How to mod beamspring connectors for tightness
Posted: 12 Sep 2020, 21:56
The blue modern 3.96mm card edge connectors that are often found on ebay/aliexpress, and are used for converting Beamspring keyboards are often a lot looser when compared to the original connector.
They are often so loose that some columns/rows don't make proper contact, and even vibrations can knock a row/column always-pressed/always-unpressed.
If you already have a converter built and soldered, then your best option to mitigate this is to add a piece of paper, to increase tightness. Keep in mind that if looking at the keyboard and connector as if you were typing on it, column contacts are on the bottom left, and row contacts are on top right. So I recommend adding a piece of paper on the top-left, where there are no contacts that are really in use. If the tightness problem is really severe, you may experiment with increasing paper thickness, or using multiple sheets of paper, and you can also try adding a piece of paper on the bottom-right, underneath the rows. (Original idea by kmnov2017).
This guide is a much better solution, but it only applies to you if you still have a pristine unsoldered connector, that you can mod to be tighter. If you follow these steps, the connector will be around as tight as the original connectors, and you will need to use more force to connect/disconnect the converter to/from the sense pcb.
Step 1 - remove the pins
Remove the pins, by grabbing the part that is solderable, and pushing them straight through with pliers.
The pins are very easy to bend, so be very careful.
Try to grab a good surface area when pushing, and always push in the direction that is perfectly parallel with the pin metal.
If something like the following picture happens, it's best not to attempt fixing this pin by bending it back. just break it off, and using a needle push it so the other end falls out of the connector. This is a good reason why to get pins that are bigger then 2x30 pins, because you have extra pins in case you break some. (Also right now 2x30 pin variants don't seem to be available anyway)
(If you don't have any extra pins, then really-really pay attention to make sure something like this doesn't happen, and I guess if it does, try to save it, but set it aside, and only use it for contacts that don't carry any signals.)
I recommend pushing out all pins at once, rather then modding pin-by-pin. This allows you to be faster. So after you pushed out all pins, you have an empty plastic connector, and a pile of pins:
Step 1b - Perform any cuts
All the cuts that need to happen to the plastic are best done at this point, in order to avoid damage to the pins.
Examples are:
* If bought 72-pin connectors, cut off the excess pins
* If building a compact beamspring connector, the extra plastic on the left side should be cut off, because the pro micro will not leave space for it.
* If the controller can be used for 327x/3101 keyboards, then the sense PCB can be assymetric so a slot should be cut in the right end of the connector. See this post for more details. viewtopic.php?p=473635#p473635
Step 2 - First Bend
This is what a single pin looks like:
Bend the contact part of the pin upwards by 15-20 degrees: (does not have to be very perfect)
Because of the little guide-holes in the connector plastic this bend is not sufficient. The little guide holes would bend the pin back into its original shape, if you inserted it like this into the connector: Step 3 - Second Bend
So you need to add another bend in the middle of the contact part of the pin. Try to make it so the two marked blue lines are roughly parallel. But again perfection is not necessary: Angles are not so important to be perfect, but try to make so that the position of the second bend is consistent across pins, for aesthetics. This will still work even if the position of the second bend is inconsistent. To make the second bend, I held the pins with tweezers, and I applied pushing force where shown by red arrows: After I took the picture I realized that I have stronger tweezers the tips of which are made out of ceramic, so I did all the remaining pins with the ceramic tweezers. My needle nose pliers were too thick for this, but if you have very thin needle nose pliers, I recommend using those instead.
Step 4 - Gently push the pins partway back
Push the pins back into the connector until part of the pin goes through the hole on the back of the connector.
Do not apply force on the contact side of the pin to make the pin snap back into place.
This step only places the pin back halfway:
Step 5 - Pull the pins from the other side, with pliers, until they click
Step 6 - Solder the connector to your controller
Do not try to put the connector on the beamspring after modding the connector without having it soldered to a controller.
The modded connectors are much-much tighter, and require force both to put the connector on, and take it off.
You risk bending the pins, and also you risk some of the pins popping off while you take it out.
Soldering it increases its mechanical stability. Solder it first, and only then try it!
Results
Here you can see a non-modded connector on the left, and a modded connector on the right.
