Building Jumps

[JohnnyB.89]

Hello
My friends and i have found a piece of land and we have started work building some dirt jumps and a drop (only about 4ft) and we have a ruff design which includes:
2 small berms
a road gap and
3table tops
and a big double(not sure how big just yet)
i have a ruff design 2 show you all which i will post once i work out how. Any ideas or other designs would be a help.

p.s. we have minimal experiance with building jumps so we would be making it up as we go along and the area we are building on is a flat spot at the bottom of a hill which is rather rocky and today we encounted a rather large rock which we have smashed about half of but stopped as it snapped the handle of our sledge.

 

[JohnnyB.89]

thers a ruff paint version of what it will look like. The drop will have one side with a lip and the other just normal:

 

[donthucktoflat]

tip: dont bother smashing hge rocks. just incorporate them. (ie, put dirt over it to make it a roller, make it a lip or something.

tip2: dont build tabletops. too much dirt and effort for the minimal reward. just make doubles and if you need something i the middle then make some case pads out of pallets

 

[JohnnyB.89]

this rock has 2 go as its in the middle of where our drop needs 2 be and we got most of the way through it before the sledge hammer handle broke

 

[allan_key]

is the big double gona be at the start of the track?

make sure you have lots of drainage as all your hard work will be stuffed the first time it rains. dont build anything you dont thing you can do, start small and keeping adding.

 

[Atomikryder]

try using mud or clay for the upramps and downrampsas it is easier to shape and like donthucktoflat said dont build tabletops because they are a waste of time and energy

 

[JohnnyB.89]

the big double will be at the finish. we dont have alot of space so the jumps are really just an up ramp and a downramp very close to each other. the idea was that u came down the hill down onto the first berm off the drop then up a little bit and then down the second berm and that gave u the run into the rest of the jumps and by the end u would have good speed 2 get massive air off the double.

 

[luke.b]

A tip for working with rocks; Crowbars. Now, for the smashing of this huge rock, if you really want to do it, I suggest using one of the straight, massive crowbars that are about 6 foot long, not the 3 foot ones with the bend and the split foot on it. Also, with the large crowbar, you have more chance in just levering the whole thing out, rather than just smashing it to the crapper. Hope that helps, and good luck and happy building mate.

 

[JohnnyB.89]

thanks for that yea will be using a different sledge and a crowbar 2morrow hopefully we can get the rock out if not we may get some explosives. talking about that cracker night is in a few weeks and we have a permit can we use the gun powder or the cracker its self 2 blow the rock apart or are we better 2 get light explosives?

 

[spyderman_au]

thanks for that yea will be using a different sledge and a crowbar 2morrow hopefully we can get the rock out if not we may get some explosives. talking about that cracker night is in a few weeks and we have a permit can we use the gun powder or the cracker its self 2 blow the rock apart or are we better 2 get light explosives?

You are much better to leave explosives well alone if you don't really know what you are doing.
And it sounds like you don't!

Stay safe kiddies use a sledgie and bar.....

 

[arpit]

thanks for that yea will be using a different sledge and a crowbar 2morrow hopefully we can get the rock out if not we may get some explosives. talking about that cracker night is in a few weeks and we have a permit can we use the gun powder or the cracker its self 2 blow the rock apart or are we better 2 get light explosives?

Standard fireworks probably won't be much good. I'm assuming since you have a permit that you'll have a trained operator. HOWEVER, that operator will probably be trained to use display fireworks, NOT to do demoliton work. IT's likely that if you try, you'll get some big bangs, but not a whole lot of damage to the rock. Fireworks are low explosives which deflagrate. Ideally you'd want to use high explosives which detonate, expanding faster than sound. Its not the safest idea if you can't get trained people.

And to be honest, it'd be quicker and cheaper if you just hired a small excavator.

 

[JohnnyB.89]

would it work if we got a cordless hammer drill and drilled holes all round the rock and then hit it with the sledge hammer. our science teacher said that if we have acess to an oxy torch or a form of intense heat we could heat it up really hot then use ice to cool it down very fast and then hit is because this would make it alot easier to break. we tried hitting it again today but nothing came of that so we started digging around it and tomorow we will try and lever it out with a crowbar if that doesnt work it looks like the drill is our only option except maybe a small excervator or a dingo.

 

[billy b]

if you dont have a lot of space to build your jumps and if you want lots of jumps make them steeper with littler gaps therefore leaving more room for more obsticles(me, no 20", atomikryder are in the same pickle...sorta )
p.s what sort of track are you building??? trails dh or just a track with a bit of everything??

hope it helps fella

 

[JohnnyB.89]

well its a abit of everything the jumps arent really tabletops they are just a real steep jump with lots of lip that u go up and then down then down the end we will have a big double which is where all the action will happen.

 

[arpit]

would it work if we got a cordless hammer drill and drilled holes all round the rock and then hit it with the sledge hammer. our science teacher said that if we have acess to an oxy torch or a form of intense heat we could heat it up really hot then use ice to cool it down very fast and then hit is because this would make it alot easier to break. we tried hitting it again today but nothing came of that so we started digging around it and tomorow we will try and lever it out with a crowbar if that doesnt work it looks like the drill is our only option except maybe a small excervator or a dingo.

A masonary chisel may help.
http://www.tpub.com/content/construction/14043/css/14043_240.htm

 

[JohnnyB.89]

http://www.dingodepot.com.au/pages/hire_a_dingo.html would this be the way to go. we are not on the mornington peninsula but you can hire them from sherrin hire for the same price as i understand this would give us the abilty to build our berms and that in about a day and our friends brother would be able to drive it.

 

[sich nich]

cut the rock up cold. heating it can be dangerous too. ever thrown a rock or pebble into a camp fire? 5mins later and it pops? some forms of rock hold moisture inside them. heating it up could cause it to bust open all over the place, and it doesnt care if youre on or near it when it does go.

anyone feel free to correct me.

also, about incorpoating the rock into the track...
expand your horizons. the track you have designed my be good and fun looking to ride, but compromises can be made and the result can be plentiful.
experiences from build years ago, spending hours busting up rock for trails when we were kids, now look at the trail and say "wow look at where that rock was, that would have been a siik gap." the effort of busting the rock is better put into goin around it, or better yet, using it.

 

[Weddas]

ya i wouldent make them table tops unless you arnt very good and you need something to brake your fall other than falling into the pit . but it really is up to you. personal preferance

tip: dont bother smashing hge rocks. just incorporate them. (ie, put dirt over it to make it a roller, make it a lip or something.

tip2: dont build tabletops. too much dirt and effort for the minimal reward. just make doubles and if you need something i the middle then make some case pads out of pallets

 

[JohnnyB.89]

thats a new plan that gives u an idea of where the rocks is

 

[caseyjones]

yer the rock has to go john