Faber 375

The number is on the box.

A fine and very solid instrument, made by A.W. Faber.

This sliderule was seized-up, but otherwise undamaged. No chips or worn spots and nearly completely straight still, but the tongue was held very tight - nearly unmovable. Even the cardboard box is still in good shape. The instrument needed only a little light cleaning to be very presentable. The tongue being 'stuck' made it 'unusable' however. It is obsolete of course and not for actual use, but I do like the 'analog collectable objects' to be as functional and working as possible.

Loosening the five (5!) adjustment screws that control the 'grip' of the stock would yield a gap between tongue and stock (i.e. much too loose) and still the tongue was barely movable (i.e. much too tight). Somehow the sliding surfaces of the parts had become roughened to 'grip' with even the lightest clamping force. Having tried a few remedies, what finally brought the friction back to usable levels was applying a very little vaseline. (This was actually the method advised by Danish manufacturer Diwa for their sliderules.)

Like most continental sliderules, it has the Rietz arrangement of scales - the scales are not marked, but follow the conventional arrangement. Being an older sliderule, it hasn't got the inverse C scale.

Instead of the more usual mahogany, this sliderule is made of Swiss pearwood. This makes it relatively light in colour and surprisingly heavy. In comparison, a Keuffel & Esser Polyphase sliderule weighs about 57 grammes, this Faber sliderule weighs 113 grammes. Though the Polyphase is admittely slightly smaller, both have a 25cm scale and offer the same functions and accuracy.

The datecode on this sliderule is a simple '1' on the right and a '9' on the left - these should be for month and year (in the 1920-ies). From the information in the Sliderulemuseum, this would mean this Faber 375 sliderule was manufactured in September 1921 or January 1929. The German patent 365673 listed in the well was issued in April 1922. The sliderule does have the patent's construction - so it will be January '29.

Whichever exact year, it was made during the Interbellum for export to The Netherlands. The table with conversions and constants is in Dutch. The seller was able to share that it was owned (and probably purchased new) by a teacher in a technical college. Probably well cared for and little used.

The A.W. Faber or Faber-Castell company is still in business. What's more - until very recently at least you could still purchase a new (NOS) sliderule from them online. Since last year however, this article seems to have been taken offline...

No need to buy a new one though. This instrument is still in good shape - obsolete of course, but very usable :)

New brushes for the E6 motor

Putting the E6 motor together again with the fixed parts, it unfortunately still did not work. It seized up and the current draw was too high as well - tripping the circuit breaker used to protect the battery. (That circuit breaker is an original ~1937 Meccano item made exactly for this purpose - 'Retro Tech Holland' here :-)

Measuring the windings of the armature and the stator suggested these were all as they should be - in the 1 Ohm range. Comparing with another E6 motor of similar vintage, showed that the main difference was the resistance of the brushes. This motor has copper-filled brushes with very low resistance, unsure if those are original or later replacements. 

Additionally the brushes are very worn, short enough to tilt and wedge themselves between holder and commutator. Even though the armature rotated freely, when powered the brushes seemed to wedge and lock-up the armature - totally blocking the motor.

Buying new brushes for such a motor is a bit of a challenge, not a common size today. Unexpectedly, there is a ready supply of graphite rods sold as electrode! Sourcing a couple of graphite electrodes of nominally 5 mm diameter was easy enough and surprisingly affordable. The rods are "almost round" and closer to 5.2 mm, but readily ground down to about 4.8 mm (3/16" probably). Then sawing off two lengths of almost 10 mm (3/8" seemed right) and adding a slot gave reproduction electrodes. ('Repro Tech Holland'...)

With the new graphite brushes, the motor again runs - starting up fine without tripping the circuit breaker. With hardly any arcing/sparking too.

To give the motor a test-run - bring it into use again - it was built into a simple crane model out a 1928 instructions booklet.

It still needs some adjusting, as one direction runs smoother than the other. This is not unexpected, probably needs further tweaking of the positions of the brush holders relative to the motor-axle and of course some running-in of the brushes.

How well the graphite electrode brushes will stand up to wear remains to be seen of course, but for now they will do. 

So, the happy outcome is that this wrecked 87 year old E6 motor is again 'up and running' :)

A fixed part for the E6 motor

Continuing the 'repair shop' treatment of the old Meccano electric motor; now the fixing-up of damaged parts. The base plate of the switch was damaged, with all four mounting pins broken off and a corner chipped. Not sure what the 'plastic' part is made of, possibly bakelite - notable is that it wasn't fully moulded, but at least partly machined. The studs were not moulded protrusions, but separate pegs that were inserted in drilled holes. Edit: or a previous owner tried to repair broken-off studs by drilling holes to fix with screws.

The pegs form studs that hold the switch in place when sandwiched between the motor side-plates. The holes in the side-plates are 3.2 mm diameter, or rather, 1/8". The holes in the switch base seem to have (had) thread, quite likely 6BA for mounting with screws. (Screw-mounting was used on earlier versions of the motor.) For repairing this motor, could have used new screws, but plastic pegs would be more correct for this 1933 Meccano motor, so scouting for 1/8" plastic pegs. 

Where to get black, rounded-top plastic pegs of 1/8" diameter?

It took me a while to realise, but there was a ready supply of 1/8" plastic rods in the house!

