Q: Does anyone make router bits sized to make dado grooves that fit standard MDF thicknesses? Unfortunately, MDF is not sold in nominal fractional thicknesses, as most router bits are.

Carol Reed: Router bit manufacturers make undersized "plywood" bits; however, my experience with MDF is that it is much closer to "standard" thicknesses than plywood.

Richard Jones: It's difficult to get that just right. You might consider an alternative strategy which I usually use. If your boards are a nominal 3/4", run a 3/8" or 1/4" groove or housing (aka dado) and create a tongue on the joining part to match. You can easily adjust the tongue thickness to suit the groove worked, and you get extra strength due to the interlocking of the returns in the joint, and the extra glue line length.

Michael Dresdner: MicroFence makes a micrometer equipped router fence system that allows you to cut in extremely accurate measured increments. With that fence, paired with a half inch bit, for example, I can cut any dimension groove between one half and one inch in only two passes, and be accurate within one or two thousandths of an inch.

Q: I see a lot of router bits made in China -- none branded -- which appear to be bargains when it comes to price and appear to be well made. Are they a good buy or should I pass them by?

A: Rob Johnstone: My father used to tell me, "Buy the best you can afford and you will only cry once." There is indeed a difference in the quality of steel, carbide and machining as you move from bit maker to bit maker. As with most things, the old saw: "you get what you pay for," is true for router bits. The quality of steel, carbide and machining, along with the geometety of a router bit's design, are all things that are hard for average Joe's like you and me to evaluate. So the way that I make my first quality assessment is by looking at price. Then, when I use a bit, I do my second evaluation.

One question I ask myself with any tool purchase is: Am I going to be using this tool a lot, or just once or twice? If the answer is the former ... I opt to spend more money on the tool; the latter, and I look for a bargin.

A. Michael Dresdner: "Yes, if you take too hefty of a cut with certain types of bits they try to "walk up." They can either pull the bit out of the collet, or jiggle the router setting upwards. The first step is to find out which is happening. Mark the bit with a sharpie where the shaft enters the collet. That will tell you if the bit itself is slipping in the collet. If so, try cleaning or degreasing the collet and bit with naphtha, and make sure neither is scored. Seat the bit far enough so that the collet faces grab all they can, but don't bottom the bit out. If the bit is not moving, then it is the router adjustment. Clean it, tighten it, and make sure all mating surfaces are smooth. Finally, use a sharp bit and take modest cuts."

A. Simon Watts: "The wrenches supplied with routers are usually too short to be effective as well as being hard on the hands. I suggest you invest in a couple of open end wrenches of appropriate size."

A. (Michael Dresdner) "It depends on the shaper. Some have accommodation for a collet in place of the spindle. These typically have more than one speed. Remember that the speed of the cutting tip relates to the diameter of the bit. A larger bit requires a slower RPM, but conversely, so does a small bit require a higher RPM."

A. (Ellis Walentine) "Yes, but with some limitations. Some shapers offer router bit collets as either a replacement spindle or an add-on to an existing one. The problem is that shaper spindles usually operate between 6,000 and 10,000 rpm, which is rather slow for routing, especially with small-diameter bits. It would be a fine speed for larger diameter bits, for example, panel raising cutters or big round-over bits."