Shop Reference

---
name: shop-reference
description: "Use when correcting a woodworking or metalworking misconception, looking up a speed, feed, moisture content, drill or tap size, or fit tolerance, finding the resources, or needing a quick-reference picker — plus the current state of US table saw safety regulation and welding fume exposure control. Companion to the other wood and metal shop skills."
---

# Wood and Metal Shop Craft: What's Live, Misconceptions, Numbers, and Resources

> **Part 5 of 5** of the *Working with Wood and Metal* reference (plugin `working-with-wood-and-metal`), covering §27–§32. Sibling skills: `shop-materials-safety-reading-wood-and-stock` (§0–§4), `shop-woodworking-tools-sharpening-joinery-and-finishing` (§5–§12), `shop-metalwork-cutting-drilling-and-machining` (§13–§18), `shop-welding-forging-heat-treatment-and-shop-setup` (§19–§26). Section numbers are shared across the set; a reference written as §N → `skill` points into that sibling skill.
>
> **Currency:** The craft is centuries old. Two areas moved. See §27 for US table saw safety regulation, and welding fume exposure control.

> **⚠️ Two materials that punish opposite mistakes.** ⚠️ **Wood MOVES forever and forgives
> imprecision; metal is dimensionally stable and forgives nothing.** **⚠️ Wood is worked
> with the grain and cut fast; metal is worked against resistance and cut slowly.**
> **The habits that make you good at one will actively hurt you at the other.**
>
> **Complements a manufacturing reference (industrial process and tolerancing), a
> materials/furniture reference (wood movement and finishing at the design level), and a
> thermodynamics reference (heat treatment physics).**
>
> **⚠️ SAFETY IS §2 → `shop-materials-safety-reading-wood-and-stock` AND IT IS FIRST FOR A REASON.** ⚠️ **This document describes techniques;
> it does not substitute for supervised instruction on machinery. The table saw, angle
> grinder and welding arc each injure large numbers of people every year, and the
> mechanisms are specific and learnable.**
>
> **⚠️ GOTCHA** boxes mark the habits that cause injuries and the received wisdom that's
> wrong.
>
> **The three ideas that organize this document:**
> 1. **⚠️ SHARP IS SAFE** (§7 → `shop-woodworking-tools-sharpening-joinery-and-finishing`). **A dull tool requires force, force removes control, and
>    loss of control is how people get hurt. Sharpening is not a side skill — it's the
>    gateway to everything else.**
> 2. **⚠️ The material is not neutral** (§3 → `shop-materials-safety-reading-wood-and-stock`, §14 → `shop-metalwork-cutting-drilling-and-machining`). **Wood grain direction, and metal's
>    heat and work-hardening behaviour, determine technique. Fighting the material is
>    the definition of doing it wrong.**
> 3. **⚠️ The invisible hazards are the ones that get you** (§2 → `shop-materials-safety-reading-wood-and-stock`, §26 → `shop-welding-forging-heat-treatment-and-shop-setup`, §27.2). **Wood dust
>    and welding fume are classified carcinogens with no warning symptoms — and they're
>    the risks hobbyists systematically ignore in favour of the dramatic ones.**

---

## §27. What's Live — verified August 2026

### 27.1 ⚠️ US table saw regulation: a reversal
**⚠️ Directly relevant to §9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`, and the outcome went the opposite way to what the sector
expected.**

- **⚠️ The background**: **SawStop petitioned the CPSC in 2003 for a performance standard on
  blade-contact injuries.** ⚠️ **A 2017 proposed rule, supplemented in 2023, would have
  required table saws to limit the depth of cut to 3.5 mm or less when a test probe
  contacts the spinning blade at a radial approach rate of 1 m/s.** ⚠️ **The 3.5 mm figure
  derives from UL's identification of 4 mm as the threshold between simple and severe
  finger lacerations, minus 0.5 mm for the epidermis — below it, cuts should not damage
  nerves or arteries requiring surgery.**
- **⚠️ CPSC testing showed the standard was achievable**: ⚠️ **SawStop saws produced depths
  of cut from 1.5 to 2.8 mm and Bosch REAXX from about 1.8 to 2.5 mm.**
- **⚠️ THE REVERSAL: on 20 August 2025 the CPSC announced it would WITHDRAW the rule**,
  ⚠️ **as part of dropping "several existing and pending rulemakings that no longer align
  with agency priorities, and which fail to advance safety" — with the table saw standard
  leading the list of six.**

