How to Make a Dust Shield for a Router Mortising Machine
A router mortising machine makes quick work of cutting accurate mortises, but it can also send chips and dust flying around the shop. Adding a clear shield in front of the router is a simple way to help contain some of that debris without blocking your view of the work.
One of my favorite shop-built tools is the Router Mortising Machine featured in Woodsmith Issue 217. It's a versatile setup that uses a router to cut mortises accurately and consistently.
After using it for a while, I decided to make one small improvement: a clear acrylic dust shield mounted directly to the router clamping block.
The shield is easy to make from a flat piece of acrylic. With a few simple machining steps and a heat gun, you can form the plastic into a shape that fits around the router.
Making the Acrylic Dust Shield
The shield starts as a flat piece of acrylic plastic.
Acrylic is a good choice for this accessory because it's transparent, relatively easy to work with, and can be formed into a new shape with carefully applied heat.
The first step is to cut the acrylic to the required size and lay out the mounting slots.
These slots allow the shield to attach to the router clamping block.
Drill and Rout the Mounting Slots
Start by marking the locations of the mounting slots on the acrylic.
Drill a hole at each end of the slots, then remove the waste between the holes at the router table.
Use a suitable bit and take light passes to avoid overheating or chipping the plastic.
After routing the slots, round the corners and smooth any sharp edges.
How to Bend Acrylic with a Heat Gun
Once the mounting slots are complete, the next step is to form the acrylic into the shape needed for the shield.
You don't need a specialized plastic-bending machine for this. A heat gun and a few scrap boards will do the job.
Step 1: Clamp the Acrylic Between Boards
Sandwich the acrylic between two straight boards, leaving the portion you want to bend extending beyond the edge.
The boards hold the plastic securely and establish a straight reference line for the bend.
Clamp everything firmly so the acrylic can't shift as it warms.
Step 2: Apply Heat Slowly
Set a heat gun to its low setting and move it steadily along the exposed bend line.
The goal is to soften the acrylic gradually and evenly.
Avoid concentrating the heat in one spot, which can cause bubbling, scorching, or distortion.
As the acrylic warms, you'll notice the unsupported portion begin to soften and droop slightly.
That's your indication that it's ready to bend.
Woodsmith Tip: Work in a well-ventilated area and follow the acrylic manufacturer's heat-forming recommendations. Keep the heat gun moving and avoid overheating the plastic.
Step 3: Form the Bend
Once the acrylic has softened, use another board to gently bend the exposed section downward.
The board spreads the pressure across the width of the plastic, helping produce a smooth, even bend.
Hold the acrylic in position until it cools enough to retain its new shape.
Install the Shield on the Mortising Machine
With the acrylic formed, the final step is mounting it to the router mortising machine.
Position the shield in front of the router and secure it to the router clamping block using the mounting slots.
The slots provide some adjustment, allowing you to position the shield where it helps contain flying chips without interfering with the router or workpiece.
Before using the mortising machine, verify that the shield is securely attached and that there's adequate clearance around all moving parts.
Safety Note: The acrylic shield is intended to help deflect chips and dust. It isn't a substitute for a properly designed router guard, eye protection, or dust collection system. Keep the shield clear of the cutter and moving components, and don't assume ordinary acrylic provides impact protection against a broken router bit.
A Simple Upgrade for a Shop-Made Mortiser
This clear acrylic shield is a small addition that makes a useful shop-built tool even better.
It helps contain chips and dust while preserving visibility around the router. And because the acrylic can be shaped with a heat gun and a few scrap boards, it's an easy accessory to make without specialized equipment.
If you've built the Router Mortising Machine from Woodsmith Issue 217, this is a practical upgrade worth considering.
Build Your Own Router Mortising Machine
Take the guesswork out of mortise-and-tenon joinery with this versatile router mortising machine. This shop-built setup makes it easy to cut consistent mortises for furniture, cabinets, and other woodworking projects. Add the clear acrylic dust shield shown here for an extra shop-made upgrade.
GET THE ROUTER MORTISING MACHINE PLANS → Cut Accurate Mortises with a Shop-Made Machine
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