Swift Audubon HR/5 - repairing the eyepiece arm

[DaveL59]

Not sure if this should be in DIY or here under binos, mods feel free to move if you feel the need  

So I recently bought a pair of Swift Audubon HR/5 which from the description had the dioptre eyepiece cup detached. Figuring it may just be loose grub screws I figure take a punt. They arrived yesterday and initial look were a bit grubby but intact.

Eyecup was definately off and sorting the grub screws it refitted ok, tho I note the plastic body has a split so this will need attention. Dioptre was smooth and sticking, closer inspection shows why that was

The carrier arm has broken at the hinge loop. Oh dear.

Further inspection then revealed:

oh no! A lemon then 😢

Cleaned the lenses in and out then put it back together while I decide what to do and gave them a test. Out of alignment before I opened them up, but having teased the chipped prism up a touch that seems to have sorted the alignment - well when you get the eyepiece in the correct plane. Image is nice and sharp but of course awkward to get the RH eyepiece to sit right as you focus. Luckily the chip doesn't seem to interfere with the view, possibly just outside the FoV but I'll try masking that with some matt black later on just in case it affects the contrast. Almost tempted to try windscreen chip-repair to flatten it out but it'll be the wrong optical index so maybe a bad idea, other that it might stop the chip worsening.

Having had a look around for ideas on the arm, came across this thread and in particular this post
https://www.cloudynights.com/topic/700039-celestron-30x80-giant-brokenrepair/?p=10066320

Interesting, a bit of metal plate shaped to suit and spliced in, sounds like something I could do, tho no milling machine so it'll be files and drills to achieve it. Definitely worth a go, since none of the junk spare pairs I have suit then as a cut-n-n-shut donor to splice in for that part of the arm. I'd seem a previous effort using fibreglass board but I think metal will be easier to work.

 

 

[DaveL59]

so thinking a bit on the arm repair, and not having aluminium plate laying around at the moment (might find a bit at my dads tho), what other options...

Well I've some thick penny washers, looks to be M11 hole needed. Found a couple but they're 12.6mm, too loose on the shaft, but might it work I wonder?

hmmm it might actually be an option. Just needs to be re-worked to the right shape

In fact like this it'd reinforce the broken part and could be fixed above the arm with epoxy, perhaps. Downside is that'd reduce the amount of thread holding the centre screw in place so perhaps not.

So cut it into the arm sounds like maybe a better plan, so I'll need a thicker washer (2.7-3.0mm ish)

Just ordered M10 2.5mm thick penny washers in stainless, when they arrive I'll see if this is viable. Plan will be to grind back the broken hinge overlap down to half the arm thickness or just under. Then once a washer has been shaped to suit the job, secure together with epoxy and once set, drill and tap and use a couple 2.5-3mm grub screws to give some torsional relief to the joint.

Will update as I go...

 

[DaveL59]

thought I'd test the idea a little by placing a penny washer I do have and see:

yep it's under the bottom arm and the break is in the top one, the hole in this washer is large enough to allow the hinge locator pin to pass through and engage too with the washer offset for this. Tightened down the centre screw and now the focus action is smooth and the arms both stay aligned level with each other, allowing the occulars to move easily in their tubes. Of course this does limit the focal range toward infinity since the occulars can now not travel in by 1.5mm ish. But it does support the idea that a solution with a thick washer is possible.

Now I'd guess that working a metal plate isn't going to be that much less work if I actually had one laying around that is. But I'm thinking stainless steel at 2.5mm would have more durability than aluminium in this use case.

