For as long as I can remember, miter saws have ridden on rails. This design works very well except for one shortcoming: You need to set up away from the wall because the rails protrude from the back of the machine. Bosch recently introduced a 12-inch dual compound sliding model (GCM12SD) designed to solve that problem – and several others, too. It's called the Glide miter saw because instead of sliding on rails, the motor "glides" forward and back on articulated arms (which don't protrude from the back of the machine). To test this tool, I've been using it in my finish carpentry business since October. Here's what I found out.
Axial Glide System
The GCM12SD's axial glide system consists of a pair of two-piece arms that support the motor from a vertical post at the back of the base. The arms pivot on sealed bearings, straightening out when you pull the motor toward you and folding up when you push it back toward the fence.
The glide mechanism operates smoothly – so smoothly, in fact, that the manufacturer includes a tension adjustment that allows you to put some drag on the motor so it doesn't move too easily. It's a matter of personal preference: I'm fine with the easy motion, but some carpenters prefer more resistance. The motor tracks consistently as it moves in and out from the fence, so the saw cuts very accurately. I did notice, however, that when I was making kerf cuts, the depth sometimes varied from end to end. For me, this is a minor problem – I rarely dado on miter saws, and I found that if I slowed down the feed rate, the depth cut was more consistent.
The controls are easy to find because they're color-coded. Red ones perform a function, such as adjusting a miter or bevel, releasing a detent pin, or clamping one of the base extensions. As with other models from Bosch, the bevel lock lever is out in front so you never have to reach behind the saw. I particularly like the miter and bevel scales; the graduations between the marked angles vary in length so it's easy to read them quickly. The miter scale has common rafter angles, which would be of help to framers and came in handy for me when I cut box beams for a cathedral ceiling.
There are two safety switches for the trigger (one on the left and one on the right) so you can operate the tool with either hand. When I first started using this saw, I had a hard time seeing my cut marks through the sighting slot in the blade guard. The slot is low, and I found myself bending over to sight each cut. After about two weeks of using the saw, it occurred to me to look through the top of the clear guard housing – and that made it a whole lot easier to see the marks.
The GCM12SD will make up to a 14-inch crosscut at 90 degrees. Some other 12-inch saws can go wider, but 14 inches is more than enough for most of the work I do. When locked into chop-saw mode, the Bosch can cut pieces up to 5-1/2 inches wide. Chopping is faster than sliding, so we use this mode when we have to cut many narrow pieces.
The vertical capacity against the fence is listed at 6-1/2 inches. I found this spec to be accurate in most circumstances, but when you miter to the right with the stock on the right of the blade, you'll be limited to a 4-1/4-inch cutting height. This is because when you swing the table all the way to the right, the belt assembly hits the stock before the blade is all the way through. Carpenters who cut tall baseboard against the fence may not like this, but it didn't bother me because I prefer to cut baseboard on the flat.
You can cut up to 6-1/2-inch crown in the nested position. You can cut even wider crown if you cut on the flat. We cut crown on the flat, and I like the way the saw is set up to do it: There are detent stops on the miter and bevel scales for 38-degree spring-angle crown molding, and marked icons for the 45-degree crown molding settings. This makes for quick setup because there is no confusion about which detents to use.
Size and Weight
This machine has a small footprint for a saw of its capacity. It takes up less real estate in the back of our truck than our older 10-inch saw, though it does require a bit more vertical clearance. But at 65 pounds, it's pretty heavy to haul around. I made the mistake at first of grasping the carry handles in the base and lifting from the front, which felt really awkward and unbalanced. The manual says to lift the saw from behind; when I tried it that way the saw was a lot more comfortable to carry.
Still, if I owned this tool I'd only take it to projects where I'd be setting up for a while; otherwise I'd leave it in the shop. For quick in-and-out jobs I prefer to travel with a lighter machine. Too bad there isn't also a 10- or 8-1/2-inch version available.
Dust collection is important to me because I usually work in occupied homes. When I used the included dust bag, I found the GCM12SD's ability to collect dust merely average; it's better than nothing, but not up to the standard I am looking for. In fairness to Bosch, I feel this way about most collection bags.
However, when used with a vacuum, the dust collection on this saw is very good. I estimate that it collects a good 80 percent of the dust; the manufacturer says 90 percent. I attribute the effectiveness of the dust collection to the funnel-like dust deflector on the dust chute and to the chute's placement: Dust chutes are usually part of the blade housing, but this one is independent of the housing and in a fixed location behind the blade.
Collection efficiency depends in part on how you cut. If you cut on the flat and push the blade forward at a moderate pace, you'll collect more dust than if you cut very quickly or stand the material against the fence. This is because there is nothing between the blade and the chute when you cut on the flat. When you cut material in the vertical position, there isn't a straight path to the chute until the blade comes out the other side.
The saw comes with a 60-tooth blade and a work clamp. A 60-tooth blade may be okay for general-purpose cutting but isn't good enough for the finish work we do, so I immediately replaced it with a 100-tooth model from Tenryu. The work clamp is for holding jigs and material against the table. To use this clamp you must thread the screw down until it's in contact with the work. I much prefer a quick-acting clamp because it allows you to make large adjustments without having to turn the threads.
The Bottom Line
I like this saw and would recommend it to any carpenter who needs the capacity of a 12-inch sliding model.
It feels solid and well-made, and the glide mechanism is smooth and precise. I appreciate its incremental scales, small footprint, and effective dust collection (when used with a vacuum).
There are only a couple of things I don't like about the saw: It's one of the heavier 12-inch models around, and the dados it cuts sometimes vary in depth. That's another way of saying that no tool is perfect but this one comes close.
Jesse Wright is a finish carpenter for Architectural Molding in Pleasant Hill, Calif.