Looking for info on the L42 L1A1 scope turrets

Could I bother anyone here who has an L42 with an L1A1 scope for a picture of the JUST the top of the range drum. Nothing else is required.
I have had several L1A1 scopes in for repairs over the last year and the tops of the range drums have holes drilled all over the place for aligning the drum to the inter gear wheel stud or bushing.
Several looked like a drunken woodpecker had been at them.
Many are in gawd awful condition and I am wondering if Donnington shipped out a pile of crap when they surplussed out the L42's, or just what is the story.
Just PM me and I will give you my email address to send the picture to.
I really appreciate any help I can get on this, as it purely personal, academic and I will share the results here if I get enough responses to make it meaningful.

Attachment 123464

Hi Warren,

Photo of the top of my L1A1 Scope should be attached, I don't see any of the multiple drill holes you mention. If you want any more detailed photos just let me know and would be happy to help.

Thanks for the photo
I cannot expand the photo very much but it does look like an extra hole at 4 o'clock
I will try and find the photo of one that had 3 or 4 extra holes and post it
cheers,
Warren

Closer photo attached

Attachment 123469

Attachment 123470

This one is not bad compared to a couple that I have in for repairs.
I would love to see the original spec's on the upgrade from Mk.3 to L1A1

https://www.milsurps.com/attachment....71&cid=1&stc=1

My two dont show any thing like yours Warren. Though one windage drum has been re drilled but not the centre post. Looks to me done to a line the marks.

Greetings Warren

Here are my L1A1's, if it helps rifle conversion dates: 70, 71, 71, 74 All but the 70 have the correct "M" marking, so I do not know if the 70 still has its Mk 3 scale or if they did not mark the "M" until later??

Lance

Lance, a few of the metric scales were not marked with the 'M'......I've had a couple. If you compare how far the 1 to 10 range grads go round the circumference of the scale ring you'll be able to tell one way or the other.

Sorry I've not contributed Warren........but I simply do not own a single L1A1 scope anymore! I'm watching the thread with interest though.

Thanks, Roger! I just checked and the grad lines have the same spacing as the "M" scales and are way different from the No. 32. In all these years I have never looked. My tidbit of learning for the day!

The Mk 3 should have 60 clicks between 0 & 10 and the L1A1 is 48 clicks. That's how I was told to tell the difference (numbers from memory)

If you look closely you will notice the graduations are not the same distance apart between the M and the standard drum.
I have them displayed flat in a file and see if I can show the difference.
Doing that was an interesting exercise with the drum on a mandrels, the camera on the carriage of the lathe and bull gear on the lathe rotated a few teeth each shot.
Lots of fun and the things we do playing with Lee Enfields and scopes.
The ranges due to the tooth difference using the .303 plates and 7.62 are not the same but lose enough.
There is an issue chart showing the correction factors and I have one here...someplace.
Going to get some charts made up ..someday :-)##

Is this the chart you mean Warren?

Attachment 123486

Quote:

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Originally Posted by Warren

There is an issue chart showing the correction factors and I have one here...someplace.
Going to get some charts made up ..someday :-)##

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Is this the chart to which you refer ?

How strange (and not for the 1st time).

Warrens was the last post showing before I posted the 'chart'.
After I posted another post appeared, made 2 hours earlier but not on view.

Never mind, better to get it twice than not at all.

Thanks guys, I do appreciate it.
Yup, that is the chart.
I have one someplace on my desk as I just had it out the other day and was trying to see if it would photocopy.
I am thinking of send one along with the No. 32 scope "sight in target" I include when I return repaired No.32 scopes.
Just a little added touch..

Good Day Warren and All,
Here are a few pictures of elevation turret. Pictures have been emailed to Warren directly.

