Decide the heat-set insert family (Mouser-orderable vs. current McMaster short inserts) before v3 release

[HuggeK]

Summary

Before the enclosure gets a proper v1 release + build guide, decide which heat-set insert family (and screw standard) the CAD is designed around. The current 2026-08-12 assembly drawing specifies McMaster part numbers, but McMaster is hard to order from outside the US. Both radars (OPS243-A-CW-RP and IWR6843LEVM) are on Mouser and the main repo already ships a shared Mouser project in docs/PARTS.md, so the goal is: one Mouser order covers radars + inserts + as many screws as possible, with a McMaster equivalent for US builders.

Update: PEM's short tapered IUB "-1" series (stocked by Mouser) is a near drop-in for the pockets already in the CAD. The required change shrinks to "widen the M2.5 bosses" — see the recommendation below.

Update 2026-09-04: after the Discord discussion the decision is the plain, full-length IUTB family for all three sizes: IUTB-M2, IUTB-M2.5, IUTB-M3. The short codes (IUTB-M2-318, IUTB-M3-343) are dropped because they are not reliably stocked, and the tapered IUB "-1" recommendation in the first draft is superseded. The Mouser project already carries IUTB-M2.5; the fit table, pocket spec and order table below are updated to match, and the M2.5 derivation is in the section "M2.5: from IUB-M2.5-1 to IUTB-M2.5" below. Later the same day: the camera-board M2 screws turned out to be on Mouser after all (APM HEXSEAL RM2X4MM 5701 in stainless, Essentra 50M020040D006B in nylon), so no M2 screw is left on the Amazon list, and the M2 washer line was dropped; the tables below reflect both. The follow-up findings (M2.5 derivation, CNC Kitchen comparison, kickstand detent, M2 screws and washers, case ports) are the sections after "Extra mounts"; they were first posted as comments and have been merged here. The one screw still forcing an Amazon order, the M2.5×35 through-bolt, is now written up as a CAD option: rework the housing joint so the through-bolt is 16 mm or shorter with the inserts at the flange, and every screw comes from Mouser (see "Design option for the CAD owners" under the screw table).

What the drawing currently specifies

From 20260812-OpenFligh-Assm.pdf (McMaster part numbers):

Item	Part	Qty
Inserts M2	93502A108	4 (camera board)
Inserts M2.5	93502A109	14 back housing + 4 front housing + battery board (count TBD, ~4)
Inserts M3	93502A111	2 (handle / kickstand peg)
Screws	91290A012 M2×5, 92290A055 M2.5×5, 91292A313 M2.5×35 (×8), 91290A117 M3×12	all DIN 912 socket-head cap screws

McMaster lists 93502A108 under "Any-Orientation Heat-Set Threaded Inserts for Plastic" — i.e. the short, symmetric insert style.

What the CAD bosses are actually cut for

Parsed from OpenFlight_LF.STEP (the assembly in the drawing; the copy in the main repo is an earlier revision with fewer bosses, but the pocket style is consistent throughout). Every insert boss is one pattern:

Ø6.0 boss  →  Ø3.1 × 2.0 mm pocket  →  Ø2.1 pilot, 7–12 mm deep   (M2.5 points)
Ø6.0 boss  →  Ø2.9 × 2.0 mm pocket  →  Ø2.1 pilot, 7 mm deep      (M2 points)
Ø4.0 × 5.0 mm pocket                                               (M3 points)

That matches the common short brass insert: M2 ≈ Ø3.2 × 3 (hole 2.9), M2.5 ≈ Ø3.5 × 3 (hole 3.1), M3 ≈ Ø4.5 × 4 (hole 4.0).

What Mouser stocks (PEM / SI brand)

PEM makes two heat-stake families, both on Mouser. Dimensions from the PEM SI datasheet (p.5 IUB, p.6 IUTB, p.10 performance, p.25 boss guideline).

IUB "-1" — short, tapered (superseded, kept for reference). PEM's standard ultrasonic/heat-stake insert for moulded bosses; the tapered hole self-aligns the insert.

Part	Mouser	Length	OD	Hole Ø bottom → top (8° taper)	Min depth	Pull-out ABS
IUB-M2-1	not stocked by Mouser (PEM catalog only)	2.92	3.58	3.00 → 3.12	3.94	334 N
IUB-M2.5-1	SI/IUB-M25-1	3.43	4.37	3.89 → 4.04	4.44	334 N
IUB-M3-1	SI/IUB-M3-1	3.43	4.37	3.89 → 4.04	4.44	356 N

IUTB — straight-wall thru-threaded (chosen). Longer; the standard M2.5/M3 need 6.5 mm depth. Only the plain codes are used: the short -318 / -343 codes are not reliably stocked.

Part	Mouser	Length	OD	Hole Ø	Min depth
IUTB-M2-318 (short code)	not orderable on Mouser — the product URL resolves to an empty placeholder page, no stock/price	3.18	3.73	3.23	3.94
IUTB-M2 ✅	SI/IUTB-M2 (also mouser.co.uk); stainless twin SI/IUTC-M2	4.00	3.73	3.23	4.76
IUTB-M2.5	SI/IUTB-M25	5.74	4.55	4.01	6.5
IUTB-M3	SI/IUTB-M3	5.74	4.55	4.01	6.5

There is no short M2.5 in the IUTB family (the datasheet lists only the 5.74 mm body). For M2 the only Mouser-orderable SI part is the full-length IUTB-M2 (4.00 body, Ø3.23 hole, 4.76 deep) — IUB-M2-1 is not stocked and the IUTB-M2-318 page is an empty placeholder. Rather than mix short and long codes by size, the Mouser set is the plain IUTB family throughout: IUTB-M2 + IUTB-M2.5 + IUTB-M3.

