3D Printing Cores- Is It Possible?

[Jim Cassedy]

I frequently work with 70mm film. The price of 70mm cores, when you can find them
has gotten ridiculous, as you can see from this e-bay listing. $21.95 for one friggin' core!
70mmCore.jpg
This listing is a bit extreme, but prices of $8 - $10each are not unusual.
I remember being able to walk into the professional section of Camera Mart in NY City,
or into any booth supply house & there were often bins of used cores of different sizes
for maybe 25 or 50¢ each or less. Even thru the early 2000's I could find a bucket of
them at Adolph Gasser's Camera Store here in SF for under $1.00 each.

SO- - I'm just curious:
☞How practical would it be for someone to 3D print their own 35 or 70mm cores?
Has anyone here ever tried?

Of course, piles of 'free' 35mm cores are still pretty plentiful in many old film booths.
So, for now, If I don't have a spare 70mm core handy, I use "the poor man's 70mm core"
~ ~ two 35mm's and a bit of gaffer or gorilla tape. ~ ~ and it works just fine!
70mmCore2.jpg

[Michael Zarits]

Has anyone here ever tried?

Yes!

[Brad Miller]

Send me an email Jim. I can take care of you.

[Mark Gulbrandsen]

Jim, Yes... taping two 35mm cores is common as well....

[Steve Guttag]

Most would glue the cores together rather than tape to make a 70mm out of two 35mm. Kodak still makes them. Part number 1699800. Christy's Editorial will sell used ones (and possibly new). Goldberg Brothers may still carry them though I suspect that the need has significantly dropped), likewise for Hollywood Film Company (aka Hollywood Media Services). Fotokem probably has them as they still process 70mm. Brad has indicated above that he can help too.

[John Eickhof]

pick up some ACRYLIC plastic cement, line up two 35mm cores on a 1" wood dowel and cement them together, works excellent, but make sure the cement will weld ACRYLIC plastic, other glues will not work as well do ont use 'super glue' or similar cements. you may have to order it, I get mine from mc master - carr ive been using it for decades to repair sign letters. Once joined they will set fast the just trim off surpluscement with a knife, sandpaper or file, no muss no fuss!

[Marcel Birgelen]

We do have three 3D printers. Looking at the cost to run them, the raw materials and including manual labour needed to finnish the product, I doubt I could produce 70mm cores for much less than $16 per core.

[Thomas Piccione]

Yes! I've printed both 70 and 35mm cores, and they work great! They can even be stronger than commercially produced cores if you really want them to.

[Leo Enticknap]

An archivist friend wanted 9.5mm cores a couple of years back (I now forget the reason why she didn't want to use 16mm ones and not worry about the extra height, but she had a good one): we were able to find a company that would scan one of her last spares, and from that create a file. I was able to print a couple using my cheap, $300 liquid resin printer: as Marcel alludes to, the problem was that it took 3-4 hours, and likely cost $6-7 in consumables. Not a problem if you only need one or two, but she anticipated using 40-50 a year...

[Thomas Piccione]

If anyone would like the 3D models to print out either 16, 35, or 70 cores, I've uploaded them here: https://www.printables.com/model/266...ure-film-cores

[Randy Stankey]

I suggest making a mold of one of your existing cores out of silicone then casting duplicates out of acrylic resin. It would be a lot easier, cheaper and you could make many of them in a lot less time.

Do you really need them to have the exact design of the original? Why not get a long cylinder of an appropriate material in the right diameter, such as Delrin, then cut it into slices of the right thickness. Drill a hole in the center then use a saw, a chisel or a broach to cut in the key slot. The same goes for the slot to hold the tail of the film.

Let's go one better. Why not find a machine shop to make them for you? The design would be fairly easy to draw in AutoCad or with some other similar software. It's just a donut of plastic with a hole in the middle. Precision isn't even that critical is it? A tolerance of ±1 mm. would be more than sufficient. Even an apprentice machinist should be able to produce a plastic donut to that spec. If you find the right shop, you should be able to verbally describe what you want or even give them a hand drawn diagram. Bring them an example to copy and it would be even easier.

Further, once you have designed your part and have approved your prototype, the final design could be kept on file in case you need more. You could have as many as you need, whenever you want, just by making a phone call and submitting a new order.

You could even recover some of your expenses by having extras made then sell them to others.

I live half a mile from the place where I work. There is a machine shop just two miles down the road where my company has their machining work done. We have a large, refrigerator-sized 3D printer that the engineering department uses to prototype fixtures and other things that are used in production. Once the design is vetted, it is sent to that shop to be machined out of metal and/or Delrin.

The place is a, literal, fifteen minute bicycle ride from my house. If I needed something like your film cores to be made, that is the first place I'd call.

[Leo Enticknap]

Thomas - thank you so much for sharing those designs!

The attractiveness of 3-D printing is that you can just pop one out in your home, office, or booth, without any of the investment in time or money needed to work with a machine shop or an industrial 3-D printing/scanning business.

16mm and 35mm film cores are still readily available items (e.g. from Christy or Urbanski), and so if you need them in significant quantities, the easiest and most cost effective solution is simply to place an order. 70mm is a little harder to come by, but Christy claims to have them. 8mm and 9.5mm I'm not so sure about.

If I just needed one or two then I likely would go the 3-D printing route: the sheer convenience would make it worth several bucks a core. But for any more than that, it doesn't really make sense. The only possible concern I would have is offgases if I wanted to mount an archival element on one. I don't know enough about the chemistry of 3-D printing resins and filaments to know whether that would be an issue or not.

[Thomas Piccione]

I don't know enough about the chemistry of 3-D printing resins and filaments to know whether that would be an issue or not.

My understanding is somewhat limited, but going off what I've learned from people I've worked with, the most common thermoplastics used in FDM 3D printing (PLA, ABS, PETG) don't really offgas much at all as soon as they're done being printed. If you really want inert materials, printing in polypropylene is technically possible, though quite a pain.

Resin prints may be a bit more of a minefield. Off-gassing from a completely cured resin part shouldn't be a huge concern, but if your parts aren't completely cured it could definitely be an issue, ignoring the risk of also having liquid resin that could get on film.

With resins though, given their curing is a catalytic chemical process, I would be a little more scared about undesired reactions with the film in contact. I have no solid ground to stand on in saying that though, it's just a hunch.

[Brad Miller]

https://store.film-tech.com/film-products/film-cores

Brand new actual archival plastic cores, designed to fit literally every split reel, flange, adapters and even all designs of clip-together reels. Unlike many of the cores out in the wild, these spin absolutely true to the center, so they won't create cinch marks on the film. They are also the most durable core out there. These are made in 5 inch and 8 inch. Remember the smaller the core, the more stress there is on the film. We have 70mm as well, it's just not listed there yet.