How can I make a hole in this

I have made a little holder that I intend to 3D Print… But want to make a hole in it…

Since its got a curved face, I can’t just draw a circle, so I had the idea of drawing a line jutting out into space… And then drawing a circle which intersects this line and “pushing” it back through the model.

Then I could just delete it and erase the hole, but its not working and makes a complete mess of the geometry.

Anyone got any tips on how I can achieve this?

I have attached the 2 SKP files and hope someone can show me what I am doing wrong.

Thanks in advance.


No Hole.skp (1.1 MB)

Trying to make hole.skp (1.2 MB)

Are you available now? I’ll just show you “live”.

In a nutshell, you need to work at a larger scale because of the tiny faces you’re trying to create.

Many thanks for the offer… I am in the UK, so went to bed right after posting that.

It seems that I have fallen foul of the “too small” limitations again… So I just scaled it up by 10x and was able to do it.

Just to be clear on what I did, is this the correct way to do it.

  1. Draw a line radiating from the spot that I want to “cut” the hole
  2. Draw a circle on this line
  3. Push it through the face
  4. Click on the column I just created and “Intersect Faces with Model”
  5. User eraser to get rid of the all of the geometry I don’t need.

One question… How do I show it like you, where it has ‘clean’ faces instead of all of the lines on mine?


Edit… I have now run into my second problem… What I am ultimatly trying to achieve is to cut a slot from the hole to the top… So I expected to be able to draw a line from the left/right sides of the hole, to the top and then erase everything.

When I try this, bits the geometry start to disappear on the walls either side of the slot I am trying to cut. The right side seems OK, but not the left… Again, any thoughts on how I do this? New files attached
With hole.skp (1.2 MB)
Trying to cut slot hole.skp (1.2 MB)

Just got home. it might be easier to show you directly if you have time now.

If not, the trick would be to draw the entire shape of the “cutter” and extrude it through the wall before Intersect.

As for making mine look “clean”, I just softened the edges.

Doh… Of course… Thats a better way of doing it… The last thing I want to do is curve the top… Ultimately I am trying to make this… The original was easier as it had a “flat” front face… This one is curved, so harder to work with.

Normally, on a flat face, I would just draw an arc and push it through the model creating the curve… But I can’t do it on this one due to the curved face… Again, I guess I could draw this into the “cutter”… Is that the best way?

11. With Cutout at front.skp (1.2 MB)

So draw whatever shape you need and use it to trim the top, round over the corners and so on. Intersect all of that and you’re good to go.

Sorry… I dont quite follow that last bit… I was with you right up until then.

I get that you can create a “cutting tool” by positioning it in space and pushing it through a wall… But i am not sure i follow how you would do it with a curve and i can work out how you would line it up.

Also… When you intersect the cut out and then delete everything, is there a quick way to remove what you dont want… Or is it a case of just using the eraser, zoom and a bit of patience to clean it all up?

Maybe I misunderstand your use of "The last thing I want to do is curve the top.

Can you have a look at the last file i uploaded, that will give you an idea of what i want to do… I just want the opening of the slot to be rounded at the top.

Yes. I’ve been looking at it. Even the radii at the top of the slot could be drawn as part of the cutting shape.

Cheers… I am in the process of trying… Managed to do exactly what you said above (i.e making the whole cutout in one go)… Will now try to add the curves at the top of the cutout…

Thanks for the tip about “smoothing”… I thought it was a view option, but it didn’t look the same as yours… So then I googled “soften” and realised it is an eraser feature… THat has changed everything,… I have always wanted to know how to get rid of the extra geometry, so a huge thanks for that (And all your help for that matter).

Soften can be done with Ctrl+Eraser but you can also select the geometry, right click on it and choose Soften/Smooth from the Context menu.

I am really struggling with putting these last 2 curves at the top… I guess I could go back and do the whole cutout again, but I have smoothed everything and changed the back of the model and I would rather learn how to make modifications to a design,rather than be forced to start from scratch each time.