Also on Mouser: Adafruit 4255 (M3 × 4 mm, OD 4.2, 50-pack, about $6) — the hobby-style M3 insert; drops into the existing Ø4.0 × 5 pockets unchanged. Not used: with IUTB-M3 the M3 pocket goes to 6.5 mm anyway, and one family keeps the insert BOM to three lines.

PEM boss guideline (p.25): boss Ø ≈ 2 × insert Ø; "thinner walls and bosses may be used but will affect performance."

Fit against the current bosses

Points	Current pocket	With IUTB	Change needed
M3 (handle)	Ø4.0 × 5.0	IUTB-M3	Ø4.01 hole already matches; deepen from 5.0 to 6.5 for the 5.74 mm body; boss ≥Ø8 (guideline 9.1)
M2 (camera)	Ø2.9 × 2.0 + Ø2.1 pilot	IUTB-M2	widen to Ø3.23 (+0.08), deepen to 4.76 — the Ø2.1 pilot already runs 7–12 mm so depth is free; a Ø6 boss leaves a 1.4 mm wall, fine for a camera board
M2.5 (~22)	Ø3.1 × 2.0 + Ø2.1 pilot	IUTB-M2.5	pocket → Ø4.01 +0.08 × 6.5 deep (the Ø2.1 pilot already runs 7–12 mm, so the depth is free on the housings); boss Ø6 → Ø8 (guideline 9.1; Ø8 leaves ~1.7 mm). Every M2.5 PEM makes has a ≥Ø4.37 body, so the wider boss is unavoidable for any Mouser M2.5 insert

With IUTB the M2.5 bosses get both wider and deeper, and the M3 pocket deepens to 6.5 mm. That extra depth was the argument for IUB in the first draft; the Discord discussion took the straight hole and a single insert family over the smaller CAD change, since the depth is free wherever a pilot already runs below the pocket. Check the LIS3DH and battery-board bosses, which were specified flush with the base and need 6.5 mm of material under the pocket.

Options

A. Redesign for the plain PEM IUTB family and make Mouser the reference vendor (chosen).
Widen the M2.5 bosses to Ø8 and deepen their pockets to 6.5 with the pocket spec below; open the M2 pockets to Ø3.23 × 4.76 for IUTB-M2; deepen the M3 pocket to 6.5 for IUTB-M3. McMaster's equivalent for US builders would be their straight-wall heat-set inserts (part numbers to confirm — McMaster does not sell PEM-branded parts). Pros: one Mouser order, one insert family, datasheet hole specs, more thread engagement than the current short inserts. Cons: a CAD pass on the M2.5 bosses and the M3 pocket.

B. Keep the short-insert design and spec it by hole size.
BOM says "M2 insert for Ø2.9 hole", "M2.5 insert for Ø3.1 hole", "M3 insert for Ø4.0 hole". Global commodities (Prusa, CNC Kitchen, 3DJake, Amazon/AliExpress assortments; McMaster 93502A for the US) — just not on Mouser. Pros: no CAD change, cheapest inserts. Cons: not a Mouser item, and OD varies by brand so the hole spec needs a tolerance note. The second vendor is not really extra: the Geekworm X1202/X1206 UPS HAT and the InnoMaker OV9281 camera in docs/PARTS.md are Amazon items already.

C. Hybrid. Adafruit 4255 / IUB-M3-1 at the handle now, short inserts elsewhere. Only worth it if A is rejected.

Decision from the Discord discussion (2026-09-04): A, with the plain IUTB family throughout. Single-vendor ordering is the whole point, and the boss change is mechanical, not a layout change.

Pocket spec for the CAD / drawing (option A)

M2   : Ø3.23 +0.08 straight wall, ≥4.76 deep, boss ≥Ø6, pilot below for screw-tip relief   (IUTB-M2)
M2.5 : Ø4.01 +0.08 straight wall, ≥6.5 deep,  boss ≥Ø8, pilot below                        (IUTB-M2.5)
M3   : Ø4.01 +0.08 straight wall, ≥6.5 deep,  boss ≥Ø8, pilot below                        (IUTB-M3)

All three are straight holes, so there is no taper to model; the pilot below each pocket gives screw-tip relief for the thru-threaded inserts.

