Cleaning and waxing of stacker mechanism for 2501 card reader

DISASSEMBLED AGAIN

Because their was too much friction and sticking, I pulled everything apart to work on the parts. My first attempt using 409 did not remove enough of the deposits to allow free and easy movement of the parts. There was also a shaft around which the cam roller and levers turn in order to move the card shifter left and right, but it was barely turning because of sludge inside.

PUT RUSTED/CORRODED PARTS IN CONCENTRATED VINEGAR AND SCRUBBED

All the parts that were interfering with smooth movement due to layers of rust or corrosion were soaked in a 30% vinegar bath for hours to loosen up and dissolve what it could. I used a sanding block to break away the surface coatings. I was able to reduce the irregularities in the surfaces far enough to allow the parts to move smoothly. 

APPLIED PASTE WAX TO REDUCE FRICTION IN CARD SHOE AND ROD

After the rust and other dirt was removed from the rod, it still had some rough surfaces because of corrosion pitting. I used an automotive type paste wax to reduce friction on the rod. I had cleaned out the hole in the shoe as well. 

In addition, the surfaces that the shoe glides upon - the side plates in the reader plus the top of the shoe - were waxed to give it less friction. The result was an acceptably free card holder sliding to the right under spring tension but giving way to the left as cards are added to the stack. 

GREASED THE SHAFT ACTIVATING THE CARD SHIFTER

The shaft with the cam roller and levers pivoting on it needed a bit of grease applied in order to have the parts rotate easily on the shaft. This is far enough down that there is no risk of the grease contacting any cards, thus it was safe to lubricate here. 

IBM 1130 typewriter (console printer) repair and adjustment - part 7

BENT HORIZONTAL LUG FOR TAB INTERLOCK SWITCH

The objective with the positioning of the horizontal lug is to allow the tab trigger lever to maintain a small space between the latch lip on the lever and the tab torque bar, so that the tab trigger lever will positively catch the latch lip when the torque bar first rotates. It must also keep the trigger latch lever pushed down enough to keep the tab interlock switch activated until the tab torque bar returns to its full rest (vertical) orientation when tab movement ends at the target column. 

I held the tab torque bar so it didn't rotate and applied bending pressure to the horizontal lug until it satisfied the conditions above. The first testing was with manual rotation of the typewriter using the hand cycle wheel, both slowly and with a quick acceleration at the start that had previously always caused the interlock switch to reset. 

This worked, even with a rapid twist of the hand cycle wheel. I then applied power to the IBM 1130 so the typewriter motor was spinning and did some tab activations using the front panel tab pushbutton. The Tab Interlock Switch was clearly active for the entire travel time of the carrier until it reached the destination tab and stopped. This works properly now. 

Cleaning up the stacker mechanism

REMOVING CRUD AND CORROSION ON PARTS

Most of the brown caked crud on the parts, which looks like rust, is actually a mix of mouse urine, dirt and a bit of aluminum or other metal corrosion rather than iron oxide. I was able to remove much of it with 409 spray and in some cases a mild sanding block to break free the layers. 

Example of corrosion

The rod that the card stacker shoe slides along cleaned up quite nicely. With a bit more work on it and some cleaning of the side plates that the shoe slides underneath, I should get it to return rightward under spring tension and move freely. 

MORE DISASSEMBLY IN ORDER TO CLEAN AND LUBRICATE CARD PUSHER PARTS

I removed the metal arch that converts the card motion from horizontal to vertical as it enters the stacker. This gave me good access to the card pusher plates that should oscillate smoothly left and right to move cards leftward to join the stack of other cards. 

I did a trial assembly after the cleanup and lubrication and found that everything moved reasonably well, but still had some resistance that kept the return spring from always pulling the card pusher plates rightward. The cam which causes the pusher plates to oscillate will move the plates leftward at its high spot but when the cam profile lowers, the spring must move the plates rightward to ensure smooth back and forth action. 

