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slerman
14-Mar-2020, 12:34
Could use some help on a couple of things. First, is this a Century 8A? If not, what is it? Second, everything works except the geared focus. The parts are all there except for the geared wheel that goes on the shaft of the adjustment knob. How can I go about finding a replacement? The diameter of the shaft is about 1/4" and the track has 14 teeth per inch. Thanks!
201685201683201684201682

jnantz
14-Mar-2020, 19:23
hi
your camera doesn't look like an 8A ( or it might just be the way you photographed it ? )
http://www.historiccamera.com/cgi-bin/librarium2/pm.cgi?action=app_display&app=datasheet&app_id=1462
not sure where you can get parts for your century, I have an 8A and have been looking for parts on and off for 15+ years
with no luck at all.
good luck !
John

Jim Galli
14-Mar-2020, 22:53
Is the lensboard area 9" or 10" square?

Mark Sawyer
14-Mar-2020, 23:57
McMaster-Carr.

slerman
15-Mar-2020, 14:15
Jim, the lensboard is 10#.

slerman
15-Mar-2020, 14:19
Mark, I'm pretty sure there will be a pinion available from McMaster-Carr that will work with the rack. I just have to figure out which one! 201738

slerman
15-Mar-2020, 14:49
John, Looks like some of the photos of Centurys online. The molding in the front. the knurled knobs in the back--although others seem to have a wood, not brass, central track lock. The back also has the raised piece at bottom that, the back's groove fits into. The back tilt and swing seems the same. What doesn't match with yours? Hmmm. Thanks, Scott

201740

Jim Galli
15-Mar-2020, 14:50
201739

It is an 8a. My pinion has 21 teeth

slerman
15-Mar-2020, 14:59
That is very helpful Jim. I had ordered a 20 tooth .25" bore pinion as a guess. Any idea what's the right pitch?201741

slerman
16-Mar-2020, 19:03
201766

Jim Galli
16-Mar-2020, 19:56
That is very helpful Jim. I had ordered a 20 tooth .25" bore pinion as a guess. Any idea what's the right pitch?201741

I’ll work on it tomorrow. Too cold t go back upstairskr

Jim Galli
16-Mar-2020, 23:22
That is very helpful Jim. I had ordered a 20 tooth .25" bore pinion as a guess. Any idea what's the right pitch?201741

Made it back upstairs. 32 pitch. I'd err on the side of too many teeth not too few or diameter might be shy enough for it to "skip".

slerman
17-Mar-2020, 05:37
Thanks for braving the cold Jim! Haven't found one yet that exactly meets that spec. When it is delivered, I'll carefully try out the one I ordered. It is 32 pitch. May be able to shim the plate the positions the shaft to avoid any skipping.

slerman
17-Mar-2020, 07:11
Been trying to date the camera by serial #-- 51567-- on the rear frame. The various online sources don't seem to match up. Any ideas?201781

Jim Galli
17-Mar-2020, 08:40
No idea on ages or how long they were catalogued. Mine has the bigger wood knobs on everything. Also the shaft on mine goes all the way from side to side so that both knobs turn when it's rolling out or in. Mine is in the 125XXX number so likely newer than yours. Also the way the geared movements work is less machined and probably cheaper to produce. All this stuff changed during long runs.

tonyowen
18-Mar-2020, 08:38
That is very helpful Jim. I had ordered a 20 tooth .25" bore pinion as a guess. Any idea what's the right pitch?

The tooth pitch is measured from the rack. The number of teeth on the gear [pinion] is the circumference of the outside diameter divided by the rack pitch and then reduced to the next, or next but one whole, number. Since the number of teeth and pitch are measured at the pitch diameter of the gear [pinion] which is smaller than its outside diameter.

Conversely, if you know, or can guesstimate, the pitch diameter of the gear/pinion then (pitch diameter x pi [3.1416])/ number of teeth gives the pitch

regards
Tony

slerman
18-Mar-2020, 18:13
Tony, never would have figured that out on my own. Thanks, Scott

tonyowen
19-Mar-2020, 07:01
Tony, never would have figured that out on my own. Thanks, Scott

You're welcome
A point of clarification - to measure the pitch of the teeth on the rack - measure over a 'large number of teeth' then divide that value by one less than the number of teeth. The more teeth over which you measure will give a more precise value of pitch --- (distance measured over N teeth)/[N-1]
regards
Tony

jnantz
19-Mar-2020, 14:26
John, Looks like some of the photos of Centurys online. The molding in the front. the knurled knobs in the back--although others seem to have a wood, not brass, central track lock. The back also has the raised piece at bottom that, the back's groove fits into. The back tilt and swing seems the same. What doesn't match with yours? Hmmm. Thanks, Scott

201740
hi Scott

never mind, it was the way you photographed it !
John