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Measured draft outwards

gsieben

Member
Hello,

Maybe there's a feature for this I am missing (or maybe it could be an added feature), but imagine the following scenario:

I'm making a simple mold, and I need to put a channel (or groove) in this mold, for another mold above it to have a matching tongue to fit into it. I could use draft angle to put, say, a 30-degree angle on it, so that my channel narrows by 30 degrees; but what if I wanted the bottom of my draft to be exactly 1/4" or 1/2"? I have to manually go and calculate what angle, as close as possible, depending on the depth of my channel, produces that distance. I could always use other tools like drawing a sketch, offsetting it, and similar to create such a precise angle; but if there was the ability in Draft to manually specify that distance and have it automatically find the appropriate angle, that would seem very useful.
 
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DavidJ

Administrator
Staff member
You could cut the groove with parallel sides, then either add draft to the sides, or add chamfers to the sides.

OR even create a plane at desired depth, sketch bottom of groove on that plane, then extrude cut upwards with draft (or even use thin wall cut with draft from bottom of groove)
 

gsieben

Member
You could cut the groove with parallel sides, then either add draft to the sides
My natural workflow (what would immediately come to mind as the most logical way to build this), would be to take a look at my solid, draw the outermost edge of the groove on the surface, then Extrude Cut downwards, and add Draft to the sides. However, if I add Draft to the sides, I can't say 'come out 1/4"', I have to say "come out 18 degrees."
sketch bottom of groove on that plane, then extrude cut upwards with draft
Maybe I'm incorrect... but does that just require specifying an angle as well, or can I extrude upwards to an edge?
 

DavidJ

Administrator
Staff member
You can extrude cut "to geometry" (the top face).

Another option is to loft between top and bottom of groove, use project to sketch and offset to make one profile from the other.

There are often multiple options to tackle any modelling task. No single "correct" answer.
 

HaroldL

Alibre Super User
Still another method, to ensure absolute alignment between the two mold halves, is to model the tongue on one half of the mold. Then use that mold half to create a Boolean Subtract on the other half. That way the tongue controls the size of the feature in both halves.

By chance will you be using a Boolean operation to create the mold cavity?
 
Ah, I was assuming a trapezoidal runner which is only on one half of the mold. I use the section method for this because it is easier to define the shape required and more stable to sweep the shape when the runner is not flat.
 
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