Am now so tempted to glue a washer to the top of that arm and fit it as a temp fix just to see how it does. Will do my best to resist, since the new washers should be here in a week-ish. Meantime it can live as it is with the washer under the arms and at least be usable for quick looks around the garden  Collimation is a tiny bit I think off but not so much as it feels like eyes being ripped out, not really going to get much real use till I've done a "proper" bodge repair on them tho  

[Peter Drew]

Interesting thread.  I also read the CN topic facing the same issue, I'm pretty sure the washer reinforcement option is the best way forward.  I would certainly use steel rather than aluminium as I don't think the latter would offer enough stiffness.  The Swift "Audubon" 8.5x44 is a well regarded binocular and well worth repairing.  I look forward to hearing how it all works out as I have a binocular with the same problem that I have been meaning to repair for years.  It is a 60 year old Kershaw "Monarch" 12x40 which not only belonged, from new, to my late father but was the very instrument that started me on my astronomical career, so of immense sentimental value.    🙂

[DaveL59]

thanks Peter, that bodge with the washer under, I added some double-sided tape now too to hold the broken arm steady and was just out testing, working quite well just like this and can focus on distant clouds. Was hoping to get a peek of Venus but lots of cloud that way so no luck there.

Am hoping that a reshaped washer will do it, similar to what the CN thread did with a plate he made. Am now also thinking some M3 or M4 countersunk screws as I could chamfer the steel and thread the ally under so there's no sideways motion. Not sure brass grubscrews would have the strength in use, tho if I epoxy the 2 parts together then they'd just be a bit of reinforcing rather than taking the full load.

Nice that you still have the monarch's esp since they are sentimental to you. Hopefully you'll also be able to fix them up and get them back to fully functional  

[DaveL59]

Well Venus is now peeking out of the blue sky between clouds and guess what?

The HR/5 with that 1.5mm washer under the arms actually hits focus on her right at the stop! Lovely sharp image to boot so I think these HR/5's are definitely worth trying to get repaired. In fact they're a better fit to my hand that the older MK2's which are the bulkier body format. Both give really nice views though so likely will stay in the collection.

Will need to sort a case for these once I get done but if I needed inspiring to get it done that view of venus sure did it for me. Earlier I was seeking the birdies in the oak tree out back and I could make out small insects and spiderwebs at the very top of the tree so resolution on these is excellent.

[NGC 1502]

Thanks for that, interesting read because over many years I’ve fixed things up with all sorts of DIY solutions.  Some of these worked well and others needed a second or third attempt.  A few turned into a disaster however. My shed is full of bits and bobs that may come in handy.  Problem with that is sometimes I know I have something but cannot locate it.....it’s in here somewhere 😀

Ed.

[DaveL59]

I so know what you mean Ed, took me ages to locate those washers and I'm sure I've a thicker one somewhere but didn't find it. Was hoping one of the junk bino's would have an arm that fitted over the centre pin as I could've sacrificed the part to do a splice onto this, but Swift seem to use a larger pin and wider arms, hence deciding another route would be best.

Definitely worth saving these if I can, they're pin sharp and bright, lightweight and for my hands much easier to use than the older wide bodied 804's. Handy to have another project to work on too while I wait for the paint to cure and some flocking to arrive before I pick up the TAL-M refurb again  

Edited May 20, 2020 by DaveL59

[PeterW]

Good luck, sounds like for the JB Weld, rough up all the surfaces to get a good bond. I’d leave the chip, unless you’re playing tennis with them it shouldn’t get any worse... shouldn’t be and internal strain to change it... or the glass would be all birefringence.

good luck 

peter

[DaveL59]

so slowly picking this up again tho progress will be slow after a spell in hospital so not feeling quite up to serious fettling at the mo.

The penny washers arrived, offering one up it looks OK

but marking up the edges, its a little too narrow an overlap I think

certainly not much metal to support a couple small threaded holes and screws if I want this to be a durable fix. Oh well, a larger penny washer may have worked but hard to find in 2.5mm or above thickness.

So just bought one of these metal brackets from the local DIY, 2.75mm thick and the right width so when I feel more capable I'll have a go at opening up the hole to correct size and working the end to fit with a deeper overlap onto the original arm. Should be a lot easier too given it'll have a squared end which will be simpler to file the original arm to match.

