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Photo Forum / Film Photography / Medium format / August 2004120/220 spool/film dimensions
Hello: Does anyone know 'spec' or typical spool measurements for 120/220 film? I measured one, and it's kind of 'ovoid', of non-circular cross section. I am doing some calculations to scale for larger film spools. I averaged the two different diameters. It would seem that the film must wind 'lumpy' also. Thanks Murray Some of the dimensions can be found at http://medfmt.8k.com/bronfilms.html Length: 2.466 inches Flange Diameter: 0.990 inch Core Diameter: 0.468 inch At http://www.medfmt.8k.com/mf/620.html you can find the following: = = = = = Begin Quote = = = = = 120 width is specified by Kodak as min. 2.41, max 2.45 inches, while 620 was specified as 2.421 and 2.425 respectively. 120 film and paper will fit inside the flanges of a 620 spool, since the inner flange-to-flange dimension of both 620 and 120 is for all practical purposes identical, and of course hundreds if not thousands of re-spoolers know that from experience. The the exterior flange-to-flange dimension is a different story. Here are some caliper measurements 120, metal spool flange thickness, approximately 1.4 mm (quite variable). Total spool length is about 65.3 to 65.5 mm. 620, metal spool flange thickness, 0.5 mm. Total spool length, about 63.7 mm. = = = = = > Hello: > [quoted text clipped - 10 lines] > > Murray Thank you. While on the subject...dumb question... 6x6 and 6x4.5 - are the spacings a bit more than that due to frame separation? I think I measured 47 mm (4.7 cm) between numbers the other day. I'm trying to determine empirical numbers for spool diameter increase with each frame for 4.5, 6 and 9 cm frame width, or whatever their actual numbers are. This is to perform film 'counting' by winding knob turns. 'Fill factor' will be less than 100% probably due to variable tension. Thanks Murray > I'm trying to determine empirical numbers for spool diameter increase > with each frame for 4.5, 6 and 9 cm frame width, or whatever their > actual numbers are. Does it work simply to measure the printed numbering on a discarded paper backing? (I ask instead of measuring it myself :)). Seriously, I can hit the trash and measure one if you like. I measured numbers on processed film...here's a laugh...I measured the spacing of the first pair and the last pair of numbers, and I was both impressed and puzzled how similar they were...for a few seconds...then I realized they're supposed to be!!! It's the number of turns that will change as the spool 'fattens up' with film. I guess the undeveloped film won't me much thicker than the developed - my Agfa XPS 160 per data sheet has 18 micron (0.0007 inch)thickness...so I can just measure the thickness of film. I have a some scrap 120 paper somewhere too... I was just asking intead of misinterpreting what I see. Murray Hi Murray! ;-) just a pointer, that different 120 films have different spool dimensions, a problem which I/we uncovered and documented in http://medfmt.8k.com/mf/spool.html I also suspect you will find this very VERY sensitive to your starting point when loading film. The "fix" for some Kiev and other film spacing problems has turned out to be as simple as adding another inch or so on the takeup spool past the arrow when first starting. Enough to be "Fatter" around the spool than without the extra turn(s), and enough to space out some of the film, but not enough to go off the end of the last film shot So you may find yourself being "alice in film-spool wonderland" ;-) and discover that Ilford is different from Fuji which is different from Kodak spool dimensions - and they have in the past all differed, it seems ;-) hope this helps, or at least clarifies some "got-cha's" ;-) regards and good luck in your project bobm  Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* >So you may find yourself being "alice in film-spool wonderland" ;-) and >discover that Ilford is different from Fuji which is different from Kodak >spool dimensions - and they have in the past all differed, it seems ;-) Going by recent worrying news, at the current rate, there'll only be Fuji left producing 120 film soon, and the problem will be solved. :-( Ugh - too complicated... Considering the imprecision with which I am counting turns, I think I will just load 220 leader paper taped to old 120 film on both my folders, take count for each (tension may vary), and log my shots. The first frame will be the smallest roll diameter on the takeup (wind), so if I use that number for turns, it'll be overly generous later in the roll (wider spacing). I am going to gamble on reasonably similar leader/trailer lengths between brands of film (famous last words). Murray > Ugh - too complicated... > [quoted text clipped - 10 lines] > > Murray Murray why not design an indexing plate that will set the spacing for you? Murray why not design an indexing plate that will set the spacing for you? Not sure what you mean - you can probably tell from my thinking that I am not as mechanically inclined as I need to be to get myself out of some of the trouble I get into. Murray Most modern magazines have an indexing or dividing plate with slots cut in to the edge and is designed for 120 or 220 film, the plate sets the frame spacing along the length of the film. Mamiya, Hasselblad and Bronica all use this type of system. A much easier system then trying to calculate roll diameter and the parts are available off the shelf so to speak. Mike > Murray why not design an indexing plate that will set the spacing for > you? [quoted text clipped - 4 lines] > > Murray I think it'll take a few more steps for me to figure it out and mechanically implement it (if possible for me) than it will to test drive a roll...if I fail dismally, I'll consider a more elegant solution. I took a 'doomed to success' approach...I bought a 5-pack of 220 film, and since I'm stuck with it, I have to do the experiment. Murray I think it'll take a few more steps for me to figure it out and mechanically implement it (if possible for me) than it will to test drive a roll...if I fail dismally, I'll consider a more elegant solution. I took a 'doomed to success' approach...I bought a 5-pack of 220 film, and since I'm stuck with it, I have to do the experiment. Murray |
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