The Machine Base RFQ Checklist

Everything a fabricator needs to quote a machine base properly, in the order they will look for it, so three quotes describe the same job and can be compared.

Most machine base enquiries arrive missing the same handful of items, and the fabricator either guesses or asks, which costs a week. This is the list, in the order a shop actually looks for it. The RFQ is the third step of the machine base supplier path, after choosing the construction and auditing the shortlist.

1. What the structure is

• Type: base, bed, column, gantry, table, frame, weldment.
• What machine it carries, and roughly what that machine does. A shop that understands the application will spot a problem in your drawing.
• Overall envelope: length, width, height.
• Target finished weight, or the weight of the machine that sits on it.
• Whether a bolted split is acceptable, and where.

2. Construction

• Grey iron, ductile iron, welded steel, filled weldment or mineral cast. If you are not sure, say so and ask for an opinion: that is a legitimate question and the answer changes the quote.
• Plate grade and thickness if fixed, or the load case if you want the fabricator to size it.
• For castings: grade to EN 1561 or EN 1563, governing section thickness, and whether a pattern already exists and who owns it.

Background on the choice: cast iron against welded steel.

3. Quantity and timing

• Real quantity now, and realistic annual quantity. This changes the recommended construction, not just the unit price.
• When you need the first unit.
• Whether this is a one-off, a batch or a recurring programme.

An honest number beats an optimistic one. A shop that tools up for twenty and delivers two prices the next job defensively.

4. Machined geometry

The part most often under-specified, and the part that drives the price.

• Which faces are functional and what mounts to each one.
• Flatness, parallelism, squareness and position per surface, with the datum scheme.
• Bore sizes, tolerances and their relationship to the datums.
• Surface finish where it matters.
• Which faces must remain bare.

Mark functional faces as raised pads where you can: it cuts machining time and makes the requirement unmistakable. See GD&T for machine bases and designing weldments for machining.

5. Fabrication standards

• General dimensional tolerance class to ISO 13920, typically B for machine frames.
• Weld quality level to ISO 5817.
• Welding quality standard, commonly ISO 3834 with the quality level.
• Any welder or procedure qualification requirements.

Omit these and each shop assumes, differently, and your quotes are not comparable.

6. Stress relief

• Method: furnace thermal cycle or vibratory treatment. These are different products at different prices and not every specification accepts both.
• Where it sits in the sequence: after welding only, or again between rough and finish machining.
• Whether you want the chart or certificate.

This is the item most often left out and most often argued about later. See stress relief and flatness.

7. Inspection and documents

• Which dimensions are pass or fail, and which are recorded for information.
• NDT scope: visual, MT, PT, UT, and on which welds or zones.
• Dimensional report requirement, with the support condition and temperature: see measuring flatness.
• Material certificates required.
• Whether third-party inspection will attend, and at which points.
• The document pack you expect in the box.

Ask for what you will actually read. Every document is hours in the price.

8. Finish

• Surface preparation standard.
• Paint system, colour, number of coats and dry film thickness.
• Protection for machined faces.
• Any areas to be masked.

9. Packing and shipping

• Destination and the Incoterm you want quoted.
• Crate specification, and whether fumigation-free timber is required.
• Lifting point locations and marking.
• Access constraints at your end: crane capacity, door height, floor loading.

Details in shipping heavy machine bases.

10. Commercial

• Whether an NDA is required before drawings are shared.
• Payment terms you expect.
• Whether tooling, patterns or fixtures are to be owned by you.
• Who owns the pattern or mould, and where it is stored.

The files to attach

• 2D drawing as PDF, with tolerances and datums.
• 3D model as STEP or IGES.
• Any weld detail drawings.
• Your general tolerance and welding specifications, if you have house standards.

A realistic expectation

Provide all of the above and a competent shop can quote firmly within a few working days. Provide half of it and you will get a range, a list of questions, or a quote hedged against the worst interpretation of every gap.

The single most useful page you can add is a short cover note saying which three things matter most on this part. Shops allocate effort, and telling them where the difficulty lies gets you a better answer than leaving them to guess from a drawing that tolerances everything equally.

Ready to send one? Use the RFQ form and we will match it to fabricators who build structures of that size and class.

Common questions

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