Building 3d printed parts and using inserts
Hey. im looking at threaded inserts for a stealth press, the tool you make to do inserts. anyway the manual says insert m3x5x4. the inserts i have say m3x4x5. whats the spec here
ChatGPT said:
Hey! Good question — this comes up a lot with confusing spec formats for threaded inserts.
Let’s break it down:
🔩 M3 x 5 x 4 vs M3 x 4 x 5 — What do the numbers mean?
These typically refer to:
- M3 = Metric thread size (for M3 screws)
- The other two numbers usually indicate:
- Length (height of the insert)
- Outer diameter (OD of the knurled body, usually the widest part)
But here’s the catch:
Some manufacturers list the dimensions as:
Thread size x Outer Diameter x Length
Others do:
Thread size x Length x Outer Diameter
So:
| Format | M3 x 5 x 4 | M3 x 4 x 5 |
|---|---|---|
| Interpreted As | M3 thread, 5mm length, 4mm OD | M3 thread, 4mm length, 5mm OD |
This means:
- The one your tool recommends is 5mm tall (length), 4mm wide (OD)
- The one you have is 4mm tall, 5mm wide — shorter but fatter
⚠️ Which matters more?
For heat-set insert tools like the Stealth Press, length is often more important for grip depth and strength in the plastic. If your insert is shorter, it may not grip as well or may sit too shallow.
Also, if the OD is bigger than expected, it may crack the part during insertion or not fit the hole size the STL was designed for.
✅ Recommendation:
- Measure your inserts with calipers to confirm actual OD and length
- Match the tool to the insert you’re using, or
- Get inserts that match the recommended spec (likely M3 x 5mm length, 4mm OD)
You said:
Funny the voron kit inserts are 4 tall 5 wide. the stealth press build instructions specifically says uses voron m3x5x4. which means they are using thread size, height,width
ChatGPT said:
Exactly — you’ve nailed it. It’s really common for this kind of spec confusion, especially since:
- Voron tends to use M3 x Height x OD (i.e. M3 x 4 x 5)
- But in the Stealth Press documentation, when they say M3 x 5 x 4, they clearly mean 5mm height, 4mm OD — even though that doesn’t match what Voron kits actually ship.
So yeah — classic case of either a typo in the manual or inconsistent spec format.
✅ Here’s the truth:
- Voron kits almost universally include M3 x 4mm tall x 5mm OD inserts — that’s what their printed holes are designed for.
- So your inserts are correct for a standard Voron build.
- The Stealth Press instructions probably meant M3 thread, 4mm height, 5mm OD but wrote it as M3 x 5 x 4, flipping the numbers.
🔧 What to do:
No worries — your M3 x 4 x 5 inserts are exactly what you want if you’re working with Voron printed parts or using the Stealth Press to match Voron spec.
If you’re ever printing your own parts:
- Hole size: ~4.0mm diameter
- Depth: ~4.0–4.2mm deep
- Tapered or stepped hole is ideal for clean insertion with a tool like the Stealth Press
Want a cheat-sheet PDF with insert sizes, hole design, and typical materials (ABS/PLA) settings? I can whip one up for you.
Chat said:
Yep — that confirms it. This image shows M3x5x4 (VORON) listed as the insert size, but as we’ve established:
They actually mean:
M3 thread, 4mm tall, 5mm outer diameter
✔️ Which matches your M3x4x5 inserts perfectly.
🔍 What’s really going on here?
They wrote M3x5x4 in the manual, probably intending:
- M3 thread
- 5mm OD
- 4mm height
But that is not a standard way to list inserts. Almost every supplier lists them as M3 x Height x OD, like:
- M3 x 4 x 5 = 4mm tall, 5mm OD
✅ TL;DR:
Your inserts marked M3x4x5 = correct size for Voron and the Stealth Press.
No need to change them — just match hole dimensions to:
- Hole diameter: ~4.0–4.2mm
- Hole depth: 4.0–4.5mm (match insert length)
🔩 M3x5x4 vs M3x4x5 — Clearing Up Threaded Insert Confusion (Voron & Stealth Press)
If you’ve built a Voron 3D printer or are using the Stealth Press insert tool, you’ve probably seen the spec M3x5x4 thrown around in manuals or diagrams. But what does it really mean? And is it the same as the M3x4x5 inserts that many Voron kits come with?
I recently ran into this and decided to dig in.
📦 What the Manuals Say:
In the Stealth Press assembly manual, the required insert size is listed as:
M3x5x4 (VORON)
Seems simple, right? Not quite.
🧠 What’s the Standard Naming Format?
Most suppliers (especially on AliExpress, Amazon, and McMaster-Carr) list heat-set brass inserts in this format:
Thread size x Height (Length) x Outer Diameter (OD)
So:
- M3 x 4 x 5 =
- Thread: M3
- Height: 4mm
- OD: 5mm
If we apply that logic to M3x5x4, it would mean:
- Thread: M3
- Height: 5mm
- OD: 4mm
But that doesn’t match the actual Voron hardware.
🧪 Reality Check: Voron Inserts Are…
Pulling inserts from an official Voron kit and measuring confirms:
- 4mm height
- 5mm outer diameter
So technically:
✅ M3 x 4 x 5 is the correct label
Which means the manual is just flipped in its format. When it says M3x5x4, it’s describing a 5mm OD, 4mm tall insert — they’re just using a nonstandard spec order.
🔧 Why It Matters
If you go by the manual and order M3x5x4 from a strict supplier, you might get a 5mm tall insert that’s only 4mm wide — which won’t fit Voron parts and could split your prints.
The Stealth Press tool and Voron STLs are all designed around:
- Insert OD: 5mm
- Insert height: 4mm
So if your insert says M3x4x5, you’re good to go.
✅ TL;DR
| Label | Meaning | Good for Voron? |
|---|---|---|
| M3 x 4 x 5 | 4mm tall, 5mm OD | ✅ Yes |
| M3 x 5 x 4 | 5mm tall, 4mm OD (as written) | ❌ No |
| M3 x 5 x 4 (Voron docs) | Actually means 4mm tall, 5mm OD | ✅ Yes |
Stick with M3 x 4mm height x 5mm OD for Voron and Stealth Press compatibility.
🛠 Bonus Tip: Heat-Set Hole Design
When printing parts for heat-set inserts:
- Hole diameter: ~4.0 to 4.2mm
- Depth: 4.0 to 4.5mm
- Tapered holes help with alignment and smooth insertion
Want a downloadable cheat sheet or STL test part for insert sizing? Let me know and I’ll send it your way.
Let me know if you want this in Markdown, PDF, or Word format, or posted somewhere you can copy-paste cleanly.
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