Mouser order — fasteners for one build

Mouser / MPN	What	Qty
SI/IUTB-M25	M2.5 insert, 5.74 long	50 (22 as drawn + 4 LIS3DH + 4 if the Pi mounts to the case; check MOQ)
SI/IUTB-M3	M3 insert, 5.74 long	10
SI/IUTB-M2 (IUB-M2-1 and IUTB-M2-318 are not orderable on Mouser)	M2 insert, 4.00 long	10
Keystone Electronics 29314	M3×12 pan head, steel zinc	10
Keystone Electronics 29301 (6 mm) or 29300 (4 mm)	stand-in for the M2.5×5 board screws (incl. 4 LIS3DH, 4 Pi-to-case)	25
APM HEXSEAL RM2X4MM 5701 (Mouser 608-RM2X4MM5701)	M2×4 Phillips pan head, 18-8 stainless with a Viton O-ring under the head: the one metal M2×0.4 screw on Mouser (page 2 of the M2 × 0.4 category, 1,850 in stock, about SEK 12 each). Camera board, 2.4 mm into the IUTB-M2 through a 1.6 mm PCB	4 (buy 5)
Essentra 50M020040D006B	M2×6 nylon cheese-head slotted screw, in stock, the cheap alternative for the same four holes (4.4 mm into the insert, tip into the pilot). Essentra's 5 mm codes are 4-week non-stocked	10 (if nylon)
Keystone Electronics 4692	#4 flat washer (ID 3.25, OD 7.1, 0.64 thick) under the heads of the 8 × M2.5×35 through-bolts. Recommended, not in the drawing: a DIN 912 M2.5 head is only Ø4.5, so it bears on a 0.8 mm ring of printed plastic around the Ø2.9 clearance hole and embeds a little each time the case is opened and re-tightened; the washer spreads that load over three times the area. Skip them if the CAD gets counterbores sized for the bare head	10

Screws needed for one build (as drawn)

Screw	Qty	Fastens	Engagement check with the inserts above	Mouser
M2×5 (or ×4 / ×6)	4	camera board (1.6 mm PCB)	3.4–4.4 mm into the 4.0 mm IUTB-M2 for ×5/×6; the 4 mm stainless gets 2.4 mm, six threads in brass, plenty for a camera board; the tip lands in the pilot	✓ stainless: APM HEXSEAL RM2X4MM 5701 (M2×4 Phillips pan head, O-ring seal screw, in stock). ✓ nylon: Essentra 50M020040D006B (M2×6 cheese slotted, in stock) or D004B (M2×4); D005B and the 5 mm pan heads are 4-week non-stocked. Both are on page 2 of the M2 × 0.4 category. Keystone Electronics's "M2" is 2-56 titanium (21203/21204, wrong pitch) and RAF M0266-SS is a 10 mm captive panel screw, out of stock
M2.5×5	14 + ~4	OPS243, IWR6843, sound detector, battery board	3.4 mm into the 5.74 mm IUTB-M2.5 (thru-threaded; the tip clears into the pilot)	✗ 5 mm; Keystone Electronics 29301 (6 mm) works if the pilot below the insert is kept, 29300 (4 mm) gives 2.4 mm engagement
M2.5×35	8	screen → back housing (4), front → back housing (4)	through-bolts into the front-housing inserts	✗ any vendor. Mouser's longest metal M2.5 is 16 mm (Keystone Electronics 29306; APM HEXSEAL stops at 12 mm, Essentra nylon at 20 mm), so this is the one screw that keeps a build from being all-Mouser. If the joint were reworked so the through-bolt is 16 mm or shorter (inserts at the flange instead of deep in the housing), every screw would come from Mouser
M3×12	2	kickstand peg → handle, from inside	5.74 mm insert; ~6 mm of the screw is in the peg	✓ Keystone Electronics 29314
Washers	8 × M2.5 (recommended, not in the drawing)	under the heads of the 8 M2.5×35 through-bolts; the order table says why	—	✓ Keystone Electronics 4692 (#4, ID 3.25 / OD 7.1). No M2 washers: the four M2 heads sit on the camera PCB's pads, and the M2.5 heads (Ø4.5 socket, Ø5 pan) already cover the OPS243's Ø3.175 holes

Head style: the drawing calls out DIN 912 socket heads (M2 Ø3.8, M2.5 Ø4.5, M3 Ø5.5). Keystone Electronics/Electrokit substitutes are pan heads (wider, shorter). No counterbores were found in the STEP, so either fits; keep DIN 912 as the spec so the drawing stays consistent.

Not on Mouser from any vendor: M2.5×35 (spec as DIN 912 / ISO 4762, A2 stainless — black-oxide alloy is a poor choice for a device that lives outdoors). M2.5×5 exactly is not there either, but Keystone Electronics 29301 (6 mm) stands in for it, so the eight through-bolts are the only screws that force the Amazon order. They go on the Amazon order that the BOM already needs for the UPS HAT and camera — DIN 912 A2 assortments and insert kits are stock items in the US and EU. Net result for a builder: two orders total, Mouser + Amazon, and one CAD change (through-bolts of 16 mm or less) would make the screws all-Mouser; that change is written up next.

Design option for the CAD owners: shorten the through-bolts and the screws go all-Mouser

The 8 × M2.5×35 through-bolts (4 screen → back housing, 4 front → back housing) are the only fasteners that keep a build from being a single Mouser order. They are 35 mm because they run the full depth of the housing to reach inserts seated deep in the front housing. Mouser's longest metal M2.5 is 16 mm (Keystone Electronics 29306, pan head, zinc-plated steel; 29304 is 12 mm), so no sourcing trick fixes this; only the joint can.

The change: rework the front-to-back joint (and the screen-to-back joint) so the bolt is 16 mm or shorter, with the IUTB-M2.5 inserts sitting at the mating flange instead of deep in the housing. In practice that means moving the four insert pockets up to the parting line (or adding bosses / ears at the flange on the front housing), so the bolt only passes through the back-housing flange and the washer before it reaches the insert.

