Working with Foam - Page 6

shotgunefx · 12-13-2006, 01:36 PM

Quote: Originally Posted by GoHybrid

i'd be more concerned about the solvents melting the foam than the heat...

I was refering to smoothing wax of minor tool marks with the heat comment.

GoHybrid · 12-13-2006, 01:44 PM

i was referring to the using fiberglass over floral foam comment.

shotgunefx · 12-13-2006, 02:18 PM

Quote: Originally Posted by GoHybrid

i was referring to the using fiberglass over floral foam comment.

I know, but I believe that was a reply to my reply LOL

GoHybrid · 12-13-2006, 09:05 PM

.... and that's all i got to say 'bout that.

shotgunefx · 12-14-2006, 05:16 AM

Quote: Originally Posted by GoHybrid

.... and that's all i got to say 'bout that.

Suppose that didn't really clarify things, thought Yevmeister was misreading my heatgun comment about wax and thinking I meant foam, then you replied to Yevmeister, and I was just saying, I was talking about wax.

Make sense? Me niether

Giuliano · 12-14-2006, 05:29 PM

Today I received two 2"x2"x4" sample blocks of RenShape 440..

It's very nice stuff, very dense - about the same density as blocks of oak wood..

It should hold a very nice shape when milled, but can still be hand finished, sanded, and carved with sharp tools - like woodworking ones.

It's rather expensive, though - a 2"x20" board 5 feet long is some $260 or so.. but then again, it is five feet of material..

I'm thinking I might be able to put these free samples to good use..

GoHybrid · 12-14-2006, 07:14 PM

mmm the gears are turning again. I think another project is in order. Is there anything in particular that someone would like to see done? I'm particularly interested in exploring the creating of thin-walled parts, multipart molds, and fiberglass molds to help create high-strength/structural parts with. But I'm up for a new challenge. Lay it on me!

turbocad6 · 12-14-2006, 08:36 PM

once your up to those kinds of prices, why not just use wood? I mean, if it's just to make a prototype for the shape & then cast a mold, wood & clay can do this much cheaper... I mean in the end, whatever your going to use to make the plug for the mold is then just garbage.. it's not like the foam has much significance in the end result.... is there any significant advantage to that foam?

parksgm · 12-14-2006, 08:41 PM

Quote: Originally Posted by turbocad6

once your up to those kinds of prices, why not just use wood? I mean, if it's just to make a prototype for the shape & then cast a mold, wood & clay can do this much cheaper... I mean in the end, whatever your going to use to make the plug for the mold is then just garbage.. it's not like the foam has much significance in the end result.... is there any significant advantage to that foam?

Mid-density foam is easier to shape than wood.

Edit: I didn't see the post above... $260? For 1.4 ft3 of FOAM? "Use the right tool for the job" is my mantra, but that's one expensive tool. Couldn't one have a part custom CNC milled from billet aluminum for a bit more than $260?

GoHybrid · 12-14-2006, 08:49 PM

the advantage i see is in the ultimate stability and chemical resistance of the foam and the ability to hold extremely close tolerances in higher densities. I also find it much easier to work in it's various densities than wood or clay. Temperature resistance... So it's not so much about the end result as it is about how you get there, and what exactly you can do with the end result.

parksgm · 12-15-2006, 11:06 AM

As you posted above, the foam allows you to cast a part from the silicone mold requiring almost no surface finishing, so I definitely see the advantage there...and since the finishing work often requires the most time, a hobbyist who has limited time to work on the project would especially benefit.

Just for grins: GoHybrid, how does the density of the foam you used for this latest project compare to that of the spray foam insulation material that comes in a can? I thought that using a spray foam might allow one to generally mock up the part with very little time or effort...of course the amount of time required to finish the surface would be proportionate to the size of the bubbles in the finished foam. (And yes, I realize that sounds ludicrous compared with the attention to detail you've exhibited throughout your project thus far :-)

GoHybrid · 12-15-2006, 12:30 PM

The density of my foam (the RenShape 5025) to that of spray foam (i assume you're referring to Great Stuff or similar products) is the difference between a marble slab and a mattress. If i remember correctly, the stuff Giuliano bought is even harder and more dense.

Giuliano · 12-15-2006, 12:54 PM

The RenShape 440 is indeed much denser - if I press hard with a fingernail, it barely makes a mark.

The RenShape 440 is $250 for a 2" x 20" x 60" (5 foot) sheet, and can be shipped UPS (non-hazardous).

So, the cost of material breaks down to:

2" x 20" x 12" = $50.00
2" x 12" x 12" = $30.00
2" x 2" x 12" = $5.00
1" x 1" x 1" = $0.10416~

I can think of a lot of parts I can make masters of out of a 2" x 2" x 12" bar of foam...

The advantage of the foam over aluminum is that it doesn't weigh a ton, and can be cut with a table saw.

The advantage over wood is that it doesn't have a grain, and can be cut / shaped in all three dimensions.

The foam can also be epoxied together to form large or odd-shaped pieces - super glue also works well for this.

GoHybrid · 12-15-2006, 02:03 PM

Giuliano: Check out Repro fast cast urethanes from Freeman as well. Unfortunately I made countless models gluing pieces of 5025 together with superglue not knowing about this stuff, but they have a number of formulations that are both color and hardness matched to various types of RenShape. They say you can mix this stuff up and use it as a glue, rather than a casting media for the foam. That way you don't have to worry about superglue squirting out and creating a hard line that you can't sand away. Shouldn't make a ton of difference if you're CNC machining because of the precision of the tool, but for hand-shaping and finishing, that's a nice benefit to have.

flomas · 12-16-2006, 01:48 AM

Hybrid,
Are you willing to sell a couple of those molded parts?
Would love to purchase a few from you, please let me know..
I have the 05 corolla screen mount dilema and it's driving my crazy...
If I could get my hands on a couple of your molded pieces I might have a better chance...
I say a couple just for saftey sake, the Lillput 7" Touch screen I have is supposed to be for double din application it's size is 4.5" Tall and 7-5/8" wide. I'm wondering if I should have gotten that one ... well, live and learn I guess .. let me know if your willing to sell some of your corolla molded parts.. Oh, Are there two differant styles you made or does your screen pop out some that's why it looks differant in the pic's.
Thanks!

my screen
http://cgi.ebay.com/New-Lilliput-7-T...em170060796934