Odhner 129, performing of stop division

Jet another vintage calculator has undergone a pretty needed service although this one was in a sort of functioning condition. This time I found an Odhner 129 on a local auction site. Just at the right time when you want stuff cheap - in the middle of the summer season when pretty much every one else is on vacation etc.

I must admit I'm a bit sorry that I didn't do the stop division in reply to Minipimmer's pi approximation since his machine don't allow this type of division (no tens transmission in the quotient register). So what we're op to now is this, I believe, ancient Indian approximation of the square root of 2, that is 577/408 calculated with the stop division method. The idea of stop division is that no greater thinking is involved you just subtract until the main register goes under zero, move carriage one place, then add till it goes over zero, move one place, subtract until it goes under and so on. This is also the method used by electrified mechanical calculators with automatic division. As said before this method requires that the calculator is equipped with tens transmission in the quotient register which cheaper models isn't - mechanics for the quotient register is a _great_ deal simpler without tens transmission!

Last, sorry for the video quality. I don't have a better camera which allows me to record with greater resolution.

Category:

Howto & Style

Tags:

• Odhner
• calculator
• square
• root
• mechanicel
• vintage

[HifiCentret]

Btw. Just learned that tens transmission in the quotient register doesn't have to be that complicated. Take a look at Rokli, Schubert and a few other German machines.

While the pros of being simple the cons is that it requires more force when more digits require transmission as they all turn at once.

[citroen2cv]

I didn´n ever use this kind of division till today. It's longer but virtually error free (if the bell works).

[HifiCentret]

I would say it depends. Some examples are longer while other are shorter. Nothing stops you from going under at some digits while not on others as well as you can take digits in what order you like. When reached the lowest number in the result register you're done with the devision (not zero means devision is not exact, just the best that can be done with available digits). It however requires some mental effort since it can be a bit harder to see what will be the shortest approach.

[jeffshubert]

Can you imagine if this were your job everyday. Bzzzt, Bzzzt, Bzzzt, Bing. I'd go absolutely mental!

[liveoles]

it sounds like that the machine has caught cold and it sneezed all the way

[ChrisCaelanThomas]

It would be much less work to just do it in your head.

[Minipimmer]

Nice addition, this looks even easier to do than the other way.

You are right: mine is unable to do this because it doesn't have the needed carry transmission. Nevertheless, it's still possible to do a similar thing turning always in the same direction but doing a reverse turn each time the bell rings.

The main problem I've found is that when the sign changes, a great number of digits change its value at the time and this tends to make the machine get blocked if it's not properly oiled.