Blocking sections of a cnc mold

[Walking Dead]

Anyone blocking sections of their mold without permanently modifying it? What are you using?

i want to block off a portion of a couple of molds with a filler of some type, one to get a “cupped” look and another in a claw mold.

thanks.

[AZ Fisher]

I think I've heard guys use high temp RTV silicone. I know my buddy uses it in his lead molds and that's a much higher temp.

[Jig Man]

The only problem with using the rtv silicone is getting it out.  I have it in some lead molds and it is a bear to get out when I want to change something.

 

Have you tried pouring some plastisol where you want the block, letting it cool really well than coating it with some kind of slickum then shooting the regular bait.  That might let the new stuff peel off.  Just a thought.  Maybe even plumbers putty.

[curt k]

you could make an insert with jb weld steel stick putty , you'd just have to take the obvious precautions not to weld the two halves together . You should be able to fill in the area that you need , put the halves together to form it then take it apart and let the insert harden . A dusting of talc or corn starch should prevent it from sticking to the aluminum when you form it

[Walking Dead]

I am going to give the clear silicone a try and see what happens.  I will put one of my dust gathering sand cast molds up as the sacrifice.

[mark poulson]

You could try bondo, too.  It won't be as hard to remove later.

 

[Fishermanbt]

Give air dry clay a try. I’ve done it on a few cnc molds to block off areas.  Over fill both areas and clean away excess as needed.  Just be sure to give it plenty of time to dry out. Once your done or if you don’t like it scrape the majority off with a plastic knife and scrub with a brush and Dawn soap. Good as new. 

[Walking Dead]

Thanks

[CNC Molds N Stuff]

On 1/27/2018 at 10:44 AM, Jig Man said:

The only problem with using the rtv silicone is getting it out.  I have it in some lead molds and it is a bear to get out when I want to change something.

 

Have you tried pouring some plastisol where you want the block, letting it cool really well than coating it with some kind of slickum then shooting the regular bait.  That might let the new stuff peel off.  Just a thought.  Maybe even plumbers putty.

I would think a little UMR in that area would make the silicone easy to get out.  I use it when casting urethane in aluminum molds.  It should work for silicone as well.  That being said, I don't recall having any issue with food grade silicone from Smooth-On.  I make candy molds out of it in aluminum master molds with no issues.  I've never used a mold release.  I use the same silicone with machinable wax to make rubber stamps.   (For personal use.  The Rubber Stamp Man makes rubber stamps to cheap for me to compete.)  The only one I use is the Smooth-On Sorta Clear with the 4hr cure time.