HP48 - WHY where were they made so difficult to open up?

As any HP 48 owner will know.
These machines are practically welded together, & literally require peeling off metal face plates & cutting or drilling through plastic to open them up & dismantle them.

Now whilst i acknowledge the: 'why would you want to open it up' brigade. That argument goes for most other devices anyway/
But most other devices have had & still use SCREWS!!!
Why didn't HP make these calcs easier to open for maintenance purposes? Surely considering the original sale price, they didn't deem these calcs 'throw' away? - Meaning a replacement would be cheaper than opening it up..

Your thoughts...

Edited: 30 Sept 2011, 5:19 a.m.


In comparison to, let's say, the HP35s or the HP50G, the HP 48 is easy to open: I use tire irons, one of those made of plastic, to get into the groove at the side between the LCD and the function keys where the top latches are. As soon as you got the first tire iron into it and succeeded to manage a breach you may put the second tire iron into the breach and move it downwards (where the + or ON key is) to separate both halves. You will have to apply some force to get the rivets out of their holes and will hear a seemingly unpleasant crack but you won't have to damage the bezel or drill holes into the calc.

But anyway, I suppose you did not want to hear the 1000th description of how to open an HP 48. From a more philosophical viewpoint I would conclude that the cases of HP calculators that contain screws to easyly acces the interiors were made by engineers whereas the other ones were produced by designers. Because designers don't care about the interiors whereas engineers always want to keep a path open to them.


In comparison to, let's say, the HP35s or the HP50G, the HP 48 is easy to open

I beg to differ, I think the 35s and 50g are quite easy to open.

I think HP considered them sufficiently durable to not need to be opened. Also, if HP was interested in repairing them, the plastic cases and keyboard mechanisms were probably seen as cheap enough to not be worth reusing.


Design for Manufacturability versus Design for Maintenance can have conflicting requirements.

For many reasons, within the last several decades (in many markets - electronics, vehicles) there has been a dramatic shift to Design for Manufacture.

Witness the fact that on some modern cars, it requires about $100.00 just to replace a headlight lamp (because it requires over an hour of effort). Again, the vehicle was easily and quickly assembled, with less attention paid to the maintenance cost.

The HP48 series were designed to be simple/easy/cheap to manufacture; not necessarily to be serviced.



...the HP 48 is easy to open: I use tire irons...

Wow, That'll get it open alright, but then what's left? {;-)


As any HP 48 owner will know.
These machines are practically welded together, & literally require peeling off metal face plates & cutting or drilling through plastic to open them up & dismantle them.

Actually, it is possible to open the HP48 series calculators with nothing other than a nail clipper, a toenail clipper, and patience. And you can open the HP48 and close it and have the calculator looking as it did before you opened the calculator.

I guess my webpage for the instructions have been removed. They used to be at http://www.math.uiuc.edu/~handuong/hp48/open. I have long since graduated from there, and they've finally decided to remove my files.


I prefer dynamite blasting caps...with the dynamite if possible. That gets rid of one more of these dogs. :-)

The Clamshells are even more resistant to opening. I recommend double the blasting caps used for the 48-series.

HP in the post-Pioneer era has at least returned to case closures like that used on the HP 50G...extremely easy and non-damaging to open and close.

It's about time...even the extremely capable, extremely un-repairable (epoxy blob internals), extremely inexpensive Casio fx-115ES is, yes, extremely easy to open and close. HP in the 48S/G, Clamshell, and Pioneer eras had its head up its butt in many areas, not the least being deliberate construction to discourage repair outside of replacement, even by HP!


Luckily I downloaded it before it disappeared.


Now someone needs to make an article of it here.


I can post my archive of it, but I don't think you can create posts here with attachments.


Or, Wayback machine link
No pictures, unfortunately...



Hi Han,

somehow your pictures made their way to hpcalc.org, or weren't these yours?

I used this method and recommend it highly. In a previous post I was completely serious about using plastic tire irons for bikes. They are very robust, do not bend and don't damage the case of the calculator as a metal device (e.g. nail clipper) would.

Possibly Related Threads…
Thread Author Replies Views Last Post
  [HP-Prime] connector made with printer3D CompSystems 0 1,013 10-18-2013, 04:53 PM
Last Post: CompSystems
  Do You Think a Listing Error Was Made? Jim Johnson 13 3,900 09-04-2013, 09:23 AM
Last Post: Eddie W. Shore
  About changing or deleting content after replies were made Raymond Del Tondo 1 1,133 08-26-2013, 05:01 PM
Last Post: Massimo Gnerucci (Italy)
  Self-made WP-34s flashing cable? Victor Koechli 6 2,966 08-15-2013, 10:11 AM
Last Post: Les Wright
  How to open 82162A Thermal Printer Chassis? Ron Fredericks 1 1,173 07-17-2013, 03:58 AM
Last Post: Tony Duell
  any open source HP 10BII emulators? John 15 4,755 06-12-2013, 09:58 AM
Last Post: Kimberly Thompson
  Programming cable for hp-30b -> wp-34s Open letter to Gene Nigel Rowe 37 9,821 08-02-2012, 12:30 AM
Last Post: Guy Dufour
  Custom Made Leather Cases for Voyager Calculators Juergen Keller 8 3,010 01-09-2012, 02:47 AM
Last Post: Paul Dale
  HP48 open/repair guides back online Han 2 1,302 11-04-2011, 11:15 PM
Last Post: hpnut
  An "Open" letter to "DIY" and "Repurposed" calculator projects Ethan Conner 40 9,555 10-21-2011, 04:41 PM
Last Post: Ethan Conner

Forum Jump: