How do I turn off angle snaps for 3-point arc?

[bwallaceEWGNX]

I'm trying to create a family of a light fixture where the housing is almost, but not quite a semi-circle; a slightly less than 180-degree arc. I'm running into an issue where Revit is wanting to automatically snap the arc of my extrusion to 180 degrees. I've turned off all snaps besides endpoints and midpoints, as shown below. 

Tabbing through snaps does not seem to work in this instance. I need the top of the arc to snap to a defined reference plane, but as I approach the plane the whole arc jolts just beyond it to snap at exactly 180 degrees.

My cursor in the screenshot below is sitting right on the plane that the top of the arc needs to snap to, but you can see that the arc has gone beyond that to snap to 180 degrees instead. My cursor is snapped in the correct position where the X is, but the arc is not for some reason. Again, tabbing through snaps is not working for this issue.

Any help would be appreciated.

[eizinmyat]

Hello, 

Could you try checking mark at Angular dimension snap increments and press the tab button during creating arc and directly type the degree that you want on keyboard?

[M_Meshal]

When you are drawing the arc, simply click on (SO) shortcut from the keyboard, and snaps will be disabled.

[bwallaceEWGNX]

Hey thanks for the reply, unfortunately trying this seems to just adjust the length of the arc from the start and end points, not the center.

[bwallaceEWGNX]

Hey thank you for the response. I did try using SO before, but turning off snaps completely is not ideally what I want. I need the top of the arc to snap to the reference plane I have defined. Using SO just turns off the snaps all together so I'm just sort of guestimating the position.

[ToanDN]

Assign an angle parameter to the arc and you can set it to a specific value.

[danielWCC5E]

It doesn't turn them off completely. it only turns it off for the next click