Tapered rectangle by extruding?

CodyH

Is there a quick and standard approach to extruding an object, such as a rectangle, with all four sides tapering to a particular dimension? I'm still learning the basics of Onshape and this is eluding me. Tapering two sides would simply involve extruding a sketch, but I don't get how to symmetrically extrude to a taper. For instance, I want a 41.5 mm x 16.5 mm x 60 mm rectangle to taper down to 40.5 mm x 15.5 mm x 60 mm. Thanks! 

_Ðave_

There's no direct way to taper to a specific dimension as you described. You can taper by degrees or you can 2 dimension chamfer the edges  one dimension would be 60 and the other would be .5 in your example.

shanshan

CodyH, why not use "loft"?you can get a taper directly with "loft"!

CodyH

It was a few more steps than I thought to get the taper how I wanted, but the loft did the job! That could also be due to my lack of experience. The only thing I'm not sure about is centering the smaller rectangle with the larger one so the taper is even all around. I ended up drawing a couple lines and making them coincident with the midpoint of the lower lines for each rectangle. There must be a more efficient method, but at least it got me going forward.Thanks for the help guys! 

_Ðave_

Cody

 Here's a simple method to center the 2 rectangles.

CodyH

Hey thanks for that extra advice! That sure is a lot more sensible than my approach. Sometimes you just need your eyes opened to a concept you were totally missing. 

_Ðave_

Narayan_K

@ CodyH, If you know how much degree should be the tapper then you can use draft also.

CodyH

Narayan,

Yet another simple solution that totally escaped me! I hadn't worked with that tool yet. It literally does exactly what I want. Although I'd have to play with the degree settings until I arrive at the measurements I need, it sure saves a lot of steps. Actually, just plugging in 0.5 degrees on the second attempt got me REALLY close to what I was looking for. Probably even close enough for this tool's application. Now if only there was another feature that allowed us to set the dimensions of the extruded surface instead of using angles then it'd be even more impressive. Thank you! 

matthew_menard

If you're going to define the model by the top or bottom dimensions (not both) and taper angle, the draft option in a regular extrude is probably best.  If you're going to define the model by the top and bottom dimensions, the loft will probably be best.  It depends on whether you are concerned about the taper angle or the top and bottom faces being accurate.

simon_jolley

Guys, As a complete novice, (1 week only) I want to draw concentric and eccentric piping reducers, so;
1. How do I get 2 planes, 1 above the other at a fixed distance (48mm)
2. When I use draft, I followed the "bath tub" example, and a guessed angle, but I cannot select the base circle.as shown in the example.

Any tips please?

Simon

jakeramsley

simon_jolley said:

Guys, As a complete novice, (1 week only) I want to draw concentric and eccentric piping reducers, so;
1. How do I get 2 planes, 1 above the other at a fixed distance (48mm)

Use an offset plane.  

1. Right click on the plane you want to offset from and choose 'Offset plane...'  This will start a construction plane with the offset option selected.  It will take a plane of the same orientation and move it a specified distance in the normal/perpendicular direction of the plane.



2. Change the distance to be 48mm and hit the green checkmark.  These two planes are now 48mm apart.