How to copy a countersunk hole

[brtech]

I've been getting myself really frustrated over what seems to be a simple task.

I'm building a jig with a large flat surface that has a couple of T tracks in it. The T tracks screw into an MDF bottom.

To do one of these, you lay out a circle, push pull to the opposite face for the screw shank, flip over to a bottom view, place a circle with a wider diameter centered in the same place, push/pull the bigger circle in 1/4" or so for the countersink for a washer and nut. This works fine.

I can't copy this. As far as I can tell, there is no way to do that.

I can copy the 2D circles, with the 3" spacing one way, then box select the row and copy the row for the other track.

There is an add-on that will, in some circumstances, let you box select a row of holes and push pull them all in one operation. It doesn't work for me to do that with 2d array of holes, but it works for a row. If I do that, I can't seem to get the hole on the bottom to show me a center to start the countersink. I can get around that by doing the original screw hole from the bottom, but even then, you can't box select just the outer circles, you have to do that by shift select each one.

I actually completed this by doing the push pull on each hole one at a time, but that seems really silly.

Any ideas?

[AMarshall]

Yeah, this is one of those irritating ones. Seems like it should be simpler. The short answer is that there isn't an easy way to do that that I am aware of. You'll have to edit each hole manually, though there may be a slightly simpler way than you have described.

Best method I can tell you is to draw one complete "assembly" and then box select around the entire thing - all three circles and the walls of the shaft. Use the move tool to copy this to wherever you want, making the 2d array as you described. This will give you all the geometry you need for all the holes & shafts, but it won't punch the holes in the faces of your surface. Final step would be to box select all the holes, then right click and intersect them with the model. This will create distinct inner and outer surfaces using the circles. Then you have to go along the top and bottom selecting and deleting the faces inside the circles.

Another option is to create a component out of your original hole. If you create it correctly using the "glue-to" and "Cut opening" and "set Axes" options you can make a component that can be placed on a surface and will punch its own hole in the surface. But this only works for one surface, say the top face in your example. You'd still have to fix the bottom face manually.

[Dan S]

If I'm understanding you correctly, the best way to do this, is all from one side. Drill the large hole with forstner bit, then use the center nick created by the forstner bit to center your through hole.

[brtech]

If I'm understanding you correctly, the best way to do this, is all from one side. Drill the large hole with forstner bit, then use the center nick created by the forstner bit to center your through hole.

I know how to build it. I'm trying to model it accurately in sketchup.

If you want to know the real truth - I have a CNC, and it will "build" it, if I create a good model.

When I try to copy the whole thing as a 3D model, I can't seem to copy it in any way other than sitting on top of the face I copy from. It won't copy "in" to the material. I can copy the 2D circles, but as soon as I make them 3D, I have copy problems. I have problems even selecting the 3D model. It's not at all easy to box select the faces and the hole wall surfaces. It's easy to select the 2D parts. I had the best success with X-ray, tilted just right, zoom in to see the walls of the hole in the "middle" of the model. That can get me the 3D shape, but it's hard to get both faces as well as the wall surface. But if I get the selection right, when I copy, the shape sits up to high in Z, and nothing I know of allows me to move it to the right place.

[Dan S]

So you have like a solid of some type in Scketchup and you want to put countersunk holes in it? I'm pretty sure the only way you can do this reliabably is with the push/pull tool and one at a time.

[blindleader]

I've been getting myself really frustrated over what seems to be a simple task.

Didn't you know? That's the primary function of Sketchup.

I can't copy this. As far as I can tell, there is no way to do that.

Yes there is, and it's pretty straightforward in a devious, Sketchup, sort of way. With 3D copying you have to do an intersection [edit][intersect faces][with model] or [right click][intersect...

So you have your hole, counterbored from both sides. Select the entire hole geometry. Viewing in X-ray mode speeds up the process of verifying you've got the whole hole (heh). I assume you know how to drag-copy stuff. Do that along the face to the new location. Now, without un-selecting, or re-selecting it if you forgot, do the intersection as described above. You have to be careful that all the large circles on the faces really do intersect with the appropriate faces.

That's the technique I use for most solids modeling. A counterbored hole is trivial (still a pain, though) compared to some of the shapes I've done. For really difficult ones I make a solid in the shape of the area I want cut out of the work piece (your hole wold look like a dumbbell), make it a group, maneuver it carefully into exact position, explode it and intersect. Sometimes there's a lot of careful deleting of superfluous lines to do afterward.

edit: After re reading the thread, I see that Aaron said the same thing. But I don't see that it's such a big deal. Drag-copy the hole, intersect, delete two surfaces for each copy.