Why 3D printing in machine building?
Machine builders work in small numbers. One gripper per robot cell, two jigs per assembly line, a handful of spare parts per customer. At those quantities an injection mould never pays off, and machining from solid takes a lot of time and material once the shape gets complex.
3D printing needs no mould and the price depends mainly on the part's volume. One part costs roughly the same per piece as ten. You can also change the shape between two orders without paying for new tooling.
Below are four applications every machine builder runs into. For each you'll find the typical question, the technology that fits and a worked example: the part's volume times the material's starting price, excl. VAT and finishing.
1. Gripper fingers and end-of-arm tooling
The question: a robot has to pick up a new product and the standard fingers don't fit. You want fingers that follow the product's shape, are light and are quick to swap.
The approach: MJF in grey PA12. PA12 is tough, wears little in contact with the product and flexes slightly rather than snapping. MJF gives an even surface and consistent dimensions from part to part, which matters when fingers work in pairs. Pockets, ribs and a seat for a suction cup or sensor go straight into the design.
Worked example: 30 cm³ × €0.52/cm³ = from €15.60 per part, excl. VAT. A set of two fingers therefore comes to double that. Your actual price is shown in Quotebase; volume × material price is just a starting point.
2. Jigs, fixtures and locating aids
The question: a fitter must mount a sensor in exactly the same place and at the same angle every time. You want a locating aid that holds the part, so it no longer matters who does the assembly.
The approach: for a first version, FDM in PETG makes sense. It's affordable, sturdy enough for daily workshop use and quick to change if the fit isn't right yet. Once the jig works and you need several, or it has to fit tighter and last longer, move to MJF in PA12. FDM isn't in Quotebase yet: request a custom quote via info@makernaut.be.
Worked example: 60 cm³ × €0.35/cm³ = from €21.00 per part, excl. VAT. The same jig in black PA12 (MJF) comes to from €42.00 per part, and that price does show up straight away in Quotebase.
3. Spare parts for obsolete machines
The question: a machine still runs perfectly, but a plastic guide or chain tensioner has broken and the manufacturer no longer supplies it. Buying a new machine for one part isn't an option.
The approach: SLS in white PA12. SLS needs no support structures, so internal channels, clips and undercuts of the original part are all possible. PA12 is an engineering plastic that handles oil, grease and repeated loading well. You do need a 3D file. If no drawing exists any more, someone has to model the part first from the original or the broken pieces.
Worked example: 25 cm³ × €0.65/cm³ = from €16.25 per part, excl. VAT. Keep the file: you can order the next one without redrawing it. Your actual price is shown in Quotebase; volume × material price is just a starting point.
4. Brackets and wear parts in 316L stainless steel
The question: a bracket or guide has to be metal because it gets hot, takes high loads or sits in a wet or aggressive environment. The shape is too intricate to machine cheaply, or you want to merge several parts into one.
The approach: SLM (metal printing) in 316L stainless steel. The part is melted layer by layer from metal powder and comes out as solid metal. Fits and bearing seats are machined or reamed afterwards, and that's listed separately in the quote. For a simple rectangular bracket, CNC milling is usually the better choice; SLM pays off when the shape is complex.
Worked example: 15 cm³ × €3.99/cm³ = from €59.85 per part, excl. VAT. Post-machining of functional faces is extra. Your actual price is shown in Quotebase; volume × material price is just a starting point.
Overview of the worked examples
| Application | Technology and material | Volume | From, per part, excl. VAT |
|---|---|---|---|
| Gripper finger | MJF, PA12 grey | 30 cm³ | €15.60 |
| Locating aid (first version) | FDM, PETG (custom quote) | 60 cm³ | €21.00 |
| Locating aid (series) | MJF, PA12 black | 60 cm³ | €42.00 |
| Obsolete spare part | SLS, PA12 white | 25 cm³ | €16.25 |
| Metal bracket | SLM, 316L stainless | 15 cm³ | €59.85 |
All amounts are starting prices per part, excl. VAT and finishing. The volume is that of the part itself, so a hollowed or pocketed shape lowers the price directly.
Design tips for machine builders
- Don't model a solid block. Pockets and ribs make a part lighter and cheaper, because you pay per cm³.
- Keep wall thickness even. Big differences raise the risk of warping, especially on long parts.
- Treat precise fits as post-processing. Model a hole slightly undersize and have it reamed or redrilled when a shaft or bearing must fit tightly.
- Use inserts for threads that get opened and closed often. Threads cut straight into plastic wear faster than a metal insert.
- Merge parts. An assembly of three machined parts and screws can often become one printed part, with less assembly time.
- Put the part number in the part. An engraved number makes a spare easy to trace later.
Choose the technology by function
- Choose MJF in PA12 for functional plastic parts in small runs, with consistent dimensions part to part.
- Choose SLS in PA12 for complex one-offs and spare parts, or when you need flexible TPU.
- Choose FDM for first versions of jigs and fixtures you still expect to adjust.
- Choose SLM when the part must be metal and the shape is too complex to machine economically. If the shape is simple, choose CNC machining.
Makernaut does FDM and SLA in house. SLS, MJF and SLM run through selected partners. For CNC machining, request a quote in Quotebase and you'll get an answer within one working day.