Tuesday’s create hole matched the allowance chart and still scrapped on finish marks or lobing—then someone opened the PCD reamer drawing as if stock millimeters were the whole story.
This page is the pre-hole quality gate: roundness, axis wander, torn or smeared walls, work-hardened skin, and cross-hole steps—plus a short go/no-go before you ream. Size the stock on PCD Reamer Allowance & Pre-Hole Size. Do not treat this page as a reprint of the allowance mm path, an RFQ field encyclopedia (PCD Reamer RFQ Checklist), or a full drill–expand–ream route essay (Hole machining process route).
Allowance sets stock; pre-hole quality decides whether a PCD reamer can hold size and wall finish. Check roundness, axis wander, torn or smeared walls, hard skin, and cross-hole steps before you ream. Some defects ream through; others need a re-drill or process change—use the go/no-go cues below, then send print data on the RFQ checklist.
Roundness / lobing after drill
A create hole can sit inside the allowance band and still carry two- or three-lobe form from drill whirl, uneven entry, or holder runout. The reamer follows that path more than it “averages it away.”
Fail signals: periodic size swing on a roundness trace; finish bands that repeat each flute pitch of the create tool; first-article pass on the dial, then lobing returns when stickout or fixture load changes on the next shift.
Ream risk: lobing that exceeds what the reamer radial stock can erase shows up as finish variation and local oversize—even when mean diameter looked fine on a two-point dial.
Disposition cues: light, stable lobing inside the reamer’s stock window → often go (ream and verify roundness). Severe, unstable lobing or lobing that grows with depth → no-go; fix create (holder, point, feed entry) or re-drill before blaming PCD geometry. Drill/ream role split stays on Reamer vs drill bit for precision holes.
Axis wander & location error
Walked axes and location error are create problems. A finishing reamer mainly sizes and finishes the wall it is given; it is a poor true-position corrector.
Fail signals: hole center drifts from print datum; entry and exit axes disagree; positional scrap repeats while diameter stock looks “in band.”
Ream risk: forcing the reamer to “pull” a walked hole loads the lead unevenly, raises chatter risk, and can leave tapered or banana form that looks like a wrong reamer diameter.
Disposition cues: small, stable wander within positional tolerance after ream → cautious go with measured first-offs. Clear walk past print true position, or exit that fights entry → no-go; re-drill / pilot / fixture before a reamer revision. Full route context (when expand or bore belongs in the chain): Soft hole process route—do not merge that essay here.
Wall finish / tear / smear
Longitudinal scratches, torn aluminum, or BUE smear on the create wall often transfer into the reamed finish. PCD edges cut clean stock well; they do not reliably erase deep tear tracks or sticky smear bands.
Fail signals: axial scratch lines that survive ream; sticky residue or stain after wash; local oversize bands where smear was thickest.
Ream risk: recutting damaged wall consumes radial stock unevenly and can restart built-up edge on the reamer—scrap then looks like “reamer finish life” when the create wall was already compromised.
Disposition cues: shallow, cleanable marks inside stock → often go after clean. Deep tear, packed smear, or chip-scored walls → no-go until create chip control and wash practice stabilize. Drill-side chip packing and through-coolant choices live on Soft through-coolant solid carbide drill—one handoff line only; no coolant decision essay on this page.
Work-hardened skin / interrupted entry
Cast skin, prior cold work, or an interrupted entry (slot, window, prior cross feature) can leave a hard or uneven first-engagement zone. The reamer lead then sees shock loading before the full bore.
Fail signals: first-millimeter chatter or edge nick; entry bellmouth; scrap concentrated at start of cut while mid-bore looks acceptable.
Ream risk: hard skin or interrupted entry can chip a sharp PCD lead or force an early offset that then fights the rest of the bore.
Disposition cues: mild, consistent skin with controlled chamfer/entry → go with verified lead engagement. Heavy cast skin, broken entry, or repeated first-mm scrap → no-go; rework create entry (chamfer, pilot, skin removal) before changing reamer diameter or margin. Do not invent life-% claims for “hard skin recovery.”
