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Abstract:
This video details the comprehensive build process of a high-precision, feature-rich miter fence designed primarily for an oscillating belt sander but adaptable to other machines with T-tracks, like table saws. The project emphasizes accuracy, user-friendliness, and robust construction, moving beyond typical designs. Key innovations include a gear-driven angle adjustment mechanism, a precise detent system ("clicker ring") offering positive stops every half-degree, integrated cam-lever locking that doesn't disturb the angle setting, and a smooth-sliding fence rail with custom guides. The build showcases a wide range of techniques including CNC milling and routing of aluminum and phenolic, intricate lathe work (including challenging threading operations), advanced resin 3D printing (Formlabs Form 4) for gears and scales, manual machining, TIG welding, and the use of specialized tools like the Proxxon Microsonic cutter. Collaboration with Stefan Gotteswinter was necessary for the high-precision milling of the final steel clicker ring. The video documents the design choices, fabrication steps, troubleshooting (like lathe threading issues and 3D print optimization), and final testing, resulting in a highly accurate and satisfying custom tool accessory.
Building a High-Precision Miter Fence: From Concept to Finished Tool
0:00 Project Goals: The build focuses on five key points: accuracy (positive half-degree stops), speed (quick locking), user-friendliness (large scale, levers), versatility (use on sander/other machines), and overcoming common miter gauge issues (slop, difficult locking).
01:08 Machining the Base Plate: An aluminum bar is machined on a CNC mill to create the main body, including precision holes for alignment pins.
03:31 Built-in Adjustability: Pockets with expanding grub screws are added to allow fine-tuning of the base plate's alignment within the T-track.
04:05 Complex Lathe Work: A critical component requiring turning, precise diameters, custom 28 TPI threading, and a wrench flat is machined.
04:47 Lathe Threading Challenges: Difficulties arise cutting the fine thread, including uneven pitch and incorrect direction, requiring troubleshooting of the lathe's lead screw/split nut engagement.
08:40 Machining Brackets: Side brackets and the fence rail pivot are CNC machined from 8mm aluminum plate, including pockets and chamfers.
10:23 Phenolic Components: Phenolic sheet is used for parts requiring stability and machinability, cut on a table saw and finished on a CNC router.
10:45 Initial Assembly & Friction Reduction: Parts are assembled, and low-friction (Teflon) tape is applied to ensure smooth sliding motion.
11:33 Gear-Driven Angle Adjustment: Instead of a simple pivot, a gear mechanism is designed for fine angle control, inspired by lathe compound rests.
12:47 High-Accuracy Resin Printing: Initial FDM 3D printed gears lack precision, leading to the use of a Formlabs Form 4 resin printer (SLA/LCD) for highly detailed and accurate gears, scales, and knobs. The process involves printing, washing, and UV curing.
14:33 Support Removal Tool: A Proxxon Microsonic ultrasonic cutter is demonstrated for cleanly removing delicate support structures from resin prints.
16:20 Post-Processing Resin Prints: Resin printed parts like the main gear are machined oversized and then turned/reamed on the lathe to final dimensions for perfect fitment.
18:29 Addressing Gear Backlash: The initial gear fit is too tight; new gears are printed with calculated profile shifts (0.1mm and 0.2mm) to achieve optimal backlash for smooth operation.
19:46 Positive Angle Stops (Clicker Ring): To ensure repeatable accuracy, a detent mechanism is designed using a spring-loaded ball and a ring with 120 teeth, providing positive stops every 0.5 degrees.
21:07 Precision Machining for Detent: The housing for the ball detent is carefully machined on the lathe, requiring a highly precise reamed hole for the ball to function correctly.
23:16 Ergonomic Enhancements: A channel is added to the adjustment knob, and a flexible resin insert is printed to improve grip.
23:54 Creating the Angle Scale: A detailed angle scale is resin printed, featuring fine lines and numbers for easy reading.
25:00 Scale Alignment: The printed scale is carefully aligned with the clicker ring mechanism so that each click corresponds precisely to a half-degree mark on the scale.
26:38 Cam Lever Locking System: Quick-action cam levers are chosen for locking the angle and the fence position, modified slightly for clearance.
27:24 Integrated Locking Knob: The angle locking cam lever is cleverly integrated into the main angle adjustment knob assembly.
28:10 Custom Pivot/Locking Pin: A complex pin is machined and TIG welded (with some difficulty) to serve as both the main pivot and the anchor for the T-slot locking mechanism.
31:10 Troubleshooting the Lock: An issue where tightening the lock lifts the fence is traced to interference within the cam lever housing, requiring modification with the ultrasonic cutter.
32:47 Improving the Fence Rail: A standard aluminum extrusion is used for the fence. Teflon tape is added for smoothness.
33:29 Custom Fence Guide Roller: To prevent the fence rail from binding when slid, a custom roller is machined from POM (Delrin) to guide it smoothly in the slot.
34:54 Upgrading to Steel Clicker Ring: Realizing the resin clicker ring would wear over time, a steel version is made for durability.
35:39 Collaboration for Precision Milling: Stefan Gotteswinter assists with high-precision machining, using a rotary table and dividing head on a milling machine to accurately cut the 120 teeth into the steel ring blank.
37:29 Accuracy Verification: The completed fence's angle settings are checked against a digital angle gauge, confirming the half-degree increments and overall accuracy of the system.
39:04 Final Shaping & Finishing: A clearance bevel is sanded directly into the fence rail using the belt sander itself. All parts are deburred, and a 3D printed end cap is added.
40:15 Demonstration: The finished miter fence is demonstrated on the belt sander, showcasing its smooth operation and accurate angle setting capabilities.