> **⚠️ GOTCHA — the patent dimension is why this was never a simple safety question, and
> it's worth understanding before taking a side.** ⚠️ **Critics argued the rule would
> effectively mandate a patented technology, creating a government-mandated monopoly;
> SawStop sued Bosch, and in 2017 the ITC prohibited Bosch from importing REAXX saws for
> infringing SawStop patents — removing the main alternative from the US market.**
> ⚠️ **SawStop also filed suit against Felder in 2024 over the alternative technology CPSC
> had cited.** **⚠️ A bipartisan bill was introduced to bar any such rule until at least
> five years after the relevant patents expire, which one analysis calculated could mean
> 2043.**
> **⚠️ Note the counter-argument is equally concrete: CPSC estimated the rule would have
> prevented or mitigated over 49,000 injuries annually, and its own 2019 analysis found
> NO reduction in table saw injuries from 2010 to 2018 despite the voluntary modular
> blade guard standard adopted in 2010.**

**⚠️ The practical upshot for anyone with a table saw**: ⚠️ **AIM technology remains
available and voluntary rather than required, it is not being retrofitted or mandated,
and — importantly — **it addresses BLADE CONTACT, not KICKBACK**.** ⚠️ **The riving knife,
push stick and stance in §9 → `shop-woodworking-tools-sharpening-joinery-and-finishing` remain the controls that matter, and they cost nothing.**
**⚠️ Scale note: CPSC estimated roughly 33,400 emergency-department-treated table saw
injuries in 2015, and around 54,800 medically treated blade-contact injuries annually in
earlier analysis.**

### 27.2 ⚠️ Welding fume: the numbers behind the ventilation advice
**⚠️ §19 → `shop-welding-forging-heat-treatment-and-shop-setup`'s PPE paragraph, quantified — and the figures explain why casual stainless welding
in an unventilated garage is a genuinely bad idea.**

- **⚠️ Hexavalent chromium — Cr(VI) — forms when arc welding heats chromium-bearing metal,
  principally STAINLESS STEEL.** ⚠️ **IARC classifies all hexavalent chromium compounds as
  Group 1 carcinogens.**
- **⚠️ The OSHA permissible exposure limit is 5 µg/m³ as an 8-hour time-weighted average
  (29 CFR 1910.1026), with an ACTION LEVEL of 2.5 µg/m³ that triggers monitoring and
  medical surveillance.** ⚠️ **That PEL is a tenfold reduction from the previous limit and
  is reported as 1,000 times lower than the PEL for general welding fume.**
  ⚠️ **NIOSH's recommended exposure limit is reported at 0.2 µg/m³ — 25× more protective
  than OSHA's.**
- **⚠️ The exposure risk is not theoretical.** ⚠️ **An estimated 558,000 US workers are
  exposed to airborne Cr(VI); welders with high exposure are reported to face an 85%
  increased lung cancer risk, and stainless steel welders nearly double the general
  population's risk per meta-analysis.**
- **⚠️ How fast you reach it**: ⚠️ **one industry source quotes an air quality specialist
  saying that MIG or stick welding on stainless for more than about ten minutes will
  overexpose you — "the limit is that low."** ⚠️ **Treat that as illustrative rather than
  precise, but the order of magnitude is the point.**

> **⚠️ GOTCHA — the control hierarchy applies here exactly as in §2 → `shop-materials-safety-reading-wood-and-stock`, and OSHA is explicit
> about the order.** ⚠️ **LOCAL EXHAUST VENTILATION at the source is the primary engineering
> control, supplemented by general dilution ventilation — and OSHA has determined
> engineering and work-practice controls must be the PRIMARY means, not respirators.**
> ⚠️ **General dilution ventilation "cannot replace LEV for high-hazard operations."**
> **⚠️ Note also a documented trap: the safety data sheet for a chromium-containing alloy
> will list chromium in its neutral state, which is NOT a carcinogen — the Cr(VI) is
> CREATED by the arc.** ⚠️ **So an SDS that looks clean does not mean the operation is.**

**⚠️ The other fume hazards in the same breath**: ⚠️ **manganese (neurological effects,
which is why ACGIH's value is set to mitigate brain damage), nickel, and iron oxide
(⚠️ OSHA PEL 10 mg/m³ — the least toxic common case, which is why mild steel is the
comparatively benign scenario).** ⚠️ **European practice sets a general respirable dust
limit of 1.25 mg/m³ with 0.010 mg/m³ for Cr(VI) and 0.006 mg/m³ for nickel compounds
(TRGS 900), and applies a MINIMIZATION principle for carcinogens — exposure reduced as far
as technically possible even when the limit is formally met.**
**⚠️ For the hobbyist, the honest translation**: ⚠️ **weld mild steel with your head out of
the plume and a fan drawing across; ⚠️ do not weld stainless or galvanized without real
extraction and respiratory protection; and treat "it's only a short job" as exactly the
reasoning that produces cumulative exposure.**

