Blow molding vs. Vacuforming

[Dr. Snuts, M.D.]

Which is easier and cheaper with the least margin for error for a beginner? I understand it probably depends on the subject more than anything else. Does one work better with male or female plugs? Which gives the best level of detail? I have a big honking compressor but no vacuum pump. I'd be interested in making some pieces anywhere from 3-12"+. Any advice or links would be greatly appreciated.

Thanks in advance,

Paul

[kenlilly106]

Depends on the level of detail you're looking for, you really can't go wrong with a good female mold when it comes to detailed parts.

I think one of the advantages to a standard table is that atmospheric pressure (14+ psi) is working for you, while with blow molding you'll have pressurize the mold to that, which means the mold will have to be stronger since you're making a small bomb.

What exactly are you planning on making?

Ken

[DX-SFX]

Technically, blow moulding is done inside a rigid two part mould. It's like inflating a hot plastic balloon inside a hollow mould then splitting the mould open when it's cooled. Vac forming over a male mould means the surface of the pattern doesn't have to be brilliantly finished since the surface against the pattern will be on the inside but if you want your finished item to have recessed panel lines then you need to vac into a female mould. The blow facility on most vacuum formers is for releasing pulls from the pattern or blowing large hemispheres freehand.

[kenlilly106]

Another thing about blow molding is that I've never seen something blow molded that had a sharp level of detail, it's softer than a female vac molded kit, but a little sharper than a male molded vac kit.

Ken

[Dr. Snuts, M.D.]

Thanks for the info guys. My plan was to make a one-off hollow styrene hull for a larger starship idea I had. Since its a one time thing, I can add the detail after the main shape is formed so I guess a make mold would work. The difference in the level of detail was really what I was curious about. Its something I never tried and thought I'd give it a go.

[DX-SFX]

Carve a pattern and vacform it.