Ok.. so. On a pc now so I can can give a worthwhile response.
Welding is critical and so are proper tools, equipment, and PPE. Shitty welds means lots of repairs down the road. Incorrect equipment means decreased productivity and potential safety hazards. A decent MIG machine with at least 1/4" capabilities is what you want. I'm stuck with a Miller 140 at the moment and every day that I use it it makes me wanna walk in front of traffic. It overheats constantly and laying a bead takes so god damn long compared to an appropriate machine for the job.
When designing park features there's a TON of things you have to take into consideration before materials are even ordered. I see so many resorts that put very little logical thought into building features and it just blows my mind. It's all about finding a balance between the right materials and the design you've come up with. I'll just talk about a few that come to mind atm.
Material sizes and lengths
. Wasting materials makes you an idiot. If you're going to spend $400 on a sheet of 1/2" UHMW you better get the most you can out of it.
Plastic - Sheets in the US will usually come in 5'x10, 4'x10', or 4'x8' depending on the supplier. If you have 4'x10' sheets and you're making a box with 1' wide plastic, cut it at 11-7/8" so that you account for the width of the blade. You can get 40 feet out of the sheet that way with zero waste. However... If you want to make a box that's 1' wide with 2" coping included, you can get away with 7-7/8" wide plastic and that will give a total of 60' per sheet. As a skier, that's my personal favorite size box. That width lets you grip it on your edges pretty nice.
Skirting - This depends on how you build your frames but I'll just tell you how I like to build mine. A flat feature's skirting width is between 4' and 6' depending on the size of the feature. A down feature at 15 degrees will always be about 5' 3". Kind of an odd number but on a 4'x8' sheet the leftovers could get you an additional 2 pieces of skirting for another feature.
Steel - Pipe is usually going to come in 21' lengths square or rectangle pipe will usually be 24', flats are 20', c-channel is 20', and angle is 20'. Talk to your local supplier.
- The strength of the frame is going to dictate how long the feature's lifespan is.
FACT: Cat operators are going to hit your features.
How much damage that occurs when they do depends on how you design your frame. This is where corners can be cut to initially
save time, money, and weight. Don't.
3 or 4 years down the road is where you'll regret it when you're cutting out bent sections because you had verticals spaced 8' apart and the cat bent it the first time it was pulled out of the snow... Or you're scrapping a 3 year old down bar because it get several hundred hits/hour and not having an additional horizontal support under your sliding surface has made it in to a very wavy down bar.
Build your features so that you can toss them around with a cat or a skidsteer without a worry. You'll be happy you did. Trust me.
A couple more quick thoughts because I'm tired right now..
Square coping on boxes is for lazy people who like to do lazy welds and don't care how rough it is to slide. Round coping or get the fuck out.
45 cuts on coping are alright I guess but I like to use 90 degree elbow fittings just so it's not as harsh of a potential impact.
If you have exposed holes that you think you can get away with leaving open. CAP IT. This is what happens when you don't cap your ends. http://i.imgur.com/C5l5s7m.jpg http://i.imgur.com/6Bg82mJ.jpg
That's all p-tex buddy!!!
Hardware for plastic and skirting: 1/4-20 Stainless. Stainless for 2 reasons. Thermal expansion and contraction of plastic will shear hardware right off if it's crap stuff from home depot. Shitty hardware will also leave rust marks on your skirting if you're in a rainy climate forcing you to paint when it might not be necessary. A universal hardware size on your features is definitely the way to go.
Take pictures of all your features and make binders of your whole rail fleet. Put them in every single snow cat that enters the park. Your operators will thank you.
Any box width 2 feet or under...just make a t-style frame. It saves weight, time, and money. The idea of putting fully boxed out frames on anything with plastic can jump in a time machine and go back to 2002.
For the love of god put feet on your fucking rails. When features aren't falling over on top of your crew members while you're setting them up they'll thank you. Having a few guys balance a several hundred pound feature with no feet is reckless and that's how people get hurt. You'll also thank yourself when you're working on them in the off season when they're standing up straight. Some people make a big deal about putting feet on features because "OemGEE, what if an operator hits a foot when they're digging out a a feature and it falls off?!?!" Answer: They get out, pick it up, and you weld it back on in the off season. The way I weld feet on they're designed to come off when they're hit too hard with a blade.. that way they don't twist up the frame and fuck shit up.
That's a bit of sore subject for me...I've had features fall over on me and pin me while setting them up. It's not fun and it's just plain easier to set features with feet on them.
abortionator is fully familiar with the struggle of no feet on features and boxed out boxes.
That's all I got for now. Any questions just holler at me.