Regards,
Michael

https://www.milsurps.com/images/impo...HwuCuhPl-1.jpg
https://www.milsurps.com/images/impo...H7DjOZcl-1.jpg
https://www.milsurps.com/images/impo...cyXZsBSl-1.jpg
https://www.milsurps.com/images/impo...9f3enkfl-1.jpg

Hmm, interesting in that the BA10 locking screw is missing.
I am finding so much hit and miss on the L1A1 scopes I am beginning to think they were overhauled in India by the lowest bidder.

IIRC Warren, PL told me that some of the last replacement drums were not fitted with the tiny locking screw. When I fit replacements I do not fit the screw either, & they work fine. There seems to be enough 'friction' between the two parts for them not to slip.

Hi Warren

Here's a pic of mine. For info it also has "DON/88" in white paint on it. An overhaul date?
If you need it emailed please let me know.

Kev

Attachment 123502

Quote:

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Originally Posted by Roger Payne

IIRC Warren, PL told me that some of the last replacement drums were not fitted with the tiny locking screw. When I fit replacements I do not fit the screw either, & they work fine. There seems to be enough 'friction' between the two parts for them not to slip.

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That is just slipshod, poor workmanship and cutting corners on the part of the military rebuild program.
Some are tight and others are quite loose. There are not many I have to use the wrench on to get the range drum off. The odd one you have to drill out the BA10 screw but not many.
I am not criticizing your work Roger, as you are one of the grandfathers of the 32 scope refurbish program, but why use 4 or 5 wheel nuts on a car rim when one will do. If it is there originally why not put it back. I for one sure would not want to be in the field and have the turret unscrew on me.
It just irks me when the people who designed the thing are not adhered to.
Sort of like the better mouse trap.
Hope I do not or have not insulted anyone but just my 2 cents on the issue.
I am finding the majority of the L1A1 scopes to be in only fair to mediocre condition mechanically, with lots of galled and worn parts. This opinion based is of the ones I have seen and even my own L1A1 scope.
Like the astronauts thoughts when going up: " everything here is by the lowest bidder!!!"

Thanks for your input Warren. You've done a lot more than I have. I should have clarified, that where I rebuild scopes with the original parts (ie. with the provision for the locking screw) I always refit it. However, where I have used a few of the later manufacture drums, I have not drilled them. It might be beginners luck, but so far they seem fine & are giving good service.

I just did not want to think I was sniping as to the grub screw.
I really find it amazing that the rebuilds did or did not have it and some looked like the result of a drunken woodpecker.
I think the record was 7 holes in the turret.
I wonder if they were converted by the Military or by a private contractor.......
I just do not feel comfortable leaving one without the grub screw and I think I would even think twice about a wee drop of blue Loctite.
Just my 2 cents for what it is worth.

Another of those cases like ocular lens retaining ring screws, sunshades and pads, where repeated loosening and tightening causes wear to the threads, and in some cases a bit of stretching perhaps, necessitating a bit more rotation to maintain a similar degree of tightness...

Impressive degree of concretion in there Lance: https://www.milsurps.com/attachment....9&d=1642935393

Dig it out and send off to a pollen specialist maybe? You might have a bit of the Omani desert in there? ;)

What a bugger. Jost posted a long answer and it's disappeared. Here we go again but shorter........

Interesting question with several easy/simple answers. But first.....

What I'm going to say about them is only based on my limited experience of seeing thousands and working on say, a thousand or so. So it's pretty limited......

Just to answer an ambiguity that I think I detected. THE CLICKER PLATE in the No32 Mk2/1, the Mk3 and the L1A1 is the same. It is the RANGE SCALE on the drum slipping scale that is calibrated differently - as someone has already pointed out. The toothed clicker edge extends through 360 degrees for ease of manufacture on late Mk2's, 3's and L1A1's

As for the range drums, what RP says is correct. Later production drums from X&X had the thumbscrew part staked in place to the central axis/spindle (the brass ring between the thumbscrew and the lead screw locking screw). You can clearly (?) see the remains of the 3 equidistant stake marks on the photo of Desperate Dans (DD hereafter) photo. But, this relaxation was only ever successful until it was undone the first time. Then, due to the mechanics of it all, as the thumbscrew is undone on the cleanroom bench, by default, the staked lock is broken. Thereafter, as in DD's scope, on reassembly you MUST revert to the 10BA grub screw. No screw = crap job - I say!!!!

