Calculator blog

Musings and comments about our common interest


Published on by

New low post part

We have been using for already a couple of years our lower post repair piece. It is designed to replace both lower posts of the HP41c, since these are often broken in the full-nut HP41c clculator, and which are key for the calculator work since they hold in place and under pressure the nut processor circuit. The idea for the part was to have a single piece for both posts - the attachment on one side provides torque resistence for the other side and vice-versa.

This has been quite a success but it requires good alignment of the piece with the original holes, and it depends heavily on the glue quality. If the pulling force was too strong, we risked to have the piece off the keyboard circuit. This is despite having given a wide gluing area. 

We have created a new low post repair part that requires some drilling of the rest of the original post, and introducing "claws" inside the hole. The piece is designed so that when the screw enters in, it pushes the 3 "petals" of the claw to clip below the keyboard circuit - making it much less dependent on the glue!. It is really strong - the longer the screw the stronger it is. Definitely an advancement over the previous method. What you lose having to drill deeper the original posts, you gain ensuring a perfect alignment, and a much better resistance to pulling forces.

Here are some pictures of the piece (sorry for the bad lightning conditions!) and 3D-renderings too:


Read entire post