ByYourCommand.net

when i click on the image nothing happends

Huttman wrote:when i click on the image nothing happends

I'm not sure why it won't work for me either

Looks like it is just a small picture... no larger view to show = no click.

Cylon-Knight wrote:Looks like it is just a small picture... no larger view to show = no click.

Yea it is....that's the only pic they had

How do you figure out how much resin to use inside a mold for roto-casting?

I want a wall thickness around 1/8 inch (3mm)

groupleaderzeta wrote:How do you figure out how much resin to use inside a mold for roto-casting?

I want a wall thickness around 1/8 inch (3mm)

I personally can't answer that but I'd bet Skullbeast, Jclayman, or Flightldr. could...I searched for the answer on the supply sites but came up empty.

I'm sure it has to do with the size of the mold and the type of resin you are using.

But I'm sure the pro guy's have a calc for it.

groupleaderzeta wrote:How do you figure out how much resin to use inside a mold for roto-casting?

I want a wall thickness around 1/8 inch (3mm)

That, my friend is a tricky feat indeed. It boggled my mind for the longest time. Its too easy to simply give it up Its right there in front of you! ;-)

groupleaderzeta wrote:How do you figure out how much resin to use inside a mold for roto-casting?

I want a wall thickness around 1/8 inch (3mm)

Awesome question and I hope this helps. I found this on the Alumilite page although I think this is for a solid part cast in a RTV mold, It may help.

Amount of Resin Needed to Cast a Part

Note: There is .554 ounces in 1 cubic inch of Alumilite Resin.

Formula for a Square/Rectangular Piece: Length x Width x Height

Example: If your piece is 3" x 4" x 2" = 24 cubic inches. Take 24 cubic inches x .554 ounces per cubic inch = 13.25 ounces.

Formula for a Round Piece: Pi x Radius (squared) x Height.

Use the same formula as the RTV round mold (section 1) to calculate resin needed. Then multiply that by .554 ounces per cubic inch to determine ounces needed.

I was thinking of something similar, get solid volume. I use the dried rice method. Take that number and divide it by 3. Then use the result as my needed material.

I guess a new experiment is in order.

Calculating Resin amount for Rotocasting


I searched the internet for the calculation of resin used to make a part by Rotocasting and could only find calculations for Mold Making rubber and solid Resin casting.

I searched many suppliers sites and found that alot of hobby guy's are useing "Smooth On" as they make resin specially formulated for rotocasting.

I sent them a request for the calculation and this is what they sent back.

I hope this helps




8-23-2011

How do you calculate the resin amount needed for rotocasting a hollow part? (Costume Helmet such as Stormtrooper, Cylon etc)

we would like to achive a 1/8 inch thickness


I have scoured your site and can only find the calcs. for making molds and casting solid parts.

Please help




Date: 2011-08-24 10:52:08
Name: Jason Reese:


Al,
You would need to know the surface area to be coated.
The calculation is similar to determining the amount of rubber needed for a brush-on mold.
For example, using Smooth-Cast 65D as an example resin:
- A one-gallon unit of 65D weighs 16.75 pounds.
- The yield of the resin - per the TB - is 26.4 cubic inches per pound.

1. 16.75 lbs. x 26.4 cubic inches per pound = 442.2 cubic inches of material in a gallon unit
2. Divide 442.2 cu. in. by .175 (1/8") = 2527 square inches
3. Divide 2527 by 144 (no. of square inches in a square foot) = 17.5 square feet
4. A gallon unit of Smooth Cast 65D will cover 17.54 square inches at 1/8" thickness.

Jason Reese
Smooth-On, Inc.

Calculation of Rubber needed for a Brush On Mold (Smooth On)


In the previous post, the Smooth On rep said the calc for the resin needed was similar to the calculation of rubber needed for a Brush On Mold.

Here is that Formula


Brush-On Mold**

**The volume of clay used to cover the model directly corresponds to the volume of rubber needed to make the mold.

To Estimate the amount of rubber

1.) Form clay into a cube and calculate the volume of the clay.

Volume = Length x Width x Height


Our goal is to make a brush on mold of the cube (used in our example above) by brushing a

I guess its time to dust off the calculus and see if I remember how to use it.

That's alot of calculations

^ Very nice find, Zeta. Are you going to do some of that?

in regards to that video, i think all those steps are a bit overkill. As far as rubber silicone goes, i think its worth using the stuff that you let sit overnight. You will get more pulls from the mold