Friden Model DW10

Serial No. 280275JJ

Date: 1950s

Capacity: 10x11x20

Price paid: £5

This impressive and rather very heavy machine actually works (for the most part).  It can perform semi-automatic multiplication and fully automatic division (to a pre-set number of significant figures).  The main niggles with the machine are that the carriage return/clear function doesn’t operate properly, and that the machine doesn’t completely reset itself following a division calculation.  However, these faults can be worked around and are probably not worth the effort to fix (bearing in mind the very real risk factor of rendering the machine completely inoperable).

A video of the machine in action can be seen here.


Friden Model STW10

Serial No.

Date: 1950s

Capacity: 10x10x20

Price paid: £25

This machine is similar to the DW10, but has a dedicated keypad for the entry of the multiplier for fully automatic multiplication.  This machine does not work, but has the potential to, once I get brave enough.  The problem with it is that the gear wheel which moves the carriage left and right has lost a tooth – I have a replacement, but fitting it involves dismantling two machines – the donor and the recipient.  At least the donor machine (not shown) is beyond repair so the experience gained in harvesting the gear wheel won’t carry any risk.  Whether I’ll be able to fit it to the “good” machine – who knows?  Apart from the carriage not moving, everything else seems to work – except that the motor runs too fast.  I have a spare motor too, if I need to swap it out.

Repairing this machine will be, I think, something of a (far) future project, but it will be worth it if I can get it going properly.  Cosmetically, the machine looks good.

The instruction manual for this machine can be found here.

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