Pivot driven by cam moves card pusher back and forth

Shoe at bottom sliding on the rod

WORKING ON EASY MOTION WITHOUT ADDING OIL

Normally with mechanical parts I would add some oil or grease to reduce friction and ensure smooth motion. However, the stacker parts can come in contact with the punched cards. Since they are made from paper they will wick up some of the oil. 

That would cause the card to swell up. The throat in a card reader that allows just one card to enter at a time is based on the nominal thickness; a card that is too thick will jam up and bend. 

Therefore I have to find a way to reduce friction without the oils. I will use a combination of paste wax and more work removing sludge and corrosion from the moving surfaces. 

DISINTEGRATED BUMPER THAT MUST BE REPLACED

Below you can see the broken fragments of the bumper that the cards will fly up into and come to a stop. Fortunately I was warned about this and already have a replacement part in the works. 

The sound deadening foam that was glued between the ribs above has disintegrated. This is pretty typical of the foam used in 1960s IBM gear. I will remove it since it has no functional role, simply reduces sound levels. 

DISCOVERED MY ISSUE WITH HOPPER GEAR ALIGNMENT DOESN'T EXIST

In prior posts I was concerned about the timing between the picker knife actuation cam and the timing disk. The solenoid for the knife is triggered at the time of the CB 3 pulse from the timing disk and released at CB 1 time. This timing also starts the card feeding from the pre-read station out through the read photocells and into the stacker. 

I was worried that if the knife moves at the wrong time when the previous card hasn't cleared the pre-read station, we could have a jam. I wanted to get a copy of the FE Maintenance Manual to learn how to mesh the gears for proper synchronization.

However, that was due to a big misconception of mine. It appeared that the gear with the timing disk on it was meshed to other gears that not only turns rollers to move cards but also turns a cam to move the picker knife. Thus, the two gears would have to be set in the proper relationship in order to turn the cam at the right time. 

The diagrams in the Parts Catalog appeared to match that assumption. However, as I disassembled the card reader I realized that the cam for the picker knife is on the SAME shaft as the timing disk. The shaft has a key that orients the timing disk to the shaft, thus the timing between feed and pickerknife are assured. 

DRILLED OUT AND REPLACED A FROZEN RUSTED SCREW

As I was removing side plates to get access to the card stacker shoe and rod, one of the screws was too rusted in place to turn with a screwdriver. It was a recessed head screw as well, thus harder to apply turning torque to the end of the slot. I had to drill out the head in order to get the screw turning. 

Fortunately, it was a pretty standard type of screw that I could buy and use as a replacement when I reassembled the stacker assembly. 

Alerted to another plastic item on 2501 card reader that has failed with age

BUMPER STOPS UPWARD CARD MOVEMENT AS IT IS EJECTED INTO STACKER

As cards are fed through the read station, they continue to the left and curve upwards to be ejected out into the stacker. The card strikes an elastic bumper that arrests its movement and allows it to fall downward gently. 

The card pusher oscillates left and right at the bottom to gently move the card leftward until it is against the stack of cards previously ejected. The stairstep shape of the card pusher initially places the ejected card higher than the top edge of the stack, but then nudges it down the steps while the card slides down to end up well aligned against the other cards in the stack. 

WARNED TO CHECK THE CONDITION OF THE BUMPER

The bumper is another of the materials IBM used in the 1960s that degrades with the passage of time. Foam insulation, rubber and plastic parts outgas the chemicals that provide the elasticity and other characterists, so that by now they are brittle, crumble or in some cases have turned to a sludge. 

It sits in the area marked A in the diagram below at the top of the stacker assembly. The card flying up from below will bounce to a stop off the bumper, then drop to where the card pusher can move it against the other cards. 

The bumper itself consists of a holder (61), a soft elastic material (60) and a tougher outer face (62). 

EXPERTS WHO RESTORED A 2501 IN EUROPE ALERTED ME TO CHECK THIS

Friends who have restored 1130 systems for a museum had previously restored the 2501 Card Reader as part of that effort. They encountered the broken plastic gears during that work and were the source of the design files I used to fabricate my replacement parts. 

