Properly photographing a 3.5" floppy disk for archival is annoyingly complicated. The label has THREE sides!
I've already built an automated system to take a picture of the front of a disk, but really I need to take THREE photos if I want to get the whole thing.
That means either three cameras or I need to rotate the disk 90° and then 180°, which is going to really stress the limits of my mechanical engineering skills.
Turntable? With the floppy sitting in the middle, on its side edge? With the camera fixed in position, the top edge will be a little closer to the lens, but can be rescaled?
@foone May I suggest a PCB holder that is commonly used for soldering? That should work with the size of a floppy disk.. and I'm sure you could attach a servo to the axis to spin it automatically.
So the front is easy. The disk slides down a slide, it's stopped by a servo, I take a picture with a camera aimed down at it.
The back... Either I flip the disk, or I have a camera under the disk which takes a picture aimed up.
And the edge is the worst. I can't have a camera aimed at it unless I either move the camera out of the way of the disk, or I make the disk move in an L shape
The only downside then is that the focus can't be exactly right, since the back/edge will be further away. I'd need to either adjust the focus while taking pictures or have some of the sides slightly out of focus
And the question of where to place the mirrors gets tricky. I'm not 100% I can even place them appropriately without getting really complicated with multiple mirrors, or having the mirrors be in the path of the disk
Mirrors could also cause a slowdown: if I can't mount them well enough that the motion of the disk and drive mechanism doesn't shake them, I've got to add an additional delay while I wait on the mirrors to stop vibrating so I can get a clean picture
If I can rotate the disk sideways I might be able to solve the edge problem. Then I could just have a second camera that aims at the edge.
I could rotate it sideways with some static obstacles, but I may need a servo mechanism or something to do a 180 flip to get the back, unless I do the transparent glass thing.
The disk comes out, it whacks into a bumper and rotates 90° sideways, and three separate cameras photograph it at once, then something ejects it?
The problem is that all possible answers for this problem (other than "don't worry about the edge and back") are either going to be tricky to design and fiddly to operate, and expensive in terms of cameras.
The best designed option would probably be a sort of carrier that rotates. It'd have to grab the disk by the edges, but if it could move the disk from the original orientation, to 90° for the edge pic, then 180° for the back pic, it could then rotate to like 270° to drop the disk.
That might be the most reasonable option.
It would require variable focus on the camera, since the surface it's photographing is closer for the edge picture.
My idea is to replace this slide & stop-servo system with a rotating cylinder carriage. It'd have grooves down each side where the floppy can slide, and it's stopped from sliding all the way down by the enclosing 3D structure. Then it can rotate to different positions for different photos, then finally to a position that lets the floppy fall out the bottom
Quick first pass/mockup. The floppies slide into this, and then it's embedded into a larger structure that can use a motor to rotate it. One camera, three positions of the carriage, and then it rotates to drop the floppy out.
@foone@The4thCircle I'm almost certain for the money you're spending on multiple cameras and 3d printed gadgets you could just hire a couple poor slobs on fiverr and make them take the pictures by hand...
@kerio A big lens? I talk about setting up a mirror system earlier in the thread. I'm not sure what you mean by a big lens, though. I need to photograph three sides of the object at once.
And I'm not gonna do this destructively, especially because I have thousands of disks like this. I don't want to destroy them all!
Next step: Widen up the slide area a bit so it's smoother (ideally I'd have metal or something here, but maybe I can sand down the 3D printed surface), add holes for rods to hold it at the right width, a mount for a bearing on one side, and a servo motor on the other side.
The servo motor might not be the best way to go, it might be better to use a geared system with a stepper motor, but that's more complicated. So I'm probably going to build it with a servo motor and only look at the stepper motor option if that doesn't work out
@foone May I share unsolicited printer advice? It looks in this photo as though the nozzle is partially clogged and is causing extrusion issues. You may get better results / less fragile prints if you get a needle or nozzle unclogger folks sell.
@k1m yeh, it's a known problem. These were done very quickly when I didn't have time to clean the printer. I'll definitely fix it before I do the actual prints.
To avoid the dual camera you can put the camera on a sliding carriage moved by another servo (via a lever) to adjust the focus when imaging the side. two positions 1.75 inch apart are enough.
@foone That's awesome! I'm wondering if you can avoid having to focus the camera if you rotate the floppy at the edge and center the camera on the edge?
I made a little cardboard model: 1. Floppy goes in, picture taken of back. 2. Rotate 90 degrees, picture of spine. 3. Rotate 90 degrees, picture of front. 4. Rotate a little more and dump the floppy.
The camera distance remains the same without distortion and gravity does the alignment. Hopefully. I have no idea how finicky this would be. 😅
@foone this does not solve the out of focus edge problem. One solution is to have the cilinder radius be double the floppy height. This way the edge is exactly at the center, so when you rotate, the subject is always at the same distance from the camera
@foone for single camera use, you could ~double that radius with the floppy sitting between one edge and the center, so that when rotated both sides and the edge of the label are the same distance from the camera.
@foone You don't have to have the pivot point for rotating the disk in the center of it. If you put the pivot point right next to the edge you also want to photograph, both sides and the edge will be at the same distance to the camera.
@foone could you maybe slide the disk down already 90° rotated to the left or right? Then you could have one of the sides transparent or have slot there to take a photo of the top of the disk?
@foone I don't know the actual copier mechanic: How about an old-fashioned linear CCD sensor mounted above/below the drive entry and scanning the disk when it enters/leaves the drive?
That leaves more options for scanning the top, including scanning them in the hopper in bulk (requires on opening) or by moving another linear CCD across the drive slot while the disk is being copied.
(Your nice rotation device prototype would go unused, however 🤷)
@foone I have been looking for something like this for 20 years. Would you happen to release the prints as well as full instructions on how to replicate it? Got me loads of disks that I'd like to copy, but stopped because manual work...
@mctwist I intend to release my designs once this is more finished, yeah.
The big problem is that it depends on an existing floppy copier which you need to retrofit: so it's not a from-scratch solution. I don't know if I'm going to get to a design I can build from scratch, but it'd be nice
If you let the disk fall/slide into a slot shutter-side-first (and stop it there for a while, presumably with another servo) you could probably use the same camera for front and side.
@foone wouldn't focus and vibration be mitigated by fast shower speed and high f stop? Then what you need is either high ISO or a lot of light. Alternatively you could see if you can automate your set up to use focus stacking for the different planes.
@foone it would take work to make a tool that could un-distort the pictures, but you could have like, a toaster-like holder with cutouts for the label, put disk in door-down
mirrors on the sides, flat on the table
and then in some fixed setup, take two pictures, one at each known focal distance (mirrors, labels), and then have the computer stitch them together into one long label with your custom tool (one may exist without much tweaking i dont know the space)
@foone should be easy: two mirrors, one for the front, one for the back, the edge is directly exposed to the camera. Both sides are then the same distance away. With enough light and a good lens you should be able to get enough depth of field to cover the length to both sides and the edge. Worst case the edge is slightly out of focus. It’s probably the least relevant anyway.
@foone With some more mirrors you could get all 3 distances to be closer to equal (getting them exactly equal is not that helpful given that even one side is not at a constant distance from the focal point, unless you arrange for some lens arrangement that has an effective focal point very far away).
@foone what if you put the disk on its side and used a single 45° mirror for each of front / back / side? You could have a trapdoor at the bottom to drop the floppy out once it's photographed.
@foone I wonder if a 180 degree wide angle camera could get a decent pic that could be processed and separated into 3 images. Super useful if you get this figured out!