• Length budget: 16 mm bolt − 0.64 mm washer − 5.74 mm insert leaves about 9.6 mm, so the back-housing flange can be up to ~9 mm thick and the bolt still fills the insert with its tip in the pilot. With 29304 (12 mm) the flange limit is ~5.5 mm.
• Unchanged: Ø2.9 clearance hole, the Keystone 4692 washer (or a counterbore sized for the head), the IUTB-M2.5 pocket spec above, and the DIN 912 callout on the drawing (Keystone pan heads remain the Mouser substitute).
• Order impact: the Amazon line "8 × M2.5×35 DIN 912 A2" is replaced by 8 × Keystone 29306 (Mouser 534-29306) or 29304 (534-29304), chosen once the flange thickness is fixed. Every other line in the order table stays as it is, and the Amazon order then only carries the UPS HAT, cells, camera and the kickstand ball plunger (none of which are fasteners).
• Until then: the two-order rule stands and the M2.5×35 through-bolts stay on the Amazon list.

Amazon order — everything Mouser does not carry

Item	Spec	Amazon (US)	Qty needed
M2.5×5 socket head	DIN 912, A2/304 stainless	DIN 912 M2.5×5 SS, 300 pc B00BNCQ9R2 · 100 pc B01H2106US	14 + ~4
M2.5×35 socket head	DIN 912 / ISO 4762, 18-8 stainless	Newport M2.5-0.45×35 18-8 SHCS, 25 pc B082GJTKTY	8
Option B inserts (no CAD change)	short tapered brass, sized to the drawing's Ø2.9 / Ø3.1 / Ø4.0 holes	initeq M2.5 B077CJQ3J3 · initeq M3 B077CL322T · ShineNow M2/M2.5/M3 kit B09MK3C9XW · search: M2 short heat-set insert	4 M2, ~22 M2.5, 2 M3
Geekworm X1202 UPS HAT	already an Amazon item in docs/PARTS.md	B0CRZ4ZXQW	1
InnoMaker OV9281 camera	already an Amazon item in docs/PARTS.md	B09WTP5GZH	1 (optional)

Amazon caveats: ASINs are amazon.com listings found by search and not verified in a cart — check the title (thread, length, DIN 912, stainless) before ordering, since sellers rotate stock. EU storefronts (amazon.de/.se) carry different ASINs; search the same spec string there. For option B, insert OD varies by brand, so the drawing needs a hole-size tolerance note rather than a part number.

Extra mounts not in the drawing (Touch Display 2, Pi-to-case, LIS3DH)

Measured from the Touch Display 2 STEP (Onshape export, 7-inch, includes a Pi 5 model) and the Adafruit LIS3DH board file.

Touch Display 2 rear — eight threaded M2.5 points, no inserts needed:

Feature	Count	Geometry (from STEP)	Use
Pi standoffs	4	Ø5.0 posts, 8.5 mm tall, M2.5 tapped ~5.7 deep; 58 × 49 mm Pi pattern	Pi 5 bolts straight on with the 4 included M2.5 screws
Corner pads	4	~8 × 5.3 mm rectangular pads standing 3 mm proud of the back plate, M2.5 tapped ~2.4 deep as modelled; 70.7 × 140.0 mm pattern, each 24.7 mm in from the bezel edge	display-to-case mount: screw in from behind with the other 4 included M2.5 screws, length = case wall + ~2.5 mm

Bezel outline 120.2 × 189.3 mm (matches the published 120 × 189.5), back plate 99.7 × 168.5 mm and 6.3 mm thick. Real thread depth of the corner pads should be confirmed against the official mechanical drawing (pip.raspberrypi.com); the STEP only shows the modelled hole.

If the Pi screws to the case instead of the standoffs (jamorros variant): +4 M2.5 inserts and +4 M2.5 screws for the Pi (Ø2.7 holes, 58 × 49 mm). Screw length = 1.6 mm PCB + boss height + 3.4 mm engagement; M2.5×6 (Keystone Electronics 29301) for flush bosses. Note the 8.5 mm standoffs then still touch the Pi unless it is moved off the display pattern.

LIS3DH inclinometer mount (planned): the Adafruit 2809 board is 17.78 × 25.4 mm with four plated Ø2.5 mm holes (Ø3.2 pad) on a 12.7 × 20.32 mm pattern. It is a 1.5 g board that must sit rigid and flat on the base (docs/inclinometer/README.md), so use all four: +4 IUTB-M2.5 inserts, +4 M2.5×5 (or Keystone Electronics 29301 M2.5×6) screws, bosses flush with the base, same pocket spec as the housings. No washers needed — the DIN 912 / pan head covers the Ø3.2 pad. The Mouser order below already covers this in quantity; only the counts change.

M2.5: from IUB-M2.5-1 to IUTB-M2.5 (Discord, 2026-09-04)

After discussion on Discord, the shared Mouser project carries the straight-wall, thru-threaded SI IUTB-M2.5 for all M2.5 points, in place of the short tapered IUB-M2.5-1 of the first draft.