Cross-hole steps & burrs into the bore
Where a cross hole intersects the bore, steps, burrs, and local oversize pockets act like interruptions for the reamer. Allowance mm on the main bore does not describe that local geometry.
Fail signals: witness rings or steps at intersection; burr folded into the main bore; scrap or chatter that spikes only at the cross-hole station.
Ream risk: the reamer may wipe a soft burr and still leave a step that fails seal or flow; aggressive stock at the intersection can nick margins.
Disposition cues: light, removable burr with no hard step → often go after deburr. Hard step, deep pocket, or intersection that eats radial stock → no-go; fix cross-hole sequence / deburr / expand strategy on Soft hole process route before a reamer redesign.
Go / no-go before reaming
Use this short gate after stock is sized on the allowance article—not instead of it. Freeze the create-hole photos and gauge notes before the reamer blame circle starts.
| Cue | Prefer | Why |
|---|---|---|
| Roundness / lobing light & stable; wall clean | Go — ream | Stock window can finish form |
| Axis wander within print after create; entry OK | Go — ream + verify TP | Reamer not used as position fixer |
| Deep tear / smear / chip score on wall | No-go — re-drill / fix create | Finish will inherit damage |
| Clear walk / banana axis past print | No-go — re-drill / fixture | Reamer cannot true the axis |
| Heavy hard skin or broken interrupted entry | No-go — rework entry | Lead shock / early nick risk |
| Hard cross-hole step into bore | No-go — fix intersection | Local geometry ≠ mean allowance |
| Stock mm out of band | Leave this page → allowance | Quality gate assumes size path done |
Measure before blaming the reamer drawing: (1) confirm allowance band, (2) record roundness / taper / wall condition on the create hole, (3) note holder runout at production stickout, (4) freeze gauge + temperature practice, (5) only then open a reamer geometry discussion.
What to put on the RFQ (quality notes · not a field dump)
Log create-tool changes, reamer offsets, and scrap against accepted holes—see the shared frame on Cost per Accepted Hole. Do not turn this section into a slogan or a full field encyclopedia.
For quotation, send the short quality evidence pack and use Soft PCD Reamer RFQ Checklist for the complete field list:
- Drawing + material (Si% when aluminum)
- Measured pre-hole size band (allowance method) and quality notes (roundness / wander / wall / skin / cross-hole)
- Create tool / holder / stickout / coolant mode (one line; not a coolant essay)
- Current scrap mode (finish streaks, lobing, entry nick, intersection fail)
- Acceptance rule for the finished bore
Photos that help: create-hole wall, entry, and chip/packing evidence—adjectives alone stall review.
Frequently Asked Questions
Allowance is correct but holes still fail—what else to check?
Roundness/lobing, axis wander, torn or smeared walls, work-hardened skin or interrupted entry, and cross-hole steps. Quality defects can fail the bore even when stock mm is in band—use the go/no-go table above before revising the reamer.
Can reaming fix a walked drill axis?
Usually no. A PCD reamer finishes and sizes the wall it inherits; clear walk or banana form needs create/fixture correction or re-drill. Small, stable wander inside print may still go—verify true position on first-offs.
How is this different from the allowance page?
Allowance & pre-hole size sizes stock (mm / method). This page qualifies the hole (form, wall, inheritance, go/no-go). Use both; do not merge them into one chart.
What pre-hole photos/notes help an RFQ?
Create-hole wall, entry, and chip/packing evidence, plus measured size band and short quality notes (roundness, wander, tear/smear, skin, cross-hole). Full field list: Soft RFQ checklist—do not paste that table here.
Next step
Qualify the create hole with the go/no-go cues, size stock on the allowance sister, then send measured bore data—not adjectives alone. Stay through first-article with Sample Validation Process and How PCD reamers are made in the loop when wall or lobing talks back after ream.
Soft (read first): PCD Reamer Allowance & Pre-Hole Size · PCD Reamer RFQ Checklist · Reamer vs drill bit · Hole machining process route · Through-coolant solid carbide drill · Cost per Accepted Hole · Sample Validation Process · How PCD reamers are made
Product: Custom PCD reamer
Hard: Custom cutting tool RFQ — send drawing, material, measured pre-hole (size + quality notes), create tool/setup, and scrap mode.