Changing slide sizes, Trays and Barrettes

Some more details as I promised.

Changing Sizes

I must admit I never tried to find out how the Planox works with 45x107 slides (I don't possess any!) but I was asked by a friend on the Forum so I decided to figure it out... Here goes.

This is the standard 7x13 configuration:

In order to convert to 6x13 (apart from the difference in trays) you need to add this bracket, which reduces the window opening to 6x6. It clips on the bottom two brass lugs:

Going to 45x107 is slightly more complicated. When the slide is picked up by the magnets, it is guided in place by two rail paths that are attached to the four brass lugs you see on the picture. In order to accommodate the narrower slides, the lugs are used to move the rails towards the middle to reduce the width of the path (the path can be seen just behind the viewing aperture):

In addition, there is a metal plate that restricts the viewing window:

This also fits on the lugs, when they are in the correct position for 45x107:

Of course you also have to switch the switch on the side, which restricts how high up the mechanism lifts the slides:

Trays

NOTE: These descriptions only relate to the later Planox that use bakelite trays, not the earlier ones with wooden trays that have a very different mechanism.

This is what a normal tray looks like (full and empty):

The 6x13 and 7x13 trays are physically the same size:

However the guide you see in the front is at a different height, so when they are dropped in the frame the tops of the slides actually end up at the same height:

Barrettes

The whole principle of the Planox mechanism is based on the fact thta there are magnets that lift the slides up to be viewed. In order to do that, each slide needs to be fitted with a metal bar on the top, called a barrette.

Each barrette is about 9.5 cm long and is common for all slide sizes (as far as I know...). This is what the barrette looks like:

... and here is the profile:

Inside the barrette, there is a wavy metal plate, which grips the glass plate allowing for different widths:

I hope that gives you a good idea... Any more ideas on what you want me to describe, keep them coming! :-)

Back to the drawing board

It's a year since the last blog entry, and that's not good. Due to other commitments I had to abandon the restoration project. I did however finish cleaning the planox and putting it back together, so it's now back in a functional state. Friends and family can have a go again and share the intrigue.

In the meantime, I've also been back to Greece and have managed to transport (safely!) all the glass plates and the smaller of the two cabinets with the two drawers. It looks a lot more "complete" again :-)

Planox - Restoration - Part 2

The wood

I used first some cloth and then 0000 steel wire with wood furniture cleaner to remove the grime from the surface on the outside. This has taken off most of the grime but has left a dull finish on the wood. Hopefully, the French polish will recover this. [I have to say that I have never French-polished anything in my life before, so discovering the technique is now part of this game! It’s very tempting to take the easy way out and use clear varnish, but what’s the fun in that? Having grown up with the Planox around me I don’t think I would like the effect. Varnish is always a thicker layer than French polish and a lot more obvious. It also does not give the same high quality lustre finish. ] After buying some French polish, finding an old T-shirt and experimenting with making wads and applying 8-figures, I started practicing on the main unit. One of the good things about French polish is that shellac (its base) is dissolvable with white spirit. So, if you don’t like the results, or something has gone wrong, it’s relatively easy to remove the last layer and start again! Obviously that is easier when it’s not completely dry yet, but that takes several days. And believe me, I was thankful for this particular property a couple of times: Shellac has this annoying habit of drying very quickly, and one of the key advices on all French-polishing textbooks is to make sure that you continuously move the polishing wad. I didn’t realise how important that was, until the first few attempts. Having done a quick layer of French polishing on the front and the top, I’ve come to appreciate another point that is highlighted in the textbooks: French polishing will not cover, but highlight any blemishes already there. So if you want blemishes to disappear, you really need to treat them before the polishing starts, otherwise you are just accentuating them. So, now that the first coat has gone on it’s quite obvious that I need to stop and do some more careful preparation with sanding and filling before I French polish it properly. I still don’t intend to go down to bare wood, but there are some particularly ugly scratches that I would like to try and cover if possible.