Something else now. No lock screw means that when you rotate the drum around to 0-zero, it's usual position a bit heavy handedly it could start to unscrew. And guess what......... As they tell all first day mechanical engineering apprentices. If something can, then eventually, it WILL. So take that advice on board.

And while we're here, another thing. When the thumbscrew is removed from the spindle, always mark the underside of the spindle with the letter R (or A, azimuth or D deflection) so that the thumbscrew goes back on the same spindle. That way, the 10BA locking screw holes will(?) coincide again and all is well. If they don't or overturn slightly DO NOT turn the thumbscrew back a bit until they do align again. That is ****-poor engineering practice and the hallmark of the devil!. Tighten thumbscrew up and if necessary, re-drill and tap, new grub screw, job done perfectly.

If you reverse the thumbscrew to re-align then all you are doing is to make BIGGER problems the next time because each time the not-properly-tightened drum turns back and forth, the little STEEL screw is chaffing away at both sides of the thumbscrew and spindle. First you notice a tiny bit of backlash between the thumbscrew and spindle until it gets worse and there the problem really starts. The grub screw is sat in a stripped hole and you can't get it out. Yes....., you an screw it in further (maybe) but the problem is still there - and getting worse. This time you will have to drill it out. That is fine - until the threadless grubscrew rotates under the loading of the drill and simply won't come out because the drill cannot grip it to cut it out!.

I've never had one fail on me yet but I have had a few where the owner has attempted to unscrew it with the sunken grub screw still in place. It’s all lessons learned from the really experienced old instrument teccies and my few years since the 60’s

On a well used telescope that’s been around the block a few times it’s only natural that there will be signs of previous grub screw locations. Waste not, want not of course. I recently had one, almost at the end of its life from Brian Dick that had more vacant semi circular holes than a second hand dart-board! Maybe Brian should put a picture of that one up. And that telescope was a picture of what I’ve explained here. I tightened it up, tested the operation and guess what….. Yep, had to drill and tap yet another locking screw hole. But it’s fixed for good.

Maybe I have explained now why some of these old telescopes have lots of holes around the drums and why some of the holes look a bit moth eaten – or look like they’ve been got at by a butcher-bubba king. It’s because instead of getting the tele looked at when you feel the backlash coming on, the users just leave it and leave it and leave it….. Holes get elongated, threads strip and before you know it, it’s xxxxed!

At the workshop instrument bays we always had a drawer full of rebuilt drums using inspected parts built up into serviceable assemblies. Those made up from mix-and-match parts from others, broken for spare parts always had a few extra unused holes. On these – and on telescopes sent out into service – the open holes around between the thumbscrew and the spindle, we pressed a black mastic sealant called LUTING into the hole which covered it up and kept the damp/moisture out. Simple

And something else too. Never, never not ever drill the 10 (or later, 9 or 8BA) holes freehand. Always set up un a drill press and universal table. I had one with the broken drill bit in the hole!, but an easy fix

One other thing I ought to point out is that if you have unscrewed the grub screw and the thumbscrew won’t unscrew, DO NOT blindly turn it regardless. Sometimes there’s a second grub screw below the first as added security – just to xxxx you about.

There, that wasn’t too bad was it. All you need to do is ask and I’ll try my best to answer

For the very bravest repairers, where the grub screw holes DO align but the thread is stripped OR where they are almost in exact alignment, then we could and did drill out to 9 or 8 BA and re-tap. That way we could use the little 3/16 grubscrews from the No2 binocular ocular cell assembly

Thanks Peter. I obviously only remembered half of what you'd said! I'll drill them or carefully centre pop them (where I'm using new parts) in future.