• Mouser: SI/IUTB-M2.5 (mouser.se) · mouser.com
• PEM catalog page: IUTB-M2.5

What changes for the CAD (M2.5 points only; M2 and M3 are covered by the same family, see the fit table):

	IUB-M2.5-1 (was)	IUTB-M2.5 (now)
Length	3.43	5.74
Body OD	4.37	4.55 (E), 3.86 at the lead-in (C)
Hole	Ø3.89 → Ø4.04, 8° taper	Ø4.01 +0.08, straight wall
Min. hole depth	4.44	6.5
Boss (2 × OD guideline)	≥Ø8 (guideline 8.7)	≥Ø8 (guideline 9.1; Ø8 leaves ~1.7 mm wall)

Why this still fits, and what to check

• Depth. The M2.5 pockets sit over a Ø2.1 pilot that already runs 7–12 mm, so the 6.5 mm the IUTB needs is available on the back and front housings without adding boss height. The LIS3DH and battery-board bosses were specified flush with the base; those need 6.5 mm of material under the pocket, so check them.
• Screws. IUTB-M2.5 is thru-threaded, so the M2.5×5 board screws (about 3.4 mm of engagement through a 1.6 mm PCB) and the Keystone Electronics 29301 M2.5×6 both work, and the pilot below the insert still gives tip relief. The eight M2.5×35 through-bolts are unaffected.
• Modelling. A straight hole is simpler to model and print than the 8° taper, and IUTB is the same family chosen for the camera board (IUTB-M2), so the M2 and M2.5 pockets share one style.
• Counts. Same as the order table: ~22 as drawn + 4 LIS3DH + 4 Pi-to-case; MOQ still to check on Mouser.

Dimensions are from the PEM catalog page linked above (A = length 5.74, E = 4.55, C = 3.86, hole Ø4.01 +0.08, min. depth 6.5) and the IUB figures earlier in this issue.

CNC Kitchen "Standard" inserts vs IUTB (the Amazon / 3DJake alternative)

Jamorros' point that the CNC Kitchen inserts are the de facto standard. Dimensions from the 3DJake product pages and the PEM catalog:

Size	IUTB (Mouser): length × OD, hole × min depth	CNC Kitchen Standard: length × OD, hole (min wall)	In the IUTB pocket
M2	4.00 × Ø3.73, Ø3.23 × 4.76	3.0 × Ø3.6, Ø3.2 (1.3)	fits, sits 1 mm shorter
M2.5	5.74 × Ø4.55, Ø4.01 × 6.5	4.0 × Ø4.6, Ø4.0 (1.6)	fits, sits 1.7 mm shorter
M3	5.74 × Ø4.55, Ø4.01 × 6.5	5.7 × Ø4.6, Ø4.0 (1.6)	fits, same envelope

The two families are interchangeable in one direction: the hole diameters are the same (Ø3.2 / Ø4.0 / Ø4.0 against Ø3.23 / Ø4.01 / Ø4.01) and the CNC Kitchen parts are the same length or shorter, so the pocket spec above, cut for IUTB, takes either. A pocket cut to CNC Kitchen depth (4.0 mm for M2.5, 3.0 mm for M2) would leave an IUTB standing proud, so the IUTB depths stay the spec. CNC Kitchen's minimum wall of 1.6 mm around a Ø4.6 body gives a Ø7.8 boss, which agrees with the Ø8 boss already specified. M3 × 5.7 × Ø4.6 for a Ø4.0 hole is also a commodity size sold under many brands, so any insert with those numbers fits the M3 and M2.5 pockets.

For the BOM this gives the two-order rule an answer on the insert line: Mouser: IUTB-M2 / IUTB-M2.5 / IUTB-M3; Amazon or 3DJake alternative: CNC Kitchen Standard M2 / M2.5 / M3 (or any M2 × 3 × Ø3.6, M2.5 × 4 × Ø4.6, M3 × 5.7 × Ø4.6 insert for Ø3.2 / Ø4.0 / Ø4.0 holes), same pockets either way.

Where the CNC Kitchen inserts can be bought

• CNC Kitchen store (DE) and 3DJake (EU/UK; M3 Standard 100 pcs about £11, M2.5 and M2 100 pcs about 139 kr each).
• Amazon EU marketplaces: the 200-piece M3/M4/M5 Standard set B09CL4KY59 (also .de/.be), B09D57FHYW on amazon.co.uk, and the M3 Short 100 pcs B09FXNX6WF.
• US: Printed Solid is the reseller; no CNC Kitchen-branded listing was found on amazon.com, but same-envelope generics are there (e.g. M3 × 5.7 × Ø4.6, 120 pcs B0FKBLXGW8).

Listings found by search, not verified in a cart; check thread, length and OD in the title before ordering.

Kickstand detent: what McMaster 6052N11 is, and where else to get it

The drawing's only non-fastener McMaster part is the kickstand detent: 2 × 6052N11 "Press-Fit Ball-Nose Spring Plunger", pressed into the two Kick-Stand-Peg parts (BOM item 2: "Press-fit spring plunger into Kick Stand Peg"). It is what holds the kickstand in its 10° position. McMaster does not publish the part outside its own site, so the size was read straight out of Open-Flight-Monitor-2.STEP (the 6052N11 component, three revolve bodies):

Feature	From the STEP
Housing body	Ø3.0 mm, 4.0 mm long
Press-fit collar	Ø3.5 mm band at the top of the housing
Ball	Ø2.4 mm, protruding 0.7 mm above the housing
Bore under the ball	Ø2.4 / Ø1.5 mm

Those numbers are, to the tenth, the Ganter GN 614 size 3 press-in ball plunger (d1 = 3, d2 = 2.4 ball, d3 = 3.5 collar, l1 = 4, stroke 0.6, protrusion 0.7). So the part to specify is generic: "press-fit (push-fit) ball plunger, 3 mm body × 4 mm long, Ø2.4 stainless ball", and the peg hole is Ø3.0 mm, +0.1 / H7, at least 4 mm deep (Ganter's hole spec for that size). In a printed peg, print or drill the hole at Ø3.0 and let the Ø3.5 collar bite.