Planox - Restoration - Part 1

As I described earlier, the unit is in relatively good condition. So, what I have decided to do is to try and restore it not to its original state, i.e. not a complete strip-down and rebuild, but to the state that it should have been today, had it been maintained properly as an antique over the years. In other words, my intention is not to make it look as new, but as a well preserved antique. The first step in the process is cleaning. Over the years a lot of dust has accumulated both in the inside and the outside. On top of that, the combination of dust, dirty fingers and atmosphere pollution has also added a layer of grime to the outside of the unit. After removing the parts that need removing, i.e. the light housing on the back, the opaque plate and the bayonet lenses on the front, I started off with just a good vacuuming of the inside, using a soft brush to remove a lot of the dust. Next, was a basic maintenance of the mechanism: a careful spray of a little WD-40 on all the sliding parts and gears. Although I have no plan to dismantle any of the main unit I did remove the four screws that hold each mounting mechanism for the viewing lenses, in order to be able to treat the wood surface underneath. It would have been impossible to clean and polish the front part of the viewer otherwise. The mechanisms of the viewing box got a similar first treatment with some WD-40 on the metal gears.

I then carefully removed the two sliding wood panels that manage the intra-ocular distance. Extending them beyond their normal sliding range, allowed me to take them off the rack-and-pinion mechanism and slide them further out, without taking them completely off. The panels are designed using tongue-and-groove fitting which I cleaned and treated with some plain candle wax. The panels now slide tightly but easily in and out, without stressing the metal gears as they did before.

The Brass

The brass decoration was next on the agenda. I used some 0000 steel wire with wood furniture cleaner, to lightly scrape off the dried French polish from the brass parts. Thankfully the engraving is quite deep so there was no risk of removing the black enamel paint inside it. The brass however now looks a lot cleaner and the contrast is highlighted.

I then covered all the brass parts with some Scotch magic-tape (the type that does not leave a residue) to protect them from the French polishing of the wood.

Planox - Condition

Over the years the Planox has seen several house moves, a fair amount of dust and grime, exposure to the harsh heat and polluted air of Athens, air-conditioning, central heating and significant neglect. All of these have taken their toll of the wood finishing but have caused no structural damage to the unit. A lot of dust has accumulated over the years on the inside as well.

Hopefully, all of that can be cleaned and restored. There is no rust on any of the mechanical parts and all the wood fittings have not warped or worked with age. Nevertheless, the wood can do with some cleaning and polishing with wax on the mechanisms to allow drawers and trays to move more freely, as they tend to stick at the moment. At some point in the past, someone must have attempted to re-polish the unit but did not do a terribly good job. Apart from the fact that you could see the polishing strokes on the finishing, French polish was also covering most of the brass metal parts.

On the top of the unit there is a circle ring, obviously from a hot cup that someone leant on the unit.

On the front of the unit there seem to be several dents and scratches in the wood but not too severe. Other than that, it’s generally in a very good condition.

Planox – The main unit

The front

The front of the unit is dominated by the two eye pieces which look a bit like a submarine periscope or a pair of old binoculars. There is one lens for each eye, separately attached to a wooden panel, and there is a number of adjustment controls. There is rack-and-pinion mechanism which moves the whole viewing box with the two lenses in and out, allowing you to focus on the slides. On the left side there is a separate double helicoidal rack-and-pinion, which symmetrically moves the two lenses apart from each other to be able to adjust the distance between the two lenses (intra-ocular). By grabbing both adjustment knobs and giving a sharp tug forward, the whole face of the unit tilts forwards, opening up to reveal the inside mechanism. It also exposes the sliding frame where the slide trays are loaded into the unit.

Right side

Obviously designed for right-handed use only, the right of the machine hosts two perpendicular sliding mechanisms. The vertical one, moves up and down to raise and lower the glass slides from the tray into the viewing position. The horizontal one has a numeric index which allows you to move the slide tray forwards and backwards, to select a specific slide.