The found that the bumper on their reader was cutting or damaging cards because of its degraded state, so they replaced it. Because of this, they warned me to check the bumper on my 2501. The bumper was sitting there seemingly good but when I touched it to check the elasticity, it broke apart. 

Fortunately, the team had produced a design file for the bumper holder onto which they glued some firm foam. I was given the file and will build the holder. I already have suitable firm foam to add to it. 

2501 Restoration - mainly working on stacker section

VACUUMED OUT THE 2501 CARD READER

I used a shop vacuum to remove the fragmented plastic gear reside, mouse hair, dust and other junk from the card reader as the first step in cleaning it up. I will follow up with 409 and Simple Green for general cleaning. There is rust on a number of non-critical parts that I will partially sand and then treat with a rust converter but not right now.

STACKER ASSEMBLY NEEDS TO BE DISASSEMBLED

The card stacker is a mechanism into which cards are ejected at the end of a read/feed operation that will hold them in a neat stack for eventual removal by the operator. The card flies up and bounces off a bumper at the top to arrest its motion, then is nudged leftward by an oscillating assembly to result in the card fitting against the prior cards in a neat stack. The stack of cards is on a slider which is spring loaded so that it moves leftwards as the stack of cards grows until it reaches a 'stacker full' microswitch that causes the reader to become not ready. 

The slider moves along a chromed rod, with a shoe fitting under guide rails and having the rod pass through a hole in the center.  A spring attached to the shoe pulls the slider rightward. The chromed rod has rust and corrosion on it, so that the slider can't easily move left or right. This will need to be treated to allow easy movement of the rod through the shoe. 

The oscillating assembly that nudges cards to the left once they fall down from the bumper is jammed. It consists of a base plastic piece with steps formed into it, plus two thin plastic pieces that move left and right in slots cut into the base piece. The thin plastic pieces are moved by a lever underneath that is oscillated by a cam on a shaft. The shaft is turned by the stacker gear that I replaced, converting rotary motion into the back and forth nudging action. The thin pieces don't move due to solidified grease and dust. 

I have to remove quite a few screws and plates to open up the stacker assembly to remove the slider rod as well as to reach the thin pieces where they are frozen in place. This is mostly done now, but I need a bit more work to uncover the front side thin piece because the card reader motor is in front of it. 

Once I clean up the rod and the thin pieces, I have to reassemble the stacker. A number of the parts have room for movement so that they can be adjusted to specific widths or relative positions. In particular, the path that the ejected card moves through, as it moves up to the bumper and falls down onto the nudging assembly, may have a target range of adjustment.

I do not have access to the IBM 2501 Field Engineering Maintenance Manual, the document in which IBM would detail all the adjustments and specifications for reassembling parts of the card reader. This worries me as I will be doing even more disassembly of the reader, with those parts also having specific adjustment targets. If anyone knows of someone with this manual, such that I could get it scanned, it would be a great help. The parts catalog and FE Theory of Operations are available online already, but not this key manual. 

I will clean the rod, then sand down any high spots and finally try a rust converter to produce a smooth enough surface for the shoe to slide over it easily. The rod has a notch in it at the right for a circlip that holds it in place in the assembly, so simply buying a replacement rod of the right diameter and length isn't enough. 

Determined how to mesh geartrains in 2501 card reader

CONTINUOUSLY RUNNING SHAFTS AND SOLENOID CLUTCHES

The IBM 2501 Card Reader has a motor that is spinning continuously while the device is ready for card moving and reading operations. A number of drive belts connect different shafts both side to side and front to back in the machine to provide energy to various rollers and other devices.

The card stacker where cards are ejected after reading is connected to one of these shafts and via a cam converts the motion to side to side movement of the bottom of the stacker. This helps move each newly ejected card to the left where it can fit closely against all the cards that were previously ejected. 

