Glued gears for 2501 and worked on 1053 typewriter adjustments

BACK IN THE SHOP TODAY

Once I was able to drive myself places, beginning towards the end of last week, everything was ready for my return to the workshop. I still have to elevate and ice the knee pretty often, plus do exercises and attend physical therapy sessions. I also enjoyed some outings with my wife and friends in the free time I had. Today, I put in a couple of hours in the shop which was very satisfying.

GLUED 3D PRINTED GEARS ONTO ALUMINUM DISKS

I first did test fits of the printed gear rings onto the disks to form the complete stacker and hopper gears for the 2501 card reader. As you can see, they fit perfectly without any bending or force. 

They mesh properly inside the machine as seen in the picture below of the stacker gear in place (but prior to being glued to the disk). 

This fits on the disk and extends out from it far enough to ensure a good mesh with the metal gear teeth at the top of the picture above. Contrast that to the thinness of the teeth in the version that was (mis)printed by another 3D printing service - below. 

GLUED TOGETHER USING A POLYETHYLENE GLUE (GORILLA GLUE)

The PETG plastic used to print the gears had to be bonded onto the aluminum disk that will spin it around. After some research on glue performance to PETG and to aluminum, I chose the original Gorilla Glue as polyethylene glue seems to provide the best results. 

Although the glue was firm at the end of the two hour session, it doesn't reach full strength until 24 hours after application. I set these aside and will fit them back on the 2501 at my next session. I have several appointments tomorrow (Monday) so that may have to wait until Tuesday.

ADJUSTING OPERATION CLUTCH FOR CR AND LF OPERATIONS

The continually turning operational shaft has two clutches attached to it. One of them will turn 180 degrees when engaged, while the other makes a full turn on each trigger. The latter is used to power the line feed and carriage return operations. 

That latter clutch would work when triggered but it bounced back and forth a bit steadily at all other times. It should have been held in the rest position by a latch when it finished its 360 degree spin. I needed to adjust an eccentric screw on the clutch in order to fix this.

I loosened one screw on the other side of the yellow clutch disk and turned the eccentric until I got a clear firm stop to the clutch after each activation. This left only a couple of items to finish up on the typewriter - the tab interlock operation and proper shifting between red and black ink. 

MORE WORK ON TAB INTERLOCK BUT NOT YET WORKING WELL

The purpose of tab interlock is to signal to the IBM 1130 that a tab movement is in progress, so that no further commands such as typing a character or carrier return will be issued. The process of starting a tab movement uses a half turn of the operational shaft to twist a torque bar which runs left to right with the carrier moving just behind it. The half turn takes about 65 milliseconds, the same as the duration of a character printing cycle. 

The twisted torque bar latches an arm at the rear of the carrier which frees it so it can be pulled to the right by the cords coming from the wound up main spring. The time it takes for the carrier to be pulled by the spring depends on the distance between the column the carrier was at when it began the tab and the column that has a tab stop set to end the movement. 

This time is variable and longer than the duration of the tab activation turn of the operational shaft. A microswitch to generate the interlock signal is mounted at the left rear of the typewriter frame and activated by the tab torque bar. When the torque bar twists, the switch is activated and remains that way until the torque bar returns to its rest position. 

The initial twist of the torque bar comes from the operational mechanism during the 65 milliseconds of tab activation. The bar must be kept twisted once that initial force is removed, staying twisted until the carrier unlatches the arms after it strikes a tab stop at the target column. 

The job of keeping the torque bar twisted is given to a bendable tang on the tab activation lever. When the torque bar first twists it latches the carrier into tab operation. The space and backspace pawls are pulled away from the teeth in the racks that lock the carrier to a column normally. The arms that do this remain latched until the tab stop releases the latching action.

Thus, the tang on the tab activation lever should keep enough twist on the torque bar to ensure the tab interlock microswitch stays activated. If that tang doesn't do its job, the torque bar snaps back to rest position after the 65ms activation, rather than remaining twisted through the entire tab movement. 

After my adjustments today, the torque bar remained partially twisted during the movement but the tab interlock microswitch didn't remain activated. This may be an issue with the mechanism for tab interlock near the switch, or I may need to bend the tang even further. I ran out of time to complete this today.