Could you do me one last favour and tell me how I would go about doing it from this point?

I have tried to think of a way to create a point in space where I could draw the arc and “push” it back into the model, but its never accurate enough.

Thanks in advance

7. With Slot.skp (1.1 MB)

Sometimes it’s just easier to redraw than to modify. In this case you could cut off the top and use Push/Pull to bring the remains back to height. Draw a new cutter and work through Intersect.

I am in awe… You do this so effortlessly…

I would never have thought of the cut and pull technique to remove the existing cutoutmand restoring the original shape… I would have spent ages filling it in and deleting the geometry.

I am still a little unsure how you make the 2D “cutter” accurate enough that the arcs end up in the right place and do the job. I assume just good use of the tape measure to get it spot on.

Am i right in thinking that to start, you use the line technique that i started with, on which you draw the 2D cutter?

I will have a go the morning…

Thanks again…


Actually, no. I didn’t draw the line like you did. I used some guidelines placed with the Tape Measure tool to layout the location of the cutter.

With practice it will become effortless for yo, too. The key things are learning what you can do with the tools and to think ahead because steps you do early in the process can impact things you need to do later. You’ve already seen this a few times on this model.

I have now realised how little I know about Sketchup as I can’t scratch the surface of what I am trying to do.

Before I even start, how do you “cut” the top of an object? This sounded like such a good idea but today realised I don’t have a clue how to do it. I am thinking that I just make a rectangle and push it through the model… Is it as simple as that? (Just tried and it worked… I ended up with the model ‘filled’… But a bit more “intersect with model” allowed me to delete the fill. So I assume I am on the right path with that.)

So I just went back to an earlier version and tried to make this cut out and frankly I don’t have a clue what I am doing…

First of all, I would need to find some points such that the slot is in teh middle, but because its curved I can’t work out how to even measure it.

And then the guidelines? I just can’t seem to place them where I want…

But even if I did, when I start to draw, I just can’t get the cutter to form on the axis that I want…

Its turning into a mess, and I am conscious that I am taking too much of your time, after duping you with a “how do a cut a hole” question.

Sorry. I figured you’d been cutting stuff all day and this is basically the same.

Draw a rectangle to use as the cutter.
Intersect it with the model.
Delete the waste above the cutter and the rectangle.
Pull it back up to height.

You have a nice straight line at the back which has a midpoint you could use to find the center of the shape. Put it at the top and you can measure down to locate the center of the radius at the bottom of the slot.

After you get the center sorted out, maybe you’d find it helpful to draw a rectangle out in front and layout the shape of the slot on it.

I don’t think it’s such a mess, yet. By the time you get finished, you’ll be able to draw this thing in your sleep. :slight_smile: And don’t worry about “duping” me. These things often go that way. It’s a sort of conversation.

you are a top man… Going to sit down later with a cuppa and work through this… Thanks for the tips/pointers.

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After a frustrating 30 mins, I think I have managed to do it… Although I am not sure if I am doing it quite right.

Initially, I couldn’t even work out how to draw the “tape” lines… They always wanted to go from left/right… And never front to back.

But I then found, completely by accident that I could grab the red, green or blue axis lines and position them where I want, and using this, I managed create them… Is this the same method you use.

I next had to draw the rectangle, and really struggled getting to to go on the correct axis… I managed in the end, but I am still not sure I am doing it right as the rectangle never wants to draw along the red axis (and I tried using the cursor keys to force it, but it didn’t work)

The only way I was able to draw the same rectangle as you, such that it was directly in the middle, was to draw one to the left of the tape line… And then the same size to the right… Again, I am sure there is a better way.

But once I did this, my rectangle was grey… Yours white… Is that a problem? Why is mine grey?

Finally I was able to draw a 2d shape on the rectangle… Delete what was left… Push it… Intersect… And delete. And I was left with the nice cutout that I wanted… So I am almost there… But it would be nice to fine tune my method.

Can you spot any errors in what I am doing?