I’m attempting to make a curved door. Why is it not smooth? It never lines up no matter how close or far I move the part to union. (The door is in the bottom right of the picture. Sorry it’s not showing the whole thing, but I had to do it like that so you could see how it’s not lining up)
If you Union a Cylinder or Sphere with other Parts its shape changes. I find it best to make the Cylinder or Sphere a Union first, then align it with the other Parts, and Union them together then.
Same goes for Negating Cylinders or Spheres.
1.Turn on increments for moving parts
set it to whatever amount you want, I’d advise doing something like 0.25 or 0.1 since it is easily divisible by whole numbers
2. Make the cylinder the same size as the rectangle/square below
eg 4,4,4
3.
Copy the position of the square/rectangle and paste it into the cylinder so both parts are in the same space 
4. Drag out the cylinder
Having both shapes the same size and then moving it to the same space helps align the parts. This allows you to get a seamless transition between the two parts so there won’t be that bulge like in your picture.
6 Likes
Try using explorer and properties to match the positions.