---

## §28. Misconceptions

| Misconception | Correction |
|---|---|
| A sharp tool is more dangerous | ⚠️ **Dull needs force; force loses control** (§7 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Sharpening is an advanced skill | ⚠️ **It's the prerequisite for everything** (§7 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Hardwood means hard | ⚠️ **Botanical, not mechanical. Balsa is a hardwood** (§3 → `shop-materials-safety-reading-wood-and-stock`) |
| Kiln-dried wood is stable | ⚠️ **It moves with humidity forever** (§3 → `shop-materials-safety-reading-wood-and-stock`) |
| Measure carefully and it'll fit | ⚠️ **TRANSFER instead of measuring where you can** (§5 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Use the fence and mitre gauge together | ⚠️ **Traps the offcut. Classic kickback cause** (§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| The blade guard is the main protection | ⚠️ **The RIVING KNIFE prevents kickback** (§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Flesh-detection makes a saw safe | ⚠️ **It addresses contact, not kickback** (§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`, §27.1) |
| Clamp harder to close the joint | ⚠️ **A joint needing force is cut wrong** (§11 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Glue squeeze-out will sand off | ⚠️ **It blocks finish. Remove it wet** (§11 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Gloves protect you around machines | ⚠️ **NEVER near rotating machinery** (§2 → `shop-materials-safety-reading-wood-and-stock`, §18 → `shop-metalwork-cutting-drilling-and-machining`) |
| Push harder to cut metal faster | ⚠️ **Rubbing work-hardens; then nothing cuts** (§14 → `shop-metalwork-cutting-drilling-and-machining`) |
| Cutting fluid is optional | ⚠️ **It's cooling. Heat destroys edges and tempers** (§14 → `shop-metalwork-cutting-drilling-and-machining`) |
| More thread engagement is stronger | ⚠️ **~75% is standard; more just snaps taps** (§17 → `shop-metalwork-cutting-drilling-and-machining`) |
| Mild steel can be hardened | ⚠️ **Not enough carbon** (§22 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| Hardened steel is ready to use | ⚠️ **Brittle until tempered. Never skip it** (§22 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| A cutting disc can grind a little | ⚠️ **Side loading shatters it** (§2 → `shop-materials-safety-reading-wood-and-stock`, §16 → `shop-metalwork-cutting-drilling-and-machining`) |
| Arc eye happens immediately | ⚠️ **Symptoms hours later. Bystanders too** (§19 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| A dust mask handles welding fume | ⚠️ **It doesn't. Extraction first** (§26 → `shop-welding-forging-heat-treatment-and-shop-setup`, §27.2) |
| The SDS shows no carcinogen, so it's fine | ⚠️ **The arc CREATES Cr(VI)** (§27.2) |
| A shop vac controls wood dust | ⚠️ **It misses the dangerous fine fraction** (§26 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| Wood dust is a nuisance | ⚠️ **Classified carcinogen; hardwood especially** (§2 → `shop-materials-safety-reading-wood-and-stock`) |
| Welding fixes a bad fit | ⚠️ **Fit-up determines weld quality** (§19 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| Weld it all at once for strength | ⚠️ **Distortion. Tack and stagger** (§19 → `shop-welding-forging-heat-treatment-and-shop-setup`) |

---

## §29. Numbers

```
⚠️ Wood MC for heated interiors  ⚠️ ~6–8%
⚠️ Tangential movement  ⚠️ roughly 2× radial
⚠️ Sharpening angles  ⚠️ ~25° primary, ~30° secondary (bench chisels)
⚠️ Hacksaw  ⚠️ minimum 3 teeth in the cut
⚠️ Tap drill  ⚠️ ~75% thread engagement standard
⚠️ Brazing vs soldering  ⚠️ ~450°C dividing line
⚠️ Caliper realistic resolution  ~0.05 mm · micrometer ~0.01 mm
⚠️ Table saw AIM standard (proposed)  ⚠️ ≤3.5 mm depth of cut at 1 m/s
⚠️ Measured AIM performance  ⚠️ SawStop 1.5–2.8 mm · Bosch 1.8–2.5 mm
⚠️ CPSC rule withdrawn  ⚠️ 20 August 2025
⚠️ Table saw injuries  ⚠️ ~33,400 ED-treated (2015); ~49,000+ the rule
                       would have prevented or mitigated annually
⚠️ Cr(VI) OSHA PEL  ⚠️ 5 µg/m³ 8-h TWA · action level 2.5 µg/m³
⚠️ Cr(VI) NIOSH REL  ⚠️ 0.2 µg/m³ (25× stricter)
⚠️ Iron oxide fume PEL  10 mg/m³ — ⚠️ 1,000× higher than Cr(VI)
⚠️ US workers exposed to Cr(VI)  ⚠️ ~558,000
⚠️ Lung cancer risk  ⚠️ reported +85% in high-exposure welders
```

