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RF Cam dimensions and adjustment?
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RichS



Joined: 18 Oct 2001
Posts: 1467
Location: South of Rochester, NY

PostPosted: Sat Jul 08, 2006 6:26 am    Post subject: Reply with quote

I have just noticed yet another slight oddity and again decided to see if anyone here might have an idea or two?

I am playing with the rangefinder adjustments on a 'parts' Super graphic that really needs some adjustments. No problems so far with the camera. Then I ran into a problem with cams...

I have always held that the cams must have two dimensions that are always identical. The length and the infinity height. The length should be obvious. The infinity height also seems obvious. The rails are always in the same position, all the way back. At this point, the camera will always be focused at infinity. To do this with the RF, the cam arm must always be in the same position, so the cam height must then be the same for all cams. Obvious to me... If I'm wrong, let me know. If I'm just explaining it poorly, let me know

Now, out of 5 or so cams, one has been completely field proven. That's my working 135mm cam. I trust it and use it to compare other cams. While working with the new RF, I didn't want to bother taking out my working cam so used another one. Okay, got the adjustments made and was happy. The next day, I installed the 135mm cam for a final test. Infinity was way off... Out comes the digital mic. Seems all my other cams don't measure up at the infinity point. They're all short b y various amounts. The other thing to notice is that the 135mm cam has been "adjusted" by hammering the bottom tab at the high end. This of course causes the metal to extend and makes the cam higher. But this cam works as does my other 135mm cam which also shows the hammering.

Okay, let's say the 135mm cam is off and the rest of the camera was adjusted to fit. Could be except for one thing, the infinity height on all the rest of the un-hammered cams are not the same. They vary considerably so no two cams agree or could be used at infinity. These cams all look brand new...

So, the dumb question... Were the cams perposefully made short to be hand adjusted later? Or could four other brand new cams be that far out of tolerance as no two cams are the same height?

Either way, this make little sense to me. As I said, the infinity height should be a set standard. There is a specified set standard stated for the Pacemaker cams. I can't find any mention for the Super, in case someone knows this dimension? Why would the cams not be made the correct height?

The other possiblilty I have thought of is that "new" cams we can get now may be left over factory rejects that will be that far out of spec... However, it seems to me that out of 4 or 5 cams, one of them would be the correct height? Just seems odd to me...

Anyone possibly know more details on this? Have I just gotten so many bad cams? Were they designed to be hand adjusted? And does anyone know the height spec for the infinity position, most probably an "alignment cam". It's not stated in the repair manual (although I have been known to miss the most obvious of things).

I can easily adjust all my cams to be the exact same height so this isn't a big problem. I've tested this using my home made cams and it's pretty simple. Before I do this, I would like to know what that specified height should be though?

Thanks for any input...


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Rick from OZ



Joined: 05 Jul 2006
Posts: 37
Location: near Melbourne, Australia

PostPosted: Sun Jul 09, 2006 5:30 am    Post subject: Reply with quote

G'day Rich,

I'm by no means an expert, (this is only my second post) but I'm wondering how you are measuring the height. The cam I have for my Super has angled sides, and the top edge is a curve, so I guess identifying where on the base to measure height from would be tricky. And any inconsistency might explain a small difference ?

I don't have digital calipers to check, and don't know how (or whether we can) to post pictures. But I have uploaded a 40X40mm (4X4cm) scan of my own P33 to my website, in case it helps. Here's the link:

http://graphics.thehills.id.au/SuperGraphicCamP33Rick.pdf
I'll also check with a few friends who might have calipers or micrometers to measure with.

At least this way you can check your 135 to mine.
Compare apples with apples, as they say.

PS: Thanks for providing the scans on your site, too. Pity there isn't a 127mm yet !

Hope it helps.
Rick

[ This Message was edited by: Rick from OZ on 2006-07-19 04:53 ]

[ This Message was edited by: Rick from OZ on 2006-07-19 04:55 ]
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45PSS



Joined: 28 Sep 2001
Posts: 3197
Location: Mid Peninsula, Ca.

