Adam, the pivot cups came today. Thanks, they'll be put to good use and are greatly Appreciated!
Thankx again Jeff
Needed Pivot cups
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Duane Delaney
- Posts: 6
- Joined: Fri Sep 05, 2003 2:00 am
- Location: Providence
nylon tubing for pivot cups
If you follow Wesley's method, but start with nylon tubing, it is much easier to get a good result. I have a supply of tubing which is 1/2" OD and 1/4" ID which fits exactly into the pivot hole before you even start. then you melt it in and jam in the hanger until it cools. I find it easiest to heat up the end of the baseplate on a gas stove, then go to work. Anyone wishing to have some of this tubing can have it, at the low, low, price of free. Contact me at duaned@4tpg.com. The material is a slightly softer grade of nylon used in brake tubing, so it works even better than hard types.
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Pat Chewning
- Pat C.
- Posts: 1400
- Joined: Mon Sep 16, 2002 2:00 am
- Location: Portland Oregon
Pivot cups
You might try using hot-melt glue from a glue gun. It might work since it's designed to be heated up. The material might be a little bit too soft for a pivot cup though....
-- Pat
-- Pat
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Wesley Tucker
- 1961-2013 (RIP)
- Posts: 3279
- Joined: Tue Aug 27, 2002 2:00 am
Carsten,
My experience with melting polyvinyls of any sort is not good. I'm not a materials chemist, but from what I can just extrapolate from empirical data (meaning this is what I've done myself in my garage,) the higher the melting point the better a plastic is for reshaping.
Remember what I said about plastic boiling, getting bubbly and becoming brittle? Well, PVC does that if you leave it out in the sun too long (not really, but you know what I mean.) I am assuming it has a very low boiling temp and thus an even lower melting point. Trying to avoid making crunchy candy out of this stuff is almost impossible.
Conversely, other plastics appear to me to have a much higher melting point, a higher boiling point and thus it's easy to avoid getting crunchy, crumbly results. Anyone who has built a model airplane and tried to "weld" a piece with heat knows styrene has a pretty good resistance to heat. Unfortunately, it's too delicate a material for skateboards no matter what condition it's in.
That leaves me with Nylon and teflon. The problem with teflon, though, is that even though it's inertness makes it great for keeping things from sticking, it's not very resistant to wear and tear. I guess I could say it's maximum durometer is pretty low, so it's soft and gets softer. So you make a cup out of Teflon and it dissolves in the pivot in three days. Not very effective.
So we're left with Nylon. Of course, all these things I've mentioned as reasons why I wouldn't use some other plastic might be why manufacturers use Nylon in the first place for skateboard parts: tough, easy to work, injectionable, resistant to heat, lasts a little longer than other materials and most importantly, CHEAP.
Oh, here's a tip for anyone wanting to give this a whirl: where do you get good, raw pure Nylon for a source material? Simple: get out the phone nook and look up "Print Shops." Go by and ask the owner if you can have his old "cutting sticks" off his "Paper Knife." They are worthless to the print shop owner, but perfect for making skate parts. Trust me.
My experience with melting polyvinyls of any sort is not good. I'm not a materials chemist, but from what I can just extrapolate from empirical data (meaning this is what I've done myself in my garage,) the higher the melting point the better a plastic is for reshaping.
Remember what I said about plastic boiling, getting bubbly and becoming brittle? Well, PVC does that if you leave it out in the sun too long (not really, but you know what I mean.) I am assuming it has a very low boiling temp and thus an even lower melting point. Trying to avoid making crunchy candy out of this stuff is almost impossible.
Conversely, other plastics appear to me to have a much higher melting point, a higher boiling point and thus it's easy to avoid getting crunchy, crumbly results. Anyone who has built a model airplane and tried to "weld" a piece with heat knows styrene has a pretty good resistance to heat. Unfortunately, it's too delicate a material for skateboards no matter what condition it's in.
That leaves me with Nylon and teflon. The problem with teflon, though, is that even though it's inertness makes it great for keeping things from sticking, it's not very resistant to wear and tear. I guess I could say it's maximum durometer is pretty low, so it's soft and gets softer. So you make a cup out of Teflon and it dissolves in the pivot in three days. Not very effective.
So we're left with Nylon. Of course, all these things I've mentioned as reasons why I wouldn't use some other plastic might be why manufacturers use Nylon in the first place for skateboard parts: tough, easy to work, injectionable, resistant to heat, lasts a little longer than other materials and most importantly, CHEAP.
