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05

Aug
2016

In Ukategorisert

By antiform

Building a backyard mini ramp DIY-style

On 05, Aug 2016 | In Ukategorisert | By antiform

This probably isn’t the worlds most helpful mini-ramp building guide. It involves some pretty unusual tools – both software and hardware – which isn’t to everyone’s disposal. You will however find some useful tips on carpentry and using skatelite for surfacing.

Employing high-end VFX-software tools to realize your childhood dream.

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CNC at work

After talking about how I wanted to build a ramp at my cabin in my open office area, one of my colleagues tipped me about a robot woodcutter we have at the prop building department at NRK – a so called CNC machine. You can feed this machine vector drawings with perfect accuracy from Illustrator, and it will cut with 1mm error margin.

And that was what triggered it all. How cool wouldn’t it be to use 3ds max to plan and construct every nook and cranny of a backyard mini, and then have a robot cut perfect curves?

I measured up a small miniramp at Torshov, Oslo, which served as the base of my own ramp. The plywood sheets I bought for the curves allowed a slightly larger curve than the ramp a Torshov featured, so I added roughly 6 cm but kept the radius. These drawings where all made in Illustrator using accurate measurements and fed to the CNC.

The curves turned out absolutely perfect, with the ones in the middle of the ramp having cut outs even for the 2by4’s – saving me a lot of manual labor.

Drawing initial measurments in Illustrator and 3ds Max.

All in all I had 8 of these sheets, which would have support construction attached to them. These were all made during winter, while I waited for the snow to go away. A nifty feature (that I at least didn’t expect) is that if you draw thing to scale in Illustrator and import them in 3ds Max, scale will be retained. That makes all the measurements so much easier to keep a hold of.

I made all the initial curves and heights in Illustrator (as seen in the illustration above) and then imported it to 3ds max to plan what kind of construction I would need, measurements of all the 2by4’s and the top sheets. Building the whole thing in 3d also made the purchasing process a lot easier, I could now calculate excactly how much wood I would need to buy.

Viewport grab from 3ds max

These screengrabs show the level of detail. Every plank is included. Below is a snap of the finished curves and the top sheets, all organized and waiting for spring. The scene file can be downloaded at the end of the article.

 

 

Using PFtrack for permits.

Finl previz made in 3ds max and tracked with PFtrack. Rendered with mental ray.

Building things close to water (lakes, shorelines) is highly regulated in Norway, so you’ll have to get a permit to build pretty much anything, ramps no expeption. I textured the ramp in 3ds Max, took a bunch of photos of the premisses with my DSLR and tracked/solved the entire scene in PFTrack. I then sent some pretty darn accurate previzualisations to the local government, and got approval. Additionally, getting the correct scale and features of the physical space was helpful for figuring out where the ramp would actually be.

When the snow finally disappeared (which is a weird thing to say for a die-hard snowboarder as myself), the real dirty work would begin. The ramp needs to be 100% level. The entire space doesn’t need to all level, as a ramp should rest atop pillars to keep it clear of the ground. But the pillars need to be level. 101%.

I used a laser level to get the job done, stacking up dirt or showelling it away as needed. The pillars are placed at all high impact points, and fairly dense.

 

Measuring the diagonals – the red diagonal lines need to be exact same length, or your corners won’t be 90 degrees.

When the ground work was done, I could finally pick up my premade curves and start raising my baby. Making all corners 90 degrees and all curves parallell is (not surprisingly) a lot harder to do in real life than on a computer, but thanks to my dad with 60 years of real-life experience and a technique called “measuring of the diagonals” we got it approximately right. Measuring the diagonals is done by standing in opposite corners with a steel string dragged tightly across. Move over to the other opposite corners, and make sure the string is exactly the same lenght corner to corner. If not, move the corner, repeat until perfect. This is the absolute most critical thing you do, so get it right. If you mess up, your top sheet will start poking out when you put it down.

When the curves where all raised up and aligned, we popped in all my precut 2by4, which would be foundation for the top sheets. I used three layers of top sheets; #1 – 6mm thick, #2 – 9mm thick and #3 – Skatelite.

Surface sheets and Skatelite.

I’ve ridden too many worn-out ramps through the years to know that when building my own, I wanted it to last. Therefore, all wood would be treated and raised above ground (using the pillars as described in the previous chapter), all sheets would be waterproof, and the surface would be finished off with Skatelite.

Skatelite is durable, has perfect friction and – is not cheap. It also has some prerequisites, like it needs screws every 20cm, both in width and length. It’s also so hard that all the holes for the screws needs to be pre-drilled and countersinked. To state the bleeding obvious – these holes needs to match up with the 2by4s underneath. Also, since the skatelite will have thousands of screws, you need to use as few as possible for the first two sheets, so that you don’t hit these underlying screws when you get to the skatelite. So plan ahead.

Make sure your sheets is laid firmly, without wobbles or gaps, on to the 2by4s. I fastened a temporary 2by4 along the bottom to steady the sheets against, moving it around as I progressed. I let all my sheets overshoot the coping by 5-6 cm, and cut all down to equal lenght at the end.

When lying down Skatelite, you need to leave a 3 mm betweent the short ends, and a 5 mm gap along the long side. This might seem much, but the skatelite will expand  over time (especially in warm weather) and needs room to grow. Another thing worth mentioning is screw dimension. I started out using Fischer 5X60mm, but as many as 70% snapped during the first year, so I had to replace them all. I upgraded to 6.5X60, which will hopefully do the job better. Since there was no easy way to remove the snapped bit inside the sheets/2by4s, I had to offset the skatelite to not hit them when inserting the new ones. Not fun, take notice.

Final stages – coping

The coping is a 6.5 mm stainless steel tube, with 3 mm walls. Because I’m such a dandy, I wanted the coping to have hidden fastening, not the usual drill holes. To achieve this I got a friend of mine to weld some metal plates onto the side of the coping, which would be hidden beneath the surface sheets.

Coping seen from above and from the side

So there you have it, my childhood dream realized. Theres a few more images in the gallery below, and here the link to the entire scene made in 3ds Max. Hope you enjoy it, and let me know on twitter if you actually put any of this knowledge into action!