Going back to the range scales - both of those shown are metric, as can be seen by the same spread of range grads from 1 to 10, but only the one is 'M' marked. Presumably a few slipped through the net.

Peter:
Much thanks for chiming in.
I was rather hoping you would.
Nice to see you back.
I was really taken by the poor quality of the L1A1 scopes that I have seen.
They were quite abominable in MY OPINION...
Some L42's were almost mint and others were as you say over the pond "bog standard".
No attempt was made to clean out the dried paint on the adjusting screws, stripped screws and galled heads, etc.
Roger and I had a long chat about this the other evening and he shared with me what he remembered of what you had told him on the subject of the missing grub screw.
I still think it is poor workmanship to send something out the door like that and I must assume the designers had something in mind putting it in on the original No.32, Mk.3.
Was the conversion done in house or done by an outside contractor???
Outside contractor might explain the poor quality of some conversions or as I now see them.

---------- Post added at 11:33 AM ---------- Previous post was at 11:27 AM ----------

I have found the second 10BA grub screw more than once.
Also the mess that results from unscrewing a drum without removing the grub screw(s) using vise grips on the turret and bushing.
I will post some pictures of the resultant mess that can occur as I kept them as examples of what comes in.

"Just a quick clean up and dust the lenses
There is not really that much wrong with it."

The rifles were sent for conversion to Enfield from the various Ordnance Depots around the Country on a rotating basis due to the shortage of serviceable No4T's in the system. The telescopes were shipped out to the various Base or Command workshops around the country, close to the Ordnance depots, to be converted, cleaned, tested and returned. It wasn't a difficult job. Once converted, they were returned to the Ord Depots where they were mated up with the rifle again.

There was always a bit of confusion over the engraving..... Hence the reason for the slight variations you will encounter. Until it was finally codified..

Some owners might see that their scope started out as a No32, then converted to an L1A1, then re-engraved to suit the codified engraving - and then re engraved to revert it back to No32 Mk3 in order to equip the No4T's that were part of mobilization stockpiles. At the end there was a total shortage of telescopes that the equally easy converted 2/1's were converted. Mind you, telescope shortages were but nothing compared to the shortage of wood furniture.

The L1A1/L42 was a good - or bad - example of something being done on the cheap. As was said at the time, new build on the zillions of new ex Fazakerley bodies was a far better option but so said, the skills required were not available then. That ignores the fact that while BSA rifles were selected because of continuity of manufacturing tolerances, so were the new 50's production Fazakerley bodies. And they were new.

Thread 26. I always wondered where my little engraving head tool went DRP!

A few examples of what comes in the door.
I think I tossed a couple in the bin.
The bushing has had the die run on it to clean it up as as originally the threads badly smeared.

If you think the British engraving is convoluted you should see the early production REL Mk.1 !!!
The engraving runs 360 degree around the tube with some info on the top, some at 3 o'clock, some at 6 o'clock, etc.
But, we learned to how to make world class optical glass in less than 6 months.
We were casting billets of optical glass that was second to none but we did not have bombs dropping on our head either.
Our problem was with sealing the scopes and I have had the opportunity to open a number of early REL scopes that still had the soldered over screws.
The seals were oiled cotton twine....Nothing else.
I know it is used on valve packing and Vickers guns but not sure it is kosher for a scope adjustment movement.
The saga of soldering the mounts to the action was also a real bone of contention, as Canada did not solder the pads and there were copious letters back and forth between the UK and Canada on that subject.

I would slightly ........, no vehemently, disagree about REL optical glass Warren, especially with regards REL No32's. There was a soecific instruction called a 'Miscelaneous Instruction Tels,Searchlights and Instrument EMER relating to any Canadian REL telescopes that are in UK military service. To the effect that due to the non interchangeability of the lens optical patters, it may be necessary to replace the lenses as a set with UK production.

