The FMT base unit retails for around $700 (see Sources, page 83). That’s a lot of cash, but we found the quality and performance of the jig are truly exceptional. It’s a tool that small professional shops or those who want a dedicated mortise and tenon machine will find well worth the investment.
The FMT base package includes the main jig, a router sub-base, five joint guides, a 5/16-in. spiral router bit and a thick, well-written owner’s manual (Photo 1). The sub-base comes with mounting hardware and can be attached to any currently available plunge router.
This basic setup enables you to cut 5/16-in.-thick tenons that are 1/2-in. to 1-1/2-in. wide, plus the corresponding mortises. Additional joint guides and router bits are available as options. With them you can make 17 additional standard-size joints as large as 1/2-in. thick by 2-1/2-in. wide and as small as 1/4-in. thick by 5/16-in. wide. By combining different router bits and guide templates you can make joints as small as 1/16 in. by 1/8 in. Now that’s a tiny joint! With all the options, the price of the FMT is over $900.
How it Works
The basic principle behind the jig is that the router sub-base has two guide pins that follow corresponding guides in the top of the main jig (Photo 1 and Fig. A).
The joint guide is interchangeable and width and length of the joint. The tracking guide is fixed. Its function is simply to direct the right side of the router side to side. The guide pins are tapered and can be adjusted up and down, which makes them ride tighter or looser against the joint and tracking guides. You control the fit of the joint by adjusting the pins. Turning the pins one-eighth turn will change the joint fit by .001 in. Getting good-fitting joints is a cinch considering that a mortise and tenon joint should have about .005 in. of clearance for glue.
The FMT produces only round-ended mortises and tenons (Photo 2). If you want a square joint you’ll have to trim the parts by hand or with another power tool. This machine also makes angle tenons, thanks to a pivoting front plate (Photo 3). This feature came in really handy when I cut the angled joinery on my dining room chairs.
The FMT has a dust port that attaches to a vacuum hose. It’s not perfect, but it does catch the lion’s share of the chips. Most importantly it draws the chips away from the cutting area and prevents them from getting packed in around the joint during routing.
Improvement Wish List
Having run the FMT through its paces and having successfully made several dozen perfect joints, I came up with only two gripes. The first one is that the hole in the sub-base for the router bit is only 1 in. in diameter. This makes it tough to see where you’re routing when cutting a joint. Second, I wish there were a few more template sizes for 3/8-in. and 1/2-in. router bits. The owner’s manual shows how to make custom stops for the existing templates to get in-between sizes, but I found those stops a hassle to make and use.