How can one chamfer 45deg entering a chamfer length?

box drawn in ortho view using lines I need it with 0.25inch long chamfers on each corner.
Googled this can’t find an answer.
I wish to enter 0.25inch for length of chamfer then click the two lines and have a 45deg chamfer.

I dont have grasshopper , so no fancy code blocks please.



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Use the chamfer command and enter 1.768 for each of the two distances before selecting the two lines to chamfer.

[2.5 * sin(45) = 1.768]

In Rhino 7 you can enter 2.5*sin(45d) directly into the distance field to avoid having to get the calculator out. Note d is for degrees, if omitted then Rhino assumes radians.


EDIT: Careless me, out by a factor of 10… Should be 0.1768 and 0.25*sin(45d).
Resolution: always proofread.


so for the moment its the sin table and a calculator.

I did it the long way, draw line through corners of the square, circle dia 2.5 on both ends line, line tan to circles, intersect with square, draw line, trim etc.

I am most surprised that entry of chamfer length was not a tool option.

when I ever get to run v7 on win10 then I shall use that 2.5*sin(45d).

awaiting buying hardware, but scuppered as new credit card applied for and won, they wont carry fwd to it the existing cards credit limit, same financial circumstances, as in possession of the existing/just closed card, no change, closed the existing card down and because I did so they wont honour its credit limit, asking why, 'cos you closed it, but that’s 3 weeks ago, may as well be 3 decades ago, appeal with same data as was three weeks ago and 3 yrs ago when I took it out, , rejected, ask why, no answer as yet. Complaints team will have to deal with it, I only rang up to say thank you for allowing me a new card to replace the existing ! Not good vibes to have to be filling in complaints forms, could deter them, they engineer it then snag you with it,
If I cant build a new pc then they are affecting my financial circumstances and money earning, and engineering my demise, then they will say ‘told you so, we were right’ !
I feel it coming !


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In my opinion, this must be a dedicated “Command line” option clearly visible to everyone.

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When you finally get to using V7 you can just type .7071*.25 (or whatever your chamfer length at 45° should be). This will give you a chamfer length of 0.249998 - which is close enough to .250 for pretty much any purpose. If you want more accuracy than that you can type what Jeremy said, or .25*sqrt(2)/2

If you are running 45° stuff, then the \sqrt{2} plus the half of it are important numbers to have in your head.

1.41 for general stuff
1.4142 for more precision

0.7071 for \sqrt{2}/2

Sorry Steve, see my correction above. That should read .25*sin(45d).

Caveat: All the discussion here assumes that the lines to be chamfered meet at 90 degrees.

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Lines that meet at an angle other than 90 degrees require a slightly more complicated equation, and knowledge of the angle.

If the lines meet at an angle θ degrees then the distance, D, is related to the length of the chamfer, C by the equation D = C / (2 * sin(θ/2)).

So in R7, for a .25 chamfer on a 60 degree angle you would enter the distance value as

[although this is a silly example because, for an angle of 60 degrees, you can of course just enter the chamfer length as you are constructing an equilateral triangle. :wink:]

other workaround that involves no calculation is to extrude your curve and chamfer the edges with the distance between rails option, then afterward DupFaceborder

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Can’t you fillet and then trim the circle with a straight line joining both end points?

Sorry, no that doesn’t work:


Caveat 2: Straight lines only - doesn’t work for curves.

Hi @Gijs,

My brain’s too tiny to follow that - could you flesh out an explanation (with an example if possible).


Or, possibly, FilletEdge with DistanceFromEdge rail type, then replace the fillets with a loft across.



Never been able to figure out, if FE is able to do this, why CE can’t…

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Yeah, I forget about ChamferEdge, that works as well.


Thank you. Nice lateral thinking.

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It does if you input the correct radius though:

R = 25/√(2)
R = 17.6776695297

Fair enough, specifying “correct radius” makes all the difference. I hadn’t thought to include a calculation step.

But if you have to do a calculation, you might just as well do one in the chamfer rather than calculate for a fillet, draw a line, delete the fillet and join the lines.

And if your lines are not perpendicular…