We ask for a sample part on almost every machine order. Some customers send one willingly. Others ask, a little impatiently, “why can’t you just build it from the drawing?”
This article answers that question with two real projects. They were so similar on paper that they looked like the same order. They ended very differently, and the difference was a single machined part that arrived in a box before the order was confirmed.
The Two Orders
Both customers made the same kind of part: a hardened steel component needing a deep hole of a specific diameter and depth, drilled with a gun drilling machine.
Customer A was in a hurry. The order had to ship before the end of the quarter, and sending a sample meant losing a week to international shipping. The drawing looked complete — material listed, dimensions called out, tolerances on the page. They signed off and the machine went into production.
Customer B took a different path. They shipped us two of their actual parts, unfinished, straight from their machining line. No pressure, no deadline talk — just “here, drill these the way you’d do it for real.”
What Customer A Discovered, the Hard Way
Customer A’s machine arrived, was installed, and the first trial run immediately went wrong. Not dramatically — just persistently. The holes were coming out with poor surface finish, and tool life was far below what we had quoted.
The investigation took weeks. And when the root cause finally surfaced, it was one that no drawing could have caught:
- The drawing said “steel.” The actual material was a pre-hardened steel, roughly 15 points harder on the Rockwell C scale (HRC). The difference sounds small, but in deep hole drilling it changes everything — tooling selection, speeds, feeds, coolant requirements.
- The real tolerance was tighter than the drawing. The customer’s downstream process needed a straightness the print didn’t state. Their engineers had assumed “standard” — our engineers had assumed the print.
Neither mismatch was anyone’s fault. Both were invisible on paper. But they meant the machine, as configured, could not reliably hit the customer’s actual requirement. The fix — a different tooling package, adjusted parameters, and a modified guide bushing — took another several weeks and ate into the quarter the customer was trying to protect.
What the Sample Part Caught for Customer B
Customer B’s sample parts told us things the drawing never could:
- The true material state. We cut the sample and measured it. The hardness, the machinability, the way chips came off — now we knew what the machine would actually face, not what a supplier datasheet claimed.
- A geometry the print didn’t show. The part had a pre-machined feature that sat right in the path of the drill entry. On the 2D drawing it was easy to miss. On the real part, it was obvious: the drill would need a different entry angle and a guide bushing configuration that the standard setup didn’t include.
- The real tolerance requirement. When we drilled the sample, we could measure straightness, surface finish, and cycle time on the actual geometry — and we could ask the customer the pointed question: “is this the accuracy you need, or does it need to be better?”
The result: we changed the configuration before the machine was built, at a cost of a couple of design hours — not after installation, at a cost of weeks of lost production. Customer B’s machine hit its acceptance criteria on the very first production part.
Why a Drawing Isn’t Enough
A drawing is a promise about what a part should be. A sample part is evidence of what it actually is. In deep hole drilling, the gap between the two is where expensive surprises live:
- Materials get substituted, heat-treated differently, or arrive with batch-to-batch variation.
- Tolerances that matter to the final assembly are rarely written on the drill print.
- Existing machined features — the ones already in the part when it reaches the drill — are never as clean as they look on the CAD model.
A sample part closes that gap while the machine is still on our floor, where a change costs hours, instead of on your floor, where it costs weeks.
What to Send, and How
If you are ordering a deep hole drilling machine, here is what to send when we ask for a sample:
- One or two actual workpieces — finished, or as close to finished as you can get before drilling.
- A note on orientation — which face is the reference, where the datum is, which direction the hole must enter from.
- Any current pain — what does your current process struggle with? Scrap, cycle time, tool life? We tune the machine to solve the problem you actually have, not the one the drawing describes.
You do not need to send a perfect part. An unfinished blank is often more useful than a finished one, because it shows the material and stock state your machine will really see.
The Bottom Line
There is no part of the ordering process that saves more money than the sample. It costs one shipment, a week of waiting, and a few hours of our engineers’ time — and it buys you a machine that works on your actual part, the first time.
So when we ask for a sample, it is not paperwork. It is us asking to start the project the way it should start, with your real part in our hands. That is how we build a machine that does the job, instead of one that merely looks right on a drawing. It is also part of why customers come back for a second machine — a machine proven on your real part is one worth buying again.