---

## §30. Learning and Resources

| Source | Why |
|---|---|
| **A local class or makerspace** | ⚠️ **Machinery genuinely needs supervised first use** |
| **Hoadley, *Understanding Wood*** | ⚠️ **§3 → `shop-materials-safety-reading-wood-and-stock`. The book on wood as a material** |
| **Sellers / Schwarz / Cosman (hand tools)** | ⚠️ **§6–§7 → `shop-woodworking-tools-sharpening-joinery-and-finishing`, and free video is genuinely good here** |
| **Fine Woodworking archive** | Decades of tested technique |
| **Machinery's Handbook** | ⚠️ **§15–§25 → `shop-metalwork-cutting-drilling-and-machining`, `shop-welding-forging-heat-treatment-and-shop-setup`. The trade's single reference** |
| **Sparey, *The Amateur's Lathe*** | ⚠️ **§18 → `shop-metalwork-cutting-drilling-and-machining`, classic and still excellent** |
| **Hall / Workshop Practice Series** | ⚠️ **Small, cheap, focused volumes** |
| **AWS welding handbooks / *Welding For Dummies*** | §19 → `shop-welding-forging-heat-treatment-and-shop-setup` at both ends |
| **Lorena Bull / blacksmithing guilds** | §21 → `shop-welding-forging-heat-treatment-and-shop-setup` |
| **OSHA 1910.1026 and CPL 02-02-074** | ⚠️ **§27.2, primary** |
| **CPSC docket CPSC-2011-0074** | ⚠️ **§27.1, primary** |
| **Manufacturer manuals** | ⚠️ **Actually read them; the guards exist for reasons** |

---

## §31. Quick Reference

### 31.1 Picker
| Problem | Where |
|---|---|
| Plane tears out the grain | ⚠️ **Wrong direction, or use a scraper** (§3 → `shop-materials-safety-reading-wood-and-stock`, §6 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Nothing fits despite careful measuring | ⚠️ **Four-square first; transfer, don't measure** (§4 → `shop-materials-safety-reading-wood-and-stock`, §5 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Joint too tight to assemble | ⚠️ **It'll split when glued. Pare it** (§10 → `shop-woodworking-tools-sharpening-joinery-and-finishing`, §11 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Finish has pale patches | ⚠️ **Glue residue** (§11 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Saw burns the wood | ⚠️ **Dull blade, slow feed, or misaligned fence** (§8 → `shop-woodworking-tools-sharpening-joinery-and-finishing`, §9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Workpiece thrown back at me | ⚠️ **Kickback. Riving knife, stance, technique** (§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`) |
| Drill wanders | ⚠️ **Centre punch** (§17 → `shop-metalwork-cutting-drilling-and-machining`) |
| Tap snapped | ⚠️ **Too much engagement, no fluid, not square** (§17 → `shop-metalwork-cutting-drilling-and-machining`) |
| Tool stops cutting stainless | ⚠️ **Work-hardened. Sharp tool, positive feed** (§13 → `shop-metalwork-cutting-drilling-and-machining`, §14 → `shop-metalwork-cutting-drilling-and-machining`) |
| Machined part moved after cutting | ⚠️ **Residual stress. Rough, rest, finish** (§14 → `shop-metalwork-cutting-drilling-and-machining`) |
| Chatter on the lathe | ⚠️ **Rigidity, centre height, feed** (§18 → `shop-metalwork-cutting-drilling-and-machining`) |
| Weld is porous | ⚠️ **Contamination or lost shielding gas** (§19 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| Work distorted after welding | ⚠️ **Shrinkage. Tack, stagger, clamp** (§19 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| Braze won't flow | ⚠️ **Not hot enough, wrong flux, or gap too wide** (§20 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| Hardened part cracked | ⚠️ **Wrong quench, or never tempered** (§22 → `shop-welding-forging-heat-treatment-and-shop-setup`) |
| Eyes gritty hours after welding | ⚠️ **Arc eye. Medical attention** (§19 → `shop-welding-forging-heat-treatment-and-shop-setup`) |

