Need ideas on how to make an automatic photo slicer/cutter...

I'm playing with a digital photobooth which prints out 2 vertical strips per piece of 4x6 photo paper.  It works great, and I just cut the paper in half (the long way to separate the two strips.

I'm looking for a way to automate this.  I've tried pre-perforating the paper, which works but is not ideal.  I've also just manually used a paper cutter (both rotary and guillotine style).

My goal: an automatic paper cutter that will cut a 4x6 photo in half the long way.

I've actually started building a device that is basically a slot to guide the paper, and a turning rotary blade.  The paper gets dropped in the top, is drawn through the turning rotary blade in the middle, and is spit out the bottom.  It works on small scraps of paper, but lacks the power to really cut through an entire piece of photo paper.  Also, it's built out of MDF wood and I lack the tools to make it precise enough to cut accurately.

The cutting mechanism seems to be the big holdup.  I tried with my hand - a rotary blade (even a big sharp one) requires quite a lot of pressure to cut the photo, and it's not something the photo paper can just drop through via gravity.  I'd have to get a much stronger motor.

But I'm starting to brainstorm - is there a better way?  I think ideally I'd have a mechanism like an electric paper shredder - two rolling bars with disc-shaped metal blades.  The blades are not thin & sharp like a razer... just sharply-square on their edges so that paper get gets caught between them gets cut.  I'd have a paper shredder with just two of those roller/blades, so it would just cut right down the middle.

However, all paper shredders I've found are cross cut (which would pulverize the photo), or have grippy teeth that mangle the paper leaving very rough edges.

So let's brainstorm... what kind of cutting mechanisms might work?  What are make-able in a garage with limited tools?  How could I create my own custom paper-shredder type roller-blades?

Any ideas, thoughts, questions are welcome.  It seems simple on the surface, but I've built two prototypes and still don't have a workable solution.


(And yes, I'll turn it into an instructable when it gets done)

(I'll try to summarize the current ideas here)

-Use a mini saw blade and work it like a mini table saw.
-Create some kind of rotary die cutter.
-Automate a normal guillotine paper cutter (lots of electronics and sensors).

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I'll get to the bottom of things: Use paper tape to control which motor turns on or off. The tape is punched with holes, reader has electrical contacts. If the hole is there, contacts touch and turn on the motor. If it's not there, contacts don't touch and nothing happens. Use as many rows on the tape as you have motors. Each row controls a specific motor. If you research into paper tape, you may get ideas (for example, it was used on CNC machines). That way, it is completely automated. The only thing that isn't automated is the motor that is making the paper tape go round and round and round...
jeff-o6 years ago
I wonder if you could modify a strip-cut paper shredder, so that it only cuts in one place? Combined with a feeder slot, you could drop your photos in one end and they'd pop out the other side cut straight down the middle.
jumpfroggy (author)  jeff-o6 years ago
It's funny, I think this might be the easiest way to go. Unfortunately, paper shredders have gotten more and more secure, so most of them do "strip cutting" or "microcut", which cuts into strips & cuts those strips into little pieces. That would make mince meat of my photo.

I need an old "strip cut" paper shredder. I actually just bought one to test, but the blades have grippy teeth on them, so while it does cut just plain strips :) it also leaves a real jagged edge :(.

If I can find a paper shredder that a) cuts into simple strips, b) does not have jagged edges, and c) I can remove all but middle two blades, then that would probably work. But I can't find any locally, so I'd just have to start ordering paper shredders online keep returning them until I find one that works. That will get very expensive.
Well, have you tried places like kijiji or craigslist? Hey, maybe you could get one for free on freecycle...
jumpfroggy (author)  jeff-o6 years ago
Good idea... I'll start looking for those. And I'd never heard of kijiji (now ebay classifieds). Interesting. Thanks for the suggestions!
PKM6 years ago
Something like a table saw? Have the blade turning (fast) in a slot in the surface the paper slides over. It would probably shred the paper a bit but might solve the pressure problem.

jumpfroggy (author)  PKM6 years ago
Interesting... My current prototype (I should show pictures) is basically this - it turns the blade while paper goes through. Unfortunately, it's very hard to make a precise enough device. I've got it made out of MDF, a rotary blade, and a gearboxed hobby motor.

In theory, this would be cake. But as I've found, even simple things don't end up working if they're not precise. As an example: I previously had the rotary blade mounted on a threaded rod with ball bearings, and it turned easily. Unfortunately, the nuts that screwed on the rod were not machined perfectly straight (stupid home depot), so there was too much wobble and the whole thing would not turn straight. So in theory, very simple. But without precisely machined parts, it's a no go.

I think a mini-saw blade (like for a dremel) would leave a rough edge. Not sure.
caitlinsdad6 years ago
If you want to make a contraption that even OSHA would be afraid of, how about using motors, screw press, or hydraulic ram to press down on a die or fixed blade that cuts the paper in two? Those industrial paper cutters have a drop blade, and some machinery behind it to generate a lot of pressure as it comes down. Using some linkages would give you a mechanical advantage.
jumpfroggy (author)  caitlinsdad6 years ago
Thanks for the comments, caitlinsdad.

I've been thinking about this. The problem with this kind of blade contraption is not the pressure, it's the precision/alignment.

Getting two blades to line up perfectly so it cuts clean would be hard. Maybe there's some existing device I could modify or use for the cutting part?

I've thought about trying to mod a normal guillotine paper cutter to be vertical, but those are made to scissor (hinged at one end). Plus, even if it worked it'd still be hard to automate.

I'm still open to this idea. Using a die might be very interesting... is there anything like this out there?

Well, there is always cutting the paper in half beforehand, have a paperstop to guide the paper on your chopper. Adjust your printer to take in that size paper. It'll take longer to print but will spit out the cut paper without the mechanical cutter setup.

It could turn out to be a monster if you try to build a cutter since you might need a paper sensor, clamping device to activate to hold the paper, cut the paper, release the clamps, eject the paper...

Have it drop flat into a chute where is stops aligned to the blade. Have the handle on the outside of the booth. If you want your pictures, have the occupants pull down the big lever to chop their photo in half. The pieces drop out of the chute to the user.
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