DIY casting (rubber, silicone, cement, polyurethane etc casting)

[Roman]

This feels like a bit of a crossover from a few other threads. 
However I feel it deserves it's own to make light of how easy it seems* to do some basic casting which can be really beneficial for old cars where parts are unavailable or expensive.

So firstly, I'd just like to make note of that although its an absolute wanker to machine afterwards, it looks exceptionally easy to cast polyurethane.

I thought this was a decent example of the process, or lack thereof -  combined with some 3d printing for easy way to make the mould.

On the more complicated level, watched this video for casting replacement indicator lights from resin was bloody cool.
So good! 
 

The one thing that absolutely terrifies my about my older cars, is busting a tail light. They simply dont exist anymore. 
It's some level of comfort to imagine it might be possible to cast a replacement.

That's all for now, as I've not actually cast anything myself! 
But hope to cast some useful parts over next few months hopefully.
If anyone's cast some cool shit, feel free to post it up I would love to see it.

[Scrubb]

I'm keen to experiment with casting some car parts or 3d prints but I haven't yet due to cost of materials and not having a vacuum pump. Have you found anywhere in NZ that has reasonable prices for resin?

[Corbie]

https://www.fibreglassshop.co.nz/

This is the local distributor for the stuff in the video.

couldn't comment on reasonable pricing, but definately keen to have a play, some lens on my car that seem rarer than rocking horse shit.

[Roman]

19 hours ago, Roman said:

If anyone here has more smarts about this than my zero, I've ordered some of this 
https://www.barnesnz.co.nz/polyurethane/easycast-1306


 

Since I cant do any resin infusion stuff I thought I'd just dump this into my mould for gearbox crossmember and see what happens.

 

Okay so this was a fuck up. 
It's 65 shore D hardness not shore A 
Shore D is for rigid poly and shore A is for flexible 
So shore D 65 is around Shore A 100, AKA stupidly rigid as you'd expect! 
This would actually just hold my engine up as a crossmember, rather than the rubber for it haha.
However I'm happy with how well the layer lines have been minimized on the 3d printed mould with some filler primer. Even if some of it stuck to the part on the way out.

It was crazy seeing how this stuff sets. It's a yellowy transparent liquid, like water. Then after a few minutes it almost instantly turns solid and white.

Will try some 65A polyurethane rubber next.

[Bling]

I need to repair a tail light, remake fender mirror bases and indicator lenses would be a bonus at some point. Keen to see what people make in here. 

Cheapest taillight i've found was $250 + shipping from Japan, probably worse now due to exchange rate and shipping. Yeah I think i'll learn how to mold things... Will be sure to post up any progress with products used. Would be good to see other people doing so too. Saves buying crappy products if someone has used it with bad results etc.

 

What sort of resin would you go with for fender mirror bases? I was looking to make a two piece mold, somehow, and make a few spares as I need two of each side. Might be able to sell a couple to recoup some of the manufacture costs.

[JustHarry]

28 minutes ago, Bling said:

 

What sort of resin would you go with for fender mirror escutcheon

Fixed for future reference.....

/ling

[JustHarry]

When you have some success casting them. I'd be pretty keen to do a couple for the crown fender mirrors. As the escutcheons are getting real had to find in good condition 

[Bling]

Will let you know if I have success

[Roman]

Just now, Bling said:

Will let you know if I have success

Got a picture of what you need? Is it flat on the base? 

[Bling]

Imagine this sort of top design, with a thin angled tube on the underside. I broke my spoiler somehow, contents within.

 

 

I don't actually have a picture of mine as it's been put away in a box for a rainy day. Getting pretty rainy so I should probably hunt it out. Flat base for the most part though. With raised sections under the mirror. Very similar if not the same as below. Bottom tubes locate the mirror on the guard and provide the space for the threaded rod to pass from under the guard to the mirror guts itself.

 

[J-W-G]

I had a look into this for my Cortina but the lens' look way complex to cast from a one peice mould... Looks like $500-700 per lens really is the going rate

[RUNAMUCK]

On 14/06/2020 at 21:50, J-W-G said:

I had a look into this for my Cortina but the lens' look way complex to cast from a one peice mould... Looks like $500-700 per lens really is the going rate

Sure @- i5oogt - must have boxes of these??

[- i5oogt -]

14 hours ago, RUNAMUCK said:

Sure @- i5oogt - must have boxes of these??

got heaps of mk2 ones. not so many/any mk3 ones sorry

[RUNAMUCK]

Oh, mk3 

(I'm not ashamed of my limited cortina knowlrdge)

[Roman]

So I finally got around to mixing up some of the 65 Shore A polyurethane to see if it seems about right for engine mounts etc. 
I tipped some into the corner of the cut off bottom of a coke bottle.
the results - aahhhh... 

It feels weird to give a review saying these mini boobs were about the right firmness but here we are.
Definitely needs degassing, end up stirring a whole heap of bubbles into it that don't escape at all.
This stuff is very gluggy compared to resin etc.
It also took bloody ages to set. Like, more than a day.
Very different to the solid stuff I used earlier which set in about 15 mins.
I've been watching some stuff about bonding it to steel, sounds like you need to rough the surface with sandblasting, use a polyurethane friendly etch primer, then you'll get a really strong contact with the urethane poured against it.
I guess only other thing is to make sure it's somewhat petrol/oil/temperature tolerant. I guess it would be seeing how many people use poly bushes for nearly everything.
Will try find what sort of additive you can use to colour it.

[ajg193]

Might be able to use a different catalyst to kick it off quicker

Also make sure there is no moisture in your molds as that reacts with the urethane during curing and makes bubbles - that's how they make polyurethane foam for seats and stuff. 

[kyteler]

10 hours ago, Roman said:

So I finally got around to mixing up some of the 65 Shore A polyurethane to see if it seems about right for engine mounts etc. 
I tipped some into the corner of the cut off bottom of a coke bottle.
the results - aahhhh... 

It feels weird to give a review saying these mini boobs were about the right firmness but here we are.
Definitely needs degassing, end up stirring a whole heap of bubbles into it that don't escape at all.
This stuff is very gluggy compared to resin etc.
It also took bloody ages to set. Like, more than a day.
Very different to the solid stuff I used earlier which set in about 15 mins.
I've been watching some stuff about bonding it to steel, sounds like you need to rough the surface with sandblasting, use a polyurethane friendly etch primer, then you'll get a really strong contact with the urethane poured against it.
I guess only other thing is to make sure it's somewhat petrol/oil/temperature tolerant. I guess it would be seeing how many people use poly bushes for nearly everything.
Will try find what sort of additive you can use to colour it.

Not sure if relevant but I watch a guy on YouTube that makes softbaits, he puts his mixture in a vacuum after mixing to get the stirred in air bubbles out. 

[Roman]

Yeah thats the way to go for sure.

I've got a vacuum chamber here but my pump is chooched as I managed to fill it up with resin and damage the vane pump. 
Awaiting a replacement!

[kws]

Bringing this back from the dead as casting my own bushes might be the only way to get bushes for my rear axle reaction arm since they are long NLA. Has anyone had a go in the last 5 or so years?

I would want to cast them in a similar hardness to rubber, since it does need to flex and not be so rigid it breaks the arm (apparently a risk). The stock bushes are a weirdo shape, typically. The attached photo is what I need to replicate, and I could probably cast it in place in the arm if I needed, using some 3d printed moulds.

[tortron]

you can also buy blanks of nolothane if you felt like machining one