I can see signs of the prism chips on the inside of the objective so these will need a good clean internally, a bit of matt black on the chip should be all that's needed once I get to that stage. 

Still have to figure a way to sort the cracks in the plastic occular holder, plastic welding maybe? A bridge to cross later, may see if I've any metal eyepiece holders I can swap onto this pair tho the size of these occulars may make that impossible.

[DaveL59]

so with a little more energy today, decided to take a look at what to do to modify that plate to suit a repair piece. I've 10mm and 12mm drill bits but no 11mm unfortunately as that's the size hole needed. So drilled the end hole to 10mm in classic DIY style, on a wall, foot holding the bracket and in with the drill. Then filed the 10mm hole out to fit the spindle, just under 11mm diameter. OK not a perfect round but good enough. Stripped off the arms and offered against the plate to mark the pattern I will need to reshape it to:

Now if I can cut/file down to these markings it should be a reasonable top-plate for the arm, which will need to be filed down to blend it in level. Likely will need a thin shim under this as it's a little thinner than the original casting but that I can figure later - milk bottle top cut as a washer to suit perhaps.

[Peter Drew]

On 19/05/2020 at 20:30, DaveL59 said:

thanks Peter, that bodge with the washer under, I added some double-sided tape now too to hold the broken arm steady and was just out testing, working quite well just like this and can focus on distant clouds. Was hoping to get a peek of Venus but lots of cloud that way so no luck there.

Am hoping that a reshaped washer will do it, similar to what the CN thread did with a plate he made. Am now also thinking some M3 or M4 countersunk screws as I could chamfer the steel and thread the ally under so there's no sideways motion. Not sure brass grubscrews would have the strength in use, tho if I epoxy the 2 parts together then they'd just be a bit of reinforcing rather than taking the full load.

Nice that you still have the monarch's esp since they are sentimental to you. Hopefully you'll also be able to fix them up and get them back to fully functional  

I managed to effect a repair on the broken Monarchs.  I used the washer that sits under the bevelled cap with the degree engravings as a splint and bonded the lot together.  So far it has held well enough to make the binocular usable again. They won't get much use as I have better options but I look forward to a few nostalgic observations.     🙂

[DaveL59]

so this evening now its cooled down a bit, started to cut the plate to make the hinge side into shape, initial rough hack with a hacksaw

and then filed back to form the right shape

not perfect, in fact maybe filed it back a bit far, still it fits and will be strong enough

Just need to file the sides a little to match the original arm better and then cut away the section I will use to splice in. After that it'll be marking up the arm and filing that down to blend this piece in, tap 2 screw holes and go buy some 2-part epoxy to bond the 2 parts together. Then a spritz of black paint and hopefully...

[DaveL59]

so this evening's progress.

Finished filing and cutting away the repair section and offered up to test the fit

cut into the ally arm to set the point at which the repair section will be fitted

then filed back the ally arm so the repair section will sit reasonably flush. (forgot to take a pic, will add later)
So now that's done, test fit the arm and repair section, looks good

needed to take the repair section slightly further across the arm tho as the occular wouldn't fit since the arm is a little out of line. Out with a square file and corrected so that it all sits flush and aligned. Test fit together with a little double-sided tape and...

 

it works, moves smoothly thru the focus range and IPD's  

So tomorrow eve I'll see if I can drill and tap a couple small holes to get the 2 parts nicely locked together and then do a final fit with some epoxy and screws. Once done I can file the ally back to be flush with the steel repair section, spray with black paint and call it sorted I think. Then it'll be a case of clean up internally and sort the dioptre ring and these will be quite usable once more.

Edited June 23, 2020 by DaveL59

[DaveL59]

trying to decide on the best way of screw fixing the 2 sections together. Do I:

1. Drill/tap and use a couple 6mm x m1.6 brass grub screws to hold the sections together with epoxy securing the main joint area?
2. Or use a couple cap/dome headed machine screws from underneath, passing through the ally section and screwed into the steel to clamp the sections with a little more force? Perhaps no need for epoxy in this case, just a smidge of threadlock.
3. do neither and just epoxy bond the sections together and see how it goes?

