Heat-set insert test block, customizable: any hole sizes and steps

A flat test block for finding the hole size that suits your heat-set inserts. At the defaults it has 7 blind holes from 3.8 to 4.4 mm in 0.1 mm steps, each 6 mm deep with its size engraved beside it, in an 81 x 20.4 x 7.6 mm block. Set the smallest hole (2.5 to 6 mm), the step (0.05 to 0.3 mm) and the number of holes (3 to 10) to test other insert sizes too.

Customize Change it with AIFree STL, 3MF and STEP, no accountMeasured on the model

Parameters

Smallest holemm

Step between holesmm

Number of holes

Hole depthmm

Floor under holesmm

Hole spacingmm

Label text sizemm

Sliders and downloads are free. Changes by the AI designer use credits like any design; new accounts start with free ones.

It prints flat with no supports. The holes are modelled at their exact nominal size, so the one that fits on your printer may be a step or two larger than the size an insert maker lists: that is what the test shows. Press an insert into each hole with a soldering iron and keep the smallest size where it goes in with light pressure and sits flush. The labels are small, so use 0.2 mm layers or finer.

Parameters

Every slider in the viewer above, with the range the model accepts. The model rebuilds valid at both ends of each range.

Parameter	Range	Default	What it changes
Smallest hole	2.5 to 6 mm	3.8 mm	Diameter of the first, smallest hole. Start a little under the size your insert's maker lists.
Step between holes	0.05 to 0.3 mm	0.1 mm	How much each hole grows over the one before. Labels show one decimal, so with a 0.05 mm step read the sizes by counting from the smallest hole.
Number of holes	3 to 10	7	How many holes are in the row. Each extra hole makes the block one hole spacing longer.
Hole depth	3 to 12 mm	6 mm	Depth of each blind hole. Make it a little deeper than your insert is long so melted plastic has room below it.
Floor under holes	1.2 to 4 mm	1.6 mm	Solid plastic under each hole. The block height is the floor plus the hole depth.
Hole spacing	9 to 16 mm	11 mm	Centre-to-centre spacing of the holes. More room keeps the hot iron from softening the neighbouring hole.
Label text size	4 to 8 mm	5 mm	Height of the engraved size labels. Larger text reads better on a coarse print and makes the block wider.

Proof: measured on the model

What the design must satisfy and what our CAD engine measured on the model at the default values. Only measured values are shown here; nothing on this page has been printed by us yet.

Requirement	Wanted	Measured
Number of holes	7 holes	7
Smallest hole	3.8 mm	3.8 mm
Largest hole (7 holes in 0.1 mm steps)	4.4 mm	4.4 mm
Depth of the shallowest hole	6 mm	6 mm
Solid floor under the first hole	1.6 mm	1.6 mm

valid solid, one body, 81 x 20.4 x 7.6 mm, fits a 256 x 256 x 256 mm printer; overhangs: 0.0% of surface would need support.

Print notes

Orientation: Flat on its base, as shown, with the holes and labels facing up.
Supports: None
Material: The material you will use for the real parts, since the right hole size depends on it
Layer height: 0.2 mm or finer (for readable labels)
Settings: The same walls and infill as the parts the inserts are for
Hardware: 7 x M3 heat-set inserts (one per hole)
Time and filament: About 25 min and 8 g at the default size: a rough estimate from the model's volume and surface (PLA, 15% infill, about 1 mm of walls, 0.2 mm layers), not a slicer.

Print it on the same printer, in the same material and with the same settings as the part the inserts are for: the hole that fits depends on all three.
Press each insert straight down with the hot iron and stop when it sits flush. Let it cool before you judge the fit.
Pick the smallest hole where the insert goes in with light pressure, sits flush and does not turn when you drive a screw into it.
Labels show one decimal. With a 0.05 mm step, two neighbouring labels can round alike, so count from the smallest hole.

How it was designed

Designed with buildcad's AI agent, checked by the buildcad team. This is the request it started from and an edited account of what it did (more on how text to CAD works).

The request
A test block for M3 heat-set inserts: a row of holes from 3.8 to 4.4 mm in 0.1 mm steps, each labelled, 6 mm deep.

1
It wrote the checks first
Before modelling, the agent listed 5 checks: 7 holes, the smallest at 3.8 mm, the largest at 4.4 mm, each 6 mm deep, and a block height of floor plus depth (7.6 mm).
2
First build: one check proved nothing
The first block built as one valid body, 81 x 20.4 x 7.6 mm, with 7 holes from 3.8 to 4.4 mm and nothing needing support. Its depth check, though, only measured a cross-section area, which says nothing about depth.
3
It measured the depth itself
The agent read the depth of each hole from the model (6 mm for all 7) and rewrote the depth check to use the shallowest hole. All 5 checks then passed.
4
Every slider extreme
The slider sweep rebuilt all 14 extremes as one valid body each.
5
What it left to the maker
It modelled the holes at their nominal size on purpose: the right one depends on your printer, and finding it is the point of the print.

One run of the agent: 50 s, about $0.10 of model time at list price (claude-sonnet-5-5). The model code behind this page is the code it wrote, unchanged.

Change it with AI

Set the sliders, then press Change it with AI: a copy goes to your designs at those sizes and the designer opens with a suggested change you can edit. Its changes use credits like any design; new accounts start with free ones.

Change it with AI Describe your own part Use it from your own AI (MCP)