Repair of a broken camera lens

Hi all,
Looking for ideas...
My son didn't put my camera away properly, then my wife moved it and dropped it. The lens has a small piece that has broken off...
http://www.revilloc.com/lens.jpg
The piece attaches to the zoom ring and drives the internal zoom mechanism of the lens.
I have tried supergluing the piece back, but it just isn't strong enough. I guess that I will have to send it away for repair, but if anyone has any ideas first... it would be appreciated.
--
Best regards,
Dave Colliver.
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On Sun, 20 Jul 2008 12:14:17 +0100, David wrote:

Would it be possible to rotate the ring a bit, and fabricate/attach the tab to a different part of the ring?
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Not really... the markings of the zoom are in reference to the location of this.
I have been giving this a lot of thought...
My wife is going to call the sony center (it is a sony alpha camera) and see how much it costs to repair. If it is extorniate (the cost of an identical replacement is about £150), then no harm in trying to repair it myself.
If I do repair it, the idea I have had is to shorten the length of the tube probably about 5mm (accurately measured length), then turn up an alluminium stepped tube which the step will sit on the inside of the tube you see (there is actually a step on the plastic tube, which is what I would turn away).
Anyone have any thoughts on this?
(That bit of black plastic with the metal bit attached should be where you can see the grey section in the tube. It points to the center of the tube.)
--
Best regards,
Dave Colliver.
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home insurance?
--
mick



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lol...
Considered that. Not sure what our excess is. I think also our home insurance has a sort of no claims discount as well. That might make it still uneconomical.
Cheers.
Best regards, Dave Colliver. http://www.AshfieldFOCUS.com ~~ http://www.FOCUSPortals.com - Local franchises available

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Look on ebay
Bet you could find, the same cam in perfect working order for less that £150
What model is it ?
If it's older than 5 years ...digicams depreciate a lot ..
My cam, An Olympus 2050 was £350 about 4 or 5 years ago ...now I can pick the same one up on ebay for less than twenty quid ..which I have done ..I now have two extra...and mint examples ..for back-up ..£15 and £18 off ebay
And, you could put your old one up for spares and repairs on ebay ...if you are pleased with it's replacement .
all the best.markj
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Hi,
It is a sony alpha 100. They only came out 2 years ago. I bought it the day it was launched in the UK.
New lenses are only slightly more than the repair costs. (My wife has checked today.) So, no real loss if I screw the lens up.
It will be nice trying to do a repair and I think the idea I have for it will actually make it a stronger lens (won't break like that so easily).
Apart from that, if I document what I am doing (how to take the lens apart, machine the part, fit the lens back togethor), there could be quite a few people interested in bringing back their own lenses with this same breakage...
All I would need then is a CNC lathe to keep up with the demand.
--
Best regards,
Dave Colliver.
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Before you go to all that trouble (or enjoyment!) it might be worth trying JB Weld epoxy. It's something like black in colour. Judging by previous comments there may well be enough spare space around the repair to put a decent fillet of the epoxy for stiffness etc. Might even be enough for a cover plate on the outside. If it fails all you have lost is time.
Henry
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I will have a look at that, thank you.
Best regards, Dave Colliver. http://www.AshfieldFOCUS.com ~~ http://www.FOCUSPortals.com - Local franchises available

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Further to my last message re this problem...
I am going to machine a component. I have done a drawing...
http://www.revilloc.com/lens-drawing.jpg (it is 1.5MB)
I have planned most of the machining operations, but have one problem.
Another issue I have is that I have to have a really thin wall on part of the component. Slightly less than 0.4mm. This is the only clearance I have...
The drawing is not quite correct, but almost all there...
The spigot you can see in the main diameter, is about the same height as the 3mm step in the side view. The bit I am missing is that the remaining inside diameter around the spigot should be 62.2. This is my step 9, but not sure how to do it.
I will be machining it from aluminium.
If you follow the steps...
1. Turn OD 66.26mm x 12mm 2. Turn OD Step to 64.61mm x 6mm 3. Drill / Bore through to 52.25mm dia. This will give me the material to create the spigot. 4. Bore 63.85mm x 6mm. 5. Start part off (this will be the top side of the 3mm step.) 6. File 45 degree chamfer on the top edge. (not shown on drawing) 7. Finish part off. 8. Drill / Tap 2 holes. (The screws measure 1.6mm. Any ideas what they might be? I am thinking possibly BA) 9... Not sure what to do here, in order to have a uniform diameter most of the way around of 62.2mm but leaving the spigot of 10mm. What I am thinking is maybe to use something in my dremel type device mounted in the lathe and do this before step 5. The prob I have is that attempting to mount in my mill, I am likely to damage the very thin step. Another prob I could experience is that if I do the dremel thing, then when I come to part it off, I will have the spigot that may cause the thing to tear itself apart on the intermittent parting tool.
I have available to me...
4.5" lathe, Eagle 25 Milling machine. (Chester) Rotary Table Dividing Head Dremel type device Bench drill Bandsaw
Another issue I may have is mounting the blank to be turned without crushing it whilst boring. Actually, that might not be such a prob. The prob I really have is just the machining of the spigot.
Any ideas would be appreciated. I will be attempting to manufacture this this weekend.
Thanks.
Best regards, Dave Colliver. http://www.AshfieldFOCUS.com ~~ http://www.FOCUSPortals.com - Local franchises available

