New plug/master with a draft build

[raxton]

Hello I basically have a cf part that is a rectangular box with vertical walls and rounded corners. I made a split mold so I could remove the part.

Now I want to get away from the split mold due possible vacuum leaks, a small seam that requires a decent amount of post work, etc. So I have heard the minimum draft or degree of the vertical walls should be 2%. I want the parts wall to have a minimal draft so should that be adequate? I use frekote release system which has been working fantastic on my split mold.

I have been running through my head about hand building the plug as I did the first one without spending the money on cad/cnc. If all of my walls are exactly 2% greater on top then bottom that should kick out my rounded corners perfectly off the 2 axis also correct?

Any pointers would be great…

[zac]

zyvax release has a super slippery #5 I think. suitable for zero draw.

[Blackrat]

how big is the part ? whats the length of the sidewall ?

why dont you use one of your parts as a plug ?

[Roger]

2° is good for most parts. I’ve done less and I’ve done more. Deeper parts are better with more draft. For instance a shallow box of 2" depth could be almost zero draft and pull okay while a box that is 36" deep would be hard to pull (maybe impossible) at zero.

Mold longevity is also affected by draft, or lack thereof. Surfaces can get scuffed easier with low draft molds.

Now, on your question about the mold you want to build, if the panels are square, the corners will have to be conical. If you want to keep a constant radius along the corner, the panels will have to be trapezoidal in shape.

[raxton]

Thanks for the replies guys;

zyvax release has a super slippery #5 I think. suitable for zero draw.

nice will have to test that product out a bit, one concern is I am using an IMC and don’t want fish eyeing as my parts are very cosmetic.

how big is the part ? whats the length of the sidewall ?

why dont you use one of your parts as a plug ?

I want to get away from using a split and my part isn’t perfect with the angles so even pulling it from a slit mold is a little binding.

2° is good for most parts. I’ve done less and I’ve done more. Deeper parts are better with more draft. For instance a shallow box of 2" depth could be almost zero draft and pull okay while a box that is 36" deep would be hard to pull (maybe impossible) at zero.

Mold longevity is also affected by draft, or lack thereof. Surfaces can get scuffed easier with low draft molds.

Now, on your question about the mold you want to build, if the panels are square, the corners will have to be conical. If you want to keep a constant radius along the corner, the panels will have to be trapezoidal in shape.

Nice Roger, yea the part is 36" x 24" x 24" approx so it has a lot of surface area. I was thinking of also making an access on the bottom of the mold so i could get some wedges from underneath.

That answered the question that was pretty blurry in my mind, conical. So yea I think making them trapezoidal and then working off that would be my best bet. Thank you.