(3) has the advantage of simplicity, no trying to drill and tap a small hole accurately through 2 materials and in theory should hold well over the large surface area. If it fails cleanly can always clean off the epoxy and re-try using options 1 or 2, maybe.

(2) has the advantage I guess of easy dismantling but shouldn't be needed unless the repair section breaks at the hinge again, not too likely I expect, being steel. Risks a future fracture across the ally section that may render the arm non-fixable again tho. Will have to root around and see if I've any 3mm machine screws to suit, think I've some dome-head security ones kicking about somewhere.

(1) has the advantage of a large bonded area to spread load in use, smaller holes needed for the screws. The brass grub screws would be flush to the arm so less visible and if the epoxy fails may well shear before the ally section would fracture? If true would lend itself to a re-do of the repair in the future.

Either way there's always the risk it'll fracture across the ally where it's been filed down from 6mm to 3mm. Will have to be careful not to suffer a future drop/knock on the occular as has clearly happened before. Also thinking that these must've been apart since the set screw locking the centre hinge bolt is missing. Not a prob as I can easily replace that. Still reasonably happy I kept these for £20, had I returned them likely they'd have gotten chucked and they're still quite salvageable IMHO, with a little thought and effort.

decisions, decisions...

(edit: added third option)

Edited June 30, 2020 by DaveL59

[DaveL59]

ok so an update. Decided to drill and tap for the 1.6mm brass grub screws, since I had purchased the correct tap for that a long time ago, add to that I can't find a drill bit suited for a 3mm screw which I have a couple from old laptop dismantles that would have suited. So filed back the lip left after trimming back the arm for the steel repair section:

Now with the steel plate it sits just right on the other arm and pivot, no apparent need to make up a shim to pack the joint, result.

So having decided to add the grub screws to help secure things, drilled and tapped for the 1.6mm screws:

 

and now we find that the tap is oversize slightly for the screws so they aren't biting properly and the parts can come apart with the screws barely holding the threads 😢 First time I've needed to use that tap so a bit disappointed with the result.

So what to do next?
Re-tap to 2mm and order new grub screws maybe? Will need to order a drill bit to suit too, or even step up to the 3mm screws instead.
Or just epoxy the 2 sections together and let the epoxy secure the grub screws as well? 

Am thinking the latter, after all the grub screws are only to add alignment and a little strengthening to keep the 2 sections together when in use, so this might be a reasonable way to go. A bit of a bodge tho which really isn't what I was aiming to achieve. Perhaps a turn of PTFE tape will snug the grub screws and solve the issue, will try that in a while after a coffee and some cake I think...

Edited June 28, 2020 by DaveL59

[DaveL59]

having thought about this and not finding the PTFE tape, decided the 1.6mm screws are just too loose in the prepared holes anyway, so have now ordered some 2mm ones and drills for 1.6mm and 2.5mm so I've the option to re-tap to 3mm screws if I decide to go that route. Should arrive in a few days so this little job can be parked for a few days I think.

[NGC 1502]

Enjoying following this, your planning and persistence is great.  I’m often fixing up all sorts of things, don’t like today’s chuck it and buy a new one mentality.    Learn’t this off my old dad because back then a lack of money meant he had no choice but to fix it.  Dad used a garage in the next road to keep his old banger an early 50s Anglia.  One time he removed the engine, wheelbarrowed it home and spent the winter renovating it in the spare room.

Fortunately the spare room was downstairs, saved him the problem of humping the engine up the stairs 😳 at the other end of the car he fitted a new crown wheel and pinion in the back axle........

Keep up the good work 👍 Ed.
 

