Trying to Draw Water Slide Having trouble with a sloped 3d Line

brian_anderson272 · June 28

I am trying to draw a water slide and wondered if there is an easy way to draw a sloped 3D line so I can sweep my profile. This has a few curves that cross each other. I would appreciate any help.

https://cad.onshape.com/documents/7c5585c54c78d80c03d981ee/w/9664bb4b1c93cb59a2405abd/e/bef3581cc2c7db1336da54ec?renderMode=0&uiState=686018417e6d5676ec2950fe

MichaelPascoe · June 30

Looks like you found the routing curve feature. And you also are using a top sketch for reference, great start! Here are some steps that may help for a half tube approach:

⚠️Tip: Use less points so that you end up with a smoother spline.

Create the first routing curve like you have but reference the top down sketch points and only change the vertical position of the points. Remember to click the "Keep points" option.
Create another spline, also using the routing curve feature, that references those points from the first feature. Use this routing curve to control the twisting of the slide.
Use the Loft feature to loft both splines together to make a reference surface.
Sweep a profile along the guide path, use the guide surface as the lock face, so that your profile will twist with your guide.

Or if you are just sweeping a full tube profile, ensure that the tube is not intersecting with itself, and that the spline is smooth.
https://cad.onshape.com/documents/91603607368ad995d4ccca04/w/ef270109a53e643e5359e651/e/89747e36eb9…

If you are building this for real, then you will probably want more control, not just some free handed splines. For serious production, I recommend projected curves for more precise control over each segment. Or use some custom features that give you more control over the curvature of each point in the spline. Wouldn't want to get stuck in the middle of the slide 😅. A nice approach for real construction would be to make a configurable part studio or assembly, like this toy coaster example, that has one tube segment that could have a bend up / down and a bend right/left as well as a twist configuration. You could then assemble these together in a main assembly, using your freehand guide as a guide. This would make it easier for keeping all of the assembly components together and in their correct places (Bolts, supports, frames, etc…)

Derek_Van_Allen_BD · June 30

Waterslide-industry-adjacent engineer chiming in here: usually these tube slide segments are designed from a catalog of true circular arc fiberglass pieces that don't have any twist in the segments themselves but can be bolted together at any desired rotation. This saves on molding costs for unique slide parts for the whole build because fewer molds are required to construct the whole slide, and those molded segments not having twist or spline geometry makes them easier to manufacture because there's a flat plane of reference and consistent radius to check for.

Similar engineering constraints can be assumed for other big swoopy curved tube geometry and have led me to start work on a tangent arc chain custom feature but it's not yet ready for deployment.

The UI is a little clunky right now and I'd like to do more with manipulator placement of the curves and end points but the main two things this tool does is guarantee the curve segments are true circular arcs and that those arcs meet precisely at tangent constraints to one another in 3 dimensions.

Using the parts catalog to assembly approach described by Michael you could draw your segments with those constraints in mind and do most of your build at the assembly level with mate connectors between parts and get the same results.

EvanReese · June 30

This one is a great example of the importance of planning your workflow. There are so many ways to come at it, each with big advantages and disadvantages, and once you choose one, you'd have to start over to choose another one. I love helping people think through that stuff!

I do suspect that @Derek_Van_Allen_BD is right about it being manufactured from kits of arc segments. I did notice in the plan view drawing though that the transitions between straight and arc don't look abrupt. Maybe there's a transitional segment with a bigger radius? Anyway, it got me thinking about the importance of good curvature continuity for tracks with things moving on them fast, so I took a stab at it myself.

My first thought was exactly what @MichaelPascoesuggested with my Freeform Spline feature, but I didn't think I'd be able to get all of the control or precision I wanted, so I ended up constructing it from helixes and lines with bridging curves connecting them to make it G3 continuous. I was able to get a model set up where I can control the angle of the slope and the angle of the banking corners (not actually needed since yours is a solid tube, but wanted to test a workflow). Here's what it looks like.

https://cad.onshape.com/documents/44d8d349c395818360f2c649/w/9139fcd54ab67a42e57af707/e/f3f266cde828816e5add227c

brian_anderson272 · June 30

Wow thanks for all of the good information everybody! Your thoughts are much appreciated.

brian_anderson272 · June 30

Wow thanks for all of the great help and insights! I really appreciate your efforts

Derek_Van_Allen_BD · June 30

Truth be told the *real* answer is email SplashTacular LLC and ask for the CAD for the slide segments in the drawing since they're called out as the vendor supplying the parts for fabrication. Failing that, someone in the document chain before you has a Revit model or something you can use as an import. I try not to re-draw other people's work unless necessary.

Unless you work for SplashTacular, in which case I have questions.

Derek_Van_Allen_BD · July 1

Cooked up a bit of an example assembly to show how I've done these in the past. It's a little bit off base from the linework in your model but it's a little harder to be precise about these kinds of things when I don't have the slide manufacturers' CAD and physical parts in my possession to verify dimensions with. Also these things typically have fixed bolt patterns so you can't clock arbitrary degrees between segments like I did in this example, you'd have to skip over a number of bolts between segments with the real things. Maybe I could get closer through more thorough reverse engineering of the linework but tbh I'm just mashing this together for vibes and my own future reference for the next time a slide hits my office. It's weird, we work on lots of water exhibits and lots of slide exhibits, but I have yet to see a single water slide. I'm gonna bully sales into getting some of those on the books.

MichaelPascoe · July 1

.

Ok! we'll start production early next week. @Derek_Van_Allen_BD you will be the lead engineer; we'll need you to contact SplashTacular LLC asap. @EvanReese will be the curvature QA specialist, make sure no one snags their shorts or breaks their neck. And I'll go ahead and tackle the project manager role since I appear to be assigning roles.. We can call it OnshapeLand. This is going to be fun!

We will need rides to represent all the different aspects of Onshape:

Onshape-Land

*GPT Image, that is not my spelling 🤣

.

EvanReese · July 1

Love running Onshurp on my smurtphone

Derek_Van_Allen_BD · July 1

Gonna start describing Onshape as "funkeloud CAD" and there's nothing their marketing team can do to stop me.

MichaelPascoe · July 1

😂

MDesign · July 1

🤑🤣

bryan_lagrange · July 1

Can we get an Amphitheater so we can gather every 3 weeks for updates?

MDesign · July 1

And tents laid out in grids to camp out and hang out with friends between updates and rides.

Trying to Draw Water Slide Having trouble with a sloped 3d Line

Comments

Onshape-Land

Howdy, Stranger!

Quick Links

Categories