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David wrote: (The screws measure 1.6mm. Any ideas what they might

M 1.6 x 0.35mm ?
-- Peter Fairbrother
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Proops were selling taps in the M1.x sizes at a sensible price recently (but alas not dies). The camera would have to be very old to contain BA screws.
I find cousins good for small metric taps and dies http://www.cousinsuk.com/catalog/6/1112/1312.aspx
Unfortunately the price of their dies seem to have increased astronomically since I last bought one.
Alan
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Alan Bain wrote:

Yikes!
You can sometimes get M1.6 (which is the next common size down from M2) taps and dies from people who sell more ordinary sizes of taps and dies at the smallest end of the range - these can be a lot cheaper, eg RGD does a carbon steel 1.6 mm die for £3.11.
http://www.rdgtools.co.uk/acatalog/METRIC_TAPS_AND_DIES.html
[ a set of three 1.6 mm taps from RDG is £6.99, same page -
- doesn't say whether they are carbon or HSS though, for very small taps I'd only recommend HSS - small carbon taps are too brittle, especially for hand use, and tend to break.
Small carbon dies are okay though, if they break, which is less likely anyway, you don't have the problem of getting the broken tap out of the workpiece you just spent half a day machining! ]
-- Peter Fairbrother

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I could be struggling to get an M1.6 in time.
I have just cross referenced BA threads and it looks like 10BA is also very close. Would it be a problem for me to use 10ba and threadlock? (Yes, I know, the angles are different, but for the size of the screw and the amount of force on the screw, it can't be that much of a problem can it?)
Thanks for your advice. :-)
--
Best regards,
Dave Colliver.
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from "David"

I nearly suggested 10BA as a option in my previous posts. Taken as a percentage the O/d is 6.25% larger which is substantial as far as screw thread tolerance is concerned but the absolute gap between the crest of the M1.6 screw and the crest of the 10BA 'nut' when centred is 0.05mm which means that one side could have a gap as much as 0.1mm if it sits to one side. Bearing in mind that the thread flanks on one side will always be in contact the real 'gap' is actually quite large - certainly much more than the space you have between your new ring and its mating component!
I leave it to others on the group who are more familiar with threadlock or locktite to determine if this would be 'a bridge too far'.
A comparison drawing is on my site as before.
JG
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from "David"

A bit late coming to this discussion and I an going to propose a radial alturnative solution.
As you say, your drawing is incomplete and I have made some assumptions about the missing detail but hope that I have interpreted your needs correctly. I've done an accurate drawing and put it on my wb site as a .PDF - see www.special-time.co.uk/drawings and select the only one currently there.
I would not start by machining the finished size at all. I think it would be better to prepare a billet at (say) 68mm dia. x 15mm long and hold that in soft jaws to machine the internal dimentions.
Then I would machine a mandril at 63.85mm dia. with a suitable tapped hole in the centre (say M6 or M8) and a clamping disc 65mm dia - possibly with a 62.2mm reference spigot if there is enough depth to that dia - and mount the part machined ring on that to finish the outside.
The issue of the 'tab' with the two holes could also be better served by this method since you could mount the 68mm dia billet on you rotary table (again with the aid of the 63.85mm mndril) and mill the 62.2mm dia for 330° (with a 3mmØ slot drill) finishing the precise shape needed with needle files. You could also drill and tap the two holes whilst still mounted on the RT.
Another radical option with regard to this 'tab' would be to fabricate it . . . . see the section drawing at the bottom of my drawing . . . . This would allow you to finish machine the 62.2mm dia. but would require other work in milling the slot and finding a means to fix the 'tab' in place - probably a cyanoacrilate adhesive but maybe a 1mm pin as well.
I hope this has given you food for thought if not a complete solution.
JG
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Hi,
Thanks for this (and the drawing)...
After I posted the message initially, I had thought that I can use the rotary table with the chuck off my lathe fastened to it somehow. Then use a small cutter to cut the material leaving the spigot.
I would prefer to have it all as one as that will be stronger. I did try supergluing (cyanoacrilate) the plastic one in my original photo but the lateral force that the spigot needs to apply forced it off again. The spigot drives the zoom on the lens so there is a reasonable force there.
The spigot itself is level with the top of the ring rather than the bottom . My thoughts were that this obviously makes the whole thing easier to machine as I don't need to machine on the other side to the very thin wall section.
This means that I could practically almost finish turn the whole thing in one go, then mount on the rotary table to machine the spigot, drill and tap, then back in the lathe to part off. All without removing from the chuck, not that perfect concentricity is actually required.
The only thing I do need that is not on the drawing is a chamfer to the outside top of the ring. I don't think this is critical, just a stress relief of some sort and to not interfere with the ring that has to sit over this.
If I get it finished (and I will) and it works, I will take a photo of the finished article and post it. It will certainly save me £114 for a repair of my lens or £56 if they can't repair it. I could buy another compatible lens for £99 or an original for £150, but then they will still have this manufacturing defect/oversight. I think making the ring from ali rather than plastic will be much better for the lens. Aside from that, I can easily afford a new lens, but where is the fun in that? The remaining parts of this lens are in full functioning order and it would be criminal to throw it away over something that can be so easily (and cheaply) repaired.
From my original photo, where you can see the original break on the tube, that will be turned away by 3mm. The thin wall of the piece I am making will sit inside this tube and I will superglue it. I think with the amount of surface contact area will be enough to drive the zoom ring.
--
Best regards,
Dave Colliver.
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from "David"

