I have done some very small rounding of Warmoth fretboards with a sharp razor and then light sanding before doing the fretwork that I always do anyway. Just scrape the razor from one fret to the next at about 60 degrees several times then sand up to 800.
Edit. I read your post wrong. I’ve never seen anyone try to square off rounded edges.
Funny - I'm the opposite. I find squared off fingerboards unsightly and plan to round off the corners of my next purchase. Just one guy's opinion worth exactly $0.

Ahhhhh…… Thanks.The thread is not discussing "rolled" fretboard edges, it is talking about the end of the fretboard at the body end which is curved and whether to square it off.
From this shape.
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to this shape.
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What!!??? Booze and power tools go together like peas and carrots!!!!If you go ahead with this modification, please ensure you have not been drinking.
I woke up one morning after a night of partying with my band and I realized I had decoupaged one of my guitars with porn pictures cut out of a vintage magazine. I clear coated it and it became a novelty lolWhat!!??? Booze and power tools go together like peas and carrots!!!!
Don't forget the scotch!The process I'd follow:
Put a towel on your bench, and put the neck on the towel upside down (frets facing down). Leave the end of the neck out of the towel.
Take a wooden cube or something similar with flat surfaces and right angles. Stick a sandpaper on one of its surfaces. Put the cube's surface with the sandpaper against the fretboard end but while it's touching the table. This will ensure the right angle of the fretboard looking at it from the side.
The wood is sanded slowly so you can make corrections as you go.
If you want to be extra precise, you can take another neck with a square end and put it on top of the first one, align the two neck heels and clamp them with a clamp from the side, so you can use the top neck as a guide. Or just another cube shaped block of wood of similar dimensions as the heel.
For this you need a bigger block of wood and leave the surface of it which touches the top neck without sandpaper, so when you reach it, you won't damage it and use it as a straight edge.
Again go slowly.![]()
Yes! Essential for inspiration in cases like this.Don't forget the scotch!