Get started: Calibrate tip length and pipette offset
You've already calibrated the deck. Now, you'll continue with your OT-2's positional calibration by doing:
Tip length calibration.
Pipette offset calibration.
To learn more about what each part of calibration does and how they all fit together, check out How positional calibration works on the OT-2.
What you'll need
Your pipettes already attached to your OT-2.
Opentrons tips for those pipettes, in Opentrons tip racks. Even though you'll be able to use other when you run protocols on your OT-2, if you try to calibrate with other tips, they'll make your calibration come out wrong.
Your Calibration Block, if you have one.
Step 1: Begin
In the Robot tab, go to your OT-2's Pipettes & modules page.
Select Calibrate pipette offset. If you have two pipettes, pick either one to do first—It doesn't matter which.
The Opentrons App will ask you if you have a Calibration Block. Select Continue with Calibration Block if you do, or Use Trash Bin if you don't.
Tip: If you select "Remember my selection for next time and don't ask again," you can change your preference later under More > App > Advanced Settings > Tip Length Calibration Settings.
Step 2: Calibrate tip length
The first time you try to do this pipette's offset calibration, the Opentrons App will prompt you to calibrate a tip length first. This is because the process of pipette offset calibration will happen to involve attaching a tip, and the OT-2 will need to know the length of that tip beforehand.
You'll need to provide a tip rack. The Opentrons App will show you what kind. This tip length calibration will inform the OT-2 how that model of tip fits onto the nozzle of that unique pipette. For more details, see How positional calibration works on the OT-2.
If you don't have the kind of tip rack that the Opentrons App asks for, contact Opentrons Support and let us know what tip racks you do have.
Carefully follow the Opentrons App's instructions to calibrate tip length. It will guide you through:
Lowering the pipette nozzle, without a tip attached, to a flat surface (either your Calibration Block or the trash bin).
Picking up a tip.
Lowering the pipette to the same flat surface, now a tip attached, to measure the tip length.
You should see a green check mark and a "Tip Length Calibration complete" message. Select Continue to pipette offset calibration to move on.
Step 3: Calibrate pipette offset
Carefully follow the Opentrons App's instructions to calibrate pipette offset. It will guide you through:
Lowering the pipette tip to the deck, to calibrate the pipette's z-offset (height adjustment).
Centering the pipette tip over an engraved reference point, to calibrate the pipette's x-offset (left/right adjustment) and y-offset (forward/back adjustment).
You should see a green check mark and a "Pipette Offset Calibration complete" message. Select Return tip to tip rack and exit to finish up.
If you've attached a second pipette, you'll need to do tip length calibration and pipette offset calibration for that one, too.
You might have to do more tip length calibrations later on, after you upload a protocol. Each additional model of tip that your protocol uses will need its own tip length calibration.
After completing a pipette offset or tip length calibration, you shouldn't need to redo it unless you suspect something is wrong with it.
If you ever do want to manually redo pipette offset calibration, you can come back to the Pipettes & modules page at any time. To manually redo tip length calibration, come back to the Pipettes & modules page for Opentrons tips, or the Calibrate tab after you upload a protocol for other tips.