Original Odhner 227 Teardown
My Original Odhner pinwheel calculator was a dumpster find some 40ish years ago. It was covered in some form of sticky residue, so it had to be cleaned up. Except for the sticky mess that covered parts of the outside, there was nothing wrong with it. I cleaned it up and it has been sitting on the shelf as a display piece for several years now.
Some time ago, I wanted to demonstrate the mechanism to a friend, but all the moving parts had seized up. The crank for the setting register could not be released or moved in any way. The crank for the result and quotient registers had the same problem. I wasn't even able to shift or release the carriage. I'm not quite sure what had caused the issues. Maybe it had been dropped on the floor and put back on the shelf? Maybe some of the sticky residue had found its way into the mechanism ?
I had attempted to open the machine previously, but failed miserably (The Odhner construction is a bit like a chinese puzzle box :)). Just after christmas 2023, I decided to give it another go and found this video on youtube: • Odhner 239 Covers Removal (Part 1 of 2) that demonstrated how to open the machine.
After having successfully removed the cover, I discovered several problems with the calculator. The carriage release lever had been dislocated in both ends. This was an easy fix. It was also impossible to pull out the register cranks. I applied a few drops of oil and proceeded to carefully force sideways movement of the cranks. After a few minutes, I could again operate them with ease.
The remaining problem is that the most significant digit of the qoutient does not reset. It can be turned, but it requires a lot of force. I suspect that maybe one of the internal pins have snapped because of excessive force being applied or maybe because it has been dropped on the floor at some point.
PS. I mention in the video that it is a model 207, but after having done some serious research (i.e. having actually looked at the embossed model number underneath..., I guess that it is a model 227 :)).
Contents of this video --
00:00 - Intro
01:32 - Carriage lock/release bolt
02:13 - Base and carriage removal
02:46 - Carriage cover removal
03:33 - Releasing the setting register crank handle
04:04 - Removing the right side panel
04:48 - Removing the left side panel
05:06 - Removing the front panel
05:55 - Removing the top panel
06:41 - Removing the rear panel
06:47 - Inspecting the quotient and result registers
07:24 - Reinserting the carriage
08:16 - Inspecting mechanism
09:59 - Looking at stuff that was fixed
10:04 - Dislocated release lever
10:33 - Cranks
11:03 - Testing multiplication
11:26 - Square root