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bspooh
09-28-2003, 12:18 AM
Hello everyone,

My two boys have those "heelies"..(shoes with a little skateboard wheel inside of them)..basically its a skateboard wheel inside of a shoe..

My question is: What is the material that the wheels are made of?? My youngest lost one of his wheels, and instead of buying another one, i thought I could just machine one. But I have no idea what its made of..they look like they are casted..?? I don't know...Any help would be greatly appreciated...

Thanks,

Brent

Thrud
09-28-2003, 12:40 AM
Brent
Polyurethane - cast, probably 90 shore. There are a few places that sell it in rod & tube for tool & die work. But if you make a mold (spray it with silicone mold release first!) use the liquid resin - that way you can make more if need be.

shorty
09-28-2003, 01:01 AM
I gotta say, Thrud, you are a wealth of information . Cnc's to skateboard wheels....too cool.

Evan
09-28-2003, 03:14 AM
Just cut one from Nylatron. Available from any good plastics supply house. 6000 psi tensile strength, filled with molybdenum disulfide for built in lubrication. Made real good wheels for my sliding glass door. AKA "black nylon". It's not black, it's grey. I asked my wife to buy some BLACK Nylon or Delrin for me in a town 300 klics from here and the guy sold her Nylatron. Good stuff, but not what I had in mind. It's dark grey. I phoned him and asked "What shade of black is this". He says, "It's black Nylon". I says "No, it's grey". He says "No it's black!". I say "Just what shade of black do you mean? Light black or dark black? Or is it really light black?" ??????? DUFUS!!

Herb W
09-28-2003, 03:12 PM
Not a problem Evan. Black being the absence of color, just take an eraser - make sure it's a color eraser, and remove enough grey to give you the darkness of blackness that you desire. http://bbs.homeshopmachinist.net//wink.gif

Tony
09-28-2003, 06:19 PM
thrud's got it right on the nose: urethane.

typically hardness range is ~82 to 95
(at least this is what any respectable skate board shop would stock)

i imagine nylon would be too "slick"

spent the better part of teenaged years
getting around on a skateboard. could even do the tricks! in fact i still have it here in my living room, decoration now.

every now and again i get to urge to pick it up. probably remember just enough to hurt myself pretty good. http://bbs.homeshopmachinist.net//smile.gif


-tony

bspooh
09-28-2003, 10:14 PM
Thanks for all of the replies...Now I know...

Oh yeah, and hey Thrud...I am still waiting for your sisters recipe for meatloaf...I check the mail everyday...must of got lost..

brent

Shed Machinist
09-28-2003, 11:12 PM
i started using tools, and now i don't skateboard much, use to be all i did.

Evan
09-29-2003, 01:25 PM
I have a skateboard, real handy for moving appliances. The thought of standing on it has never entered my mind.

docsteve66
09-29-2003, 02:20 PM
If I stand on a skate board, it will be by accident!. Take 60 years from age and I would try one. Hell,just take 40 years and I would try a lot of things.

Thrud
09-30-2003, 04:52 AM
Brent
I don't think the recipe will help you - standard stuff. It is what the snarly she-devil does to it that makes it great armor plate.. If I could figure it out, we could bake M1A2's and make a fortune!

Makes a great anvil... http://bbs.homeshopmachinist.net//biggrin.gif

Hey, they still making good Chocky milk down there? Oh, to sit in the Mormon Tabernacle slurpping ice cold Brown moo Juice while they play "inagodadavida" on the pipe organ...Joy! http://bbs.homeshopmachinist.net//wink.gif

audrey
09-30-2003, 03:03 PM
Casting Urethane for Skate Wheels. Is the casting material difficult to purchase in its liquid state. Where do9 you get it Thrud? thanx Audrey

Thrud
10-01-2003, 10:23 AM
audrey:
I buy it from tooling suppliers locally. You could try Do-All in the US or your own tooling distributors. Some Industrial plastics distributors carry it. Any shop that supplies tool & die industry should sell it.

You can buy urethan in solid or castable form. The castable form is often used for strippers on punch & die sets. If comes in a variety of Shore ratings. Shore is the hardness or how stiff the urethane is - it ranges from about 10 to 100. The castable stuff can also made in colours by mixing pigment to the resin. 90 Shore is extremely stiff.

darryl
10-01-2003, 02:13 PM
I have a customer who uses uv curable urethane. It's only 600 cdn a gallon. Thrud, is that castable urethane a two part, or catalized, or what, to cure?

ibewgypsie
10-02-2003, 06:30 AM
www.synair.com (http://www.synair.com) Chattanooga Tn, has a two part castable resin that hardens up to 93.. I have cast gilmer belt gears with great success. Shrinkage is less then one percent.

