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--- facit_nea [2019/04/13 18:24]
clodoveu
+++ facit_nea [2019/06/15 10:29] (current)
clodoveu
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 Multiplication is semi-automatic, meaning that the operator has to hold down the multiplication key and wait for the required multiplicand digit to show up in the counter, then moving the carriage left, and repeating the process. Division is fully automatic, though: after the dividend is input and added to the left of the accumulator, the input register is cleared automatically and the divisor can be keyed in and also shifted to the left. Then the division key starts up a mechanical algorithm by which subtractions and carriage moves to the right go on automatically until the remainder is zero or the precision limit is reached.
-My TK was my first restoration, in which I found nothing broken, so I expected the same from the NEA. Upon arrival, I cleaned it up a bit, and went through the usual spots where a FACIT locks up. I soon got the clearing levers and the keyboard to work. I also put together a first version of a power cable. Testing the motor, I was able to clear the input and perform adds with the first digits -- I dared not making anything more complicated and risk forcing the motor.
+My TK was my first restoration, in which I found nothing broken, so I expected the same from the NEA. Upon arrival, I cleaned it up a bit, and went through the usual spots where a FACIT locks up. I soon got the clearing levers and the keyboard to work. I also put together a first version of a power cable. Testing the motor, I was able to clear the input and perform adds with the first digits -- I dared not making anything more complicated and risk forcing the motor. With patience and observation, I eventually got it working correctly.
-Disassembling it is my next step.
+However, the NEA and the ESA-0 have a plastic gear early in the power train. None of my manual FACITs have anything like this. The plastic gear is probably meant as a "fuse", so that if something seriously locks the machine, this gear can break and the rest of the mechanism remains unharmed. In my NEA, one tooth was already missing from this gear, and my efforts soon caused another to break, and then two more, so it's become unusable.
+I measured the gear, designed it in SketchUp and had it 3D-printed, with the help of colleagues from the Robotics lab at UFMG. I added 1mm in its thickness to try to make the teeth a bit stronger. The result can be seen in the photos below. The replacement gear, printed using ABS filament, fit perfectly.
+(I was told by gear makers that the plastic gear material is called "Celeron", as the Intel chips).
+I'll now design and try to 3D print the missing keys, fix the transparent windows, and probably repaint the case and have the reset levers chrome plated, to make it look new.
 **Have a mechanical calculator stored somewhere, and want to get rid of it? Send it to me!**
 **1946 FACIT NEA s/n 271545**
+As purchased
 {{ http://www.dcc.ufmg.br/~clodoveu/files/Images/FACIT-NEA/FACIT_NEA_as_purchased.jpg?500 | As purchased}}
+Broken original gear and ABS 3D-printed replacement
+{{ http://www.dcc.ufmg.br/~clodoveu/files/Images/FACIT-NEA/FACIT-NEA-3D_printed_gear.jpg?500 | Broken "celeron" gear and 3D-printed gear}}
+New gear in place (SketchUp design [[http://www.dcc.ufmg.br/~clodoveu/files/Images/FACIT-NEA/20190502_FACIT_NEA_main_gear_V3.skp | here]])
+{{ http://www.dcc.ufmg.br/~clodoveu/files/Images/FACIT-NEA/FACIT-NEA-3D_printed_gear_in_place.jpg?500 | Gear replacement}}
 **More about this machine**
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 [[https://www.youtube.com/watch?v=bf4zVBbo_Fs | Video: a FACIT NEA performing a division]]

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facit_nea.1555190654.txt.gz · Last modified: 2019/04/13 18:24 by clodoveu

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