Oh, here's a tip for anyone wanting to give this a whirl: where do you get good, raw pure Nylon for a source material? Simple: get out the phone nook and look up "Print Shops." Go by and ask the owner if you can have his old "cutting sticks" off his "Paper Knife." They are worthless to the print shop owner, but perfect for making skate parts. Trust me.
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Carsten Pingel
- Carsten Pingel
- Posts: 489
- Joined: Wed Apr 28, 2004 12:54 pm
Hi Wesley,
do you use this white PVC which is often used for breakfast dishes ?
Selfmade pivot cups is a very good idea !!
I'll try it !
Selfmade pivot cups is a very good idea !!
I'll try it !
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Wesley Tucker
- 1961-2013 (RIP)
- Posts: 3279
- Joined: Tue Aug 27, 2002 2:00 am
Hey, Boswell,
Make your own! Molding a nylon pivot cup is not that difficult. It just takes a little care and attention to detail and you too can be an injection molding wizard.
I have several sets of Mids, Fulls and Hafs that are all small pivot cupped. Buying replacement cups became a lost cause for me years ago. So I started making my own. All it takes is a block of pure Nylon and a heat source. Finding a big block of white nylon is not that difficult. If nothing else, get a nylon riser or tail block and sacrifice it to make pivot cups.
Simply take your truck's baseplate and tilt it so the pivot hole is straight up and down vertical. Heat the nylon and fill the pivot cup with melted material. IMMEDIATELY INSERT THE HANGAR into the pivot cup and let the nylon cool. It takes about three minutes for the plastic to go cold. Pull out the hangar and VOILA! Instant pivot cup bushing. Just take an X-acto knife and trim off any excess that may roll over the top of the base plate when inserting the hangar pivot.
One point to remember: Be very careful when melting the nylon. Make sure you heat it slowly and that the nylon remains clear and liquid. If you overheat the plastic and it "boils" and becomes bubbly, you blew it. When it cools, this plastic will be brittle and crumbly.
Anyway, about two years ago I spent an evening with the Braves on the radio, smoking a cigar, drinking beer and pouring pivot cups for my old stuff. Since then I've been able to upgrade to some newer RTs and Offsets, but I still have my inventory of home-made pivots and find the results to be more than acceptable. Next time I come to DC I'll bring some and let you check out the results for yourself.
Make your own! Molding a nylon pivot cup is not that difficult. It just takes a little care and attention to detail and you too can be an injection molding wizard.
I have several sets of Mids, Fulls and Hafs that are all small pivot cupped. Buying replacement cups became a lost cause for me years ago. So I started making my own. All it takes is a block of pure Nylon and a heat source. Finding a big block of white nylon is not that difficult. If nothing else, get a nylon riser or tail block and sacrifice it to make pivot cups.
Simply take your truck's baseplate and tilt it so the pivot hole is straight up and down vertical. Heat the nylon and fill the pivot cup with melted material. IMMEDIATELY INSERT THE HANGAR into the pivot cup and let the nylon cool. It takes about three minutes for the plastic to go cold. Pull out the hangar and VOILA! Instant pivot cup bushing. Just take an X-acto knife and trim off any excess that may roll over the top of the base plate when inserting the hangar pivot.
One point to remember: Be very careful when melting the nylon. Make sure you heat it slowly and that the nylon remains clear and liquid. If you overheat the plastic and it "boils" and becomes bubbly, you blew it. When it cools, this plastic will be brittle and crumbly.
Anyway, about two years ago I spent an evening with the Braves on the radio, smoking a cigar, drinking beer and pouring pivot cups for my old stuff. Since then I've been able to upgrade to some newer RTs and Offsets, but I still have my inventory of home-made pivots and find the results to be more than acceptable. Next time I come to DC I'll bring some and let you check out the results for yourself.
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Adam Trahan
- Phoenix, AZ, USA
- Posts: 795
- Joined: Tue Apr 02, 2002 2:00 am
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Adam Trahan
- Phoenix, AZ, USA
- Posts: 795
- Joined: Tue Apr 02, 2002 2:00 am
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Jeff Boswell
- Posts: 365
- Joined: Sat Apr 12, 2003 2:00 am
- Location: Woodbridge, VA
Needed Pivot cups
I badly need six pivot cups for small pivot point Trackers.
Thankx Jeff
Thankx Jeff