JET JBM-5 Benchtop Mortiser is a very good machine to consider.
With a street price of $299.99 (5-25-2010) the JET JBM-5 Benchtop Mortiser is a worthwhile investment that makes this traditional joint easier and faster to make. The durability of this machine makes it a solid long-term investment, something we all need in our woodworking shops these days.
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