Sourcing. Mouser does not carry mechanical ball plungers at all (its "spring plunger" hits are Mill-Max electrical contacts), so this one cannot move into the Mouser order. Options that fit the two-order rule:

• Amazon (US): generic 304 stainless "3MM X 4" push-fit ball plungers, e.g. Kondari 100 pcs B0F1YDF9L4, Vutos 100 pcs B0D66WGM3B, WALENI 5 pcs D3xL4 B0BXT6TJBV, or Northwestern Tools 3 mm, 20 pcs B07KSK4Z36 if a branded one is preferred. Check the title reads 3 mm body × 4 mm length.
• EU: the branded equivalent is Ganter GN 614-3-NI (stainless, 1.8 N initial / 3.5 N end force) or GN 614-3-NIL (light, 0.4 / 1.3 N), sold by TME and Misumi; Amazon.de lists Ganter GN 614 packs (a 4 mm one was found, search "GN 614-3").

Notes for the CAD and the choice of spring force

• The STEP housing has a Ø3.5 collar on a Ø3.0 body, which is how the press-fit retains: the peg hole must be Ø3.0, not Ø3.5, or the plunger falls out. The GN 614 datasheet asks for d1 +0.1 (H7).
• McMaster's end force for 6052N11 could not be read (site blocks fetches). Ganter's NI grade (3.5 N end) is the standard choice; the NIL grade (1.3 N) will feel loose for a kickstand. Generic Amazon parts do not state force; assume NI-like.
• Two plungers, one per peg, as drawn. The kickstand side needs a matching Ø2.4-ball dimple at the 10° position; that is already in the Kick-Stand part in the STEP, nothing to add.
• The other kickstand hardware (2 × IUTB-M3 inserts in the handle, 2 × M3×12 from inside, Keystone Electronics 29314 on Mouser) is unchanged.

M2 screws on Mouser, and why the washers

M2×0.4 on Mouser. Page 1 of the M2 × 0.4 category is all Essentra nylon, which is why the first pass concluded there was no M2 screw. Page 2 has the two parts that matter:

Part	Mouser	What	Stock (mouser.se, 2026-09-04)
APM HEXSEAL RM2X4MM 5701	608-RM2X4MM5701	M2×4 Phillips pan head, 18-8 stainless, Viton O-ring under the head (a seal screw)	1,853 in stock, about SEK 12 each
Essentra 50M020040D006B	144-50M020040D006B	M2×6 cheese head, slotted, nylon 6/6	940 in stock, about SEK 1.2 each

The APM part is the only metal M2×0.4 on Mouser and it removes the last M2 line from the Amazon list. Four of them through a 1.6 mm PCB give 2.4 mm in the brass IUTB-M2, six threads, far more than a camera board asks of them; the O-ring acts as a soft washer on the pad. The Essentra 6 mm is the cheap alternative: 4.4 mm into the 4.0 mm insert with the tip in the pilot, and nylon is the usual choice for camera modules (no galling in brass, non-conductive, tighten by feel). Essentra's 5 mm codes (D005B, N005B, G005) are all 4-week non-stocked, so the 6 mm is the one to order. Everything else in metal is a false hit: Keystone Electronics's "M2" is a 2-56 titanium screw, and RAF's M0266-SS is a 10 mm captive panel screw shown out of stock.

Why washers under the eight M2.5×35 through-bolts. The drawing has none, so this is a recommendation, not a requirement. A DIN 912 M2.5 head is Ø4.5, and over a Ø2.9 clearance hole it bears on a ring of printed plastic only 0.8 mm wide (about 9 mm²). Those eight bolts are the ones that come out every time the case is opened, and each re-tightening embeds the head a little further into PLA or PETG, so the joint gets progressively looser. The Keystone Electronics 4692 #4 washer (ID 3.25, OD 7.1, 0.64 thick) spreads the same clamp force over about 31 mm², three times the area, and it is a Mouser line so it costs nothing in ordering terms. If the CAD gets counterbores sized for the bare head, skip them. The short board screws need none: their heads sit on PCB pads, not on plastic.

No M2 washers. An earlier draft listed ~22 M2 washers on the assumption of M2 screws in the OPS243's Ø3.175 holes. Those holes take M2.5 screws whose heads (Ø4.5 socket, Ø5 pan) cover them without help, and the camera-board M2 heads sit on pads.

Case ports to design against: DC in, power button, micro-HDMI, Ethernet

Requested: a Mouser barrel jack the CAD can be designed against, and a port for the Adafruit 1358 micro-HDMI pigtail, collected together with the power button and the RJ45 so the cutouts live in one place. Dimensions come from the makers' drawings where one exists; everything else is marked "measure".