Rollers to move cards from the pre-read station through the read station and push them up into the stacker also run continuously. Most of these rollers have a spring loaded roller on the other side such that the cards will be moved.  Any card entering between a pair of rollers will be grabbed and moved leftward. 

At the rightmost side of the machine in the pre-read station, however, the first roller does not have a counterpart permanently pressing on it. Thus the card will not be moved from the pre-read station until a feed solenoid moves the counterpart roller down to pinch against the card. When pressed down, this roller starts the card moving until it enters the next pair of rollers where the pair are pressed together to keep the card moving. 

The input hopper for cards yet to be read has pairs of rollers turning just inside the opening into the reader. As long as the cards sit stacked in the hopper they are not yet touching the rollers so they will not move. A set of 'picker knives' move front to back when activated by a hopper solenoid. These have a lip that is less than the thickness of a punched card, so they only push on the bottommost card. The entry into the reader has a 'throat' that is adjusted to be less then two cards in thickness, thus ensuring that one and only one card enters per movement of the picker knives. 

A row of 12 photocells sit inside the card path so that they will sense light coming through punched holes in each column as it is moved past. Cards sit in the hopper with the face of the card down and the left side (column 1) of the card to the left in the hopper. 

READING CARD IN PRE-READ STATION

Activating the feed solenoid pinches the card in pre-read so the continuously turning rollers propel it leftward into the next set of rollers. The card moves under the photocell station where each of the 80 columns can be sensed in turn, then moved up into the stacker. 

Simultaneous with feeding a card to read it, the hopper solenoid is activated to feed in the next card from the hopper into the pre-read station where it can wait for the subsequent read request. 

FEEDING CARDS FROM HOPPER TO PRE-READ STATION

Firing the hopper solenoid will cause the picker knives to push a card into the throat, where the rollers will push the card to the rear so that it stops in the pre-read station. When the machine is initially empty, a feed cycle must be taken to put the first card in pre-read before the card reader becomes ready for operations. This is done by pushing the Start button. 

Every read operation (feed solenoid) also activates the hopper solenoid so that as long as there are cards left in the hopper it will have one ready in pre-read at all times. When the hopper becomes empty, there is still a card sitting in the pre-read station from the prior picker knife activation. The card reader will drop out of ready condition at this point, allowing the operator to add more cards to the hopper if desired. When new cards are in the hopper, pressing Start will turn on ready, read the card in pre-read and pull in a new one from the hopper. 

However, when there are no more cards to be put in the hopper, the reader has not yet read the last one since it is sitting in pre-read. Pressing the Start button without adding any cards to the hopper will turn the reader back to ready where another read request can be processed to read that final card. A special condition is raised so that the 1130 software can tell this was the 'last card' being read. 

KNOWING WHEN TO SAMPLE THE PHOTOCELLS FOR THE 80 CARD COLUMNS

The rollers pulling cards through from pre-read to the stacker move continuously, as does an 'emitter station' in the machine. When the leading edge of the card enters under the photocells, the logic detects that at least one row (actually all 12) is dark. It records pulses on the emitter station, spaced one card column apart as the emitter station rotates. 

Thus each pulse identifies the location of columns 0, 1, 2 . . . 80, 81 and then the trailing edge of the card. After the card exits the read station, the emitter station is erased to be ready for the next incoming card. Because the pulses are placed exactly as the card first enters the photocells, we have a precise start position for the card. Because the emitter station rotates in synchronization with the rollers moving the card along, the pulses mark off the location of columns very accurately. 

TIMING CB PULSES SYNCHRONIZE CARD MOVEMENTS AND SOLENOID ACTIVATIONS

A rotating disk with a permanent magnet glued on it spins continuously as the reader motor runs. It has three coils placed around the perimeter so that the magnet will generate a pulse from each in turn at specific points in the rotation of the disk. These are called CB, for circuit breaker, which is an IBM term for a circuit that is turned on or off based on motion of a cam or other mechanism. 

The three CB pulses control when the solenoids are activated, when the emitter station pulses are recorded and thus relate to the movement of cards through the machine.

