Have been wanting to work with HDPE for a while - here are a couple of things being used every day on my longboards and landpaddles.
Step 1: Items
Hi folks - thought ya might be interested in some handy recycling ideas that work really well for skateboarding/landpaddleing etc.
I have been looking into the recycling of HDPE plastic for practical uses - I have found it works well on my longboards in the trucks - this instructable goes through how I create the items.
1 - bushing bolt packer
2 - pivot cup/bushing
Both made for free and work very well for me.
Here we see the items needed.
Trucks - for casting
Hot air gun - for melting
Knife - to trim
Small vice - to hold the items
Shaping tools - to help the shaping process
File or sand paper - to finish
Plastic chips - chips made from cut up milk bottles ets
Step 2: Bushing Bolt Packer
Sooo while I have been working on my boards a couple of things annoyed me, one is that when I am fitting new bushings half the time as I try and fit the top one the bolt is forced back into the casting and I have to fiddle to get it out and get the nut on - a packer seemed a logical answer to an annoyance.
The other thing I have noticed is the poor quality of pivot bushing from time to time - they are not a great expense but a cost is a cost and if ya have to change them every five minutes it is a real pain - even the expensive ones can fail.
So! why not try out some home made items - heck even if the cups we make only lasted a month if it did not cost anything except a little time to make another then all good.
Ok - take your truck bottom, remove any old pivot bushings - now using the bushing bolt put the two items into a small vice or secure the items in such a way that you can work on them with both hands free ( make sure the bolt is tight against the metal ).
Drop in some plastic chips and using a hot air gun heat the metal from the underside, this will make the metal hot and the chips start to stick ( don't blow from above right away or there will be bits all over the place ) - using a screwdriver etc cover the plastic chips from above to stop any lose ones drifting off and bring the gun slowly up and over till the heat is blowing downwards - keep the metal hot and work on melting the chips,
DO NOT ALLOW THE PLASTIC TO BROWN if this happens the integrity will be shot and the cast item brittle and flaky, plus it will stink the place out and make you sick - always work in a vented area when possible.
Step 3: More Chips Please
If your doing it right the HDPE should become a bit like a jelly and almost clear in colour - use the gun to keep everything hot and add more chips, using a handy tool ( I use my bearing remover ) to push and mix the melting chips together ( a bit like mixing epoxy ).
Work the plastic till the consistency is even but try not to get bubbles while you mix, also be mindful to push the plastic into corners to get a nice accurate shape.
Keep going till the cavity is full, take your time, if you rush there will be bits of plastic everywhere.
Now - let the metal cool ( don't run it under a tap etc or the cast item may become brittle ) - work the material as it cools, I spray a little WD40 on it and use a screwdriver to smooth out exposed edges so the finish is as good as possible before removal.
When cool pop out the cast item and file or sand to get a nice clean finish - check out the picture, not too shabby.
Check for fit and this part is done.
Step 4: Going for the Cup
Now we turn to the pivot cup/bushing.
Take your truck axle and check out the pivot itself - mine was shocking so I smoothed and buffed it till it shone, this should really help preserve the life of you bushing, any scuffing from a rough surface will wear out the material as well as the load from above when mounted plus I rounded off the rather square corners.
Ok! - fill the cup housing with chips just like before and heat them, working them together till they are a nice squidgy blob - there is no need to fill the cavity to the very top as you will be pushing the truck axle into the goo to make a perfect fitted bush and any extra material will only be forced out and wasted.
Take a straight bar type tool and gently push into the very center of the hot plastic, working from the middle outwards make a hole roughly the size of you pivot - don't go too deep.
When your about right take your truck axle and keeping the metal nice and hot gently push into the goo - check your angle and central position. Take a look at your other trucks on a board, see how far into the pivot cups they sit.Take things slowly, if ya mess up just re heat the whole thing, sqidge it all back together and start over, when your happy remove the heat and let things cool slowly checking angles and alignment, also give the axle a gentle turn left and right just to give a little wiggle room but still a nice tight fit.
When cool trim off any extra material,
Job done - a free and very tidy finished item if I do say so.
Step 5: Time Well Spent
Hopefully things have gone smoothly and your happy with the result - cannot say how these little jobbers will hold up to heavy boarding or stunts, maybe you could get back to me so others can judge if it is worth doing this build.
Step 6: A Little Extra
Just as a side note - I tried using miliput epoxy clay to for a cast of a bush, just to see what kind of quality could be obtained - the miliput did a great job, just make sure you have a good release agent ( I use WD40 or Vaseline ) - did a nice job,pretty clean - - see what ya think, let me know if ya produce other items from this material.