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I have my upper rocker button set so that whatever pen I am using, it chooses an eraser that I like. In the Cintiq settings, the rocker is set to "eraser". This is the case on both of the two stations I have, but on the other one, pressing the rocker changes to a pen, not an eraser. This must be a setting in TVPaint that tells TVPaint what to consider an eraser, since Wacom is sending the message to switch to whatever is defined as the eraser. I can't figure out how to fix this on the other station so that the pen erases when that rocker is pressed. Any idea?

David, are you familiar with the key command (under Tools) "Swap Stylus Tips" ? This should be your best friend.
I have this Swap tool set to my numbers pad "/" ( forward slash) key. My Wacom tablet's pen is set to have "Erase" set on the bottom rocker switch.

Further, I have a custom brush set to be an eraser (I configured the oil brush tool to be an eraser). In that custom panel I also have my pencil (Pen/Brush) set to be a drawing pen.

Here's How I make it work. I tap on my pen icon and draw to make sure I am using the correct drawing tool. Then I press on my SWAP "/" keyboard key, and with my pen I tap on my eraser icon. Thus I have made my SWAP key to toggle between eraser and pen whenever I tap on the keyboard "/". I have made my eraser BTW to be a bit on the wide side.

When I press and hold my bottom rocker switch I turn my pen's nib into a small eraser (it is by Wacom's software's default the exact size of your pen). I use this way of erasing to make minute corrections in my drawing lines. When I need to erase a larger swatch, I tap on SWAP "/" to swap to the fat eraser. This way I have a triangle of thin eraser, pen, and fat eraser to rotate between.

Having described all this, I must say that with some computers setting "default" in the Wacom software to my rocker switch works better than the "Eraser" selection, so you have to experiment.

BTW, my top rocker switch is set to my keyboard key which has toggle LightTable assigned to it. This lets me draw, erase, and turn the light table on and off without ever having to take my fingers off my pen.

This is a very useful configuration. I currently have one of the Cintiq buttons set to toggle light table, which works for me too. The switch key is very useful to know, so thanks for that. Still baffled though as to how to make the top rocker be a default, larger eraser though. As I say, I have that on mine, but not on the other station and I don't know how I did that, so can't fix it on the other one. I agree that the bottom rocker is good for very fine erasing as it matches the pen, but I want the top rocker to be a more general purpose eraser. In the Wacom prefs, both stations have the top rocker set to Eraser, but they don't act the same.

if you have a key command for the fat eraser you can set the top rocker to "Keystroke" and enter the eraser's key command.

I have created a particular eraser and made it into a button, but I have no idea how to add a keystroke to a button on a panel. This is something I have wanted to do, so I would love to know. If I go into the prefs and search for eraser, I get some options, but all of them are just one particular, large, soft edged eraser, not the one I want.

Since you are on a Mac, this is beyond my territory, but can you not change the settings and configurations of the existing eraser to give it a hard edge? Something like this is usually done with the profile editor.

I don't think it's a Mac thing. I have five erasers on a panel. Different sizes and softness. So I know how to make different erasers, but not how to make those erasers connected to a key combo.

This is how I would do it on a PC -- see if any of this applies to a MAC"

First create an eraser tool and then open a new custom panel by going into the Custom Panel menu where you will find at the bottom "New Custom Panel". Click on it and look for it somewhere on your GUI.
and from the menu select "Add Action" This will open the edit part of the panel, where you will enter the name of your tool (Hard Eraser) Click on the list to find an icon you can use (later you can make your own).
Right click inside this new panel, Right Click inside the icon and select "Grab Current Tool with colors, Keep icon" and at the top click on This Panel>Rename and fill in the name (Eraser Panel).

Open the Key Command panel where on the right side you should see the name Eraser Panel. Click on it and it will show the name Hard Eraser and click on that. At the very bottom of the left side the name will Hard Eraser will appear

Find a Key name or combo (tip: select one of those esoteric long ones like Ctrl Wheel Up so you won't have to use up your simple keys because you will never be really using this eraser with a key) and click on "Assign" at the very left bottom corner.

And there you have it. Now go to Wacom and for Keystroke enter Ctrl Wheel UP and it should activate your eraser.

Thank you so much for the detailed response. I know all about making a panel and such, but had not figured out how to assign a key to a button in that panel. Now I know and that is huge! This solves this problem, but also other stuff, so THANK YOU!!

You are welcome David. When I write these answers I usually don't have in mind the person I am giving an answer to but anyone else who might not know any of this at all. Your questions are encouraging to spend a little bit of time on because you carefully formulate your questions; then we know that others down the line can benefit.

Aw darn, I thought this was solved but it isn't. On my pen, when I hit the top rocker button, it changes to a predetermined eraser which I like. On the other station, assigning that rocker to a keystroke connected to a particular eraser works, but then when you release it, it does not go back to the pen. You have to go and select the pen manually, which kind of defeats the purpose. On my pen, it toggles so that when it is released, it goes back to the pen that was in use before. So clearly it's possible to do what I want, but for some reason, I can't replicate it on the second station. On my pen, the rocker is set to ERASE in the Wacom prefs. On the other one, it is set to the keystroke, but setting it to erase changes it to a pen. So I think that there is something in TVPaint which you choose to represent the eraser. I think that has to be it. Any idea how to control that so I can get this to work for me on both stations?

If it works on one station but not on the other, shouldn't you be looking into the differences between the two computers? It can't be in TVP if it works in one station -- or can it? Anyone?

I just remembered something on the subject; Wacom's outcome can make a difference if your Wintab is turned off or on -- have you tried that?

Breaking news! I think I have figured this out. Setting the button to ERASE means that TV Paint uses the pen brush when you click that button to erase. My pen button was set at size 5 and 100%, so it gives a nice medium size eraser. If I go and change that setting while holding down the eraser button, it remembers it, so you just have to make sure that having chosen ERASE in the Wacom prefs, that you then make sure that when you press the ERASE button you have set on your pen, the PenBrush in the main panel is set to the eraser settings you want. In that way, you could make the Erase function anything the PenBrush can be set to do. On the other station, it happened to be set to a pen, not an eraser, so changing that sorted it.

It seems to me that this is a pretty necessary and basic function, yet I can't find a peep about it in the manual. Am I missing it? If not, wonder why it is not explained there clearly.

Changing the eraser settings by holding down the switch is standard practice. I left that part out because I understood that you were happy with the way it functioned by default. That the upper switch should be set to pen is news to me so I'm glad to have learned something (but I use it for LightTable) so it makes no difference to me. Just be aware that you will find yourself having to reset the bottom eraser ever so often. I'd be interested in this part because it seems to vary by computer. Please post after some time how often you have to reset -- after a reboot it will be needed for sure.