Port	Part to design against	Cutout	Notes
DC in (12 V to the X1202)	Switchcraft L722A (Mouser 502-L722A): 5.5 mm sleeve, 2.0 mm pin, 5 A / 48 V, long bushing	Ø8.0 mm hole with a flat at 7.24 mm (5/16-32 bushing, 8.0 mm long); panel up to about 5 mm; 11.0 mm hex nut on the outside; 23.3 mm body behind the panel	From the Switchcraft L712A/L722A drawing (L712A is the 2.5 mm-pin twin, wrong for the 5.5 × 2.1 adapters). Solder eyelets, so it is the cutout reference, not the no-solder part; the no-solder routes are below
Power button	Adafruit 1445 16 mm momentary button (two 0.11" tabs) + Adafruit 1152 JST XH to 0.11" quick-connect leads (Mouser 485-1445 / 485-1152), the pairing Adafruit's own 1445 page names; momentary only (the X1202 reads press length like the Pi 5 power button, a latching or toggle switch is wrong)	Ø16.0 mm hole	Plugs onto the X1202's XH2.54-2P button header, nothing soldered or crimped. The 1152 was out of stock at Adafruit and unavailable on Amazon (B00SK6M36U) when checked; Mouser stock unverified. The 12.2 mm APEM 1213A2 looked like a 12 mm answer, but its quick-connects are 6.35 mm (0.25 in), not the 2.8 mm the 1152 leads fit
HDMI out	Adafruit 1358 micro-HDMI plug to HDMI socket pigtail, 178 mm (Mouser 485-1358, mouser.se lists it)	Rectangular pocket that captures the socket overmold, or a keystone window (14.5 × 16.0 mm, wall thinned to 1.5-2 mm)	Adafruit publishes no overmold dimensions, so the pocket has to be taken off a real cable: measure. The keystone alternative would share its window format with the Tripp Lite keystone RJ45 option: HDMI keystone coupler (Tripp Lite P164-000-KJ-WH; Mouser carries Tripp Lite but this listing was not confirmed) fed by a micro-HDMI to HDMI male cable (Raspberry Pi official, 1 m, on Mouser)
Ethernet	Adafruit 4130 RJ-45 round panel-mount adapter, RJ45 socket on both sides (Mouser 485-4130, Adafruit $5.95, in stock) + Tripp Lite N201-06N-BK 6 in Cat6 patch, RJ45 M/M (Mouser, stocked), from the inner socket to the Pi	Round hole for a 1 in (Ø25.4 mm) hole saw; 30 mm flange outside, body about 29 mm deep behind the panel, panel from a few mm up to 16 mm. Same flange family as the Adafruit 5607 DC jack, so one hole saw serves both ports; confirm the hole against the drawing on the Adafruit page	Chosen over the keystone route because it is cheaper and stocked. Keystone alternative if a rectangular window is preferred: Tripp Lite N235-001 Cat6 RJ45 F/F snap-in coupler (Mouser 545-N235-001, non-stocked, about 3 weeks; Amazon B01BLFVCM2) in a 14.5 × 16.0 mm keystone window with the wall thinned to 1.5-2 mm. Amazon-only: Cable Matters couplers B00WKPK1B6, or the iGreely screw-flange RJ45 F→M pigtail with its own flange cutout

DC in without soldering: four ways, in order of preference

1. No port at all. Once the Pi and X1202 positions are fixed, a cutout in the side wall over the X1202's own 5.5 × 2.1 jack lets the adapter plug straight in. No part, no current-rating question. This is the one to try first.
2. Pre-wired panel jack + screw-terminal plug. An Amazon pre-wired 5.5 × 2.1 panel jack (e.g. DaierTek, 18 AWG leads, B0BD46CP5Y; hole per the listing, mostly Ø11-12 mm) into an Adafruit 369 screw-terminal barrel plug (Mouser 485-369, 5 A), which plugs into the X1202's on-board jack. Two screws, no solder, everything rated 5 A.
3. Adafruit 5607 panel-mount jack with a 30 cm plug pigtail, 24 AWG, 5 A. One part and the same round 30 mm flange / 1 in (Ø25.4 mm) hole as the Adafruit 4130 Ethernet port below, so one hole saw does both. Sold by Adafruit, DigiKey, RS and Jameco; not found on Amazon, and not confirmed on Mouser.
4. Switchcraft L722A with two soldered wires: the compact Ø8 D-hole above.

The X1202 also exposes an XH2.54-2P "DC 6-18 V" input header next to the button header, which would allow a pre-crimped XH lead from a panel jack, like the button. It is not recommended yet: JST rates an XH contact at 3 A (22 AWG), the X1202 wants 3 A or more at 12 V and its charge current alone reaches 3.2 A, so one XH pair sits at its rating. A 15-18 V adapter lowers the current for the same power; that needs checking before it goes in the parts list. Tracked in open-flight/openflight#251 under known gaps.

Sources for the ports section

• Switchcraft L712A/L722A customer drawing (pin 2.5 vs 2.0 mm, 5/16-32 bushing, 7.24 mm flat, 8.0 mm bushing length, 23.3 mm body, 11.0 mm nut, 8-10 lb-in nut torque).
• Geekworm X1202 wiki: DC jack 5.5 × 2.1 mm 6-18 V ≥3 A, USB-C 5 V 5 A, XH2.54-2P DC input and XH2.54-2P button headers, "External Momentary Switch", charge current max 2.3-3.2 A, never both inputs at once.
• APEM 1200-series catalog page: 12.2 mm cutout, solder-lug / 0.25 × 0.031 in quick-connect terminals.
• Adafruit product pages for 1358 (micro-HDMI to HDMI socket, 7 in), 5607 (30 mm flange, 23 mm thread, 1 in hole, panels to 16 mm), 369 (2.1 mm plug to screw terminals, 5 A), 1445 (16 mm momentary, 0.11" tabs, 1152 named as its wiring), 1152 (20 cm pairs, JST XH plug, 0.11" quick-connects).
• Tripp Lite N235-001 page: RJ45 female on both sides, keystone design for faceplate mounting, Cat6.

