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Multi-Spindle Drilling & Tapping Heads →Compare head arrangements and prepare the host-machine and hole-pattern information for a configuration review.
1. Show the geometry that actually changed
Prepare an overlay or paired views of the approved current drawing and the proposed revision. Label each hole so the supplier can distinguish moved, added, removed and unchanged features. Keep the drawing datum references visible. A statement such as wider spacing does not identify whether the entire pattern moved relative to the part or whether individual hole relationships changed within it.
Include changes in hole diameter, thread designation, depth and approach direction even when the main reason for the inquiry is spacing. State whether the outside shape and locating surfaces remain the same. For existing equipment, provide the machine and head identification, available tooling records and photographs of the current arrangement. Mark missing records as unknown; a photograph alone is not a dimensional specification.
2. Ask for a component-by-component response
Use a change record with three responses for each item: retained after review, changed within the offer, or unresolved. Ask the supplier to identify the basis for retaining an existing item. This makes the quotation useful whether the proposal involves a reviewed adjustment, replacement components, another head or a different process arrangement. It also separates engineering work from the physical items being purchased.
3. Review the fixture against the new cutting locations
Ask for a combined view of the proposed tools and workholding. A revised hole may approach an existing clamp, sit over a different support area or change the space needed beneath a through feature. These are questions for the application review, not reasons to assume that a fixture must always be replaced. Give the supplier enough information to distinguish reusable hardware from items that require redesign.
Confirm how the revised part will be located and how its finished holes will be checked. If the outside geometry is unchanged, the locating concept may still need review against the new drawing relationships. If several old and new patterns must remain in production, request a list of the configuration items for each pattern and a clear means of identifying them after delivery.
4. Separate a repeated pattern shift from a new array
Hypothetical purchasing example: one revision shifts an unchanged four-hole group relative to the component edge, while another changes the spacing between the four holes. Both may be described internally as a hole-position change, but they present different questions about the tool arrangement and fixture reference. Submit the geometry rather than prescribing the same replacement head for both cases.
Compare proposals on the complete revised component. One supplier may include a new head but retain the fixture subject to a later review; another may include both the head and fixture work. Put those differences beside the prices. Where an alternative uses more than one machining position, identify the additional steps and the drawing relationships that must be demonstrated across them.
5. Tie approval to an identified configuration
Record the part revision, head identity, fixture identity and tooling list used for the demonstration. Agree the finished-feature checks before accepting the change. Where both patterns remain within the purchased scope, identify which results belong to each configuration. A satisfactory sample from the old pattern is useful background, but it does not establish coverage of a newly reviewed hole array.
For a BINSING discussion, send the comparison drawing together with any existing equipment records and the planned production mix. Ask the response to distinguish confirmed scope, items awaiting physical review and optional future coverage. Purchasing can then order the defined change package without relying on a general claim that a multi-spindle machine is flexible.
Close each changed-feature row with a disposition, responsible reviewer and evidence reference. For example, H2 moved / revised head drawing pending is an open item, not an accepted reuse decision. Attach the approved layout and configuration-specific first-part results before closing that row. Keep any still-required old revision in the scope register so approving the new drawing does not silently remove the previous production requirement.