How to Brief an Outside Machine Shop So the First Quote Is Right

Two quotes come back for the same drawing, far apart. The usual conclusion is that one shop is expensive. Often the shops quoted different parts, because each one filled the gaps in the brief with its own guesses.

A good brief tells the shop what a drawing cannot: what the part does, which features matter, and what happens after this order. With those three, two honest shops are far more likely to quote close to each other, and the first quote is far more likely to hold up once the work starts.

Between 2020 and 2025 the shop took briefs from engineering teams as different as university research groups, automotive suppliers and plastics molders.

What to send

• The drawing at its current revision, with tolerances, and the 3D model. A STEP file opens in almost any CAD system.
• The material, and whether it is fixed or chosen out of habit. A small change in material can change the job a great deal.
• The quantity now and the quantity later. A shop fixtures a part one way for five pieces and another way for five hundred that repeat every quarter.
• Finish and any treatment, such as anodizing, plating or heat treatment, and who arranges it.
• What the part mates with, and which features carry the tight tolerances. When the tolerance is tight goes further on this.
• The paperwork you need with the parts.
• The date you need it, and whether that date is real or a placeholder.

If the part is molded rather than machined, the features that drive the price are different. What makes an injection mold cost more covers them.

Questions worth asking back

In From Idea to Product: which shop do you need? I set out nine questions for sorting shops. Three of them matter most at the briefing stage. Who is my one contact from start to finish? What happens when my job needs a process you do not run? What paperwork comes with the parts? A shop that answers those plainly before the quote is likely to answer plainly after it. Ask too whether setup is priced separately from each part, because it changes how you compare quotes for different quantities.

One job number

At Invent Art every job carries one job number. It follows the work through the schedule, the time records, the files and the invoice. That gives your team records that support an R&D tax credit (SR&ED) claim, and one reference when a part comes back for a change. What goes into a claim is a matter for you and your tax adviser. Time records are available on request.

If your drawings cannot leave your own systems, design for molding and machining when your team is full explains how we work inside your design environment.

Small on purpose

We are small on purpose. You deal with the same people every time. They learn your parts, your standards and the way your team writes a drawing. The second job is easier than the first, and the tenth is easier still. A brief that takes effort the first time gets shorter with every order after it.

The shop floor is one small team. Each technician has a focus area, and they help each other, which matters when a job needs more than one discipline. Once a quote is approved, we do the work and keep you up to date as it goes. If there is a better way to make the part than remaking it the same way, we'll propose it. And we make sure you are satisfied before the final payment.

To be fair to the other side: if your part is fully defined, the file is final and price is the only question, an online machining service is built for exactly that, and a brief like this is more than it needs. The brief pays off when the part is new, the tolerances are tight, or the order will repeat.

Before your next quote request goes out, read the drawing as a stranger would and write down everything you assumed they would know. That list is the brief.

Related services: Aluminum tooling, molding and machined parts Shop capabilities