INTERPETR Shop Reference DB: embedded From napkin sketch to shop floor.

◈ Material Playbook

Hole Saw Helper ?Enter a target hole diameter and tolerance. Shows the nearest standard hole saw size and whether it falls within your tolerance window. Hole saws are available in standard fractional inch and metric sizes.

⬡ Fastener Calculator ?Select a fastener size to see tap drill sizes for 75% and 50% thread engagement, clearance holes (close/standard fit), and STI/helicoil sizes. 75% is standard; 50% for soft materials or blind holes where less torque resistance is acceptable.Ref: Machinery\u2019s Handbook, 31st Ed. \u2014 Thread & Tap Drill Tables

⬢ Insert Hole Calculator ?Looks up the recommended installation hole size for heat-set inserts and PEM self-clinching nuts/studs. Hole size depends on insert type, thread size, and parent material thickness.Ref: PEM Engineering Catalog & heat-set manufacturer datasheets

⬣ Database

Drop shopdb.json to update
Embedded DB loaded automatically

Gauge → Thickness

Full Gauge Chart

Bend Specs ?Minimum bend radius, recommended die width (V-opening), and K-factor for air bending. K-factor locates the neutral axis: K = t/T where t is neutral axis offset and T is material thickness. Used to calculate bend allowance: BA = \u03c0/180 \u00d7 angle \u00d7 (R + K\u00d7T).Ref: Machinery\u2019s Handbook \u2014 Press Brake Bending; SCS sheet metal guidelines (SCS air-bend)

Inside radius, K-factor & min flange for SendCutSend tooling.

Bend Deduction Quick Calc ?BD = 2(R+T) - BA for a 90\u00b0 bend. Subtract BD from your flat pattern dimension at the bend line. R = inside bend radius, T = material thickness, BA = bend allowance.Ref: Machinery\u2019s Handbook \u2014 Sheet Metal Bend Calculations (90°)

BD = 2×(R + T) − BA, where BA = (π/2)×(R + K×T)

Material Reference

Design Rules Quick Reference

Fab Tips

⬡ Fit Calculator ?Calculates offset for FDM printed mating parts. Press-fit: 0.1-0.15mm interference. Snug: 0.1-0.2mm clearance. Sliding: 0.2-0.4mm clearance. Accounts for typical FDM dimensional accuracy of \u00b10.2mm and layer-dependent Z tolerance.Ref: Empirical FDM tolerances \u2014 Prusa, Bambu Lab, Stratasys guidelines

○ Hole Compensation ?FDM printers approximate circles with polygon segments, making holes ~0.1-0.3mm undersized. This calc gives the modeled diameter needed so the printed hole comes out at your target. Compensation varies by hole size and printer resolution.Ref: CNC Kitchen, Prusa Research hole compensation studies

FDM holes always print undersized. STL tessellation + bead width reduce every hole. Vertical hole (axis = Z): Add +0.2 mm to nominal Ø in CAD Horizontal hole (axis = XY): Add +0.3–0.5 mm to nominal Ø in CAD Best practice: Model slightly oversize → ream to final Ø with a drill bit. Fastest path to a precise fit.
Elephant Foot — Bottom Edge
First layer squish flares bottom edges outward 0.1–0.5 mm. Fix: add a 0.3–0.5 mm × 45° chamfer to the bottom edge of any precision feature in CAD.
Minimum Modeled Thread
Don’t model threads smaller than M5 / #10. Smaller = stripped immediately. Use heat-set inserts → see Insert Hole Calculator tab.

◈ Design Rules — click to expand

◎ Material Quick Reference

★ Shop Tips

    ⍁ CNC Router \u2014 Feeds & Speeds ?Feed Rate = RPM \u00d7 Flutes \u00d7 Chipload. RPM = (SFM \u00d7 12) / (\u03c0 \u00d7 Bit Diameter). Chipload is material removed per tooth per revolution. Too low = rubbing/heat; too high = deflection/breakage. Values are starting points \u2014 adjust for rigidity and depth of cut.Ref: Onsrud, Amana, Vortex cutter catalogs; Machinery\u2019s Handbook \u2014 Milling

    ☰ Results

    Fill in inputs and click Calculate.

