My 1926 RB Graflex Series B 4x5 camera just made a loud noise while I was winding the shutter. The shutter - at the 3/8 opening- broke apart.
Is there a way I can mend this together with tape? Also (a stupid move on my part) I have turned the shutter winder several times, so i hope I just didn't make things worst for aligning it later.

Any suggestions are appreciated.

Mark

The first thing is to download these servicing instructions
https://drive.google.com/file/d/0B1sPJkp-MdghRkRId1EwT0dpNkk/view?usp=sharing
Next you are to give me your mailing address via the private messing service of this site. I will send you a piece of shutter material to make the patch strips from or you can order some shutter cloth from https://www.micro-tools.com/
Once you have the shutter cloth cut 2 strips the width of the strips that tore 1 inch longer than the opening to be repaired. Using Beacon Fabri-Tac https://www.joann.com/fabri-tac-permanent-adhesive-8-oz/2409043.html or contact cement center the strips over the tear cloth side to cloth side.
Examine the other aperture openings for weak or frayed connections at the aperture stays. Repair weak spots in the same manner. What is done to one side of the curtain must be done to the other side at the same position to keep the curtain winding evenly. You can likely patch three places before the curtain becomes too thick to wind to the 1/8 aperture.
Clean and lube the bushings, wind gears and tension shaft and gears with light weight grease, graphite, and light weight machine oil.
3in1 oil is not good for cameras. WD40 is sometimes used for cleaning but is otherwise not good for camera lubrication. 90% Isopropyl Alcohol is a good cleaning agent.

The shutter curtain was .007 inch thick when new, it swells with age. Rip stop nylon or similar material can be used for repairs but should be .007 inch thick at the maximum.

Sorry this happened to you. I also know that sound when the spring suddenly releases. It gives you that sick feeling. My RB Series D is relatively new to me. I had it for several years before the stuck curtain released and allowed me to shoot with it for several weeks before my curtain also tore at one of the openings. Since I know nothing about the mechanics of the camera, I opted to have it professionally repaired. John Minnicks made a new curtain and did a CLA. I’ve had the camera back for a few weeks and put in a few shoots. Silky smooth and feel confident with the camera. Good luck.