The short answer
On plate and housing RFQs, **dowel-pin hole location** is not the same note as “add two pins” or a generic press-fit bore. Location DFM covers which hole is **press versus slip**, how the pattern is **positioned to the datums**, whether one hole is a slot or diamond to avoid over-constraint, and what position tolerance the assembly actually needs. Silence on the fit family, on primary versus secondary hole, and on the datum scheme, is what widens many [quote-new.php](https://3dwk.com/quote-new.php) **rates.v1.1** estimate bands—not the drill minutes alone.
This guide is for buyers packaging aluminum automation plates where CAD shows two Ø6 dowel holes with no fit or position note, or a notes cloud that says “pins as needed.” Illustrations use an **Example part** only—not a customer fixture plate. Sibling notes live in [press-fit vs slip-fit CNC bores](https://3dwk.com/resources/press-fit-vs-slip-fit-cnc-bores) and [press-fit pins and bushings in CNC housings](https://3dwk.com/resources/press-fit-pins-bushings-cnc-housings); here we focus on **location packaging** so estimators do not guess two H7 press fits 80 mm apart with a 0.01 position on both.
What location DFM means for quoting
A dowel pattern usually needs **one tightly located, tightly sized hole** and a **second hole that locates in one direction only** (a slotted hole, a diamond pin, or a slightly looser position) so thermal growth and position stack do not fight. Two identical press fits with tight true position on both often over-constrain the pair and force reaming, jig-grinding, or **needs_manual**. Process pages for automation aluminum ([CNC 3-axis Al 7075 automation](https://3dwk.com/en/cnc-3axis/al-7075/automation.html), [CNC 5-axis Al 7075 automation](https://3dwk.com/en/cnc-5axis/al-7075/automation.html), [CNC 3-axis Al 7075](https://3dwk.com/en/cnc-3axis/al-7075.html)) assume location notes when lots mix open bolt holes with dowel patterns.
Do not bury “dowel holes as CAD” inside a notes cloud. Put **Ø6H7 PRESS AT D1, POSITION Ø0.03 TO A|B|C; Ø6 SLIP / SLOTTED AT D2, WIDTH 6.0+0.02, POSITION 0.05 IN THE TIGHT DIRECTION** on the PDF and mirror it in RFQ text. Background: [datum schemes for multi-setup CNC parts](https://3dwk.com/resources/datum-schemes-for-multi-setup-cnc-parts), [position vs profile tolerances on CNC brackets](https://3dwk.com/resources/position-vs-profile-tolerances-cnc-brackets).
Press, slip, and over-constraint
Name the fit on each hole. A **press** (or transition) hole holds the pin in the plate; the mating part often gets the **slip** hole—or the reverse, if the pin is captive in the cover. Two press holes in one plate are a valid pack only when you intend to press pins into that plate and slip the mate, and when the secondary hole is allowed to float in the loose direction. Calling “all dowels H7” without saying which side holds the pin leaves both parts quoted as precision reamed pairs. Related: [reaming vs boring for CNC hole size](https://3dwk.com/resources/reaming-vs-boring-cnc-hole-size), [GD&T callouts that raise CNC quote bands](https://3dwk.com/resources/gdandt-callouts-that-raise-cnc-quote-bands), [when should I split a CNC part into two pieces?](https://3dwk.com/resources/when-to-split-a-cnc-part-into-two-pieces).
Aluminum 7075 bar/plate $/kg planning bands sit above 6061 under **rates.v1.1** material tables; material cost is rarely the dowel story—ream versus bore, position tolerance, and whether a slot is allowed are.
Pattern spacing and datums
Put the dowel pattern on the same datum scheme as the features it locates. A 0.02 true position to a weak edge datum, or a pattern that is implied only from a 3D model origin, forces the shop to invent a setup. Spacing matters: very short spans amplify angular error; very long spans amplify thermal and position stack—use a slot or diamond on the far hole rather than tightening both positions. For most automation buyers, a **press + slip/slot pack** is clearer than two identical tight holes.
Tolerance and inspection traps
Two tight positions on two press fits, mixing H7 and a “press as needed” note on the same diameter, omitting which plate keeps the pins, or asking for 100% CMM of every open bolt hole as if it were a dowel, all force **needs_manual**. Default fastener holes to ISO 2768-m or a coarse position and put functional location only on the dowel family. Related: [ISO 2768 general tolerances on CNC RFQs](https://3dwk.com/resources/iso-2768-general-tolerances-cnc-rfq), [DFM checklist before an online CNC quote](https://3dwk.com/resources/dfm-checklist-before-online-cnc-quote). Depth, chamfer, and whether the hole is through or blind belong next to the fit note.
Illustration 1 shows an **Example part** plate with a labeled press dowel at D1 versus a slotted slip hole at D2, both positioned to a named datum scheme.
Example part walkthrough
**Example part:** Aluminum 7075-T6 plate ~120×80×12 mm, two Ø6 dowel locations 70 mm apart, four M4 through bolts, ISO 2768-m general. With STEP + **D1 Ø6H7 PRESS, POS Ø0.03 TO A|B|C; D2 Ø6 SLIP SLOTTED 8.0 LONG, TIGHT-DIRECTION POS 0.05; PINS SUPPLIED IN D1**, expect a usable automatic planning band on [quote-new.php](https://3dwk.com/quote-new.php). Same geometry with silent CAD and “two Ø6 dowels, press both, position 0.01” often lands DFM notes or **needs_manual**—without inventing any customer PO.
Illustration 2 contrasts a vague RFQ (“pins as needed”) versus a labeled location pack and the clearer estimate path.
What widens bands fastest
Two identical tight press fits, missing primary/secondary assignment, position to an unnamed origin, and 100% inspection of every bolt hole as a dowel. Quantity breaks help unit minutes but do not erase location ambiguity—see [how quantity breaks change CNC unit cost](https://3dwk.com/resources/how-quantity-breaks-change-cnc-unit-cost) and [what needs_manual means](https://3dwk.com/resources/what-needs-manual-means-preliminary-quote).
What to do next
Mark each dowel as **press or slip**, assign a primary hole and a secondary slot or looser position, name the datums, then upload on [quote-new.php](https://3dwk.com/quote-new.php). Service pages: [CNC machining](https://3dwk.com/cnc-machining-service.php), [materials](https://3dwk.com/materials.php). Treat **rates.v1.1** min/mid/max as estimates, not invoices. If the UI shows **needs_manual**, answer the location questions rather than forcing a fake firm price.
Common questions
Do both dowel holes need the same position tolerance?
Usually no under **rates.v1.1** estimates. A tighter position on the primary hole and a looser or slotted secondary hole locates the part without over-constraint. Matching 0.01 on both often widens the band.
Can I press pins into both mating plates?
Only if you intend a unique pin set and a very controlled assembly process. The common pack is pins retained in one part and slip or slotted in the mate. Write which side keeps the pins.
When should I use a diamond pin or a slot?
When the span is long, when thermal growth matters, or when two round tight holes would fight. Name the loose direction so the shop does not ream both as round H7.
How should I call out hole finish or chamfer?
Put a small lead-in chamfer and a bore Ra next to the press hole if the pin is assembled by hand. Leaving chamfer only in a general title block leaves press-in risk and inspect method unclear.