Guides / Quoting
What an Hour on a Large Boring Mill Actually Has to Cover
September 22, 2026
A machining centre hour and a heavy boring mill hour are not the same product, and shops that price them with the same logic end up unprofitable on one and uncompetitive on the other.
What the rate has to carry
The machine. A large boring mill, gantry or vertical lathe is a major capital item with a long life and a foundation under it. Depreciation per productive hour is high because the productive hours are fewer, not because the machine is busier.
The floor. A heavy machine occupies serious square metres, and so does the part waiting beside it. On heavy work the part often sits in your shop for weeks between operations. That space is real cost and it is invisible in most rate calculations.
The crane. The crane over that bay exists largely to serve that machine. Its cost belongs to the work it enables.
The operator. Heavy work rewards experience more than almost any other machining. The person who can indicate a four metre weldment in once, and knows when to stop and let it cool, is not interchangeable with a machine minder. Pay for that and price for it.
Tooling. Long bars, large indexable cutters, facing heads, right angle heads, boring bars with damping. Individually expensive, and roughing through a flame cut skin eats inserts faster than any spreadsheet assumes.
Utilisation, honestly. This is the one that hurts. A heavy machine does not run three shifts of cutting. There is indicate time, crane waiting, probing, stabilisation. If you calculate the rate assuming high spindle utilisation and then achieve half of it, every job loses money and nobody can see where.
What should sit outside the rate
Keep these as their own lines, because they vary per job by a factor of five:
- Rigging and handling per setup, with crane and second operator
- Fixture design and build
- Programming, which on a multi-setup heavy part is engineering, not a macro
- Stress relief, including transport each way
- Sub-contract operations
- Inspection, especially if a laser tracker has to be hired
- Preservation, crating, lifting arrangements
Bundling these into an hourly rate averages them, and averaging makes you expensive on the straightforward parts you should win and cheap on the complicated ones you will regret.
Roughing and finishing are different rates
Roughing is heavy metal removal at full power. Finishing is slow, light, careful and often at full spindle extension where you have to drop the parameters.
A single blended rate under-recovers the roughing and over-charges the finishing. Splitting them is more accurate, easier to defend in a quote, and it makes it obvious to the buyer why removing stock they do not need is expensive.
Pricing the time nobody is cutting
Heavy work has a large share of paid time where no chips are being made. Indicating a large weldment can take hours. Turning the part over and re-proving the datums is most of a shift. Probing before finishing takes real time. An overnight thermal stabilisation occupies the machine and produces nothing.
All of it is necessary and all of it is chargeable. The mistake is not charging it. The bigger mistake is charging it invisibly, so the buyer sees a total they cannot account for. Put it in the quote as setup and handling with a setup count, and it reads as competence.
More on why that time exists in thermal growth in large part machining.
The utilisation trap
The instinct when a heavy machine is idle is to raise the rate and recover the fixed cost over fewer hours. This is the wrong lever. It makes you less competitive, wins fewer jobs, and idles the machine further.
Price the hour on what running it costs. Then treat utilisation as a separate problem with separate solutions, which is what keeping a boring mill loaded is about.
How to present it
Buyers do not want your cost breakdown and giving it invites a negotiation on your rates. What they want is scope.
A clean structure:
Machining, 62 h [single figure]
Setups, 3, including rigging and re-indicate
Fixture [figure, or "existing, no charge on repeat"]
Programming [figure]
Stress relief [figure, sub-contracted, 5 working days]
Inspection [what is measured and how]
Preservation and crating
Total, EXWSame total, but every line answers a question the buyer was going to ask, and none of them exposes your hourly rate to a procurement conversation.
What to do next
Work out your real productive hours on the heavy machine last quarter, then recalculate the rate against that instead of against capacity. Most shops find the honest number is higher than the one they quote and the total is still competitive, because the setups were being given away.
Related for shops: how to quote a large part and why shops lose large part quotes.
Frequently asked questions
Should handling be inside the hourly rate or a separate line?
Separate. Handling varies enormously between a two setup part and a five setup part, so burying it in the rate makes you expensive on simple jobs and cheap on complicated ones, which is exactly backwards.
Is a higher rate a problem when buyers compare quotes?
Only if the quote is a bare number. Buyers comparing heavy work are looking at the total and the plan. A higher rate with fewer setups and no surprises frequently lands below a lower rate with three re-clamps.
How do I price a machine that is idle half the month?
Not by raising the rate to recover the idle time, which makes you less competitive and idles it further. Price the hour on what it costs to run and fix the utilisation problem separately.
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