    ⓘ Bit Guide & Notes

    Select a material to see bit recommendations.
    Material notes will appear after calculating.

    ⚙ Milling Feeds & Speeds ?RPM = (SFM \u00d7 12) / (\u03c0 \u00d7 D). Feed = RPM \u00d7 Z \u00d7 chipload. Plunge rate typically 25-50% of feed. SFM values vary by material, tool coating (uncoated, TiN, AlTiN), and cut type (slotting vs profiling). Radial engagement affects effective chipload.Ref: Machinery\u2019s Handbook, 31st Ed. \u2014 Milling; Kennametal, Harvey Tool catalogs

    ☰ Results

    Fill in inputs and click Calculate.

    ☵ SFM Quick Reference

    Surface Feet per Minute by material and tool type. Use these to calculate RPM: RPM = SFM × 3.82 / Dia(in)

    ⓘ End Mill Types

    ◆ Chipload Reference

    Typical chipload per tooth (inches) for end milling with carbide tools.

    ⚙ Turning Speed Calculator ?RPM = (SFM \u00d7 12) / (\u03c0 \u00d7 Workpiece Diameter). Feed in IPR. Roughing: higher DOC, lower SFM, 0.005-0.015 IPR. Finishing: lighter DOC, higher SFM, 0.002-0.005 IPR. Reduce SFM for interrupted cuts.Ref: Machinery\u2019s Handbook \u2014 Turning; Sandvik Coromant, Kennametal insert guides

    ◆ Insert ID Decoder ?Decodes carbide insert part numbers per ISO 1832 / ANSI B212.4. Example: CNMG120408 = C(diamond 80\u00b0) N(0\u00b0 clearance) M(\u00b10.005 tol) G(chip groove) 12(IC size) 04(thickness) 08(nose radius 0.8mm).Ref: ISO 1832:2017 \u2014 Indexable inserts identification; ANSI B212.4

    Enter an ANSI/ISO insert designation (e.g., CNMG 432) to decode it.
    Common Insert Shapes

    ☵ Lathe Operations Reference

    ⓘ Thread Cutting Reference

    Threading tip: Use 29.5° compound angle for 60° threads (UNC/UNF/metric). This feeds on one flank for cleaner cuts and better chip control. Final spring passes at same depth for clean finish.

    ☰ Turning SFM Quick Reference

    RPM = SFM × 3.82 / Workpiece Diameter (in). Reduce RPM as diameter increases.

    ⏻ Bolt Torque Reference ?Recommended tightening torque by fastener size and grade/class. Values assume clean, dry, unplated threads (K=0.20). For lubricated: reduce 15-25%. For cadmium plated: reduce 25-30%. For prevailing-torque locknuts: add locknut prevailing torque to listed value.Ref: Machinery\u2019s Handbook \u2014 Torque Tables; IFI-5th Ed; ISO 898-1 (metric classes)

    ◈ Torque Notes

    ⇄ Unit Converter ?Convert between imperial and metric units. All conversions use NIST-traceable conversion factors. Temperature uses exact formulas: \u00b0F = \u00b0C \u00d7 9/5 + 32. Length: 1 inch = 25.4mm exactly (international yard definition, 1959).Ref: NIST Special Publication 330 \u2014 The International System of Units (SI)

    SFM

    ⚖ Material Properties Comparison ?Tensile strength, yield strength, elongation, hardness, and density for common engineering materials. Values are typical/nominal \u2014 actual properties vary by alloy temper, heat treatment, and processing.Ref: ASM Handbook Vol. 2 (Al), Vol. 1 (Steel); MatWeb material property database

