Should I turn work away or outsource it?

Turning work away risks the customer finding another supplier who then keeps the rest of their work too. If the job is profitable and you can subcontract it at a price that still leaves you margin, outsourcing usually beats declining — you protect the relationship and keep the account. Decline only when the part is outside your quality comfort zone or the margin genuinely isn't there.

How do I stop a subcontractor stealing my customer?

Keep the commercial relationship yours: you hold the customer contract, you invoice the customer, and the subcontractor invoices you. Supply the model and drawing without the end customer's identity where you can, agree in writing that they won't approach your customer directly, and have the parts delivered to you (or drop-shipped in your packaging) so you control the final inspection and the handover.

Is it cheaper to buy another CNC machine or subcontract?

A machine is a multi-year fixed commitment — finance, floor space, tooling, and someone to run it. Subcontracting is variable: it costs you only when you use it. The rule of thumb is to subcontract while the overflow is lumpy or uncertain, and only buy when you have proven, repeating demand that would keep the new machine loaded.

Guides › For machine shops

Too busy? How to outsource CNC overflow work

Your machines are booked solid and a good customer sends another order. Turn it away and you risk handing them to a competitor. Here's how to subcontract overflow work safely — keeping the margin, the quality and the customer.

The short version: if the job is profitable and you can have it made at a price that still leaves you margin, outsourcing almost always beats declining. Just keep the commercial relationship yours — you invoice the customer, your subcontractor invoices you.

Your three options when you're full

Option	When it makes sense	The risk
Turn it away	Part is outside your quality comfort zone, or the margin isn't there	Customer finds another supplier — and may take the rest of their work with them
Buy another machine	Demand is proven and repeating enough to keep it loaded	Multi-year fixed cost: finance, space, tooling, an operator
Subcontract it	Overflow is lumpy or uncertain — most of the time	Quality and lead time are now someone else's hands (manageable — see below)

The honest rule of thumb: subcontract while the demand is lumpy, buy only when it's proven. A machine is a fixed commitment; subcontracting costs you only when you use it.

Protecting the customer relationship

This is the fear that stops most shops outsourcing, and it's a fair one. It's also straightforward to manage:

You hold the contract. The customer orders from you and pays you; the subcontractor invoices you. Never introduce them.
Share the part, not the customer. Send the model, drawing and requirements — the end customer's identity usually isn't needed to make the part.
Put it in writing. A short non-solicitation line in your PO is normal and reasonable.
Control the handover. Have parts delivered to you for final inspection, or drop-shipped in your packaging with your paperwork.

Protecting quality and lead time

Send a proper package: a STEP file plus a PDF drawing with the critical dimensions, tolerances, finish and any thread callouts. Ambiguity is what causes re-work.
Ask for an inspection report on the critical features. It's cheap insurance and it means you're not measuring everything yourself.
Build in a buffer. Quote your customer a lead time that has slack behind the subcontractor's — don't pass on their best-case date as your promise.
Start small. Try a new supplier on a low-risk job before you trust them with the tight one.

Making the numbers work

Outsourced work carries less margin than work you cut yourself — that's fine, because it's additional margin on capacity you didn't have. Price it as: subcontract cost + your handling, inspection and risk + margin. If that number is competitive for your customer, take the job. If it isn't, you've lost nothing by checking.

The quickest way to sanity-check is to get a real price for the part before you commit to your customer — see what CNC machining costs in the UK for the underlying rates.

Price your overflow job in seconds

Upload the STEP file and get a real, UK-made price instantly — no phone calls, no waiting for a quote to come back. If the numbers work, order it in a click; if they don't, you've lost nothing.

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Frequently asked questions

What should I send a subcontractor?

A STEP file, a PDF drawing showing critical dimensions and tolerances, the material spec, quantity, required finish, and your delivery date. If threads or inspection requirements matter, state them explicitly rather than assuming.

Do I tell my customer the work is subcontracted?

There's no obligation unless your terms or their contract require it (some aerospace and medical customers do restrict approved suppliers — check). What matters is that you remain responsible for the quality and the delivery.

How do I find a subcontractor quickly?

Local shops you already know are the safest start. Failing that, an online platform will price and place the job for you without you having to ring round — which is the point when you're already too busy.

More: Winning subcontract work → · Reducing machining costs → · Tolerances & finishes →