### 31.2 Before you start the machine
- [ ] ⚠️ **Eye protection on; hearing protection for anything loud** (§2 → `shop-materials-safety-reading-wood-and-stock`)
- [ ] ⚠️ **No gloves, loose sleeves, jewellery; hair tied** (§2 → `shop-materials-safety-reading-wood-and-stock`)
- [ ] Guards fitted; ⚠️ **riving knife in place** (§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`)
- [ ] ⚠️ **Workpiece clamped or properly supported** (§8 → `shop-woodworking-tools-sharpening-joinery-and-finishing`, §17 → `shop-metalwork-cutting-drilling-and-machining`)
- [ ] Blade/bit sharp and correct for the material (§7 → `shop-woodworking-tools-sharpening-joinery-and-finishing`, §8 → `shop-woodworking-tools-sharpening-joinery-and-finishing`)
- [ ] ⚠️ **Push stick within reach; hands' path planned** (§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`)
- [ ] ⚠️ **Standing out of the line of fire** (§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`)
- [ ] Extraction running; ⚠️ **respirator if fine dust or fume** (§26 → `shop-welding-forging-heat-treatment-and-shop-setup`)
- [ ] Chuck key removed (§18 → `shop-metalwork-cutting-drilling-and-machining`)
- [ ] ⚠️ **Not tired, not rushing, not distracted** (§2 → `shop-materials-safety-reading-wood-and-stock`)

---

## §32. Method

**§1–§26 → `shop-materials-safety-reading-wood-and-stock`, `shop-woodworking-tools-sharpening-joinery-and-finishing`, `shop-metalwork-cutting-drilling-and-machining`, `shop-welding-forging-heat-treatment-and-shop-setup` rests on established craft practice and materials science** — **grain behaviour and
wood movement, sharpening geometry, the welding process families, heat treatment
metallurgy, and standard machine safety practice.** ⚠️ **None of it needed verification;
tempering colours and kickback mechanics have not changed.**

**Two searches were run in August 2026**, on **US table saw regulation** and **welding fume
exposure** — ⚠️ **both chosen because they are safety topics where the practical guidance
depends on facts that recently moved, and where hobbyists most commonly rely on outdated
or vibes-based information.**

**Confidence.** **High** in §2 → `shop-materials-safety-reading-wood-and-stock`, §7 → `shop-woodworking-tools-sharpening-joinery-and-finishing` and §9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`, which are the sections I'd most want read.
⚠️ **"Sharp is safe" is the single most useful principle here and it is counterintuitive to
beginners.** ⚠️ **§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`'s kickback mechanism — specifically that using the fence and mitre
gauge together traps the offcut, and that the riving knife rather than the guard is the
effective control — prevents a specific, common, serious injury.** **And §2 → `shop-materials-safety-reading-wood-and-stock`'s point that
hobbyists reach for PPE (the weakest control) while ignoring extraction is the pattern
worth breaking.**

**High** on §27.1's chronology, which comes from the Federal Register, CPSC documents and
trade reporting: ⚠️ **the 3.5 mm/1 m/s performance criterion and its derivation from UL's
4 mm laceration threshold, the measured AIM performance figures, and the withdrawal
announced 20 August 2025.** ⚠️ **I've deliberately given BOTH the patent-monopoly objection
and the injury-prevention counter-argument, because this was never a clean safety-versus-
industry question — the Power Tool Institute source is an industry body and the Consumer
Reports source is an advocacy organization, and I've identified both inline rather than
presenting either as neutral.**

**High** on §27.2's regulatory numbers, which trace to OSHA's own standard and
interpretations: ⚠️ **the 5 µg/m³ PEL and 2.5 µg/m³ action level under 29 CFR 1910.1026,
IARC Group 1 classification, and OSHA's determination that engineering controls must be
the primary means.** ⚠️ **The epidemiological figures (558,000 exposed workers, +85% lung
cancer risk, doubled risk in stainless welders) come from industrial-hygiene vendors
citing research rather than from papers I read directly, and I've marked them as
reported.** ⚠️ **The "ten minutes on stainless overexposes you" quote is from a single
specialist in a vendor publication and I've explicitly flagged it as illustrative — the
order of magnitude is the useful part, not the number.**