Guides
Design parts that fit the first time.
The numbers behind printable parts, with the reasons behind them: how much gap a lid needs, what size hole an M3 insert wants, how long a snap arm must be. Most link to a free test piece, so you can check the numbers on your own printer before you print the real part. New to Loftsmith? Start with the visual walkthrough.
3D printing tolerances: how much clearance each fit needsStarting clearances for press, snug, sliding and loose fits on FDM printers, why printed holes come out small, and a 20-minute test for your real numbers.8 min read Heat-set insert hole sizes: an M2–M6 chart for 3D printingHole diameters, depths and wall thickness for M2 to M6 heat-set inserts in PLA and PETG, how to press them in straight, and a 4.5 g test that settles it.7 min read Screw holes for 3D printing: M2–M6 clearance, tap and nut-trap sizesClearance, self-tapping, counterbore and nut-trap sizes for M2–M6 screws in FDM parts, plus when to switch to heat-set inserts and why sideways holes sag.7 min read Snap fit design for 3D printing: the one formula that stops them snapping offHow long and thick a printed snap-fit arm must be for PLA or PETG, worked examples, print orientation, root fillets and hook angles that open or lock.8 min read Print-in-place hinges: clearance, design and why they fusePrint-in-place hinge clearance for FDM (0.3–0.45 mm), knuckle and pin geometry that prints without supports, elephant foot, and how to free a stuck hinge.7 min read How much weight can a 3D printed hook, bracket or shelf hold?Work out what a printed hook or shelf bracket can carry with one formula, see why layer direction and heat matter more than infill, and design it to hold.8 min read STL vs 3MF: which file should you print from?What STL and 3MF files actually store, why 3MF keeps units, colours, parts and print settings, when STL is still fine, and where STEP fits in.5 min read How to split a model that’s too big for your 3D printerWhere to cut a model that won’t fit your bed, how to align the pieces with pins or 1.75 mm filament dowels, and which glue holds PLA and PETG.7 min read PLA vs PETG vs ASA: which filament for functional parts?Heat, sunlight, strength and how hard each is to print: pick PLA, PETG or ASA for a functional part by where it will live, not by a spec sheet.7 min read Wall thickness for 3D printing: the minimum and what to useMinimum and recommended wall thickness for FDM parts, why walls should be multiples of your line width, and how thick to make floors, ribs and enclosures.6 min read Overhangs and bridges: designing parts that print without supportsThe 45° overhang rule, how far a bridge can span, chamfers vs fillets on bottom edges, teardrop holes and orientation tricks that remove supports.7 min read 3D printed threads: when they work and how to design themWhich thread sizes print well on FDM, how much clearance printed threads need, why coarse threads work better, and when to use inserts or a tap instead.7 min read 3D printed gears: module, teeth, backlash and materialHow to size printable spur gears: module, tooth count, centre distance, backlash for FDM, the 17-tooth undercut rule, and which filament wears best.7 min read Gridfinity dimensions: the 42 mm grid explainedGridfinity sizes in millimetres: the 42 mm grid, 41.5 mm bins, 7 mm height units, 6 × 2 mm magnets and M3 screws, plus how to fit a grid to your drawer.5 min read