Design for Manufacturability (DFM) in FRC

The golden rule: design for the tools you own#

Design for Manufacturability (DFM) means making design choices that match your team's actual manufacturing capability. A part you cannot build, or build accurately, is worthless no matter how clever the CAD. Before designing, take inventory: Do you have a CNC router or mill? A waterjet? Only a drill press and band saw? Access to 3D printers? Your fabrication tools should shape your design.

Standardize on box tube and standard hole patterns#

The backbone of most FRC robots is aluminum 6061-T6 box tube in sizes like 1x1, 2x1, and 2x2 in (for example, AndyMark's box tube extrusion). The single most important DFM convention in FRC is the standard hole pattern: rows of 0.196 in diameter holes (a #10 clearance hole) on 0.5 in spacing. Designing to this pattern lets you:

• Bolt on COTS gussets, brackets, and bearing blocks that share the same pattern.
• Buy pre-drilled/pre-punched tube from vendors (WCP, REV, AndyMark) so you skip drilling hundreds of holes by hand.
• Swap and reposition mechanisms on a grid, which makes mid-season changes easy.

Prefer COTS structure when it saves time#

Vendors sell pre-cut and pre-drilled tube, gussets, bearing blocks, and gearbox kits. Buying these is often faster and more accurate than fabricating from scratch, especially for teams without CNC equipment. Use your limited shop time on the custom parts that make your robot unique.

Practical DFM guidelines#

• Use clearance holes, not interference fits, for bolts unless you specifically want a press fit; design holes around standard fasteners. The most common FRC fasteners are #10-32 and 1/4-20 socket-head cap screws — many veteran teams (e.g., Iron Panthers 5026) standardize on 1/4-20 for strength and consistency.
• Add fillets to inside corners of machined plates — sharp internal corners are impossible for a round router bit/end mill to cut and concentrate stress.
• Mind material thickness vs. tool. A waterjet cuts thick plate; a router handles sheet; a drill press makes holes but not slots.
• Use crush blocks / tube plugs where you bolt through thin-wall tube, to prevent the tube from crushing under fastener load.
• Lighten intelligently. Removing material (with tools like the Part Lighten FeatureScript) saves weight toward the 115 lb limit, but don't lighten so aggressively that parts flex or fail.
• Respect tolerances. Hand-cut tube might be +/- 1/32 in; a CNC mill holds far tighter. Design slots and adjustable mounts where you expect manufacturing variation.

Account for assembly#

DFM includes Design for Assembly: can a human actually reach the bolts? Can you remove a gearbox without disassembling half the robot? Leave wrench clearance and access. A part that fits in CAD but can't be assembled by hand is a manufacturing failure too.

Why it matters#

The teams that win consistently are usually the ones that finish a robust robot early and get practice time — and that comes from designs that build fast, accurately, and with the tools on hand. The Iron Panthers (5026) robust-design guide and the FRCDesign.org design handbook are excellent next reads.

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Quiz - question 3 - I would change the question to: When is a tapped hole generally the preferred design choice? A. Whenever the joint must be as strong as possible. B. Whenever manufacturing cost is the only concern. C. When only one side of the part is accessible or there isn't room for a nut. D. Whenever a bolt larger than 1/4" is used. (correct answer C)