Casting with hard rubber

[BHH]

I am going to make a mold of the hard plastic tool that I use when jacking up my jeep. It is included in the emergency road side tire changing kit but I don't think it is supposed to be used on such a regular basis that I use it on so I wanted to cast my own out of hard dense plastic like a hockey puck.

The only thing is I don't even know if this is possible. Do I just melt hockey pucks and pour them in? Again, not even sure if that is possible.

It has to be a really dense hard rubber because it will be used on the pinch welds as well as the rear jack points.

So how exactly do I go about making this out of hard rubber?

The tool is pictured here at the top. (it is called a jack cover)

 

[metaleltr]

The rubber on hockey pucks is vulcanized, yiu won't be able to melt it and recast it. You will likely need a two part urethane resin of some sort.

 

[Givl Reggin]

Get some sand (regular playbox sand will work fine) and mix it with synthetic oil (around 30 weight, it's not critical) mix enough oil into the sand just until the sand starts to stick together.

Then make a square frame out of 1x6's or 1x8's (it needs to be deep enough to fully cover the part plus about 2"-3" over it and all around.

Place the frame on a piece of plywood, place the part you want to cast in the middle with it's flat side down and pack the sand around it - use a rubber mallet and pound it in real good.

Place another piece of plywood on top of the frame and flip the whole thing over - carefully remove the part from the sand, repair any defects in the sand - then pour the molten liquid into the void.

Once it cools just dump out the sand and remove the cast part.

It's actually simpler and easier than it sounds... I've made many-a-part out of aluminum in my home workshop this way.

 

[goodspeed]

Why should it be synthetic oil? I'm just curious.

 

[BHH]

Get some sand (regular playbox sand will work fine) and mix it with synthetic oil (around 30 weight, it's not critical) mix enough oil into the sand just until the sand starts to stick together.

Then make a square frame out of 1x6's or 1x8's (it needs to be deep enough to fully cover the part plus about 2"-3" over it and all around.

Place the frame on a piece of plywood, place the part you want to cast in the middle with it's flat side down and pack the sand around it - use a rubber mallet and pound it in real good.

Place another piece of plywood on top of the frame and flip the whole thing over - carefully remove the part from the sand, repair any defects in the sand - then pour the molten liquid into the void.

Once it cools just dump out the sand and remove the cast part.

It's actually simpler and easier than it sounds... I've made many-a-part out of aluminum in my home workshop this way.

Thanks!

But what can I use for the hard rubber if I can't melt hockey pucks?

 

[Givl Reggin]

Why should it be synthetic oil? I'm just curious.

Higher smoking point.

If you use regular oil it will smoke quite a bit (smells bad too!) from the high temperature of the molten liquid and the sand will turn black.

 

[Givl Reggin]

But what can I use for the hard rubber if I can't melt hockey pucks?

Lead. If you're not concerned about weight. You can melt lead in an aluminum pan on the stovetop.

Another option might be JB Weld. When you're done mixing just heat it up a little bit (~100 deg F) and it will flow better.

Just popped in my mind... I'm guessing, you've already tried to order another rubber jack top from the dealer?

 

[goodspeed]

Higher smoking point.

If you use regular oil it will smoke quite a bit (smells bad too!) from the high temperature of the molten liquid and the sand will turn black.

Makes sense. I use conventional oil for oil bluing, but had never considered using synthetic due to cost.

 

[BHH]

Lead. If you're not concerned about weight. You can melt lead in an aluminum pan on the stovetop.

Another option might be JB Weld. When you're done mixing just heat it up a little bit (~100 deg F) and it will flow better.

Just popped in my mind... I'm guessing, you've already tried to order another rubber jack top from the dealer?

I don't want to use metal because I don't want it to mar or scratch anything. I wanted to hard rubber for that purpose.

There is nothing wrong with the jack top I have but it is just hard plastic not rubber hence why I want to make a rubber one.

2 reasons for wanting to make this are:

1- I want to make it with a bigger base so it fits the jack pad better.
2- The jack top is only meant to be used with the emergency kit suplied and not meant to be used several times a year like it is currently being used.

 

[Stuart in MN]

McMaster-Carr sells liquid urethane you can use for casting objects: http://www.mcmaster.com/#catalog/118/3629/=jd5s0x Some of the BMW guys use it to make heavy duty suspension bushings. It comes in different hardnesses (durometer) - a hockey puck has a rating of around 90 to 100, the stuff they sell goes up to 85 which is pretty close. However, their extra hard stuff is pretty expensive, if you go down one grade to 60 it's half the price.

 

[jamesc]

why not just buy a jack?

 

[BHH]

why not just buy a jack?

Haha I have a Hein-Werner 2 ton. I am making the rubber "tool" because it is what is designed to be used on my Jeep. It has a small square "peg" on the top as you can see in the picture. This fits inside a hole in the back to jack the back up, and it has a notch for the pinch weld in the front.

I don't want to keep using the emergency one that comes with the road side kit on the jack. I want to make a hard rubber one with a large bottom that fits the H-W square pad perfectly.

