Dimension limiting

Is there a way to limit dimensions while drawing in Sketchup? Like set it so that all my lines and push/pulls snap to the nearest 1/16th or 1/32nd? Obviously curves and formed triangles would not conform to these parameters, but I find that if I accidentally move or push/pull something a tiny fraction of an inch, I get the dreaded “~” on a dimension and if I don’t catch it immediately, I then spend a lot of time chasing down everything it affected. Sometimes it is so slight that I can’t even zoom in enough to figure out where the problem is and end up just having to redraw. I draw a lot of custom cabinets, and this would be extremely helpful.

The safest way is to click to start the operation, move the mouse a bit to set the direction, then let go of the mouse and type the value + return without clicking a second time. The alternative is to skip typing but make sure you get an inference snap to a known good location before doing a second click. Otherwise tiny unintended movement of the mouse will make the length imprecise. It often happens that one unknowingly moves the mouse when clicking, especially when working quickly.

1 Like

Yes, these are both practices that I use when modeling, but as you said, the slight mouse movement when working quickly can unintentionally throw a wrench into things. I feel like if there was a setting to limit movement to a minimum value, it would remedy a lot of these issues. I use the Sketch+ Nudge tool a lot, and that works great when moving things, but something like a push/pull nudge tool would be helpful. Maybe I just need to learn Ruby and write my own extension.

You can turn on length snapping which does exactly what you’re describing. I believe it’s on by default.

Thing is, it often leads to more problems down the line. You really should just type your lengths or use trusted inference to avoid just clicking away and hoping it’s the right length.

If you have gotten a solid inference, you have to move the mouse a fair distance before it will release the inference. Just a twitch won’t do it.

Also, don’t forget that for most tools you can type a value immediately after drawing something and it will adjust to what you typed.

As @monospaced pointed out, experience is that the snap to length setting causes more issues than it helps. Some locations in a model unavoidably contain computer arithmetic limitations/errors, and snap to length doesn’t iron these out, it just puts the next point at a similarly inexact location that happens to be a precise distance from the first one.

Length snapping is exactly what I was looking for. It seems like maybe it was on by default in the past, but not in SU '23. And yes, I normally use trusted inference and length typing, but knowing that length snapping is available is another good tool in the arsenal. Thanks!

It depends on the template you chose to to start with.

Most users find that having Length Snapping enable leads to imprecision in their models and turn if off if it’s on in the template.

Make your own default template with Units set the way you want them to be.

Ah, that makes sense. I have my own template that’s based on the stock woodworking template, so I guess it was off by default in that stock template.

Yes. The supplied Woodworking templates have Length Snapping turned off by default. That was due to requests from users to leave it off because having it enabled results in ncorrect dimensions in the model.

Think of length snapping like, 'here I have this stick that is exactly this long, now I’m going to use it to create an edge diagonally between these two points, and I will obviously use the inference engine to snap to those points.
But hang on… there is a small conflict between the length of my rod and the inference points. My Rod length overrules your inference, because that’s what you told me to do even if it means I have to move the endpoint off axis to keep the edge length correct. Meaning a square is no longer square.

1 Like

Thanks, I understand the concept, and its limitations, I just wasn’t aware of what is was called or where to find it. For my needs, it mostly comes into play with push/pull and making sure everything is limited to 1/32", so that I don’t pull something shorter or longer than that on an errant twitch.

I regret beating a dead horse, but which slows you down more, typing exact values as you go or finding and fixing tiny errors later when they do things like cause faces not to form or pushpull to refuse to stop at the far side of a wall because it is slightly out of parallel?


Most of what I do is custom cabinetry, so a lot of rectangular prisms and standard thicknesses. Causing faces not to form isn’t much of an issue, and most everything is square/flush/plumb, and every component is square to its local axis. Typing exact values isn’t always efficient, as most of the time I’m filling a gap that I don’t know the exact length of until after I’ve already pulled. Often times I’ll need to fill a gap and then back off 1/8". If I am working too quickly, sometimes I’ll twitch click before I back off that 1/8" and get something like a `~7/64" gap and not realize it until I’ve used that reference point 8 more times and my whole model is slightly off.

I see more of that in models made by users who have Length Snapping on than in those who have it off. I’ve been modeling custom cabinetry and highly detailed stuff in SketchUp for about 21 years. Leaving Length Snapping turned off has made getting precise dimensions easier and without having to fix little gaps and overruns. Each to their own, though.

1 Like

I can see where it could screw you up when getting into finer details, but I think it will be helpful in the speed stages of modeling carcasses and frames. Knowledge is power, so just knowing that it is something I can turn on and off is helpful. I’ll give it a go and if it ends up being more trouble than it’s worth, then so be it.

1 Like