PostPosted: Sun Jul 09, 2006 6:14 am    Post subject: Reply with quote

Super, Super Speed manual states for rangefinder calibration: Return to Graflex Service center for adjustment. Maybe someone can coax an engineer out of the Secret Service Center procedures.
Cam #1=36005-P34 0.7055 inches
Cam #2=36005-P34 0.7055 inches
Measurements made with high end of cam perpindicular to jaws of digital caliper, rotating edge from 800 to 1000 varries reading from .0698 to .0706

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[ This Message was edited by: 45PSS on 2006-07-08 23:17 ]
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RichS



Joined: 18 Oct 2001
Posts: 1467
Location: South of Rochester, NY

PostPosted: Mon Jul 10, 2006 4:54 am    Post subject: Reply with quote

Thanks Rick & Charles...

Okay, since I brought it up, I figured I should at least do the measurements to post here also. Unfortunately, it's difficult to get exact positions on some of the cams. So these really come out more a comparison than engineering results...

My 135mm P34:

Height at high (inf) end : .711
Height at infinity position: .695
Length total: 1.5
Length at spring: 1.430

90mm P4:

Height at high (inf) end: .710
Height at inf pos.: .691
Len Total: 1.499
Len at spring: 1.435

250mm P105:

Height high end: .686
Height at inf pos.: .687
Len total: 1.475
Len at spring: 1.440

380mm P156:

Height high end: .685
Height at inf pos.: .686
Len total: 1.470
Len at spring: 1.435


Oddly enough, it really looks like it's my 135mm that's off? The .686 or so is close with the other cams. Off by quite a bit on the P34 and by a little on the P4.
The lengths are close at 1.430 to 1.440. with the slanted sides, measuring this exactly would be more difficult than I'm doing tonight.

If I can't find the correct infinity height at some point in time, I might just have to adjust all my cams for the same height and then readjust the cameras to suit. At least all my equipment would be 'standard' then... Unfortunately, the next measurment should be the spring to infinity position on the different cameras... If that's not the same then I'll just give up

By the way Charles, I read that in the repair manual. Since there's no factory to send a camera to any more and I'm working on a 'parts' camera, I figure why not give it a try. Yes, it's difficult to adjust the arm/mirror to infinity. Deffinity not impossible. The big problem is the simple construction of the locking screw mounted on the arm being directly on the post of the mirror. It tends to move the position when tightened. So it has to be redone a few times to get it in the final position. Once set, it's set. Took me all of 10 minutes, and five of those to figure it out...
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Rick from OZ



Joined: 05 Jul 2006
Posts: 37
Location: near Melbourne, Australia

PostPosted: Tue Jul 11, 2006 12:53 am    Post subject: Reply with quote

Rich,

Another thought.

I just re-read your comment "The other thing to notice is that the 135mm cam has been "adjusted" by hammering the bottom tab at the high end. This of course causes the metal to extend and makes the cam higher" and also your comments in this last post.

Initially I thought (assuming this cam is from a different "working" camera) that maybe the infinity height was extended due to wear on the steel sprung "lever" or "pin" that adjusts the range finder and top scale. Aiming to make it a bit higher, so you still get infinity (on that camera !).

But then I thought a bit more.
I'm not an engineer, but my memories of mathematics suggest that this would change not only the height of the cam, but also the angle of the curved top edge.

I'm pretty sure the curve in the top edge is there to ensure an accurate range at all distances. Hence changing one end of the cam would change all distances on the camera by a different amount ( due to the angle) than they should be.

Still with me ? I'm, getting there !

So if the intent was to match a worn rangefinder "pin" (no idea what it's really called) in your working camera, then to maintain accurate ranges at all distances both the infinity end tab and the close up end tab would need to be hammered to make them higher, and to also maintain the curve at the same angle.

Is this the case ?
If so, then perhaps your P34 cam(s) have been modified to suit a camera with a worn rangefinder pin. If they work with your old camera, then maybe it has some grooves or wear on the pin ? If your digital calipers can reach, perhaps you can compare ?

