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Noob Problem with Assembly Mating

Hey guys,
I'm using Solidworks and I'm trying to build a shelf with metal rails. I drew two different sizes of rails and am trying to arrange them in my assembly to the right dimensions of the frame. I figured the best way to do this was to draw a construction box that has the right dimensions, then mating the corner points of the rails with the edges of the box.​

I've spent hours completely frustrated on this because the mating is being completely irrational. I click the bottom corner of a metal rail (a vertex), and shift click the corner of the construction box. I then try to do a coincident mate. However, it moves the box to a coincident mate with the TOP of the metal rail, which makes absolutely no sense whatsoever.​

This isn't a phenomenon with this assembly or this single rail. I've restarted from scratch about 10 times and get the same result. I've tried mating the lines of the rail with the lines of the box and that doesn't work either. I sometimes can even get 2 or 3 rails mounted right, but then when I mate the last one, it'll move the box to the top of the rail instead of the bottom.​

Sometimes it'll even mate with something in the middle of the rail, which makes no sense at all. Is there maybe a much better way of doing this?​

I'm going absolutely bonkers trying to figure this out. Any help or advice would be much appreciated! Thanks guys!​



New member
Try putting a hole in one corner of the metal frame to make sure it isnt instantaneously flipping the part on you. This would be odd behavior, but it is a possibility.

I see your sketch is not fully defined. This may be a souce of unwanted behavior. Turn on your planes and fully define that sketch with respect to the origin.

It is just my personal preference, but I steer clear of point point mates. Try mating the edge of the metal frame with a line, and the end face with a perpendicular line.

Good luck!