 

[DaveL59]

cheers Ed, like you I like to try to fix than chuck and replace, tho that does get harder with modern surface-mount electronics - lack of kit and old eyes limits what I can do there. Love the story about your dad, never brought the engine indoors but I used to do all the maintenance on a couple cars, more affordable than paying a garage when you've more than one to run and saved us a fortune. Dropping the engine and gearbox out of the old Sud's to change clutch etc was a big job tho, lucky I was able to get a friend to help when it came to lifting the body up and over the lump on the floor. Was the only way as you couldn't lift it up and out. These days tho the car goes to a specialist, don't have the facilities here but small stuff like the scopes and binos I'm happy to roll up the sleeves and have a go. With these, nowt to lose so I figured I can only improve things so give it a go  

[DaveL59]

ok, so while I was doing other stuff this week, these arrived, 2mmx6 grub screws and drills so I can re-tap to 2mm or 3mm if the 2mm doesn't quite work

One thing I am thinking tho, steel screw into ally, extreme cold... will the ally fracture from the difference in co-efficients of expansion, hopefully not and I won't be using them at extremes anyway. So, drilled out the holes and re-tapped at 2mm and yep, the new screws fit nice.

downside is it's not holding the 2 parts tight, as in it isn't bolting them together, simply adding alignment and strength between the 2 layers. I'll be using epoxy anyway so this should do the trick I think. Test fit and looks to be OK and once glued the arms should stay in line as focus is racked.

Decided to file back the edges level before glue which looks much better and hopefully once painted won't show much as a repair...

here you can also see the split in the dioptre ring, one I've yet to look at sorting

So some progress, I can of course still decide to tap to 3mm and use screws to clamp the 2 parts together (or just order some 2mm screws even) am yet to decide fully on that. So far it looks reasonably OK tho, just wondering if bolts would add a mechanical advantage and mean either no epoxy needed or at the least, improve strain relief to the glue in use.

Right, off for a post-lockdown haircut  

[MarkAR]

If you want more clamping force from the screws then you need some with heads, either pan or countersunk.

Also might be worth adding some score marks in the surfaces for the glue.

As for the hairline crack, I think the best way might be a brass collar press fit over the top.

Edited July 5, 2020 by MarkAR

[DaveL59]

thanks Mark, yeah was gonna rough the surfaces for the epoxy and then degrease, esp as I used a touch of oil during the tapping. Still deciding on using machine screws or not, does seem maybe a better (stronger) solution but as they say, nothing ventured... so the grubs were worth a go but am of 2 minds now. Am not in a rush so can mull it over, after all it'll be a nice small no-strain project to finish after the op if needs be 😉

ok decided to order some M2x6mm pan head screws, for £1.50 may as well check out that option... will see when they arrive, likely is the better solution tho.

Edited July 5, 2020 by DaveL59

[MarkAR]

Might be worth putting a nut and washer on the back side if screws are long enough and there's room. Might help spread the clamping load a little.

[DaveL59]

nah was going to screw up from the ally side into the steel plate with a drop of thread-lock to secure them, should be fine with epoxy adding strength and moisture barrier in the join   Don't want it to look too frankenstein after all  

Edited July 5, 2020 by DaveL59

[DaveL59]

ok, so the m2x6mm screws arrived. Levelled off the ally by fitting suitable blocks on the file and slowly reworking that section and opened up the threaded holes in the ally too so the screws are bolting the ally section to the steel repair section. Holds very nicely now, well pleased with the change of plan  

test fit and the arm runs nice and smooth and level with the occular refitted.

So, now it'll be degrease, epoxy the sections and once set, prepare and paint to get a good finish so it'll match reasonably to the original. I did get some 0.5mm nylon washers too so opened one out to fit the central pivot as I think that may be needed to counter the slight rock once the arm is fitted up. The steel is slightly thinner than the original ally section was and any rock with cause image alignment issues as well as the movement to jam.

Still to strip and overhaul the optics and sort masking the prism damage but want too get the arm sorted first as that'll determine if its worth doing the rest