STL Merge, Split & Cut Tool Community
Questions, answers and tips from people who use the STL Merge, Split & Cut Tool. Merge STLs onto one plate, split shells apart, or cut a model with a plane.
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This page shows only real posts from real people, so it starts empty. The guide below has the questions people most often have about the STL Merge, Split & Cut Tool. Pick one to start a thread, or write your own.
From the tool guide: common questions about STL Merge, Split & Cut Tool
The items below are not posts by community members. They come from the written guide for this tool and are here to get a conversation started. Use “Ask a follow-up” to open a thread about any of them.
Does merging boolean-union overlapping parts?
No — it concatenates the meshes. Slicers print overlapping closed shells as one solid.
From the tool guide Ask a follow-upHow does splitting detect parts?
By connectivity: triangles that share vertices belong to the same shell.
From the tool guide Ask a follow-upCan I cut at an angle?
Cuts are along X, Y or Z. Rotate the model first with the transform tool for an angled cut.
From the tool guide Ask a follow-upWhat this tool does
Print plates are often built from several files. The Merge tab loads two or more models and arranges them in a grid, a row, a vertical stack, or keeps their original positions (for assemblies), with a spacing you choose and an option to drop every part to the bed. Each part is colour-coded in the preview, and the result is one mesh you can download as STL, 3MF or OBJ.
How to use it, step by step
- Choose Merge, Split or Cut.
- Drop in your file(s).
- Adjust arrangement, pick shells, or move the cut slider.
- Download the result.
Tips from the guide
- Cut with the section view first, so you see where the plane falls.
- For a clean glue joint, cut at a flat area and consider adding pegs in CAD.
- Parts that overlap in 'keep positions' mode are not boolean-unioned — slicers handle overlaps as a union anyway.
- Run the repair tool first if a cut says a half is not watertight.
Common mistakes to avoid
- Cutting a non-watertight mesh and expecting closed halves.
- Merging parts at identical coordinates so they overlap.
- Forgetting the gap so parts touch and fuse in the print.
Who uses it
- Makers building a multi-part plate. Combine files without opening a slicer.
- People with a 'plate' STL. Extract single parts from a combined file.
- Printing tall models on small beds. Cut, print flat, and glue.
How to ask a question people can answer
A good thread on the STL Merge, Split & Cut Tool saves everyone time. Start with a title that names the exact problem, such as the input you used, the result you expected and the result you got. A title like “Not working” is hard to answer, while a title with the specifics gets replies quickly.
- Say what you tried. List the steps you followed and any settings you changed, so replies do not repeat what you already did.
- Share a small example. A short sample input and the output you saw is worth more than a long description. Remove anything private first.
- Mention your setup. Your device, browser and whether you are on a phone or a computer can explain many odd results.
- One question per thread. Separate topics get clearer answers and are easier to find later with the search box above.
- Come back and reply. If a suggestion worked, say so and upvote it, and if you found the fix yourself, post it for the next person.
Community rules
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