HP41 Repair Cracked Posts


I have an HP41C with one cracked and one missing screw posts both on the lower part of the calculator. Does anyone have some tips how to repair this?


I fix cracked screw posts with a plastic welding solvent available at most hobby shops. It comes in small bottles and contains the solvent methylene chloride (a.k.a. dichloromethane). It works by melting the plastic togteher. Standard and super glues will always fail.

My fix for sheared off screw posts (or missing ones) is much the same. However, I drill out the hole in the post until the screw slides into it without threading. I then fuse it to the place where the old posts was, and thread a 1/4" longer screw through the hole into the case, tighten it down and let the weld set 24 hours. The screw post now just acts like a bushing, with no screw stress on it. The longer screws thread down into the case plastic where there is a lot of reinforcing, etc.

As far as where to get the longer screws... lotsa luck finding them. They are 2-28 self tapping sheet metal screw with a type "B" point. Also something called "Plastite" (?) screws are preferred.

To replace a missing post you will need to make one either by cutting a post off a truly defective HP41 or out of ABS/styrene plastic. The diamter is non-standard (something like 11/64"?). You will need to machine down some larger rod material.

Possibly Related Threads...
Thread Author Replies Views Last Post
  Repairing HP 41C screw posts Fouad M. Kaadou 7 1,268 09-25-2011, 08:19 PM
Last Post: Randy
  Two new blog posts of interest to members of this forum Steve Leibson 8 1,362 09-19-2011, 04:38 PM
Last Post: Mark Hardman
  Repairing a cracked Spice case Jeff Kearns 3 837 04-20-2011, 07:27 PM
Last Post: Jose Poyan
  Funny Museum Posts From The Past... DavidShenk 3 784 06-27-2010, 12:01 AM
Last Post: Vieira, Luiz C. (Brazil)
  HP 97, OK I cracked the print head.. Ed Sowell 11 1,415 03-25-2010, 03:04 AM
Last Post: Ignazio Cara (Italy)
  HP41 models and susceptibility for cracked posts Nigel Bamber 2 593 03-23-2010, 04:46 PM
Last Post: Etienne Victoria
  MCODE: Where these last posts are heading: A function called "NSG" Geir Isene 12 1,752 01-13-2010, 05:34 AM
Last Post: Geir Isene
  HP 41CX loose screws (no not the posts!)... Geoff Quickfall 4 796 11-21-2008, 02:16 AM
Last Post: Geoff Quickfall
  late reply to archived posts stafford 0 380 11-16-2007, 09:57 AM
Last Post: stafford
  HP-41 Keyboard: Cracked Dome? Tom Salmon 13 1,716 01-28-2007, 03:24 PM
Last Post: Karl Schneider

Forum Jump: