Making Finger Joints using a Radial Arm Saw
Recently I needed to fabricate a replacement tray for a Craftsman tool box that had an unfortunate encounter with car. I decided to make the tray out of oak and wanted strong joints therefore the finger joint was a good choice. Online search revealed that the most common finger joint fabrication techniques used either a table saw or router. The were no references to making the joint with a radial arm saw.
Setting Up the Saw
Making these cuts involves square, accurate end cuts so you will need to use an auxiliary table that raises the work to horizontal center line of the blade. You will need fences to square the cut both perpendicular to and with the blade. I made a slot in the auxiliary table for a speed square that I could adjust for each cut.
Lay Out the Cuts
My tray was to be made from 1/4 inch thick oak so I laid out 1/4 inch finger cuts on both ends the two longer sides. I set the depth of cut at 9/32 inch intending to sand away the overlap once the box was glued. Once the longer sides were cut, I used them to lay out the shorter side cuts, keeping the marks fat to insure a tight fit. Mark each joint for fitting.
Preparing to Cut
I scribed the two sides that had finger joint cuts on the top and bottom of the sides with an Exacto knife to prevent tear out. I also used scrap 1/4 inch plywood under the sides to prevent tear out.
Making the Cuts
Adjust the speed square to carefully position each cut and securely hold the wood to the auxiliary table for each cut.
Fitting each joint
Joints should be snug but not so tight that you squeeze the glue out of the joint. Trim each finger joint as necessary, one at a time, using either the saw or even an Exacto knife.
Gluing Up
Apply a thin coat of glue to every part of the joint then fit the sides together. Less is more when gluing! Clamp modestly to seat the sides together then check corner to corner for square. Adjust as necessary then let it dry. Wipe up any excess glue with a damp wipe.
Conclusion
The radial arm saw can be used as an alternative to the table saw and router for making finger joints. The required fixturing is probably no more complicated for the radial arm saw than either the table saw nor router.
There are finger joint bits for routers that take most of the layout chores out of the fabrication but require a router with a 1/2 inch collet and cost about $100. Fairly pricey for a seldom used joint.
Setting Up the Saw
Making these cuts involves square, accurate end cuts so you will need to use an auxiliary table that raises the work to horizontal center line of the blade. You will need fences to square the cut both perpendicular to and with the blade. I made a slot in the auxiliary table for a speed square that I could adjust for each cut.
Lay Out the Cuts
My tray was to be made from 1/4 inch thick oak so I laid out 1/4 inch finger cuts on both ends the two longer sides. I set the depth of cut at 9/32 inch intending to sand away the overlap once the box was glued. Once the longer sides were cut, I used them to lay out the shorter side cuts, keeping the marks fat to insure a tight fit. Mark each joint for fitting.
Preparing to Cut
I scribed the two sides that had finger joint cuts on the top and bottom of the sides with an Exacto knife to prevent tear out. I also used scrap 1/4 inch plywood under the sides to prevent tear out.
Making the Cuts
Adjust the speed square to carefully position each cut and securely hold the wood to the auxiliary table for each cut.
Fitting each joint
Joints should be snug but not so tight that you squeeze the glue out of the joint. Trim each finger joint as necessary, one at a time, using either the saw or even an Exacto knife.
Gluing Up
Apply a thin coat of glue to every part of the joint then fit the sides together. Less is more when gluing! Clamp modestly to seat the sides together then check corner to corner for square. Adjust as necessary then let it dry. Wipe up any excess glue with a damp wipe.
Conclusion
The radial arm saw can be used as an alternative to the table saw and router for making finger joints. The required fixturing is probably no more complicated for the radial arm saw than either the table saw nor router.
There are finger joint bits for routers that take most of the layout chores out of the fabrication but require a router with a 1/2 inch collet and cost about $100. Fairly pricey for a seldom used joint.
posted by lugh lampfhota at 2:09 PM
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