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bartbob
Joined: 30 Oct 2010 Posts: 102
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Posted: Sat Jul 02, 2011 1:07 am Post subject: Making a SSG Rangefinder Cam; Error in Instructions? |
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Pulled up 45PSS's instructions on making rangefinder cams. The section listing cam height for several distances has these mid-range numbers:
15 feet - .664
10 feet - .647
8 feet - .638
7 feet - .634
6 feet - .618
Is the 8 and 10 feet height numbers correct? Plotting these on an X-Y curve, it looks like they should be a bit higher. The curve of dots on graph paper with the X axis being evenly spaced "feet" numbers and the Y axis being cam height, all the "feet" numbers except 8 and 10 plot a good curve. Maybe I'm wrong, but it looks odd to me.
I'm getting a Graflex 90mm Optar in a Wollensak shutter and will make a cam for it using these instructions. |
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45PSS
Joined: 28 Sep 2001 Posts: 4081 Location: Mid Peninsula, Ca.
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Posted: Sat Jul 02, 2011 3:36 am Post subject: |
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At the time I made the measurements I had 3 Super Speeds with factory matched cam/lens. 2 of the 3 camera/lens/cam combos has the same cam number and the third a different. The rangefinder was removed from a 4 th. body and used to make the cam measurements. All I had to do was position the cam according to scribed lines and measure between the follower and housing (cam base). I have made cams for a 100mm WFE, 162 Paragon, 203 Ektar, and 254 Wollensak. My crude cutting/grinding resulted in cams that are within .001 bed travel of perfect.
I too would like to hear from others if they have used the procedure/measurements to make cams from scratch.
So, yes I'm 99.99% sure the measurements are accurate. _________________ The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU. |
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bartbob
Joined: 30 Oct 2010 Posts: 102
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Posted: Sat Jul 02, 2011 5:43 pm Post subject: |
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Thanks, 45PSS, for the confirmation. I scanned my P34 cam from my SSG and sized it to 1000 dpi at full scale. I'll use it's X and Y values to check it's profile.
Your numbers just looked a bit off, but after reading your reply, I think I need to remeasure. |
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1banjo
Joined: 16 Nov 2008 Posts: 492 Location: kansas
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Posted: Sat Jul 02, 2011 8:07 pm Post subject: |
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Now I made my first cams more like graflex would made the first cam ever
and that is to start at a target at 300' focus on the ground and make the
cam right there then I set a target at 5' making my cam right there
then I put a line from 300' to 5' and ajusted it every 5 ' up to 75' ,150',,,300'
so focusing a target on the ground every 5'
this takes some time BUT my cams work out bether then the cams that come
with my next Super Graphic + I didn't find the right cams to work some of the Newer Lens that I have I now have cams that work from my 90mm upto
my 250mm
I never tried to use a X - Y curve
banjo |
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bartbob
Joined: 30 Oct 2010 Posts: 102
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Posted: Sat Jul 02, 2011 10:25 pm Post subject: |
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1banjo wrote: | Now I made my first cams more like graflex would made the first cam ever ......banjo | That's good, but did you "make" the cam by grinding it's curve at the point where the rangefinder arm point contacted it when focused at each distance to get coincidence? |
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1banjo
Joined: 16 Nov 2008 Posts: 492 Location: kansas
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Posted: Sat Jul 02, 2011 11:30 pm Post subject: |
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yes it end up smoth as 5' increments aint like 1/2mm apart on the cam |
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