 

[BHH]

McMaster-Carr sells liquid urethane you can use for casting objects: http://www.mcmaster.com/#catalog/118/3629/=jd5s0x Some of the BMW guys use it to make heavy duty suspension bushings. It comes in different hardnesses (durometer) - a hockey puck has a rating of around 90 to 100, the stuff they sell goes up to 85 which is pretty close. However, their extra hard stuff is pretty expensive, if you go down one grade to 60 it's half the price.

I am just worried if it is not hard enough the pinch weld will cut or destroy it. The jeep weighs 5210LBS so it has to be pretty heavy duty no?

 

[honcho]

Lead would probably work very nice, especially if you made it to fit nicely in your hydraulic jack. Anything durable enough to last will be hard enough to damage the paint over time. I've made similar ones from oak and I've never had one fail on me but the cars were lighter than your jeep.

 

[Gradyhd]

You might try 2 part epoxy resin. You can get it at arts and crafts stores. I've never tried to use it in a mold for parts, but it cures very hard. Also check this out,

http://www.caswellplating.com/resto...ing-products/alumilite-super-casting-kit.html

I've never used it, but always looked for a reason to try it.

 

[BHH]

Lead would probably work very nice, especially if you made it to fit nicely in your hydraulic jack. Anything durable enough to last will be hard enough to damage the paint over time. I've made similar ones from oak and I've never had one fail on me but the cars were lighter than your jeep.

I am really set on hard rubber.

I was planning on placing the jack cap in the center of the jack pad and then using plastic to create a mold form around the entire pad. From there using silicone to create the mold.

 

[Mickey O]

Get some sand (regular playbox sand will work fine) and mix it with synthetic oil (around 30 weight, it's not critical) mix enough oil into the sand just until the sand starts to stick together.

Then make a square frame out of 1x6's or 1x8's (it needs to be deep enough to fully cover the part plus about 2"-3" over it and all around.

Place the frame on a piece of plywood, place the part you want to cast in the middle with it's flat side down and pack the sand around it - use a rubber mallet and pound it in real good.

Place another piece of plywood on top of the frame and flip the whole thing over - carefully remove the part from the sand, repair any defects in the sand - then pour the molten liquid into the void.

Once it cools just dump out the sand and remove the cast part.

It's actually simpler and easier than it sounds... I've made many-a-part out of aluminum in my home workshop this way.

I think you were just told to pound sand.




If it's the part I think it is, can't say for sure because you have failed to post pictures of the actual piece. I'd find a big chunk of rubber and cut it to what you need or find pieces of rubber and glue them up to form the piece.

 

[dadsEH]

just throw a bit of leather over the jack and lift that sucker.

 

[88thunder]

Sure it can be done. You'll need to mold the original or make an improved one-off prototype. Then...

To mold, you'll need silicone:
If you don't have a scale or vacuum pot to de-air the silicone, here's an easy to use silicone: http://www.smooth-on.com/index.php?cPath=2_1113_1136#media

Once you have your mold, you can cast into it. Good examples of materials you can use:

Hard urethane rubber: http://www.smooth-on.com/Urethane-Rubber-an/c6_1117_1150/index.html

Softer urethane rubber: http://www.smooth-on.com/Urethane-Rubber-an/c6_1117_1147/index.html

If you want more of a plastic than a rubber, here's a rigid casting urethane: http://www.smooth-on.com/Urethane-Plastic-S/c1120_1208/index.html

These are just examples of products from one company off the top of my head. You'll also need to read up a bit on the type of mold you'll want/need to make to facilitate the removal of the original and later cast parts...i.e. 1 or 2 parts molds. Have fun!

-Bryan

 

[dadsEH]

Why not just go to the Jeep dealer...point at the part and ask him to order you a quantity from the factory.
job done.

 

[88thunder]

Why not just go to the Jeep dealer...point at the part and ask him to order you a quantity from the factory.
job done.

Best idea.

 

[BHH]

Why not just go to the Jeep dealer...point at the part and ask him to order you a quantity from the factory.
job done.

I could do that but the problem with the part is that it tends to slide around the jack pad. The one I want to make will be formed to the jack pad so there will be no sliding around.

Also it is made of a hard plastic and already the pinch weld has started to dig into the plastic so if I make one from hard rubber it will be more durable.

Last it will just be a fun project I can do. Plus maybe I will sell the part on ebay once I am done. I am sure other jeep / Chrysler products use the same part.

 

[Mickey O]

Plus maybe I will sell the part on ebay once I am done. I am sure other jeep / Chrysler products use the same part.

I'm already on it.


I think someone already makes something similar to what you're talking about.

 

[BHH]

I'm already on it.


I think someone already makes something similar to what you're talking about.

oh yeah?

 

[Man of Many Vices]

I'm a cheap *******. Since stumbling upon Garage Journal a year or so ago, my mindset has gone from, "where can I buy it, and how much will it cost?" to "how can I make it, and what tools will I need?"

With this philosophy in mind, I wonder if a thick chunk of an old truck tire would work. You can certainly hacksaw the chunk down to size, then drill out, whittle and hand-file any recesses.

Dan
Indio, CA

 

[chris fresh]

make a mold out of liquid latex and then pour it with alumilite,you tube is your friend here with alumilite and latex molding tips