enter image description hereThis is on a valve for a fancy walk in tub. The nut tightens it against the top of the tub to hold it in place.

But I have no idea what this kind of nut is called, nor what tool to use to properly tighten it. I can get it kind of tight using vice grips, normal wrenches, and hammering it with a flat head screwdriver.

Some of them are about 2 inches in diameter, others 2.5-3 inches.

But surely there is a proper tool for this? What's it called?

  • I've always just used a slotted screwdriver and the palm of my other hand. Works for me.
    – BillDOe
    Commented Oct 8, 2016 at 18:37

3 Answers 3


For slotted collet nuts I use either an adjustable or slotted spanner wrench.
Spanner Wrench
Slotted Wrench Adjustable Spanner


Although you can nearly always use something from a normal toolbox, a hook spanner is ideal. One of the top two in this image would work (the third is a pin spanner): Spanners via ja.wikipedia


The usual procedure is to use a slotted screwdriver against the tabs, and strike lightly with a hammer or mallet.

source USPTO US5374785

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