You can see how much gap there is between the pins on the unmodded connector: Here you can see the side view of the pin shape after modding:
I was very disappointed with the reliability of the non-modded connectors, but I have done this mod on 9 connectors so far, with 100% success, and they are 100% reliable now!
They are often so loose that some columns/rows don't make proper contact, and even vibrations can knock a row/column always-pressed/always-unpressed.
If you already have a converter built and soldered, then your best option to mitigate this is to add a piece of paper, to increase tightness. Keep in mind that if looking at the keyboard and connector as if you were typing on it, column contacts are on the bottom left, and row contacts are on top right. So I recommend adding a piece of paper on the top-left, where there are no contacts that are really in use. If the tightness problem is really severe, you may experiment with increasing paper thickness, or using multiple sheets of paper, and you can also try adding a piece of paper on the bottom-right, underneath the rows. (Original idea by kmnov2017).
This guide is a much better solution, but it only applies to you if you still have a pristine unsoldered connector, that you can mod to be tighter. If you follow these steps, the connector will be around as tight as the original connectors, and you will need to use more force to connect/disconnect the converter to/from the sense pcb.
Step 1 - remove the pins
Remove the pins, by grabbing the part that is solderable, and pushing them straight through with pliers.
The pins are very easy to bend, so be very careful.
Try to grab a good surface area when pushing, and always push in the direction that is perfectly parallel with the pin metal.
If something like the following picture happens, it's best not to attempt fixing this pin by bending it back. just break it off, and using a needle push it so the other end falls out of the connector. This is a good reason why to get pins that are bigger then 2x30 pins, because you have extra pins in case you break some. (Also right now 2x30 pin variants don't seem to be available anyway)
(If you don't have any extra pins, then really-really pay attention to make sure something like this doesn't happen, and I guess if it does, try to save it, but set it aside, and only use it for contacts that don't carry any signals.)
I recommend pushing out all pins at once, rather then modding pin-by-pin. This allows you to be faster. So after you pushed out all pins, you have an empty plastic connector, and a pile of pins:
Step 1b - Perform any cuts
All the cuts that need to happen to the plastic are best done at this point, in order to avoid damage to the pins.
Examples are:
* If bought 72-pin connectors, cut off the excess pins
* If building a compact beamspring connector, the extra plastic on the left side should be cut off, because the pro micro will not leave space for it.
* If the controller can be used for 327x/3101 keyboards, then the sense PCB can be assymetric so a slot should be cut in the right end of the connector. See this post for more details. viewtopic.php?p=473635#p473635
Step 2 - First Bend
This is what a single pin looks like:
Bend the contact part of the pin upwards by 15-20 degrees: (does not have to be very perfect)
Because of the little guide-holes in the connector plastic this bend is not sufficient. The little guide holes would bend the pin back into its original shape, if you inserted it like this into the connector: Step 3 - Second Bend
So you need to add another bend in the middle of the contact part of the pin. Try to make it so the two marked blue lines are roughly parallel. But again perfection is not necessary: Angles are not so important to be perfect, but try to make so that the position of the second bend is consistent across pins, for aesthetics. This will still work even if the position of the second bend is inconsistent. To make the second bend, I held the pins with tweezers, and I applied pushing force where shown by red arrows: After I took the picture I realized that I have stronger tweezers the tips of which are made out of ceramic, so I did all the remaining pins with the ceramic tweezers. My needle nose pliers were too thick for this, but if you have very thin needle nose pliers, I recommend using those instead.
Step 4 - Gently push the pins partway back
Push the pins back into the connector until part of the pin goes through the hole on the back of the connector.
Do not apply force on the contact side of the pin to make the pin snap back into place.
This step only places the pin back halfway:
Step 5 - Pull the pins from the other side, with pliers, until they click
Step 6 - Solder the connector to your controller
Do not try to put the connector on the beamspring after modding the connector without having it soldered to a controller.
The modded connectors are much-much tighter, and require force both to put the connector on, and take it off.
You risk bending the pins, and also you risk some of the pins popping off while you take it out.
Soldering it increases its mechanical stability. Solder it first, and only then try it!
Results
Here you can see a non-modded connector on the left, and a modded connector on the right.
You can see how much gap there is between the pins on the unmodded connector: Here you can see the side view of the pin shape after modding:
I was very disappointed with the reliability of the non-modded connectors, but I have done this mod on 9 connectors so far, with 100% success, and they are 100% reliable now!