    ⌖ Tolerances by Manufacturing Process ?Achievable dimensional tolerances by manufacturing method. CNC milling: \u00b10.001-0.005\u201d. Sheet metal: \u00b10.010-0.030\u201d. FDM 3D print: \u00b10.005-0.010\u201d. Die casting: \u00b10.002-0.010\u201d. Values are typical for production \u2014 tighter is possible at higher cost.Ref: Machinery\u2019s Handbook \u2014 Manufacturing Tolerances; GD&T per ASME Y14.5

    ◿ Surface Finish & Post-Processing ?Surface roughness (Ra) achievable by process. As-machined: 32-125 \u00b5in Ra. Ground: 4-32 \u00b5in Ra. Polished: 1-8 \u00b5in Ra. Bead blast: 63-250 \u00b5in Ra. Post-processing options and their typical Ra values and applications.Ref: ASME B46.1 \u2014 Surface Texture; Machinery\u2019s Handbook \u2014 Surface Finish

    ⚙ MIG Settings Calculator ?Recommends voltage, wire feed speed (WFS), and gas flow based on material, thickness, wire size, and transfer mode. Rule of thumb: 1A per 0.001\u201d of thickness for steel. Short-circuit for thin material (< 3/16\u201d), spray for thicker. Settings are starting points.Ref: AWS D1.1/D1.3 \u2014 Structural Welding; Lincoln Electric, Miller welding guides

    ⬢ TIG Settings Calculator ?Amps \u2248 1A per 0.001\u201d for steel, 1.5A per 0.001\u201d for aluminum. AC for aluminum (oxide cleaning), DCEN for steel/stainless (deep penetration). Gas flow: 15-20 CFH argon. Tungsten: 2% lanthanated (universal) or 2% ceriated (AC aluminum).Ref: AWS D1.1/D1.6 \u2014 Structural Welding; Miller, CK Worldwide TIG guides

    Tungsten Color Code
    Green — Pure W (AC aluminum)
    Red — 2% Thoriated (DC steel)
    Gold — 1.5% Lanthanated (universal)
    Grey — 2% Ceriated (AC/DC)

    ⚡ Stick / SMAW Electrode Reference

    Amperage by Rod Diameter

    ◈ Filler Metal Cross-Reference

    ★ Plasma Cutting Reference ?Amperage and speed recommendations by material and thickness. Higher amps = thicker capacity but wider kerf. Drag vs standoff cutting. Pierce capacity is typically 50-60% of rated cut capacity.Ref: Hypertherm, Thermal Dynamics operator manuals; AWS C5.2 \u2014 Plasma Arc Cutting

    Pierce vs. Cut capacity: Most plasma cutters can sever (pierce) material about 50-60% of their rated clean-cut thickness. For clean cuts with good edge quality, stay within the rated capacity. Pierce starting leaves a larger initial hole — start from edges when possible on thick material.

    ▦ Joint Design Quick Reference

    ☵ Weld Symbol Basics

    ⚡ Wire Gauge Reference ?AWG wire specifications: diameter, cross-section area, resistance (\u03a9/1000ft), and ampacity ratings for chassis wiring and power transmission. Ampacity based on 30\u00b0C ambient, single conductor in free air. Derate for bundling or higher temps.Ref: NEC Table 310.16 \u2014 Conductor Ampacities; SAE J1128 \u2014 Automotive Primary Wire

    AWG Quick Reference
    Voltage Drop Calculator ?Vdrop = 2 \u00d7 L \u00d7 I \u00d7 R / 1000. Factor of 2 for round-trip (positive + ground). R from wire gauge table (\u03a9/1000ft). Keep drop under 3% for 12V systems, 5% max for non-critical loads. Aluminum wire: 1.64\u00d7 copper resistance.Ref: NEC Article 210.19(A) \u2014 Branch Circuit Voltage Drop; SAE J1128 \u2014 Automotive Wire
    NEC recommendation: ≤3% drop for branch circuits, ≤5% total (feeder + branch). Formula: Vdrop = 2 × L × I × Rper ft

    Ω Ohm\u2019s Law / Power Calculator ?V=IR, P=VI, P=I\u00b2R, P=V\u00b2/R. Enter any two known values to solve for the rest. Use for fuse sizing (I=P/V), wire heating (P=I\u00b2R), and load calculations.Ref: Ohm\u2019s Law (Georg Ohm, 1827); IEEE Std 141 \u2014 Power Distribution

    Enter any 2 values — the other 2 are calculated instantly.