To illustrate the point, have a look at various REL Mk1's and 2's. Ocular lens sets with double sprung spacers in order to match the optical light path to focus the graticle. I've got one in front of me now. If the lenses don't match, just replace them from a known matching set from a No42 or 53.

Sorry to disagree Warren but while the glass grinding might be perfect (it is.....) the glass spec was not, hence the refractive index per lens (and there's 4x lenses per ocular set) was not to the spec. Easy to illustrate using a spotlight and a black board

I'm not sure that REL No32's were any worse than UK production regarding waterproofing. Some UK's were good while others were poor

Attachment 123557

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Originally Posted by Warren

If you think the British engraving is convoluted you should see the early production REL Mk.1 !!!
The engraving runs 360 degree around the tube with some info on the top, some at 3 o'clock, some at 6 o'clock, etc.
But, we learned to how to make world class optical glass in less than 6 months.
We were casting billets of optical glass that was second to none but we did not have bombs dropping on our head either.
Our problem was with sealing the scopes and I have had the opportunity to open a number of early REL scopes that still had the soldered over screws.
The seals were oiled cotton twine....Nothing else.
I know it is used on valve packing and Vickers guns but not sure it is kosher for a scope adjustment movement.
The saga of soldering the mounts to the action was also a real bone of contention, as Canada did not solder the pads and there were copious letters back and forth between the UK and Canada on that subject.

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Are those features ever seen on any other No.32 Mk.I's? Not that I've seen apart or taken apart; in fact was there any spec. for water or weather-proofing the non-R.E.L. Mk.I. scopes? No evidence of same that I've noticed.

Sounds like R.E.L./S.A.L. were pro-actively looking for ways to improve the design, rather than slavishly copying what was provided; a policy that is evident throughout their production - though of course they soon realized they could design better and did: the C67, Telescopes, Observing, Snipers & Stand, Monte Carlo stock for the No4(T) etc.

Can't speak to the quality of R.E.L.s glass compared to UK production, but looked through many R.E.L. and UK produced No.42s and the light transmission of the R.E.L's was clearly and considerably better in almost all cases. Perhaps a bit more spherical distortion at the edge of the f.o.v. though?

As Peter mentioned the curvature of the ocular lens doublets is different from U.K. production - ' don't know why, but commonality of production was reportedly an issue R.E.L/S.A.L. also tried to put into effect where possible.

The difference in curvature of the lenses and spacing between them is due to the different refractive index - which will affect the light convergence point - of the flint and crown glass used. Hence the need to extend the space between the ocular lenses. Not just the oculars, but the erector cell lenses too. In short, the glass used was not to the specification set. But, that said, by adjusting the focal layout of the lenses they produced, they achieved the aim with a hint of outer spherical distortion.

That said, again..... No good trying to replace a, say, cracked REL ocular or erector with a UK lens. From my limited experience once again of having fixed one or two, best start again and use a UK ocular and erector set throughout. That's why you should ALWAYS have a spare No42 or 53 handy.

Incidentally, waterproofing Mk1 and 2 turrets is absolute simplicity itself. You machine a radiused half recess into the lower edge of the thumbscrew/scale drum and a corresponding half recess into the index plate. Insert a suitable diameter x 1mm thickness neporene O ring (cheap per 100!), bit of rubber or silicon grease and that's it sealed at its weak point. EXACTLY as per the W rated No32 Mk3's and L1A1's

I'll second that. One of the most useful pieces of advice Peter ever gave me, when I started having a go at repairing some tatty scopes of my own, was to stick to using complete lens sets. You know that these have been on the optical bench & are matched.

It's not always possible, but if you can manage to turn up a nice No42 or No53 with good lenses made by the same manufacturer as the No32 you're rebuilding, the lenses (as a rule of thumb) will generally fit into the tube without too many dramas. I have several Kershaw No53's I've stashed away for using on a couple of needy AK&S No32 Mk3's........& likewise HBMCo No42's to restore HBMCo No32 Mk1's.......