That would be an ideal scenario but if you do not have a fitting you may need to make one - even if it simply locates in the chuck recess and you can then clamp the chuck body using standard clamps.

It is certainly the best option but does pose some problems - specifically there is no 62.2mm reference diameter

With a wall thickness of 0.38mm you most definitely do need perfect concentricity, and I would suggest that trying to hold it on the thin wall section would cause you far too much grief.

The likelihood is that it is there to remove the need to undercut the mating part so that there is no interference between them.
I've done some more drawings (still at wwwspecal-time.co.uk/drawings) to take account of your further detail and also to show each stage of maufacture as I would go about it. I assume that you have soft jaws for your chuck and are familiar with the concept of a sacrificial mandril. The very thin wall is the key problem here, that is why I propose that you make this one of the last operations.
I recall doing something similar many years ago when I wanted to fit very non-standard lenses (from plate cameras) to my Pentax SLR but that also involved screwcutting thin walled items.
I'msure you have thought about it but just in case it has slipped passed you, you _do_ intend to paint the inside of the finished item matt black don't you?
JG
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Hi,
I had a look around your site whilst I was there picking up the last PDF. Looks like you craft some nice watch cases. I am currently working in Matlock (Derbyshire) and just up the road from where I work, as I was walking past, I noticed a workshop with some very nice wooden skeleton clocks in fully working order. I have never seen anything like that before. They were very nice and very unusual I thought.
The way I was thinking of machining it was to make the blank deep enough and have all the machined part still sticking out from the jaws so that I don't hold it on any of the machined surface. Hopefully, this will not present any crushing problems.
Also, doing it this way, as I then have no need to remove it from the chuck, I should not need a mandrel.
I don't have a fitting for my chuck on the rotary table. I was thinking of just clamping it down then clocking the inside of the bore to get it concentric.
The thin wall will be away from the chuck and as I don't really need to machine the 'top' (from your drawing, the thicker wall is at the top, so the top is the upper surface), the 62.2 can be machined all in one setting. This means that I don't need to hold it on the thin wall at all.
To painting the item black... I can see a possibility why, but why would I need to paint it? The location of this component will never even see light, The outside will be surrounded by a non-rotating ring (this is part of the rotating ring) and the inside, there is a good 3/4" before it can see any of the actual lens tube. A problem would be is that the 0.38 wall is actually only giving me 0.02mm clearance and painting this would be a problem. I guess I could paint the upper thicker portion as if anything is exposed, it will only be this part.
--
Best regards,
Dave Colliver.
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from "David"

Seeing a wooden skeleton clock was the initial inspiration for me getting into watch/clock-making and discussion on the alt.horology newsgroup made the whole thing take on a life of its own!
If you looked at the detailed drawings you can see that I am familiar with machining thin sections even in wood! The bezel ring recess leaves a 'wall' at 0.25mm thick and the ring itself is 0.3mm thick. Stainless Steel stem tubes are often 1.6mm dia with a 1.5mm bore. Dials are 0.3mm thick in the centre and between 0.5 and 0.7 on the outside.

I only hope that my suggestins have given you 'food for thought'.
Cutting the chamfer won't cause you any problem with the way you propose to do the job and my only concern is that you won't get a fair-face to the 'top' if it is simply parted off.

That could be your next 'Project' :)

Just my cautious approach to anything 'photographic' but I would also be concerned about oxydation which would be minimised by the application of paint - I doubt that acrylic paint would be as thick as 20 microns but you could try candle smoke to take away the 'bright' alum finish.
I look forward to your photo's of both production and finished article :)
JG
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