Why now

• Ties into Proposed repository structure: versioned cases with swappable screen and sensor mounts #1 (per-case BOM in the README) and OpenFlight Sensor Layout Baseline #3 (sensor layout baseline): the insert choice fixes boss geometry, which fixes where sensors can mount.
• Changing insert family after people have printed and installed is a re-print, so it should be settled before the v1 files and the build guide are published.

Open items / caveats

• Verify on Mouser: PEM MOQs (sometimes sold in 100s). IUB-M2-1 is not stocked and the short IUTB-M2-318 has no live listing; the short IUTB-M3-343 only ever showed as a search hit. That is why the plain IUTB-M2 / IUTB-M2.5 / IUTB-M3 (all confirmed product pages) are used for every size.
• McMaster's dimensions for 93502A108/109/111 could not be verified (site blocks scraping); the STEP geometry is the source used above.
• Insert counts are from the drawing; the STEP in the main repo shows 18 pocketed bosses vs ~28 in the drawing, so treat counts as approximate.
• Touch Display 2 corner-pad thread depth (~2.4 mm as modelled) is unverified against the official drawing; keep display-to-case screws short enough not to bottom out.
• The IWR6843 mounting geometry drives launch-angle calibration; whatever insert is chosen, keep the board-locating features tight so re-assembly is repeatable.

Mouser links: product pages where a listing was confirmed; ?q= search links where it was not (Keystone Electronics 29301/29314/4692, APM HEXSEAL RM2X4MM 5701, Essentra 50M020040D006B). Amazon links: amazon.com ASINs from search results, search links where no single listing matched (short M2 inserts). Analysis drafted with Claude Code; part data from PEM catalog pages, the PEM SI datasheet, Mouser and Amazon listings, and for the later sections the 3DJake, Ganter, Switchcraft, Geekworm, APEM, Adafruit and Tripp Lite pages plus the assembly STEP.

[HuggeK]

v3 fit check (2026-09-21). Measured the insert pockets in Cormac's v3 CAD (Open-Flight-Monitor-3.step on main at e400fc4 and in PR #10 at 6f9f7cb; the pockets are identical in both) by walking the STEP's circle edges, so the numbers are the modelled diameters before print shrinkage.

Pocket	Where	Modelled Ø × depth	IUTB hole spec (PEM)	Fit
M2	camera front, OV9281 (2)	Ø3.0 × 6 mm	Ø3.23 +0.08 × 4.76	0.23 mm too tight for IUTB-M2
M2.5	x1202 UPS mount (4)	Ø3.3 × 10 mm	Ø4.01 +0.08 × 6.5	0.7 mm too tight for IUTB-M2.5
M2.5	Adafruit floor bays (3 × 4, 20.32 × 12.7 mm patterns)	Ø3.4 × 6 mm	Ø4.01 +0.08 × 6.5	0.6 mm too tight, and 6 mm deep
M3	radar front (OPS 4, IWR 4, case 4), camera front (case 2, detector 2), screens (4 or 8), adjustable feet (4, in the shell)	Ø4.4 × 6-10 mm	Ø4.01 +0.08 × 6.5	0.4 mm too loose for IUTB-M3

So the plain IUTB family does not drop into v3 as drawn: the M2 and M2.5 pockets would need opening (M2.5 to Ø4.0 with the bosses checked for Ø8), and the M3 pockets are already wider than the IUTB-M3 wants.

What the pockets do fit is what Cormac's hardware.md lists, "M3 × 4 mm / M2.5 × 4 mm / M2 × 4 mm short knurled brass": the common short inserts with OD ≈ 3.2 (M2), 3.5 (M2.5) and 4.6-5.0 (M3). If the v3 case is what the parts list points at, the Mouser insert lines in the shared project (IUTB-M2 / M2.5 / M3) no longer match the case, and either the CAD moves to the IUTB pocket spec in the body above or the parts list moves to the short inserts (the CNC Kitchen "Standard" set is close but not identical: its M2.5 and M3 want Ø4.0 holes).

Two more things the v3 shell fixes that touch this issue's "case ports" section, measured the same way on the PR #10 Shell-x1202.stl:

• Power button hole: Ø12.5 mm (right-hand hole in the rear recess). That is a 12 mm button, so the Adafruit 1445 (16 mm, in the Mouser project) does not fit unless the hole goes to Ø16.5 mm.
• DC jack hole: Ø12.5 mm (middle hole). The 10.7 mm thread of the reference DC jack fits.
• Ethernet: a ~16 × 13 mm rectangular opening with two Ø4 mm screw holes 27 mm apart (left of the recess), i.e. a flanged keystone-style coupler. The round 21.7 mm-thread coupler in the reference models and the Adafruit 4130 (round, 1 in hole) in the Mouser project do not fit that opening as drawn.

Neither the hole sizes nor the intended insert OD are in the v3 docs yet (hardware.md gives thread size and length only); the numbers above are from the CAD.