Of course, you don't always have the luxury of picking & choosing the make of No42 that turns up...........unless you have 450 of them. I wonder, does the gentleman concerned still intend to convert them all into No32's? I would have thought the appearance of relatively inexpensive copies from the Far East would have made that financially unfeasible, if it ever was.

Another turret for the survey, and serial number info in case it's useful.

Sorry to disagree Warren but while the glass grinding might be perfect (it is.....) the glass spec was not, hence the refractive index per lens (and there's 4x lenses per ocular set) was not to the spec. Easy to illustrate using a spotlight and a black board


Please demonstrate this as I would love to see it, probably along with a number of others...
Of course you cannot mix Brit and Cdn lenses that is a give. BUT" sometimes ya get lucky" and get a decent match.
Flint glass, crown glass and the Canadian Balsam used as the glue all have a slightly different refractive index, batch to batch.
That is a given. When originally making the scopes the maker had a lot of choice in assembling matched couplets and the use of a focimeter/lensometer.
I am waiting with baited breath for the lens demo with the flashlight and blackboard as I know several others will be as well.
Perhaps a short video is in order.
The optical engineer who helps me on occasion and I know he would probably be interested as well.
I have some great info from him that some of which I cannot understand and I will send it to you and I am sure you can help us all by an explanation of it, as you taught it.
Anything I can learn on the subject of the theory of simple and complex lenses is more than welcome. The mathematics and forumuli just kill me. I even built an optical bench to work at it.
The mechanical end is rather straight forward, but lens theory is a real bald spot scratchier...for those of us who are folically efficient. And, for us more mature guys.
Many of us who repair the No. 32 keep in touch with each other and share parts back and forth. Even with the exorbitant price of postage, now we manage.
Appreciate the offer of the blackboard tutorial and as most mobile phones have video clip of up to 30 seconds and more it will be a no brainer to post it here.
Hopefully, without overstepping any bounds here, if someone needs No.32 parts just ask, I just might have it.

Ignore reference to a torch - I will try to use a laser for simplicity.

Time to yawn now and nod off for a few minutes........
But back to ocular lenses. You'd think that with modern plastics, like spectacles, you'd think that you could grind or even cast new lenses from optical grade plastics. Someone had tried it, partially successfully too and gave me a set to bench test. Alas, each doublet was cast/machined as a single piece. Without the benefit of the different refractive index qualities of very hard flint flat/concave lens (the flat OUTER lens, -that's why it cracks/chips sooooooo easily) and softer crown, (the inner double convex), you loose the ability to focus on the grat and eventually the image within the distance within the telescope. (that's why we've got prismatic binos)

I did get the optical plasticised lenses to work successfully but only by inserting ONE as the internal lens in the ocular lens train while extending the distance between the lenses. For some reason that I never quite understood, I couldn't get the ocular train to work in the reverse order.

It is for the same reason that later Mk3 ocular lens sets using the plossl optical system have slightly convex outer surfaces instead of flat.
And the same reason why later, the most forward of the erector lens forward facing surface (we call it the 'screen' lens because it acts as the image screen) is very slightly convex instead of FLAT.

Here's a word of advice about erector cells. I'm sure everyone knows this so go back to sleep......
the rear lens is DOUBLE CONVEX. The most pronounced convex surface must face forward towards the graticle - AWAY from the stop-down shield
The screen lens is a PLAIN and CONVEX lens. BUT NOT ALWAYS on later production. In these cases, the most pronounced convex surfaces must face each other, towards the spacer.

