Three Different Clocks

Ask how long a 3D print takes and you get an answer about machine time: "about seven hours." That number is real and almost useless for planning, because the part does not arrive seven hours after you send the file. Three clocks run in sequence, and machine time is usually the smallest of the three.

The first clock is queue and preparation: the service reviews the file, quotes it, waits for your approval, nests the job with other work, and schedules a build. The second is the build itself. The third is post-processing and shipping, which for some technologies takes longer than the print. A seven-hour print routinely becomes a five-day delivery, and understanding which clock is dominant tells you where you can actually save time.

What Sets the Print Time Itself

Machine time is driven by geometry and settings more than by part volume.

  • Height in the build direction. Layer-by-layer processes pay per layer. A part 4 in (100 mm) tall at 0.2 mm layers is 500 layers; the same part laid flat at 1.5 in (38 mm) tall is 190. Orientation can cut print time by more than half, though it also changes strength, which is the tradeoff covered in print orientation and layer adhesion.
  • Layer height. Going from 0.1 mm to 0.3 mm on FDM cuts time roughly threefold and costs you surface finish and small feature fidelity.
  • Cross-sectional area, for resin. SLA and DLP cure a whole layer at once, so a full build plate of small parts takes almost exactly as long as one part of the same height. Batching resin parts is nearly free time.
  • Packing density, for powder. SLS and MJF build a whole chamber at once, typically 20 to 40 hours regardless of how many parts are inside. One part or two hundred, the clock is the same.
  • Supports and infill. Support material is print time you throw away. Parts designed to print without supports often finish 20 to 40 percent faster and skip a manual removal step.

Typical Machine Times by Technology

Rough orders of magnitude for a fist-sized part, roughly 4 x 3 x 2 in (100 x 75 x 50 mm):

  • FDM, 0.2 mm layers: 6 to 14 hours. Large or tall parts run 24 to 48 hours.
  • SLA/DLP, 0.05 mm layers: 5 to 12 hours, and the same for a full plate of them. The finish and accuracy differences that justify the choice are laid out in FDM versus SLA.
  • SLS or MJF nylon: 20 to 40 hours per chamber, plus 8 to 12 hours of controlled cooldown before anyone can open it. That cooldown is non-negotiable and catches people out; see SLS nylon printing.
  • Metal powder bed: 20 to 60 hours for the build, then stress relief, wire EDM off the plate, support removal, and often heat treatment. Realistic total is 1 to 3 weeks, and metal 3D printing covers why.

The Time After the Print

This is the clock most people forget entirely.

FDM needs support removal, 15 minutes to 2 hours by hand. Soluble supports need a 4 to 12 hour bath. Resin needs draining, an isopropyl wash, drying, and UV post-cure, plus support removal and sanding of witness marks: budget 1 to 3 hours per part and note that resin parts keep curing, so same-day handling matters. Powder parts need depowdering and bead blasting, and dyed nylon adds a dye bath and drying cycle.

If you want prototypes that look like product, add real finishing time. Priming, filling, sanding through grits, painting, and clear coat is a 3 to 5 day sequence with cure time between coats that cannot be rushed, as described in finishing printed prototypes. Heat-set inserts, tapped threads, and bonded assemblies each add a half day.

Realistic Door-to-Door Windows

What to actually put in a schedule when ordering from a service bureau:

  • FDM or SLA, standard service: 3 to 5 business days, plus transit.
  • Same technologies, expedited: 1 to 2 business days at a 50 to 100 percent price premium.
  • SLS or MJF: 4 to 7 business days, because you are waiting for a chamber to fill.
  • Metal: 10 to 20 business days.
  • Overnight shipping: add 1 day and $40 to $90; ground within the continental US is 2 to 5 days.

Add two days if your file needs repair. Non-manifold geometry, inverted normals, and wrong-unit exports are the most common reasons a job sits in review instead of printing, and the fixes are all preventable at export time per STL file preparation mistakes.

A Real Iteration, Day by Day

Monday morning: export STL, upload, quote back in two hours, approve by noon. Monday night: job nests into the evening build. Tuesday: part prints, comes off the machine in the afternoon, supports removed. Wednesday: ships ground. Friday: part arrives. You test over the weekend, find the boss is 0.4 mm too tight, revise CAD Monday morning, and start again.

That is a one-week loop per iteration, and three iterations is a normal number for a first mechanical part. Plan a month for a part you expect to get right on the second try. If the loop matters more than the finish, a desktop machine on your own bench changes the arithmetic completely: the queue and the transit disappear, and a one-week loop becomes an overnight one.

How to Compress the Schedule

Batch your iterations. Print three design variants at once instead of testing one and waiting. On resin and powder the marginal cost of the extra parts is small and the calendar saving is a week.

Print test coupons, not whole parts. If you are checking one snap fit, print the 1 in section containing it, not the 8 in housing. Two hours instead of eighteen.

Fix the file before you upload. Watertight mesh, correct units, appropriate chord tolerance on the export. This alone removes the most common two-day delay.

Ask for the raw part. If you are checking fit, you do not need it sanded and painted. Waive the cosmetic finishing and take the part with support nubs on it.

Use a local shop for the urgent loop. Same-day pickup removes transit entirely, and being able to walk in and look at a part with the operator solves problems that email cannot. Keep the cheaper remote bureau for non-urgent batches; prototype printing services compares the models.

Get a Straight Answer on Your Part

Projects House quotes printed prototypes with the whole schedule broken out, not just the machine hours, and flags the orientation and design changes that would cut a day or two out of each loop. Send your STEP or STL and your deadline through our contact form.