Although the cams could have come from somewhere else entirely, too !

Hope it helps, if only to remove (add to ?) the mystery
. Rick
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45PSS



Joined: 28 Sep 2001
Posts: 3197
Location: Mid Peninsula, Ca.

PostPosted: Tue Jul 11, 2006 1:29 am    Post subject: Reply with quote

I assume that the Factory instructions were something on the order of "using a collimator, ....., set mirror for hypothetical infinity by......., meaning some of us have to figure out another way.

I see that infinity is not the high edge of the cam as I thought, marked and measured mine at infinity, .0694.
My procedure:
Holding camera so that I was looking down at the cam with the door open I marked the left edge of the cam follower position with a fine point marker, removed the cam, now holding the base of the cam square to the bottom caliper edge measured at the left edge of the mark. One may need to make a jig to hold the cam and caliper square to the bottom of the cam and allow the cam to slide to either side so that the infinity spot can be read accurately. .069xx should be close enough for general purposes.

Is this simular to how you came up with your figures? Use a mirror to elimate parallax?

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RichS



Joined: 18 Oct 2001
Posts: 1467
Location: South of Rochester, NY

PostPosted: Tue Jul 11, 2006 6:27 am    Post subject: Reply with quote

Rick,

You're right about changing the geometry of the slope. But who knows how it's supposed to work?? And if you raise only one end of the cam, the change becomes less as you move away from that end. In this case, the closer you focus, the more accurate it would be. I am guessing now that the modified cam is at fault and just happens to work in the camera? I still haven't compared it to my other P34.

The arm is not worn and I really doubt it would be. A fairly hard steel arm against the soft brass cam, even though they are plated. It is a thought though? After 40 years, who knows what someone may have done? If all else fails, I'll create my own standards for my equipment...

Charles,

Yes, I measured about the same way. It was not practical to get a 100% square on one cam as the infinity spot didn't align with the bottom. The long lens cams are cut at an angle on the bottom so they can be inserted. I have no idea why they cut both corners?

All in all, if noone can find the factory specs for "infinity", then I'll just have to do some critical measuring and decide for myself what the standard will be. Physically, the cams would be easy to adjust as it certainly doesn't take much to make huge changes in the RF.

My big concern now is the stopping point of the cams. If they don't stop moving in at exactly the same position on every camera, then making a 'standard' cam is a waste of time. There's going to be a lot more measuring and comparing coming up soon...

And to think the 210 cam I made worked great... Maybe I should use that as my standard?
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Rick from OZ



Joined: 05 Jul 2006
Posts: 37
Location: near Melbourne, Australia

PostPosted: Tue Jul 11, 2006 9:34 am    Post subject: Reply with quote

G'day again.

I seem to remember in one of the many posts I have read in the past few weeks, someone offering to calculate the correct sizes and curves for the super cams (at least I think it was for supers).

Has anyone any manuals, memories, or other stuff starting with "m" that might help identify the rules used ?

I'm happy to write a macro for excel or something similar, but I only have one cam, and only your scans to go by - and now we are casting doubt on the accuracy of some of them, I'm not sure which way to go

Surely it was written down somewhere ?

The biggest question is what sort of curve is it ? An arc, a parabola, hyperbola ...
Given that, and some judicious measuring of equally spaced points, we should be able to get a computer to figure out the rest.

I'll wait, Rich, until you double check your "other" P34. My P33 looks OK (and relatively new) to me, but then I haven't got a lens to test it with yet, or any other cam to compare to either, so no idea really And it won't match your P34 either (although it should go pretty close).

But with some more measurements anything is possible.

Although I still reckon the design spec must exist somewhere ...

. Rick

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45PSS



Joined: 28 Sep 2001
Posts: 3197
Location: Mid Peninsula, Ca.

PostPosted: Tue Jul 11, 2006 6:36 pm    Post subject: Reply with quote

Rich,
Set the cam bottom against a straight edge so that it sits like it would in the camera.
Using a small square mark the base where the infinity point is square to the base.
Measure with a digital caliper or simular.


