Two grippers, same part mass, very different overhang

That gives me a concrete request, thanks. Their totals don't include hose fittings either. I'll ask for an itemised assembly and the held-part position.

Include the proposed operating movement in the assessment too, since a static mass comparison won't cover every load the robot and tooling see

And ask who owns that check in the quote; a tool supplier's yes and a robot supplier's maybe don't add up to one responsible acceptance

Good point, I was concentrating on loading; reach and release access need checking for both complete proposals as well

The longer fingers clear a lip on our receiving nest. The short tool would need a nest alteration. That's in a footnote I hadn't connected to the comparison.

Then price that alteration and have its locating function reviewed, otherwise the short tool's apparent saving excludes work required to make it usable

Check service access to the tool connections too. More precisely, ask maintenance whether either arrangement can be inspected and replaced as intended. A fitting trapped behind the adapter can make a minor cable fault a much longer interruption.

Maintenance has the drawings now. I've added the nest change and connection access to our questions. Neither supplier has yet assessed the complete loaded arrangement against the intended job.

Then neither offer is ready for a technical sign-off, however tidy the part-mass comparison looks

Purchasing has separated commercial comparison from the outstanding technical review. We still need the suppliers' assembly data. I can explain the hold now without claiming one tool is unsuitable.

Ask them to identify any assumptions in those data, especially the housing orientation; a centre-of-gravity figure without its reference frame is a pain to use

A labelled assembly drawing helps there. It should show the flange reference and the held housing location so the reviewer can reproduce the supplier's calculation basis.

Yes, and keep the tool-only and tool-with-part configurations explicit if both are relevant to the robot setup; don't leave somebody guessing which total to enter

Make the accepted assembly information part of the replacement process. Otherwise a future adapter or finger change can leave the documented load configuration describing tooling that is no longer installed.