How does the safety mechanism--the lock that prevents the curtain from being rewound when the mirror is up--on Graflex reflex cameras work?

I have been working on a Home Portrait Graflex, cleaning and adjusting it, and have gotten it just about right, but the safety lock isn't working since I took the top panel (curtain setting and release) apart and pulled out the top roller for the curtain. Does anyone know what I should look for to get the safety mechanism working again? I am delighted that the camera is working again, but would prefer that the lock mechanism functions as intended. Right now I can wind the curtain with the mirror up, but before taking it apart the curtain wouldn't wind with the mirror up.

Thank you.

jason

A picture of the gear side of your wind plate will be the most helpful.
Graflex used several versions and refinements of the wind plate from introduction of the SLR to the end of production.
The main wind gear is directly connected to the wind key and is the center of the mechanism. The wind counter is offset from the main wind gear, lays in place, and is driven by gearing on the main wind gear.
The outer gear teeth of the wind gear mesh with the top roller.
The main wind gear is held in place in a machined bushing by a pin at the wind key. There should be less than .001 inch end or side play in the wind gear/wind key assembly.

The back side of the wind gear has two ears 180° apart. One side of the ear is tapered and the other flat.
There is a regulator that mounts over the gear. It is spring loaded to the stop position. It has a slot on each end that it slides in. When at the normal position (mirror down) the wind gear will turn in the curtain wind direction only. When at the release position it allows the gear to turn in the opposite direction 1 turn.
The M lever pulls the regulator to the to the release end of its travel when it is pulled toward its travel limit. The M lever is operated by the mirror shaft when the I/T selector is in the I position. The I/T selector is pinned to the mirror shaft.

There are two possible causes for your problem, you misassembled the mechanism or wear is preventing the mechanism from reaching the proper position. Check that the M lever is moving the regulator to its travel limit when operated by the mirror shaft.

I think I resolved it, thank you. I think the brass part marked "A" had been bent, and was not engaging the tab on the gear.

And this is a design I have not seen before.
Flush it with degreaser, apply a light coat of while lithium grease to the gear teeth, the screw slots at 3, 8 and 10 o'clock, and the spring end at the regulator, a drop of oil to the A arm pivot pin, the screw at 9 o'clock, and two or three drops to the wind gear shaft at the wind key joint.
Operate it several full revolutions then wipe off any excess oil or grease.
Rotate in the wind direction backing against the stop until the curtain aperture identifier is centered in the window. Assemble at O or closed after O.

Thank you. I will clean and lube it as you suggest.

For reference, this is from a very early (~1913) Home Portrait.

I see now the A arm is riveted in two places, no need to oil it.
There is a pin in a slot at 2:45. I assume it is the M lever contact. Apply a small dab of grease at the pin to lever contact.

I cleaned out the mechanism, and the camera is quieter (relatively speaking) and seems to run better.

That said, the speeds are off. The speeds at the lowest tension are slightly faster than they should be, and the speeds at the highest tension are notably slower. For example, setting the curtain to 1" and tension to #1 should give me a speed of 1/45, but my shutter tester shows 1/55. OK, not a significant difference, but increasing the tension to #6 should provide a 1/120, while I read my camera at 1/70. Any ideas as to cause or solutions for this compressed range of speed?

Also, perhaps connected, I notice that "T" setting at any tension doesn't always close. It opens nicely, but often seems to hang up while closing.

I built a shutter speed tester from information off the net. The discussion and instructions are in the accessories section of this help board.

The tester does not read the Graflex FPS correctly. I have not resolved the issue either. I have found that photographing a gray card at the spot meter reading for the gray card and equivalent exposures results in negatives that are similar in density, scan at close to the same tone in either RGB or Grayscale.

Graflex says that if the shutter closes and locks from O on tension 1 and winds to the smallest aperture on tension 6 that the speeds will be correct.

Remove the curtain roller bushings on the left side of the camera, flush them out thoroughly, fill with graphite grease and reinstall. Adjust the initial tension in 1/2 turn increments until the curtain will close from O with the camera in any orientation and lock, the wind key will turn in the wind direction only. Test on tension 6 to see if it will wind to the smallest aperture. If it does not disassemble the lower tension assembly, clean, lube and reassemble.

The lower (tension) roller consists of 4 parts, the main barrel to which the curtain is bonded, the bushing end cap, the tensioning spring, and the shaft with the gear end cap made on. The tension spring is attached through a hole in the shaft at the gear end and a slot in the cap at the bushing end. The roller caps screw into the main barrel. Remove the shaft nut on the tension plate and the 4 or 5 screws attaching the plate to the camera body. Put a small slot screwdriver in the tension shaft end and lift the tension plate up until it clears the shaft gear. Count the turns that the shaft makes to zero tension. Oil the tension shaft at the roller caps after cleaning. Grease the tension gear and oil its shaft. Oil- 1 to 2 drops; grease- trace.
Initial tension: Graflex SLR's 8-20 turns; Speed Graphics 4-12 turns. A high number of initial turns indicates roughness, binding, wear or a weak spring.
Use only enough initial tension to get the shutter to operate properly.

Jason, which shutter speed tester do you have?

I have a calumet shutter tester.

I have had it for many years, and it didn't occur to me that it might not work well with a big FP shutter, but on reflection I did notice that the speeds seemed to change as I moved the tester around.

I read the posts about FP shutter speeds not showing much variation with a tester, http://graflex.org/helpboard/viewtopic.php?t=6105. I should have picked up on this before. Thanks for being there before me.

Are there other ways of testing a FP shutter other than film and grey card? Anyhow, I will go back and clean out the bottom roller and see if that helps.

Thank you all for your help!

Quote:

Are there better ways of testing a FP shutter other than film and gray card?

Well, you might try one of these:
http://lommen9.home.xs4all.nl/technical%20page/start.html
1908 shutter speed tester.

45PSS wrote:

Well, you might try one of these: http://lommen9.home.xs4all.nl/technical%20page/start.html 1908 shutter speed tester.

Very useful...

Jason, do you have the Calumet shutter tester's user manual? It describes how to use the tester with cameras that have focal plane shutters. If you follow the directions it will give good measurements.

I have a Calumet meter and a copy of the manuals in jpgs (that's how a kind person sent them to me). If you'd like, I can post the jpgs to skydrive so you can download them.

I do have the manual Dan, thanks for the offer. I will read it through again to make sure I was following the instructions correctly and try again this weekend.

jason

Dan,
I use http://download.cnet.com/PDF-ReDirect/3000-10743_4-10255233.html?tag=mncol;6 PDF ReDirect to create PDF files from tiff scans, works with jpegs also. It installs like a printer, works as a stand alone or through the print function of photo editing software such as photoshop and allows you to save the pdf to the folder of your choice.