The solenoids are activated at CB3 time and released at the start of CB1. Cards entering from the hopper will slide rearwards into the pre-read station near the end of a cycle. A photocell to detect whether a card was feed into pre-read is activated at around 211 degrees, we after any card moving out of the pre-read has passed fully through the photocells. 

A card being read (by activating the feed solenoid) will have its leading edge enter the photocell station around 15 degrees, as it moves rightwards, meanwhile the card from the hopper is moving rearwards at the same time. The trailing edge of the card clears the photocell station around 165 degrees, thus the entire card is out of the pre-read station sometime prior to that. The incoming card from the hopper is about halfway into the pre-read station (based on the location of the photocell that senses it) at 211 degrees and will be at rest and ready for feeding before CB3 at 335 degrees. 

This is a ballet of simultaneous card movement that must be managed lest the incoming card from the hopper jams into the card moving through the photocells. The activate time of the solenoids runs from CB3 of one rotation to CB1 of the next, which starts the movement of both cards. Thus most of the synchronization is purely done by using the CB pulses to control solenoid firing.

However, the card that comes in from the hopper is fed through the throat by the picker knives. The solenoid to release them is fired based on the CB pulses, but the physical back and forth movement is driven by a cam that is also rotating continuously along with the timing disk. If the knife moves early the card might crash into the card leaving the pre-read station. If it moves late, the card might not be fully at rest in the pre-read station when the feed solenoid is activated to start the card through the photocell station. 

A gear on the timing disk meshes with other gears that turn the picker knife cams. Thus, the relative position of the cam to the timing disk is important to ensure that we time the picker knife movement properly. 

The Field Engineering Maintenance Manual would contain the instructions for setting the gears in time with each other, but that manual is not available to me nor available online. Fortunately, there is a blurb in the Theory of Operations manual that tells me how to synchronize these.

MY PROCEDURE

I will disconnect the new white gear from the gears on the right, then rotate the motor so that the permanent magnet pole (red arrow below) will be positioned at the CB3 coil (green arrow below) when the disk and new white gear is reinstalled. Then I will turn the existing gears so the cam is in the position show in the diagram above. Meshing the new white gear to the existing gears in this orientation will give me the relative timing necessary for proper operation. 

Trying gears on 2501 reader; narrowing down failure point on typewriter tab interlock switch

GEARS INSTALLED, TURNING WELL

The glued together plastic gears and aluminum disks were installed into the 2501 card reader. The teeth mesh properly, not too loose and not too tight. I left the bubbled up Gorilla Glue since it doesn't interfere with the operation of the gears. 

Stacker reduction gear for joggling cards

Hopper gear to synchronize picker knife with reader timing

FAILURE POINT IDENTIFIED ON TAB INTERLOCK SWITCH MECHANISM

The failure I am seeing is that the tab interlock switch can turn back off as the tab movement was initiated, well before the carrier actually reaches its destination column. The torque bar remains rotated during the movement, but the switch itself turns off.

After careful study I believe it is caused by misadjustment of the horizontal tab on the end of the tab torque bar. This allows the trigger lever for the tab interlock to move up and latch on the torque bar mechanism, when it should be held below the lip on the torque bar end so that it can't latch while the bar is rotated. 

In the diagram above, you can see that the horizontal lug of the torque bar allows the tab switch trigger to ride up so that its lip can latch atop the tab torque bar. As the torque bar rotates clockwise about 20 degrees the tab switch trigger lip is pushed off the torque bar and is moved down by the lug. That causes the switch to be activated. 

The horizontal lug should keep the tab switch trigger down so that it keeps the switch activated. The crudely modified diagram below shows that situation.

Because the horizontal lug is way too high over the tab switch trigger, it allows it to pop up and latch while the torque bar is still rotated. The adjustment is done by bending the horizontal lug down so that it matches the clearance shown in the first diagram. 

MY NEW KNEE

Front and left view of my new knee. 

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.