One of the most critical steps in almost any routing operation is setting the bit to the correct height. It sounds simple enough, but depending on the type of router bit and the operation you're performing, getting that setting just right can take some trial and error.
Profile bits such as chamfer and roundover bits present one set of challenges. Joinery bits, including dovetail, drawer-joint, and stile-and-rail bits, can be even more demanding because an inaccurate setup can affect how the finished joint fits.
Over the years, I've picked up a few shortcuts that make setting router bit height faster, easier, and more repeatable. Better yet, several of these tricks let you save a successful setup so you don't have to start from scratch the next time you use the bit.
1. Make a Setup Block for Chamfer Bits
Chamfer bits can be surprisingly difficult to set to an exact height. Unlike some profile bits, there isn't always an obvious corner or reference point you can measure from.
That can mean making several test cuts before getting the chamfer exactly the size you want.
Once I have the bit dialed in, I make sure I don't waste that effort.
I rout the finished chamfer profile into a small piece of scrap and label the block. The next time I need that same chamfer, I can hold the setup block next to the bit and use the existing profile to quickly establish the bit height.
Even if the chamfer I need doesn't exactly match one of the profiles on my block, the gauge gets me close enough that I can usually reach the final setting with fewer test cuts.
Over time, you can add several commonly used chamfers to one block and keep it near the router table.
2. Set a Roundover Bit With a Straightedge
Roundover bits present a different setup problem.
If the bit is set too high, the cutter can leave a small ridge or step along the edge of the workpiece. Removing that ridge afterward can be difficult without altering the smooth roundover profile you just routed.
There's an easy way to establish a good starting point.
Lay a ruler or straightedge across the router table opening and slowly raise the bit until the outside edge of the cutter just touches it.
That gives you a quick reference for setting the bit.
After making a test cut and confirming the setup, rout the finished profile into a setup block just as you did with the chamfer bit.
If you own several sizes of roundover bits, one piece of scrap can become a dedicated roundover router bit setup block containing the profiles you use most often.
3. Align the Router Table Fence With the Bit Bearing
Many profile bits have a bearing that guides the workpiece, so technically you don't need a router table fence to guide the cut.
I still like to use the fence whenever possible.
The fence provides additional support and control as I feed the workpiece past the bit. But for this arrangement to work correctly, the face of the fence needs to be flush with the bearing.
Fortunately, there's an easy way to set it.
Place a straightedge across the face of the fence and adjust the fence until the straightedge just contacts the bearing.
Now the fence and bearing establish the same reference line, allowing you to take advantage of the added support of the router table fence.
4. Save Joinery Bit Settings With Gauge Blocks
Some of the most time-consuming router setups involve joinery bits.
Dovetail bits, drawer-joint bits, and stile-and-rail sets often require a precise setup to produce parts that fit together correctly. Getting there can involve several adjustments and test cuts.
If you don't use the bit very often, it's easy to find yourself repeating that process every time you pull it out.
A simple gauge block solves the problem.
Once you've adjusted the bit and made a successful test joint, rout the same profile into a piece of scrap. Label the block with the bit or operation and save it with your router accessories.
The next time you use that bit, hold the gauge block next to the cutter and adjust the bit until it matches the saved profile.
You'll still want to make a test cut before routing your actual project parts, but the block gets you very close to the final setting right away.
Make Setup Blocks Part of Your Router Bit Storage
I like this approach because it essentially saves a successful router setup.
Rather than recording a measurement and trying to reproduce it later, you're saving a physical reference made by the cutter itself.
If there's a router bit you find particularly frustrating to set up, that's a good candidate for its own labeled gauge block.
5. Build a Router Bit Height Gauge
For a more universal solution, you can make a dedicated router bit height gauge.
The shop-made version shown here is built from a few small pieces of MDF and several screws.
Instead of trying to read a ruler while adjusting the router, you raise the bit until it contacts the bottom of a screw. This gives you a positive physical stop that's easy to repeat.
Each screw is adjusted to a different height, giving you several preset measurements in one gauge.
This design has another useful advantage. You can use the different settings to raise the router bit incrementally for multiple passes rather than trying to remove the full amount of material in one cut.
The version shown uses brass screws. The softer brass helps prevent the screw from damaging the carbide cutting edge when the bit contacts it.
Setup Blocks vs. Router Bit Height Gauges
Both approaches make router setup faster, but they solve slightly different problems.
For router bits that I use repeatedly, I like profile and joinery blocks because they preserve the actual successful setup. For general router work, the height gauge provides a quick physical reference without having to measure directly from the cutter.
Spend Less Time Setting Up Your Router
A few minutes spent making setup blocks can save a surprising amount of time at the router table.
Once you've dialed in a chamfer, roundover, or joinery bit, save that setup in a scrap block instead of figuring it out all over again next time. Add a simple router bit height gauge and a straightedge to the mix, and many common adjustments become quick, repeatable operations.
You'll still want to make a test cut before routing your project parts, especially when cutting joinery. But instead of spending several test pieces trying to find the right setting, you'll start much closer to where you need to be.
That means less setup time, less wasted material, and more predictable results from your router.