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RichS



Joined: 18 Oct 2001
Posts: 1467
Location: South of Rochester, NY

PostPosted: Wed Jul 12, 2006 4:45 am    Post subject: Reply with quote

Rick,

Yes, it's been brought up before about calcs for new cams. I've always thought it would be pretty easy but never had the time to look into it. After all, making the cam is the hard part, by hand anyway. If we could come up with CAD dimensions, then it could be routed to an automated machine for fabrication and produced very cheaply. Someday....

beyond that, Fred Lustig is supposed to have the calcs. I've never heard of him giving them up though?

Charles:

Yes, with a little work those dimensions can be measured. Initially I didn't think this was going that far though. Now that all the cam measure differently and my #1 cam may be the actual bad one, it will have to go the extra mile for more exact measurements. I'll also have to compare cameras...

I would now venture a guess that flattening out the hammered portion of my P34 back to it's original height will only require a readjustment of the tab on the rail. That will take some checkiong too...

Right now I just don't have the time to do all the critical measurements and comparisons. Everything would have been fine if I didn't decide to try and make the parts camera work...

Hopefully in the next week or so I'll be able to devote a few hours to this and see where it all stands. Since I don't really have to worry about the cams for the 250 and 380 lenses, I just have to work out the 90, 135 and 210. Out of those three, the 90 is the only unaltered one as the 210 is home made...

Just more fun to look forward to....


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45PSS



Joined: 28 Sep 2001
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PostPosted: Wed Jul 12, 2006 8:32 pm    Post subject: Reply with quote

Both my P34 cams are factory origional with no alterations. Send me the scan specs and I'll scan them.

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RichS



Joined: 18 Oct 2001
Posts: 1467
Location: South of Rochester, NY

PostPosted: Thu Jul 13, 2006 5:48 am    Post subject: Reply with quote

Very generous offer. I appreciate that!

As far as scan specs... Hmmm. I have images that worked scanned at 300dpi and 8-bit grey scale. Makes for a fairly small image file. 600 or even 1200 DPI may be better? But a larger file... I certainly wouldn't mind the extra resolution

Thanks again...
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Rick from OZ



Joined: 05 Jul 2006
Posts: 37
Location: near Melbourne, Australia

PostPosted: Thu Jul 13, 2006 3:27 pm    Post subject: Reply with quote

Rich & Charles,

I have fairly high res. scans on my website (see above). But unfortunately only my p33/135mm Cam for a Super Graphic.

I believe "Horla" has been covering the Speed / Crown top rangefinder cams.

If someone needs a lower resolution (super cam) or something else, I'm happy to oblige. Just tell me what you want !

I'll do my best.

Thx,
. Rick
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RichS



Joined: 18 Oct 2001
Posts: 1467
Location: South of Rochester, NY

PostPosted: Fri Jul 14, 2006 6:24 am    Post subject: Reply with quote

Rick, I grabbed that high res scan from your site. Hopefully one of these days, I'll get the time to size it and add it to the graphic list of cams. It would be nice if we had available the scans from every cam. I tried to get that done a long time ago and there was little interest. So I get what I can and make it available. For the work involved, I can understand why not too many people would be making their own. It's not really all that difficult though as long as you can manage a proper sized printout.

And Charles, got the scan. Thank you very much. I'll get around to the comparisons soon I hope...


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Rick from OZ



Joined: 05 Jul 2006
Posts: 37
Location: near Melbourne, Australia

PostPosted: Tue Jul 18, 2006 12:32 pm    Post subject: Reply with quote

G'day again guys,

Rich, I have uploaded a smaller PDF file you might be able to just load or copy onto your site.

It's at http://graphics.thehills.id.au/SuperGraphicCamP33Rick.pdf

I have test printed it, and it comes out 1:1

Unfortunately it does that in the middle of a sheet of paper, so unless your printer takes 4 x 4 cm squares ... bit of a waste.

Hope it helps

. Rick

[ This Message was edited by: Rick from OZ on 2006-07-19 04:58 ]
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