    V
    A
    Ω
    W
    Resistor Color Code
    —

    🔌 Connector Quick Reference ?Common automotive and industrial connectors with pin counts, current ratings, wire gauge compatibility, and waterproof ratings (IP67/IP68). Includes Deutsch DT/DTM, Delphi Metri-Pack, AMP Superseal, and Anderson Powerpole.Ref: Manufacturer datasheets \u2014 TE Connectivity, Amphenol, Anderson Power

    🔋 Battery Reference ?Common battery chemistries: nominal voltage, energy density, cycle life, self-discharge rate, and temperature range. LiFePO4: 3.2V/cell, 2000+ cycles. AGM: 2.1V/cell, 500 cycles. Lithium-ion: 3.7V/cell, 500-1000 cycles.Ref: Battery University; manufacturer datasheets

    Series vs Parallel Wiring
    Series (S): Voltages add, capacity stays same.
    LiPo: 2S = 7.4V, 3S = 11.1V, 4S = 14.8V, 6S = 22.2V
    LiFePO4: 4S = 12.8V (≈12V system), 8S = 25.6V (≈24V)
    Parallel (P): Capacity adds, voltage stays same.
    Common notation: 3S2P = 3 cells in series, 2 groups in parallel.
    Safety: Never mix old/new cells. Match internal resistance within 10%. LiPo puffy = retire immediately.

    ⚡ Common EE Formulas Quick Reference ?Capacitor charging: V(t) = V\u2080(1-e^(-t/RC)). Inductor: V = L(di/dt). Series R: R\u2081+R\u2082. Parallel R: 1/(1/R\u2081+1/R\u2082). Impedance, RMS conversion, transformer ratios, and more.Ref: The Art of Electronics (Horowitz & Hill); IEEE reference tables

    Ohm's LawV = I × R
    PowerP = IV = I²R = V²/R
    Voltage DividerVout = Vin × R2/(R1+R2)
    RC Time Constantτ = RC
    63.2% in 1τ, 86.5% in 2τ, 99.3% in 5τ
    Capacitor EnergyE = ½CV²
    Inductor EnergyE = ½LI²
    Resonant Freqf = 1/(2π√LC)
    LED ResistorR = (Vsrc - Vled) / Iled
    dBm to mWmW = 10(dBm/10)

    🔌 Wire Bundle Builder ?Add wires by gauge and quantity to visualize the bundle cross-section. Uses circle-packing algorithm for optimal arrangement. Shows total bundle diameter and recommended loom/conduit size (fill ratio ~40-60% per NEC for conduit).Ref: NEC Chapter 9, Table 1 \u2014 Conduit Fill; cable bundle packing geometry

    Wires
    Options

    🔮 Bundle Cross-Section

    Add wires to see the bundle
    Recommended Loom / Conduit

    ⚡ Harness Builder ?Build a branching harness tree. Each segment has length, load (amps), and optional ambient temperature. Wire gauge is sized per segment to stay within your voltage drop budget. Upstream segments carry cumulative current from all downstream loads. Temp derating per NEC Table 310.15(B)(1) for 90\u00b0C rated wire (TXL/GXL/XLPE).Ref: NEC Art. 210.19 (voltage drop); Table 310.15(B)(1) (temp correction); SAE J1128

    Power Source
    Harness Segments
    Click + Branch on any node to add a downstream segment. Each segment carries the sum of all loads below it.

    🔌 Harness Schematic

    Add segments to see the schematic