It is used for casting all kinds of projects from sculpture to mechanical projects.

It is a honey and a clear, you mix the two together and it sits kinda normal till the flash off time. At that point it starts making lil white tracers then smokes and heats and flashes to a solid white. I ran outa the room when I cast it the first time.

I have read about making Nitro-glycerin. If it smokes it blowes. Hence the running like a rabbit.

witkowbj
10-02-2003, 01:12 PM
Another source is www.freemansupply.com (http://www.freemansupply.com) they have Devcon brand urethanes that are abrasion resistant and in the higher shore A range. They have alot of casting/mold making supplies as well. Shake or mix the resins prior to use, a good shake of the isocyanate prior to mix is usually enough. Silicone mold release works best, avoid wet marks from the mold release, as they can appear in the final part or cause glossy/dull areas.

Thrud
10-02-2003, 03:24 PM
darryl:
Two or three part depending on the make.

darryl
10-02-2003, 04:52 PM
Three part, now you got me going. I'm assuming one part to activate another, and a third to sort of catalyze it. hmm need to do some homework on this stuff.

witkowbj
10-03-2003, 10:18 AM
darryl:

Thrud, feel free to add anyting to this, but here is an answer to the question on the castable materials: The two parts are the resin or polyol. This is a mixture of usually polyether/polyester based polyols (long chained alcohols). In this mix is also catalysts often amine based or for elastomers they can be Tin or lead based as well, chain extenders short molecules that provide stiffness, surface/flow agents to help remove bubbles (or in foams to help regulate their formation). Plasticizers to help controll softness, and fillers such as calcium carbonate are added to control shrinkage. The second component is an isocyanate, which reacts with the polyol (a hydroxyl {OH} group on the polyol). The third component is often additional plasticizer/catalyst or modifier, this allows the manufacturer to produce larger masterbatches for the customers, and thereby reducing inventory and cost. I hope this has answered more questions than it has raised.

Brian

darryl
10-03-2003, 07:02 PM
Thanks, Brian. That's usually the kind of info I look for, to add to my knowledge of 'how things work'. When it comes to actually using a material, as a hobbyist, I should be able to make an intelligent choice from off the shelf, by actually reading the info on the package. By the time I buy something, I know far more about it than the salesman trying to sell it to me. I'm intrigued by urethanes, and will continue to learn more about them.

abn
10-04-2003, 03:36 AM
Wow, is this stuff really ~400 US a gallon? Doesn't seem like a lot of skateboard wheels/dollar. How far does a gallon go?



<font face="Verdana, Arial" size="2">Originally posted by darryl:
I have a customer who uses uv curable urethane. It's only 600 cdn a gallon. Thrud, is that castable urethane a two part, or catalized, or what, to cure?</font>

Thrud
10-04-2003, 05:15 AM
Abn

UV curable resins are ALWAYS super expensive. They are used mostly in the electronics industry where speed is the most important thing. A strong UV source cures potting compounds in seconds. Most of the Urethane resins I have used cure overnight - fast enough for me. Urethane is not cheap in whatever form it takes - including spray in insulation - it is however very cost effective.

For example a 4" punch and die is made and a 2" thick urethane stripper cast around the punch (that has been sprayed with release compound). This replaces a steel stripper plate and springs - which frequently break BTW. The Urethane ring stripper will outlast the punch and does s great job stripping plate off the punch. It takes extra tonnage to use the urethane stipper (very stiff), but the steel pops off sharply and for the cost of a couple standard die springs. The ring can be removed with a prybar so the punch can be sharpened and aligned with the die during set up and then replaced before blanking operations. If you do not use the release agent when casting, you cannot remove the ring!

ibewgypsie
10-04-2003, 11:39 PM
I think I paid less then $45 for the two quart? sized version of the Synair castable resins..

I used it to cast XL gear pulleys, I cast the aluminum pulley in lead, tapped it, pressed it out with the tapped holes. then.. Poured the resins in a cup, mixed them, poured them into the lead mold. They fit and work the machine fine. Pulleys were $27 each, so I made about ten pulleys and was ahead miles. Like thrud said, you have to put release on there or it becomes part of it.

FOr appearance you can add metal colored fillers but it reduces the hardness. You can make a belt buckle outa this stuff that looks like brass, but is much lighter.