Stay awake at the back of the class..........
HOW CAN I TELL WHICH convex surfaces are greater or smaller without an optical radius gauge. That's easy............ Get a dark shallow dish - a saucer is perfect and JUST cover the bottom with water. just a few thou deep will do Place the lens in.
On a flat surface, when viewed from directly above, the water will show over the whole lens
On a convex surface with a LARGE radius, the water will show over a small area at the centre
On a convex surface with a SMALL radius, the water will show over a large area at the centre. The two greater curvatures are to meet. The lens with the flattest curvature will act as the screen. So assemble accordingly.

There is another method by using the size of the reflection of a light but let's keep it simple

Just use a clock dial lens gauge...
Problem solved
You can pick up used ones for a 5'ver on Ebay
A perfectly flat or plano lens surface is almost impossible to manufacture.
I'll post a picture of one of mine later today.

---------- Post added at 11:28 AM ---------- Previous post was at 11:24 AM ----------

Also a big thanks for the pictures of the turrets to those that sent them to my email addie and as a PM.
It is looking about 50/50 on screws and no screws.
I just do not feel comfortable without the grub screws but if it works without ...why not.
It sure saves me time and trouble in drilling, tapping and installing a 10 BA grub screw.
I just (personally) think it is mickey mouse and was the reason I thought the conversion was done with by an outside contractor: bid low and cut corners...

Valid point of course re curvature gauge that I mentioned but I was trying to keep it simple.

I would have to admit that the quality of work on some of the L1A1's that I have seen simply beggars belief. Nt so much the optical side but just the assembly afterwards with the over use of silicon sealant that.... anyway. Poor out inspection I say....

Totally agree on matched lens sets.
Nothing like a 42 or 53 with GOOD matched lenses to replace the lens set in a buggered No.32
When you have the lenses to match up, as happened when the scopes were manufactured it is nice.
The big problem nowadays is finding a decent 42 or 53.
It appears that many ocular lenses and OG lenses in the crop of 32 and 53's out there have had the lenses cleaned with 40 grit sand paper and the crown glass is pooched.
Lenses in a No. 32 are achromatic lenses and consist of two glass lenses glued together by either Canadian balsam or nowadays an epoxy. Not sure when the Brits started to use epoxy.
One lens is crown glass and the other is flint glass. Many couplets are starting to separate or have separated after 70 years and need splitting apart and re-gluing.
I still prefer the balsam glue. Not as easy to use but if you make a mistake you can fix it. Many use the epoxy but if you miss centre they are a bugger to get apart and take another stab at it.
That is why you will see V's cut into the edge of a lens to make sure they to in the correct orientation as well as the lens centre lines up. If you have a focimeter it no problem but few do. I use one on occasion just to check the lenses before gluing them back together.
My old mentor was a advocate for separating lenses in a the frying pan with heat but I still can wait for a few days and use MEK or methylene chloride. I do not have the lenses that were available in the forces.
He was also a master of using spider web for some applications and that is an art within itself.
The glue for spider web was lacquer or ear wax....No ****..ear wax. I wonder what the stock number on that was :-)##
Minor scratches on the crown glass you can polish out with cerium oxide but if you can feel the scratch with a fingernail the lenses are toast.
Glass is not as hard as you would believe and grinding a shirt tail around it to clean the lens is death to it.
I had new glass lenses made and they are no cheap venture. I had them checked out by an optical engineer and the duplication to the original was amazing, plus or minus tolerance. Again: REL and British different.
Most of the time the problems with scratched lenses is the crown glass on the ocular couplet. Trying to match up a set is difficult, but sometimes you get lucky.
There you have a bit of what is involved with the replacement of lenses and when you have a donor scope with good lenses you are in the pink.
Get a bad ocular lens in the donor and the fun begins.
Hope this is of help to some here regarding the replacement of No.32 scope lenses.
You could write volumes on scope repair and the practical end of it . You could fill volumes, but I hope you get the idea.
If you have the basic equipment and some knowledge of optics it is not a bad job.
And, as the manual says: assemble in reverse order....and pray.