Newbie- Negative Molds

[schllac]

Hello , I am new here and I am looking for some direction and I will explain.
I want to make a negative mold of a photo from a computer and it will be about 3 inches in diameter. An example of what I want to use these molds for would be say clay forming. I want to be able to pres the clay into the mold to copy the picture in clay. I want to be able to do this by having a person send me a picture on the internet and then be able to download it to a laser or milling machine and then be able to cut the picture in aluminum to form the mold. These molds are all different as all the pictures will be different.

I am thinking of a table top cnc laser, I had asked a person if this could be done with a cnc milling machine and he suggested a laser.

Does anyone know how to accomplish this, I have to be careful as I dont want this to be cost prohibitive. I understand that the machine will be a cost.

Thank you
Schllac

[awerby]

but I suppose it depends on the look you're shooting for. Of course, you can't simply make a mold from a photo, since a photo is flat. So you have to decide what it is about the photo that you want to translate into the third dimension. If the photo is highly linear, then you can trace each line in a computer program, and then use those traces to guide your laser (or an endmill in a CNC mill). If it's more a series of gray-scale gradations, then you either have to arbitrarily decide where to place your lines to bring out the shapes you're interested in, or use a different process called a "heightfield" to create a relief where the lightest pixels are the highest, and the darkest ones the lowest points of a mesh. This can then be used in a CNC mill, which can carve it out. Of course, this process will generate certain artifacts which might detract from its realistic appearance, but that goes with the territory.

If you are planning to press clay into these molds, then plaster is a better material than aluminum, which tends to stick to clay. It's easy enough to carve your relief as a positive in machinable wax, and to make a plaster mold from that, although some people have had success in carving plaster directly.
If I were you, I'd start with some inexpensive software that can do the modeling or drawing part of this, and see how I liked the results before investing in expensive production equipment. There are plenty of people here in the Zone who can do a test carving or laser cut for you, once you have a model you're happy with.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

Originally Posted by schllac Hello , I am new here and I am looking for some direction and I will explain. I want to make a negative mold of a photo from a computer and it will be about 3 inches in diameter. An example of what I want to use these molds for would be say clay forming. I want to be able to pres the clay into the mold to copy the picture in clay. I want to be able to do this by having a person send me a picture on the internet and then be able to download it to a laser or milling machine and then be able to cut the picture in aluminum to form the mold. These molds are all different as all the pictures will be different. I am thinking of a table top cnc laser, I had asked a person if this could be done with a cnc milling machine and he suggested a laser. Does anyone know how to accomplish this, I have to be careful as I dont want this to be cost prohibitive. I understand that the machine will be a cost. Thank you Schllac

[mcphill]

You would need a very powerful laser to burn away aluminum to any depth. How deep are you wanting to carve in to make your mold?

I think I disagree 100% with whoever suggested a laser over a mill. I think milling is the way to go for this work. That said, it will also be quite expensive and time consuming to machine high quality pieces - how much were you planning to charge and were you planning to make just one copy?

[schllac]

I only want to go about 1/8 deep, I am looking for a pencil sketch basicly but I want it to resemble a reasonable facimile. I would oike it to look like a quarter with a little indent if possible. Insofar as the cost I have to keep it as cheap as possible so I dont make it unafordable. It will be a one time cut. I have been searching for some sample pictures of what I am looking for but to no avail. Basicaly I want to mold a cookie and bake it but I want to have a persolized picture on it

[eaglezsoar]

See this link for the best and least expensive software to create GCode from
BMP or Jpeg. It was created by a talented member of this forum.

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[laurencen]

Hi, little off the topic but where could I get a solid file for a skull that can be milled, I have looked around and to date have not found anything, I want to make a 3d skull and cast around it

Thanks in advance

[mechengineer]

Originally Posted by schllac I only want to go about 1/8 deep, I am looking for a pencil sketch basicly but I want it to resemble a reasonable facimile. I would oike it to look like a quarter with a little indent if possible. Insofar as the cost I have to keep it as cheap as possible so I dont make it unafordable. It will be a one time cut. I have been searching for some sample pictures of what I am looking for but to no avail. Basicaly I want to mold a cookie and bake it but I want to have a persolized picture on it

Without knowing much about what you want, I will provide my best thought of where you may want to look: If you are only doing one off's, I would look into 3D printing. A lot of new materials can withstand hot temperatures enabling you to create the "mold" to create the cookie straight from a 3D printout. Worst comes to worst, you may be able to print the mold for the clay and then go from there. I really would have to know more about this before suggesting a "good" idea though.