The Lego-brick is originally an English invention, and even today has a bit of a mix of imperial and metric dimensions. The base-dimension is 1/16" (~1.6mm), the wall-thickness of the brick. The height of a brick is 3/8", with the tile-bricks 1/8" thick - also the rods and antenna's are 1/8". Using the vast online marketplace for Lego parts, sourced a few extra of part 3957 (Antenna 1x4) in black.

The holes in the switch-plate needed drilling out to 3.2 mm. It's been remarked before that these motors are not precision instruments, the plate again confirmed this. The holes are not placed at the centre of the sides, but one set was significantly offset to the front. (Probably contributing to the chipping.) In the factory, a jig would surely have been used for drilling - this particular part must've been placed sloppily in the jig. (Or more likely - a wandering drill if done by a previous owner as a repair.)

With the plate clamped between the side-plates, the holes were drilled out without too much damage otherwise.

A short length of the rod makes a peg that was then glued in place. The chipped areas also built-up again with PVA and cut to create a reasonably flat surface again. Still visible as damage, but less glaring.

The pegs now jut through the holes and look exactly as the originals would have looked.

Next up to re-assemble and see about the windings.

A disassembled E6 motor

The Meccano E6 motor dates from an age when things were made repairable. It is mostly screwed together (of course - it's Meccano) and comes apart easily.

(The notion that you could make an expensive consumer product and explicitly design it so that it is near-impossible to repair was probably not yet mainstream.)

After disassembly and cleaning, this is what we've got:

The brass was only cleaned (soapy water) and not polished, except for the electrical contact surfaces. Decades of patina increase electrical contact-resistance and will slow these motors down or prevent them from running at all. Normally not visible, the switch-contacts are now brightly polished.

Nominally it is a 6 Volt motor, but by the look of the area around the brushes it may have been used at higher voltages, would not be surprising if a previous owner ran it at the 20 Volt that later Meccano motors needed. Not only does it look like it sparked fire, the commutator is also visibly worn down.

Now that they're clean, the fading of the paint can be seen very clearly from the difference between inner and outer face of the side-plates.

Were it not for the nicely surviving decal, these would be up for a re-paint. Maybe later - first to make it functional again. 

The bent lever of the switch was easily corrected - protecting the part with card, holding it in a vise and use parallel-pliers to gently 'form' the bent bit. (From typewriter-repair; 'forming' is bending when you mean to do it.) The brass pillars that hold the laminations likewise needed some straightening, probably more tweaking to come.

Up next; find a way to build-up and fix the broken black switch-base.

A damaged E6 motor

Vintage items bought online nearly always arrive well packed in boxes with lots of padding, some are very well packed indeed. Unfortunately this particular vintage item was merely put in a plastic envelope with two small, loose bits of foam-pad. It did not end well.

This is (or was) a Meccano E6 reversing 6 Volts electric motor. It's very sturdy, but also very heavy and got a nasty knock...  This bent and broke the switch-assembly and knocked the pillars out of shape, making the armature foul the stator. The seller was very good about the unfortunate event (he had completely run out of boxes that week), however leaves the question: what-to-do with this ~80 year old item.

As with every niche-subject, there is an astounding amount of information on the internet on Meccano and Meccano motors. From various detail features this specimen can be identified as an E6 manufactured in 1933. Originally it would have had bright brass and the paint would've been red.

The red & gold decal still looks fair, although the originally-red paint has faded to an almost-orange. It must've spent decades sitting on a shelf in a shed in the sun.

These motors are not exactly precision-built instruments, these are to a fairly 'rough' design originally dating back to around 1916. This means it should be 'forgiving' and practicable to attempt a re-build - seems a shame to have to discard (or dismantle for parts) this 87 year old toy motor. 

Will be having a 'tinker' to see what can be done.  :)

How to use Corona Floating Shift Models

 Have the typewriter, now also got the instructions to go with it.

Must admit to being a 'completist', and the Corona Speedline being a 1938 model with a gloss finish it should have a user manual that shows that finish (and not the 40-ies crinkle and stripes finish). So all illustrations in this printing show the typewriter with the plain, glossy finish.

The instruction booklet covers are a little yellowed, but other than that is in great condition. It scanned fine; so without any editing straight to PDF. Now available on The Archive: How to use Corona Floating Shift Models.

Again and still for the purpose to give all users of these brilliant portable typewriters clear and definite directions for the use and care of their machines:

:-)

Igranic Honeycomb Coil

Browsing a Meccano Magazine back issue (the November 1924 edition), an advertisement for radio components caught the eye.

Specifically the coil pictured in the left-top corner. Hadn't paid much attention to these ads before, but last week a pair of coils for use with the crystal radio had arrived. (Ordered from the global bric-a-brac shop that is the internet).

The coil in the advertisement is labeled as the number 500 and this specimen is a number '150', but other than that it's the exact same type. Complete with frequency chart and the 'what the wild waves are saying' motto.

This neatly confirm that this coil is contemporary to the 1923 Edison Bell crystal radio set that it'll be kept with. This coil and another Edison Bell number 100 coil came plugged into a little tuning component, adjusting the coupling of two coils (De Forest).  

The nickelled fitting were badly corroded and dirty, but as is often the case with nickelled parts they came back fine from an encounter with Brasso and a cloth. The black parts are hard rubber, these were simply cleaned and given a thin polish with vaseline to help preserve and make them look better. 

The little setup was bought mainly because of the Edison Bell coil that looked intact - the Igranic coil was a bonus :)