Looking to buy that No32 'scope.........

[Peter Laidler]

Good point raised by DRP there concerning the delicate subject of what do you do with a grotty tube in the first place. The only answer I know is the UK MoD answer which is a rusty/pitted tube is really academic in the great scheme of things. It’s just like a rusty pitted rifle....... It is nothing more or less than corrosion whatever nice kindly words you like to put on it! It’s just one of those things. But given the right treatment, such as the fine bead blasting and removal of all the rust then the phosphate coating (this is the actual rust proofing incidentally) then it’s ready to go. The aesthetics are really of no further concern.

Where it DOES get a bit dicey is if the bead blast operator goes a bit beserk and just turns the pitting into holes! As a general rule, the MAIN parallel tube isn’t a problem so far as blasting holes through the pitting whereas the ocular bell-end IS a cause for concern and can easily be penetrated. In that case, in the Army world, the telescope would be in for the chop of course. It’s not only those ex Indian Army telescopes that are heavily pitted and have seen a hard life either. There were plenty of well used No32’s and L1’s like this believe me! But in the civvy/commercial world, then a relatively simple grafting job is the only answer. I’m not keen on the ‘polish out the pitting’ school of thought either for sound mechanical reasons. It is what it is and like your Land Rover Chassis, if the pitting is there and treated properly, then it ain’t going nowhere else!

One alternative is to chemically de-rust the tube as detailed at some length in the restorers forum a year or so ago. This is a far more gentle process but alas, not a good key for the phosphate treatment.

In short, if the corrosion is bad, try chemical de-rusting first. Then shine a torch inside and any pin pricks of light will indicate a hole. A sound looking tube just go to the bead blaster.

But a further word of advice as raised by another forumer....... NEVER, ever, ever leave blind threaded screw holes open in the item within 100 yards of the bead blasting cabinet. Always put screws BACK INTO the holes. At all of our workshops we had some square plates that could be screwed down onto the open turrets thereby keeping the screw threaded holes AND inside the turret area free of grit.

Hope that’s answered the Q DRP.