Friday, December 30, 2016

Beige machine spotted

A beige and angular typewriter; Torpedo 'Cicero' in a shop.

Looked a bit dejected, three keys down.

To avoid any confusion, a small label explains that it is 'decoration' and not for sale. Either way, it is in a bit of a surprising spot. Placed in the cooking section next to the cutting boards. To be fair, also with cooking books. And it is a ''Chickpea' of course :)

Friday, December 16, 2016

Bausch & Lomb 32mm 4x objective

The newly acquired microscope came with two objectives on a three-position nosepiece. One empty spot to fill - ideally with a low power objective. The 10x objective is of the divisible kind, the lower portion can be unscrewed to change from a 10x to a 4x objective. (Snippet from the December 1939 issue of Popular Science.)

Even nicer would be to fit a 4x objective at the empty position. With the amazing global flea-market that is the internet, one such objective was found to be for sale. Even though it was located in Santa Barbara it was easily purchased and shipped with amazing speed to the Low Countries.

For being nearly 90 years old by now this objective is in fair shape, only one small blemish (nick) on the front lens. Whilst this will reduce sharpness in a part of the image, it is not in focus so not too damaging. This would probably make the objective be rejected for laboratory work, but for hobby-microscopy at low powers it is still fine.

To clean the objective, used demineralised water with a soft cloth. A 'camel-hair brush' to flick off larger dust or particles. When carefully wiping clean lens surfaces of 'condensed' dirt, regular tap water would evaporate and leave a thin film deposit on the lens. With demineralised water, it can be gently (!) wiped clean and dry.

With three objectives of the right pattern fitted in the nose-piece, it does look the part again. Also it now works fine for magnifications from 20x up to 430x. For practical, hobby use, that's plenty of power.

Wednesday, December 14, 2016

Fastening the iris screws

This is the item in the cleaned-up wooden case.

This is another Bausch & Lomb microscope. A biological microscope with a 3-position revolving nosepiece, condenser and simple stage with clips. Came with the original 5x and 10x eyepieces and a 43x and 10x (divisible) objectives. Overall in great shape, the finish is immaculate and all the glass still very clean. This instrument was used with care and the case did its job of protecting it very well.

From the serial number, this fine instrument was made by the optical craftsmen at Bausch & Lomb in 1939 in Rochester, NY.

One of the two small issues with the instrument was that the screws that hold the iris assembly together were loose - this is not an assembly you want to have to piece together again...

Three screws (arrow) around the circumference of the iris hold it together. These screws are however completely inaccessible in the assembled instrument. To get at the screws, the substage assembly with condenser, iris and filter-holder needs to be taken apart.

The mirror pulls out, it is held by split-end of its pin in a hole. The substage assembly then can be driven down off its rack and pinion. Then the iris assembly screws off the Abbe condenser. Because the iris lever fouls the substage frame, the condenser needs to be unscrewed from the frame first. For this, remove the three screws around the condenser flange (thus also loosing the alignment of the assembly with the tube).

The iris assembly again tightened, the whole is screwed together again and fitted back into the frame. With care, the dovetail slides back on and the pinion onto its rack. With the three screws in the condenser flange not quite tightened, the assembly can be centered again.

Compared to e.g. typewriters, there is surprisingly little information online on the repair and adjustment of these instruments. However for the centering of the condenser, there is a very helpful paragraph in the small booklet 'Use and Care of the Microscope' by Bausch.

With some tweaking, the substage is again nicely entered in the view.

The other small niggle is that the fine adjustment does not quite line up anymore. It all works fine, but even at the top of its range, the two lines do not line up. Maybe it had a knock at some time that pushed down the fine-adjustment pawl, or it got serviced and not lined up then. (The line on the arm is very faint, just above the line on the moving part of the coarse adjustment.)

Perhaps indeed from a servicing - the optics and adjustments are all fine. These parts are a bit too tricky for now to tamper with. Leaving it as it now is - a perfectly serviceable microscope!

One of the slides that was in a small box in the case; small intestine. This particular microscope will be great for the children to explore the world of the minute :)

Friday, December 9, 2016

Fine steel wool and some wax

New arrival - not in a black leathercloth case. The case has sustained some scuffs and scratches, protecting the item inside. Nickel plating direct on plain steel is not the most durable finish, vulnerable to corroding in moisture.

Started the cleaning - most satisfying when taking some steel wool to the handle. Won't bring back the plating, but it will look (and be!) much cleaner again.

Similarly taking some furniture wax to the case. The lacquer has been scratched and dented. Not going to re-finish the case, but some wax on the scratches will protect the wood and make the scratches much less noticeable.

Next up will be the item inside, some careful cleaning should do it. There's however a bit of a challenge waiting with some inaccessible screws needing tightening...

Wednesday, December 7, 2016

Small physics demonstration

In the '28 manual, there's an instruction to construct a Newton's disc. The small apparatus with a colour wheel should demonstrate that the primary colours (or colours of the rainbow) fade into white when mixed by spinning the disc rapidly.

So to build one. Built from period parts with some modifications and improvements. It seems to have been the purpose of the instruction manual to show constructions that have a lot of scope for improving. Two strips for some bracing were well within the parts-list of a number 2 outfit. Likewise some improved bearings with a bush-wheel and a two-stage x4 gearing.

The instruction manual image suggests it being hand-held, the design also works well as a free-standing little apparatus (with a set of newly printed rubber feet).

Quite surprisingly it actually works; reality conforming to theory! Hard to capture as the shutter of the camera is faster than the human eye. The centre ring still shows colour at ~300 rpm in a picture, but shows completely monochrome, light grey to the human eye. Amaze the kids ;-)

With Meccano being a construction system, then everything of course taken apart again for a next little build.

Saturday, December 3, 2016

Most dangerous substance in the house (and a use thereof)

There are a lot of hazardous substances in the house, not least things like bleach and drain cleaner. The small bottle of cyanoacrylate glue might actually be candidate for being the most dangerous substance in the house. A bit similar to how the 'Dremel' might be the most dangerous tool in the shed. A 'Dremel' looks fairly harmless, yet will do serious damage in an instant when you're not paying full attention.

The cyanoacrylate glue also looks fairly harmless - it's a small bottle of glue. But unlike the regular 'hobby' glue, you need to keep paying attention or it'll inflict damage that may require some medical attention. This glue polymerises (hardens) in seconds and sticks very well to just about anything - fingers, tables, eyelids...

That great adhesion does make it ideal to repair metal parts that have become loose or broken. One such instance is the brass boss in some Meccano parts. The bosses in older spoked wheels (19a) seem to have worked loose often. Also in this example 2" pulley, the boss is loose and can rotate in the wheel.

The key thing then is to get a small amount of cyanoacrylate glue in the gap between the boss and the pulley and not get it anywhere else. I.e. especially not touch the glue at any time - don't get it anywhere near yourself.

To do this, a toothpick is given a drop of the glue on its tip. Then this tip is pressed into the gap, letting the glue be pulled into the gap by capillary action. Resist any urge to guide or rub things with fingers...

The glue polymerises in seconds, triggered by water (moisture in the air). Giving it a minute to be sure, the boss is again fixed firmly on the pulley wheel.

A dangerous substance to have in the house - but very good for fixing loose mechanical parts (or perhaps cracked frames and castings).