Protector scopes

[Mrs Vampire]

other bits

[BCA]

A small version of the protectoscope (about 5" wide, 3/4" thick x about 3") was used the M5 Stuart, the M8/M20 armored car as well as the WW2 Canadian Lynx scout Car. These were made by the Standard Products Co (Thermo Plastics Division). They had other obscure uses too. They are a combination of a plexiglass core, thin mirrors and a black plastic protective shell outer. ........ Brian

[Mrs Vampire]

Hi Brian

M3A1 Stuart. I have been unable to source bits so I am making them .

[Ian Fawbert]

Hi Gina,

Might be abit late now, but did you see this post from Steve Greenberg on g503.com?

http://g503.com/forums/viewtopic.php?f=82&t=193757

Cheers,
Ian.

[Mike Cecil]

I see Steve G refers to trying to gluing them together, but the resulting optical qualities were not good. Resin glues tend to have a yellow colour, even when applied very thinly.

When I was training to be a geologist many many moons ago, we had to make our own thin-section rock slides for microscopy. The 'glue' was a thing called Canada Balsam which we used to glue the rock to the glass, then the cover slip to the rock and glass after grinding the face to the desired thickness. Optical qualities were not diminished. I wonder if that has an application here? It was what I was going to experiment with to make the glass vision blocks for the Dingo, but of course, relocating to the USA got in the way of that!

There are probably much more advanced mounting media these days, but microscopy could provide a type that is durable and does not diminish the optical properties of the glass.

Just a thought....

Mike

[Mrs Vampire]

I live and I learn.

Casting them costs about eight bucks a piece. The optical quality can be made near perfect if one is prepared to grind them back to a dead flat surface and polish them. I have done one and it has taken around two hours to get it right.

I am using crystal clear Polyester Styrene casting resin and Silicone casting mold.

I have abandoned that technique in favor of getting the local Perspex supplier to make me an acrylic extrusion that is optically perfect . Cost for enough to make six is sixty bucks. I only have to slice them into appropriate lengths with the little rebate at the end.

I opted for acrylic mirrors which I am assured can be bonded perfectly clear using acrylic glue'''the trick is to get the bubbles out as you glue it. I will experiment with that. The alternative is to bond then from the sides using silicone rubber.

The centre prism for the Fwd protector scopes has proven to be time consuming but straight forward. I have sliced a 15mm Acrylic sheer with a 25 deg bevel along one edge and the opposite angle on the other side. I used a Dremel tool routing tip and shaping bench to make the 1/8 x 1/4 rebate along the rear edge. works fine so long as overheating is avoided.

Perfect clarity with acrylic sheet is had by flattening and flame melting the surface....something I am happy to leave to an expert given the cost per unit.
Not counting my stuffing around I estimate around $15 a unit for the pistol port scopes and $60 for all the mirrors and windows front cover leather pads and bearing blocks for the front scopes including the direct vision side window.

[Mrs Vampire]

Have all the bits made now .