3D Printing

Plastic and metal 3D printed parts made from your CAD file, for single prototypes and short production runs.

Send a STEP or STL file and tell us what the part has to do. We check the model, suggest a process and material, and reply with a price and a ship date. If a wall is too thin to print or a tolerance is tighter than the process can hold, we tell you before anything is printed.

What we print

• Prototypes and fit-check models, to check a part before paying for a mold or a CNC run
• Jigs, fixtures, gauges and assembly aids for the shop floor
• Brackets, enclosures, covers, ducts and cable guides
• Replacement parts for equipment when the original is discontinued or months away
• Patterns and low-temperature molds for carbon fiber prototypes
• Metal parts with internal channels or lattices, such as mold inserts with conformal cooling
• Short runs of end-use parts when the quantity doesn't justify a mold

Processes and materials

Each process trades off cost, strength, surface finish and accuracy differently.

Accuracy is whichever figure is larger, so a 200 mm FDM part holds about ±1 mm. These are typical numbers for each process, not guarantees. When a bore or mating face needs to be tighter, we print it with extra material on that feature and machine it to size.

FDM (filament)

A heated nozzle lays down melted plastic one line at a time, in layers 0.1 to 0.3 mm thick. It's the cheapest way to get a part in hand, and it stays affordable as parts get bigger. Layer lines show, and parts are weakest between layers, so each part is oriented with its loads in mind. PETG and ASA are good defaults for fixtures; carbon-filled nylon when a bracket needs to be stiff.

Resin (SLA)

A laser or projector cures liquid resin in layers as thin as 0.025 mm. Surfaces come out smooth enough for presentation models and master patterns, and small text holds up. Standard resins are brittle and yellow in sunlight, so working parts should be printed in a tough or high-temperature resin, or in nylon.

Nylon powder (SLS and MJF)

A laser (SLS) or a print head and heat lamp (MJF) fuses nylon powder. The loose powder holds the parts up as they print, so there are no supports or support marks, and dozens of parts can be packed into one build. That makes it the usual choice for working plastic parts and for batches from about 10 to a few hundred. Surfaces are matte and slightly grainy, and parts are often dyed black.

Metal (laser powder bed fusion)

A laser melts fine metal powder layer by layer. Parts come out dense and strong, and the process makes shapes nothing else can, like internal cooling channels and lattices. It's also the most expensive option. Parts need supports, stress relief, cutting off the build plate, and usually machining on any surface that seals, mates or holds a bearing. Use it when the shape calls for it, not for a part that machines easily from bar stock.

Design guidelines

• Walls. 2 mm walls print well in every process. The thinnest you can go is about 1 mm in FDM, 0.8 mm in nylon powder, 0.5 mm in resin and 0.4 mm in metal.
• Overhangs. In FDM, resin and metal, surfaces angled more than 45° from vertical need supports, which leave marks. A 45° chamfer under a ledge often removes the need. Nylon powder needs no supports.
• Holes. Small holes print slightly undersize. Model them at nominal size and flag the ones that matter; we drill or ream those after printing.
• Threads. Fine threads print poorly in plastic. Model a plain hole for a heat-set insert or a tap drill instead. Metal threads are tapped or machined.
• Clearance. For parts that slide or snap together, leave about 0.5 mm between them in FDM and resin, and 0.3 mm in nylon powder.
• Large flat areas. Big flat plates can warp as they cool, especially in ABS and nylon. Ribs or a slight curve help.
• Hollow parts. Hollow resin and powder parts need drain holes of at least 4 to 5 mm so trapped resin or powder can be cleaned out.

More detail in how to prepare a file for 3D printing.

What to send for a quote

• A 3D file. STEP is best because we can measure and edit it. STL, 3MF and OBJ work for printing.
• The units, if the file isn't in millimeters.
• Quantity, and whether more will follow.
• The material, or what the part has to handle: load, heat, sunlight, oil or fuel, flexing.
• Color and finish.
• Any dimensions that matter and their tolerances, on a drawing or in a note.
• When you need it and where it ships.

Use the form at the bottom of this page, or email your files to info@a8mfg.com. For files over about 20 MB, send a download link instead.

What sets the price

• Process and material. FDM in PLA or PETG costs the least. Resin and nylon powder sit in the middle. Metal costs the most by a wide margin.
• Part volume. You pay for the material in the part and in its supports.
• Height. More layers means more machine time, so a tall part usually costs more than the same part printed lying down.
• Quantity. Nylon powder builds pack many parts together, so the price per part falls quickly with quantity. FDM and resin prices fall less.
• Finishing. Support removal, sanding, painting, dyeing, threaded inserts and machining each add labor.

To bring the price down: hollow out thick sections or use less infill on FDM parts that don't carry load, add chamfers so the part needs fewer supports, put tight tolerances only on the features that need them, and prove the fit with a cheap FDM print before ordering the final part in nylon or metal. More in what sets the price of a 3D printed part.

Scanning and modeling without CAD

Send a sketch with dimensions, photos, or the part itself. Our design service turns a sketch into a printable model, and 3D scanning captures worn or discontinued parts so they can be remade, printed or machined. For an example of reverse engineering, see the ball screw case study.

When another process is better

3D printing isn't always the cheapest route, and we'll say so when it isn't.

• For hundreds or thousands of identical plastic parts, an injection mold usually costs less per part. See what drives mold cost and our tooling page.
• For blocky metal parts with tight tolerances on most faces, CNC machining is usually faster, cheaper and more accurate than metal printing.
• For light, stiff panels and tubes, carbon fiber usually beats a printed part.

The trade-offs are laid out in 3D printing vs CNC machining vs injection molding.

Questions

Can you print just one part?

Yes. With no tooling to pay off, single parts are where 3D printing makes the most sense.

How strong are 3D printed parts?

Strength varies by process. FDM parts are weakest between layers, so they're oriented to keep loads running along the layers. Nylon powder parts are close to equally strong in every direction. Metal prints are dense, and after heat treatment their strength is comparable to conventionally made parts in the same alloy, though rough as-printed surfaces lower fatigue life. That's one more reason critical surfaces get machined.

How long does it take?

Lead time varies with the process, material and quantity, and every quote includes a ship date. FDM and resin parts are usually the quickest. Metal takes longest because of heat treatment, support removal and machining.

Can you print large parts?

Send the overall size. A part bigger than a printer's build area can be printed in sections and bonded or bolted together, with the joints placed away from loaded and cosmetic areas.

What finishes can I get?

Common requests are as-printed, sanded, primed and painted, dyed black for nylon, and bead blasted for metal. Tell us how the part will be used and seen, and the finish goes into the quote.

In Our Own Products

We're developing a ski rack mount for the Porsche 992 GT3 that combines 3D printed and CNC machined parts in one assembly. See A8 products.

3D Printing Guides

• The seven categories of 3D printing
• FDM vs SLA vs SLS vs MJF: which process to use
• 3D printing cost factors
• How to prepare a file for 3D printing
• 3D printing vs CNC machining vs injection molding
• 3D printed prototypes by development stage
• Carbon fiber prototypes without a production mold

To request a quote, use the form below or email your files.