Facit calculators work on a similar principle to the more conventional Odhner type pinwheel calculators, but their external appearance and user interface is strikingly different.

Rather than having an external moving carriage in conjunction with a fixed rotor, Facit machines reverse this arrangement and the carriage is fixed but the rotor moves.  Numbers are entered into the pinwheels with numbered keys rather than by directly setting the pinwheels by hand.

It is also noted that Facit machines are fully enclosed, and are thus less likely to be full of dust and cobwebs.

Facit machines seem to be less common than Odhners on eBay.  But Serial Number evidence points to many more Facit machines being made. The obvious conclusion is that Facit machines are more fragile or less easy to repair than Odhners, so fewer machines have survived.  It may also be true that eBay frequency isn’t much of a guide. This leads to an interesting question, that is, what is the survival rate for mechanical calculators? Is it as much as one per-cent of those manufactured? Or is it much less?

Facit Model TK

Facit Model TK

Serial No.

Date: 1949

Capacity: 9x8x13

Price Paid (including postage): £30

This entry will be updated soon.

Facit Model NTK

Facit NTK Mechanical Pinwheel Calculator

Serial No. 472198

Date: 1955

Capacity: 9x8x13

Price paid (including postage): £107.50

The Model NTK was in production between 1954 and 1957.  It replaced the Model TK, and was succeeded by the Model C 1-13, which were functionally (and probably mechanically) identical.  This particular machine is in nearly mint condition, and came with a carrying case and two instruction manuals.  This is the most expensive machine I’ve ever bought – it cost me £100 plus £7.50 postage.  Instructions for operating this machine can be found on the User Guides page here.

Facit Model NLx

Facit NLX Mechanical Pinwheel Calculator

Serial No. 501960

Date: 1956

Capacity: 10x10x19

Price paid: £0.99

This model NLx was produced between 1954 and 1956, and only 2360 were made. It has an extended capacity compared with the Model NTK, and features a moving carriage. The revolution counter and result register are cleared by pulling the levers at the ends of the carriage one-quarter of a turn towards the operator..

In contrast with the Model NTK, this is the least expensive calculator in the collection.  I paid £0.99 for it on eBay.  It was a bit grimy and very stiff to operate when I bought it, but it cleaned up beautifully, and operates very smoothly (though not quite as smoothly as the Model NTK.)

Facit Model NEA

Facit NEA Electric Mechanical Pinwheel Calculator

Serial No. 408291

Date: 1956

Capacity: 9x8x13

Price paid (including postage): £43.45

The Model NEA, produced between 1943 and 1956, is essentially a motorised Model NTK.  This particular machine was one of the last to be made before the model was superseded by the Model CS 1-13.

It can perform fully automatic division, and semi-automatic multiplication.  The result register and revolutions counter are cleared manually with the levers on the left, whereas the input register is cleared electrically.  This particular machine was bought from Germany on eBay (half of the purchase price was spent on postage).  It was initially jammed, but by sheer luck I managed to get it going, and it now performs flawlessly.

A video of the machine (with the cover removed) can be seen here, performing the division 355/113, which equals 3.1415929.

Facit Model CA 1-13

Facit CA 1-13 Electric Mechanical Pinwheel Calculator

Serial No.  655319

Date: 1958

Capacity: 9x8x13

Price paid (including postage): £43.45 + £20 for a replacement outer casing

The Model CA 1-13 can perform both multiplication and division fully automatically.  This particular example, though, is somewhat of a hybrid – the outer casing of the machine was damaged in transit, so a non-working machine of the same type was bought purely for the sake of the outer casing.  The machine from which the new casing was taken dates from 1965, by which time the outer casing had been redesigned.  However, it still fits.  The replacement casing cost £20 including postage.  The 1965 machine awaits use as a potential motor donor.  However, the machine pictured is working perfectly at the moment.  A video of it working (with the cover removed) can be seen here.

A subtle difference between the earlier and later versions of the Model CA 1-13 are that the input and result registers were renumbered.  Fortunately, this meant only that the key caps for the I and III register clearing levers required swapping over.

Facit Model CM2-16

Facit CM2-16 Mechanical Calculator

Serial No. 1089413

Date: 1965

Capacity: 11x9x16

Price paid (including postage): £40 including the Brunsviga 13RK

This (rather heavy) calculator marries a modern calculator style keypad with a traditional pinwheel calculator.  In operation it is similar to other manual Facit machines, but unlike other Facit machines it features a Back Transfer mechanism.  Not only that, but numbers can be transferred from either the result register (accumulator) or – somewhat unusually – from the revolution counter, depending on the position of the rotor within the machine.  Indeed, with careful placement of the rotor, numbers can be transferred from the right hand side of the accumulator and the left hand side of the revolution counter.  This is probably not a useful feature!

One useful feature of earlier models was that a sliding plate would cover the unused digits in the input register as it was moved to the left during multiplication.  This refinement was dispensed with in the CM2-16, presumably because it was difficult to implement while including the back transfer capability.  Either that, or my machine isn’t complete; but I don’t think so – I’ve had a look inside and the mechanism is completely absent.

The operating instructions for this machine can be found on the User Guides page here.

Incidentally, the Facit company became the subject of one of the classic case studies of what not to do if your core business is based on selling one product, which is about to be rendered obsolete.