How interchangeable are parts from donor cameras?

I'm messing around with a Ricoh 300 that I picked up recently. (You can see it in my avatar.) The lens was literally about to fall off of the camera, because several screws were missing inside. This led to the shutter leaves (is that the right term?) coming loose and just flopping around in there in front of the iris. Fortunately, none of them actually slipped out through the wide open lens. Unfortunately some of them got, well, bent. One even has an impression from one screw head or another.

 

It isn't a huge deal, because I bought the camera intending to take it apart with my son and see if we could put it back together--at least what of it that there was. This was the first one I've ever gone into. Now I'm a little bugged to get it back together right. Are these little screws so custom that I pretty much have to use another 300 as the donor, or how widely is worth checking? Other Ricohs of similar vintage? Other Japanese? Other anything? At the very least I'd like to come up with enough screws to hold this together so it can be a shelf queen. Right now it can only lie prone!

 

In any case, it has been fun and given me some confidence.

There's a Ricoh 300 up for auction on the ShopGoodwill site right now. Five days left. But that would be your best bet for a donor, right?

Back in my youth, most people who had old Triumphs or MGs, had two of them -- one for parts.

 

In modern industrial production, mass production of things like your Ricoh make interchangeability of parts from the same model a foregone conclusion.

The only exceptions may, ironically, be some very expensive low production, hand-built, bench-made cameras (are there any left?).

Models that look alike may have more-or-less interchangeable parts, particularly if they are roughly the same age.

It should be kept in mind that camera manufacturers do sometimes change product specifications, of course.

In my experience some screws are compatible and some not, and some look almost right but are not. The best solution I've found is to take apart a bunch of junked cameras, and save all the screws in little canisters, one for each camera. So, for example, there are a small number of screws from a certain kind of Minoltas that are just right for Nikon lens flanges, but there are numerous slight variations of thread and diameter that are so small it's hard to figure out except by trial and error. But it's unlikely that your Ricoh has many truly custom screws, so similar cameras will likely have similar ones. It may depend on how fussy you are about head shape and the like.

Junked cameras is exactly what I'm hoping to run across. The 300 that Bobby pointed me to (thanks Bobby) would be great except I suspect it would make infinitely more sense to clean it up rather than strip it for this one's sake. I actually just pulled a screw out of a bad Nikon D50 body (that I bought to steal a couple of parts from for my daughter) but the threading is more coarse than what I'm looking for. I don't care much about head shape for appearances since all of what I need is internal, but obviously the head has to stay out of the way of other gears and such.

I'll just keep my eyes open for cameras of the same vintage. I would have passed on junked ones previously, but now I'll go ahead and blow $5 on them and see whether they can contribute screws. (Does that sound like the first step to hoarding? If so, don't tell my wife!)

I have a 300 which needs only a touch of work on the shutter to get it back to working condition. The RF is bright & cle420.ar and on the button, and the focusing works well, although a little stiffer than my 519. Email me if interested in buying it - $20

The screws are probably metric. If they are normal flat head, pan head, or round head, it should be possible to substitute. Not that hard to find online. But you need some samples for size reference. But anything fancier than that will be a problem.

Yeah, my problem is more measuring the correct size, both diameter and thread pitch. Some of the screws, and the ones that match what I think I need, are only threaded at the very tip--shaft above that is smooth.

Is there a good way to count threads on these microscrews?

Metric screws tend to come in standard pitches. Find screw data online to get some idea. https://littlemachineshop.com/reference/TapDrillSizes.pdf If you need smaller, the data gets harder to find. Get a good magnifier and lay the screw next to a mm rule. Count the number of threads in 2 mm or so. Say you get 4. 2/4=.5 so the screw has a .5 mm pitch.