Project image
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$22,922
pledged of $47,700pledged of $47,700 goal
149
backers
Funding Canceled
Funding for this project was canceled by the project creator on Jun 26 2017
$22,922
pledged of $47,700pledged of $47,700 goal
149
backers
Funding Canceled
Funding for this project was canceled by the project creator on Jun 26 2017

What is a prototype?

A prototype is a preliminary model of something. Projects that offer physical products need to show backers documentation of a working prototype. This gallery features photos, videos, and other visual documentation that will give backers a sense of what’s been accomplished so far and what’s left to do. Though the development process can vary for each project, these are the stages we typically see:

Proof of Concept

Explorations that test ideas and functionality.

Functional Prototype

Demonstrates the functionality of the final product, but looks different.

Appearance Prototype

Looks like the final product, but is not functional.

Design Prototype

Appearance and function match the final product, but is made with different manufacturing methods.

Production Prototype

Appearance, function, and manufacturing methods match the final product.

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Prototype Gallery

These photos and videos provide a detailed look at this project’s development.

About

The Basics:

The SP-2810 will process two sheets of 8x10 or 4 sheets of 5x7 sheet film in two liters of chemistry.

It sounds simple. Just take the SP-445 and make it bigger! Not so fast. Things don't usually scale up that easily and this is no exception. To put it in perspective, the steel mold for the SP-445 tank (just the tank) weighs around 485 lbs; the mold for the SP-2810 tank is expected to tip the scales at 3000 lbs. This is a much more complicated project.

The tank: As stated above, this is a big tank. In fact, early testing shows that it will probably need a clamping mechanism to hold the lid on when inverted. You can see a prototype in the photo gallery.

The real bottleneck isn't the bottleneck: We experimented with a larger cap size, but it didn't speed things up. The limiting factor is actually the baffle plates inside. We can open these up a bit and improve the fill/drain time.

Filling it is a challenge; you can only pour so fast. Pouring in two liters of liquid as fast as you dare can get messy. A funnel is almost essential.

Film holders: First, note that an 8x10 sheet of film is fairly "floppy". (In fact, instructions for old style dip tanks warned users not to move the frames too fast, or the film might pop loose.) We also wanted to accommodate X-ray films that have emulsion on both sides. With these restrictions in mind, we designed the "book" style film holders.

8x10 frame rendering
8x10 frame rendering

The 5x7 film holder is similar but with two pockets.

Yes, we are looking into dual-sided film holders (two sheets of 8x10 per holder; 4 sheets per tank). However, we have not made the commitment yet.

Schedule:

If all goes well, we should be testing the next prototype by the end of June and the production version in July. That gives the factory August/September to finish the molds and start our first production run.

Rewards would then ship in October.

That seems like a lot of money...

Not really. Not when you consider that there are more molds and the molds are much larger. As we've said, the tank mold alone is 6x the size of the SP-445 mold. These require higher pressure injection presses. We'll probably have two molds for each film holder, a lid mold, tanks mold and maybe a mold for the baffle plates (might fit those in with the lid; not sure yet.)

The raw material cost is also much higher: the Sp-445 weighs about 7 oz; the SP-2810 weighs over 48 oz. The larger size also means longer cycle times on the press.

In addition to the molds, we've got at least two more prototypes to build and many hours of testing ahead of us.

Changes, Comments and questions

While we have a solid idea of how the SP-2810 will work, we're pretty sure there will be tweaks and modifications ahead. We'll do our best to keep you posted via this forum and our newsletter from shop.stearmampress.com.

We're always happy to answer questions and sincerely appreciate your comments. 

Please share on your social media; it really makes a difference.

Risks and challenges

The increased size means increased challenges. While none appear to be insurmountable, they must be anticipated.

1. Getting the lid to seal: we don't believe the "squeeze play" will be adequate for this large of a tank. We've already started prototyping a sliding lock mechanism.

2. Optimize the Film holders: the "pocket" that holds the film can't be too big or too small; it also needs to be just deep enough.

3. Shrink the tank: right now the tank holds just over two liters; we need to squeeze it down to under two liters.

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Support

  1. Select this reward

    Pledge US$ 117 or more About US$ 117

    SP-2810 8x10 version

    One SP-2810 with two 8x10 film holders.

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    73 backers
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  2. Select this reward

    Pledge US$ 117 or more About US$ 117

    SP-2810 5x7 version

    One SP-2810 with two 5x7 film holders.

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    6 backers
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  3. Select this reward

    Pledge US$ 147 or more About US$ 147

    SP-2810 Combo! 8x10 and 5x7

    One SP-2810 with two 5x7 film holders and two 8x10 film holders.

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    Estimated delivery
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    66 backers
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Funding period

- (30 days)