Trying to shave off edge of curved edge. Any help is appreciated

Hello,

I have a polysurface which I’m trying to shave the edge off. I am not sure how to achieve this and was hoping someone could provide assistance. I have attached a hand-sketched drawing indicating what I’m trying to achieve.

Any assistance would be greatly appreciated.

cornershave.3dm (116.7 KB)

Something like this, I think-

cornershavePG.3dm (316.6 KB)
-Pascal

On the drawing it looks like a simple chamfer with different distances:

Thanks very much for this.

It looks like it’s a simple chamfer, but I don’t think it is. The key—and what I’m struggling with—is that the bottom chamfered part needs to be a bit rounded. If you see in the picture I attached, there’s the blue circular ring. And then offset from that is a dashed outer circle. The chamfered area needs to take on the curved shape of that outer dashed circle.

Ah, I see. I misunderstood that detail. So it is something like this in the attached file.
cornershaveTW.3dm (346.0 KB)
Its hard to explain in english what I did, so any help is appreciated by a native speaking person :wink: The railcurve is a “start-end-direction” curve.

Hi Toby.

I appreciate your help. I am working with the rail sweep but haven’t been able to get the design down.

I see how you achieved the rail sweep. But I can’t get my head around how you knew to place the arc where you did (I understand the bottom give that acts as the cross for the rail)

i don’t think this is exactly what @toby did but real similar… using his file to start with:

1 Like

@jeff_hammond: not exaxtly, you did it with some tricks for a faster workflow :wink:

I don’t know if this arc is right one, this will depend on the given design, but it can be modified till the design matches. On this point the history feature can be very helpful to get the right rail.

[edit] Another way to get a nice rail is to do a chamfer (you can measure the right radius by using another 45° line) on a copy of the object first, extract the mid isocurve and copy this to the final object.


cornershaveTW_2.3dm (353.0 KB)

Note: @jeff is not the same as @jeff_hammond :wink:

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Sorry Jeff, I’ve forgotten that you have this nice feature with auto notification :slight_smile:

Hi Jeff. This is really wonderful. Thanks.

I am still having one complication (sorry!). When I do the sweep (and resulting boolean split), I am still taking a very small amount off the the end of the outward swooping part. See here for details: sweeped_edge.3dm (143.4 KB)

I have tried lowering the arc, but that seems to result in the boolean split failing (as the solid and polysurface do not full. And I have tried adjusting where the bisector occurs and how far offset the cross of the sweep is. None give me the results I am seeking.

Any help would be greatly appreciated.

Edit: I think the error might be related to bisecting as I am not at all clear on what I am bisecting nor how to use the tool. Specifically, I am not clear on how and why you set the angle for the bisect as you did in the video.

[quote=“Johannes_Silentio, post:11, topic:22944, full:true”]
Hi Jeff. This is really wonderful. Thanks. [/quote]
no problem

[quote]
When I do the sweep (and resulting boolean split), I am still taking a very small amount off the the end of the outward swooping part.
[…]
I have tried lowering the arc, but that seems to result in the boolean split failing (as the solid and polysurface do not full. And I have tried adjusting where the bisector occurs and how far offset the cross of the sweep is. None give me the results I am seeking. [/quote]

the first point of the arc needs to be exactly on the profile curve that you’ll be sweeping (the curve which was offset earlier)… if the profile isn’t intersecting the curve to sweep along, there will be a gap between the swept surface and the curve to sweep along… which will result in the problem you’re having.

when using Arc -> Tangent, make sure to click your first point at the exact intersection… prior to clicking the second point, use the option “From first point”… this will stop the tangent arc from sliding up&down the vertical line… it will be securely locked to the first point clicked.

that bisecting part is moreOrLess an arbitrary point to draw the vertical line at… i showed that in the video since it was where toby’s point was placed. (and i’m not even sure how he arrived at that being the point… maybe it just happened to be at an exact bisection of the angle…)

but using the bisector option allows you to easily split an angle into two equal halves:

Hi Jeff:

Ya, that resolved the issue! Thanks so much.

I have one more question. I am not able to control the shaving in the way I would like (basically to adjust how much is shaved off and where the shaving starts). For example, I am trying to replicate something my 3D printer did for me that looks like this: https://www.dropbox.com/s/tvbw5dirxeplaii/Screenshot%202015-08-05%2009.59.26.png?dl=0

In my file, however, the shaving is different. edgev101.3dm (125.8 KB)

So my question is this. With what you’ve suggested, I believe the variables I have to work with are (1) the offset circle, (2) the point on the offset circle where the arc begins and (3) the arc itself. (Please let me know if I’m missing something).

As best as I can tell, the offset circle determines how “deep” the eventual boolean split will go but it doesn’t fundamentally change the shape (only makes it thinner or wider) unless I want to change the shape of the offset, which I do not. The arc can only basically do one thing if I want to avoid any shaving on the far left side (as discussed in my last comment and resolved by you). I am not really clear on what the point on the offset circle does but manipulating it does not seem to allow me to control the shaving the way I want.

Would you mind explaining how I can do more to manipulate this shape?