?'s about cast your own parts from resin.

[gunter]

Hope this is the right forum for this. Here goes.

This is my first try at casting resin parts for my sub. I received everything from Micro-Mart. I had no problem making the mold. Yesterday I cast my first piece and added some of the color dye from Micro-Mart. When I opened the mold the part looked great. When I started to remove it I pulled it by the casting vent which broke off. I noticed that the vent piece was very very flexible. After removing the part I found that it was some what flexible. More than what I would have thought it should have been and if held in my hand for a few minutes it would get even more flexible. So today I tried it again. No dye this time just the resin mixed 50-50. After an hour and a half I opened the mold. Big mistake. Only about half of the part was cured. Made a big mess. Guess I should have waited the 5 hours like I did yesterday. I know that I am mixing it 50-50 and it is not over the best used by date. Is this normal for the CR-600 resin that they sale? Should it be flexible or rock hard? Which is the hardener for mix? The yellow A part or the clear B part? I have looked all over the bottles and it doesn’t say.

[Guest]

You could try heating the

You could try heating the rubber moulds a little in an oven before casting, and also postcuring the resin in the mould using the afore mentioned oven.

Andy

[anonymous]

Gunter. Your working with 2

Gunter. Your working with 2 part polyurethane? When ever I've had such a problem it was always due to a bad or old batch, moisture, or an un even mix.

It should be plenty hard soon after it kicks off. I think the yellow is the cat.

Your using silicone for your molds. Right?

Steve

[gunter]

Yes, I'm using a 2

Yes, I'm using a 2 part urethane that says to be mixed 50-50. Casting in a silicone mold sprayed with Ease Release 200 before each casting. I'm using a separate syringe for each part of the epoxy to be sure that I get the same amount, mixing in a container, and then use a third one to push/pour the mixed epoxy into the mold. I’m going to try it again today and if it doesn’t work, then I’ll be getting a new batch of epoxy. I'll let you know how it turns out. Thanks for all the help.

[tennesseejim]

Is there a good book

Is there a good book out there on doing casting in resin?

What about a book about making the molds?

Thanks.

[Guest]

There is some very good

There is some very good free information on the Smooth-on website.

http://www.smooth-on.com/default.htm

[rcade]

I have used Micro-Mart resins

I have used Micro-Mart resins and had the same problem. "Sometimes" the parts would come out still soft if I removed them when the instructions said. I used a balance to measure the parts since this is very accurate. I still had the same problem. The problem did not always occur. If I let the parts sit overnight they were always hard when removed from the mold. I think it is variations in the resin components age and/or quality. Once the parts were removed they would harden up and be servicable provided the part was not damaged during removeal.

Good Luck !!!!!!!!1

[koeze]

I think that there are

I think that there are two ways to measure the resin/hardener if I read this thread. As far as I know the correct way is to mix it based on weight.
50/50 mixing would require two equally heavy parts. You add 100 grams of hardener to 100 grams of resin. Volumetric mixing could result in an incorrect ratio since the two part may have a different density.

Correct me if I'm wrong.

EJK

[gunter]

Will I tried it again

Will I tried it again with the molds pre-heated and then heated after casting for an hour. Then the mold was left at room temp for 36 hours. The part was still soft in the middle and the part that was hard, broke very easy and looked like grainulated sugar at the break. I'm guessing that the resin is bad. I need to make some more molds which will give me something to do while waiting for more resin.

The instructions for the CR-600 resin says " Pour part A into one cup, then pour an equal amount of part b into another cup. Now pour both parts into a third cup and stir thoroughly."
So it looks like this resin goes on volume measure. Other resins might be measured different.

I'll have to check the Smooth on site. Thanks for all the help.

[gunter]

Smooth On has a lot

Smooth On has a lot of resins to choose from!!! Which one would be good for casting a prop?