I will describe this mechanism further in the section describing the insides of the unit – suffice it to say, that as the vertical mechanism reaches the bottom of its travel it automatically advances the slide tray to the next one. So, very much like the sliding knob of a View Master™ which uses up-and-down movement to move from slide to slide while you are viewing, when the Planox lever is at the bottom of its travel, twisting it a quarter turn to the right locks it in place, which has the effect of disengaging the lifting mechanism from the slides allowing you to slide the loading frame all the way forward and remove the slide tray.

Left side

The left side is relatively plain with one sliding small lever which is used to move an internal plate which normally covers the space between the two frames in the glass plate. This allows any notes relating to the slide to be written and viewed in that space.

On the right there is also a switch, which allows the mechanism to handle different plate sizes between 45x107, 6x13 or 7x13. Ass far as I know, it's the only scope that supports multiple formats, although I do not have a suitable tray for 45x107 to try it out.

The back

The top three quarters of the back of the unit slant upwards at an angle of about 20 degrees. On most examples of stereoscopes I’ve seen this houses a matt (opaque) glass, which is used to provide diffused light to the unit. On the Planox I have there is a light housing unit which attaches to the back.

I have seen no references to this light unit in any of the catalogues or examples of Planox I’ve found on the web, but whether it was there from the beginning or added later it’s definitely been designed specifically for the Planox. The unit easily slides on and off on two pivots, it’s metal in its construction and it just houses a light fitting and bulb.

The mechanism

(pictures to be added)

Inside the unit is a relatively simple but very clever mechanism. On the bottom, there is a metal tray which slides backwards and forwards. When at the very front position with the front lid open a bakelite tray pre-loaded with glass plate slides can be dropped into the frame, and there is a notch to ensure that it goes the right way around. Sliding the frame backwards with the horizontal lever on the right of the viewer brings the first slide in alignment with the lifting mechanism. This is unique to the Planox. In order for the system to work, all the glass slides in the tray have a metal bar attached to the top edge. The lifting mechanism consists of a set of magnets which are being raised and lowered. When at the lowest point, the magnet attaches itself to the glass slide and lifts it up to the correct position. When lowered into the tray the advancing mechanism engages and moves the tray one slot forward so that the magnet attaches to the next slide. When that is released, the mechanism pushes it up and raises the slides into view. When locked at the bottom position the tray can just slide backwards and forwards, prising the last slide gently away from the magnets, to either select a specific slide or bring it all the way to the front to load the next tray. The mechanism is not too dissimilar to the standard mechanism in slide projectors in that it moves the slide in and out of the tray slot and automatically advances the tray to the next slot. The main difference is that it works vertically instead of horizontally with magnets that are just strong enough to secure the plate without the risk of dropping it, but loosely enough to disengage easily as soon as the slide is back in the tray and the tray moved. A vertical groove on either side of the mechanism guides the glass plate from the tray from the tray slot to the right position.

Planox – Overview

While growing up, I’ve always known the Planox to be a major piece of furniture in the corner of my grandmother’s living room. In reality, it's not one single unit but it consists of three separate parts.

The top one, is the main stereoscope itself. This is originally designed to be a table-top viewer. [Incidentally, I’ve only ever seen another one similar to it, although a simpler version, that is on display in the War Cabinet Museum in London – Churchill’s headquarters – Which I assume was used to view aerial stereoscopic photographs.]

The second part is a base cabinet, which is specifically designed for the viewer to sit into. It provides two drawers with storage for 4 trays with slides each. The viewer and it’s cabinet are about a foot and half high.

Underneath that is a specially designed cabinet which consists of 8 pull-out drawers, each of which holds 6 trays. The top of the cabinet is cleverly built so that an embedded tray with a ring in the front, allows you to slide the whole steresoscope forward so that you can sit in front of it.

The bottom cabinet itself is about three feet high. The front of it is protected with two vertical doors. I don't know if this cabinet is standard part of the Planox, or if my grandfather had it made to order. I have not found any reference to such a piece of furniture, or anything else similar on the web. (please let me know if anyone out there knows?)

Both the planox and the base units seem to be made of mahogany wood and it’s been French polished to a darker colour.