How to quote realistic ship dates for 3D-printed orders

A customer asks when their order will ship. The wrong answer is “the print takes 5 hours.” The print’s duration has almost nothing to do with when it ships, because it isn’t printing yet — it’s behind everything already in the queue.

Lead time is a queue problem, not a print-speed problem. Once you see it that way, quoting a date you can actually hit gets straightforward.

Start with the work ahead, not the job itself

The honest first number is total print-hours in front of this order. If there are eight jobs queued and they average 5 hours each, that’s 40 print-hours of work before yours even starts — regardless of how quick your specific print is.

Divide that by how many hours a day you actually run prints. Not 24 — the realistic number, accounting for the hours nobody’s around to clear beds and start the next job. If the farm effectively produces 8 print-hours a day per machine of usable throughput, 40 hours of backlog is 5 working days before this order is done. That’s the floor. The print’s own 5 hours is a rounding error next to it.

Buffer for the things that go wrong

That 5-day figure assumes nothing fails. Something will. A part lifts off the bed, a layer shifts, a spool runs out mid-batch. Each of those is a reprint, which is more material and more machine hours, which pushes everything behind it further out.

Build the buffer in rather than quoting the perfect-world number and apologizing later. If your failure rate runs around 1 in 10, adding roughly 15–20% to the estimate covers the reprints without much drama. Five working days becomes six. Quote the six.

For anything with known risk — tall thin parts, bridging, a filament that warps, a first run of a new model — pad it more. Underquoting a risky print and missing the date costs you more goodwill than quoting an honest extra day ever will.

Count working days, and say which ones

A five-working-day estimate starting on a Thursday doesn’t mean “next Tuesday” if you don’t print on weekends. Be explicit about it. “Ready to ship in about 6 working days” is a promise you can keep. “Ready Tuesday” quietly commits you to a calendar you might not run.

Then separate ready-to-ship from delivered. Your control ends when the box leaves — the carrier’s transit time is on top of your production estimate, and it’s the customer’s, not yours, to absorb. Quote production time and shipping time as two numbers so a slow carrier doesn’t read as you being late.

A worked example

An order comes in on a Monday. The queue ahead of it holds 8 jobs averaging 5 print-hours: 40 hours of backlog. The farm produces about 8 usable print-hours a day.

• Backlog: 40 ÷ 8 = 5 working days to reach this job
• Failure buffer at ~20%: round up to 6 working days
• Starting Monday, skipping the weekend: ready to ship the following Tuesday
• Plus carrier transit, quoted separately

So the quote is “ships in about 6 working days,” not “ready Friday.” One of those you hit. The other you spend apologizing for.

Requote when the queue changes

The number isn’t fixed at order time. Take on a big rush job and everything behind it moves out. A run of failures on Tuesday pushes Wednesday’s promises. A ship date quoted from a queue that’s since doubled is a broken promise waiting to happen.

The estimate is only as good as its inputs, and the inputs change daily. That’s the case for computing it from the live queue instead of a static “5–7 business days” line on your listings — a fixed lead time is right only by accident.

One more lever most shops forget: a large multi-part order doesn’t have to ship all at once. If eight of ten parts are done and two are stuck behind a reprint, splitting the shipment can get most of the order to the customer on time and the rest a day later. Whether that’s worth the extra postage depends on the order, but it’s an option a rigid “everything ships together” rule takes off the table.

To turn queue depth, average print time, and daily hours into a working-day estimate, the ship-date calculator does the arithmetic. For a date that updates as your real queue moves, that’s what SpoolDeck’s ship-date estimates are built on.