What Information Does a Machine Shop Actually Need to Quote Your Part?

I tell clients this all the time: a quote is only as good as the information you give us. If you send a rough sketch with no details, you're going to get a rough number back. That's just how it works.

Here's what I need from you to get it right:

A proper drawing or 3D model. This is the foundation. I need to see every dimension, every tolerance, every note about threads or surface finish. A PDF of a hand sketch might work for a prototype discussion, but for a real quote, give me a STEP file or a proper engineering drawing.

Your material choice. This drives cost more than most people realize. Aluminum 6061 machines fast. Stainless steel 304 takes longer and wears tools. Brass is somewhere in between. If you're not sure what material you need, tell me what the part does and I can help.

Quantity. One-off prototypes cost more per part than a batch of 500. Setup time is the same whether I make one or fifty. Higher volume spreads that cost across more parts, and the per-unit price drops.

Surface finish requirements. As-machined is fine for many parts. But if you need anodizing, bead blasting, or a specific Ra finish, say so up front. Those steps add time and cost.

Why Do You Get Such Different Numbers from Different Shops?

This frustrates a lot of buyers. You send the same file to three shops and the quotes come back 40% apart. Who's right?

Here's what I see happening in our shop. Some shops quote aggressively to win the job and figure out later how to make it work. Others build in more margin because they've been burned by parts that look simple but are actually hard to hold. And some just use different tooling strategies.

A shop running a part on a new 5-axis machine with the best carbide tools will quote differently than one running it on a well-used 3-axis mill. Neither is wrong necessarily. But you need to understand what's included.

I always recommend asking: "Can you show me a breakdown of material, machine time, and setup?" A shop that can do that is a shop that knows its costs.

Three Questions I Ask Every Supplier Before I Buy

When I'm sourcing parts for our own projects, I don't just look at the bottom line. I ask these three things:

"What's your experience with this type of part?" A shop that has made similar parts before will spot problems early. They know which features are tricky and how to hold tight tolerances on your specific geometry.

"Are there design changes that could lower my cost?" This is the big one. A good machinist can look at your drawing and suggest tweaks. Maybe a tighter corner radius means a standard end mill instead of a special one. Maybe adding a slight draft angle eliminates a secondary operation. These small changes can cut 20-30% off the cost.

"What's your inspection process?" I want to know how they'll verify the parts. Do they use a CMM? Do they provide a full inspection report? If the answer is vague, that's a red flag.

My Take on Price Versus Value

In my experience, the cheapest quote is rarely the best deal. I've seen parts arrive undersized because a shop pushed feeds too fast to hit their quoted price. I've seen late deliveries because a shop took on more work than it could handle.

But I've also seen mid-range quotes that came with excellent communication, on-time delivery, and parts that measured exactly right. That's the sweet spot.

The shop that asks good questions during quoting is usually the shop that delivers good parts. If they care enough to understand your design during the sales process, they'll care during production too.

Send your CAD files to chen@aoomtech.com for a quote within 24 hours.