Home | Contact Us | FAQ | Search & Site Map | Link to Us
Sign In | Join | Other 45 Sites in Network
Home
Discussion Groups
General
ModelsRailroadsRockets
Radio Controlled
Air ModelsHelicoptersLand ModelsWater Models
ModelGeeks.com
Contact UsLink To UsSearch & Site Map

Model Forum / General / Models / August 2008



Tip: Looking for answers? Try searching our database.

Repair of a broken camera lens

Thread view: 
Enable EMail Alerts  Start New Thread
Thread rating: 
David - 20 Jul 2008 12:14 GMT
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.

Signature

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

_ - 20 Jul 2008 20:22 GMT
> Hi all,
>
[quoted text clipped - 11 lines]
> guess that I will have to send it away for repair, but if anyone has any
> ideas first... it would be appreciated.

Would it be possible to rotate the ring a bit, and fabricate/attach the tab
to a different part of the ring?
David - 20 Jul 2008 20:53 GMT
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.)

Signature

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

>
>> Hi all,
[quoted text clipped - 19 lines]
> tab
> to a different part of the ring?
mick - 20 Jul 2008 22:07 GMT
> Hi all,
>
[quoted text clipped - 11 lines]
> guess that I will have to send it away for repair, but if anyone has any
> ideas first... it would be appreciated.

home insurance?

Signature

mick

David - 20 Jul 2008 22:15 GMT
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

>> Hi all,
>>
[quoted text clipped - 13 lines]
>
> home insurance?
mark - 20 Jul 2008 22:52 GMT
> lol...
>
[quoted text clipped - 30 lines]
>
> - Show quoted text -

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
David - 21 Jul 2008 18:11 GMT
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.

Signature

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

> lol...
>
[quoted text clipped - 36 lines]
>
> - Show quoted text -

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
Dragon - 21 Jul 2008 20:01 GMT
> 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).
[quoted text clipped - 3 lines]
> a few people interested in bringing back their own lenses with this same
> breakage...

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
David - 21 Jul 2008 20:45 GMT
I will have a look at that, thank you.

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

>> 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).
[quoted text clipped - 13 lines]
>
> Henry
David - 23 Jul 2008 20:38 GMT
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

> Hi all,
>
[quoted text clipped - 11 lines]
> I guess that I will have to send it away for repair, but if anyone has any
> ideas first... it would be appreciated.
Peter Fairbrother - 23 Jul 2008 21:23 GMT
(The screws measure 1.6mm. Any ideas what they might
> be? I am thinking possibly BA)

M 1.6 x 0.35mm ?

-- Peter Fairbrother
Alan Bain - 23 Jul 2008 22:37 GMT
>(The screws measure 1.6mm. Any ideas what they might
>> be? I am thinking possibly BA)
>
>M 1.6 x 0.35mm ?

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
Peter Fairbrother - 24 Jul 2008 01:20 GMT
>> (The screws measure 1.6mm. Any ideas what they might
>>> be? I am thinking possibly BA)
[quoted text clipped - 9 lines]
> Unfortunately the price of their dies seem to have increased
> astronomically since I last bought one.

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

> Alan
David - 25 Jul 2008 18:46 GMT
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. :-)

Signature

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

>>> (The screws measure 1.6mm. Any ideas what they might
>>>> be? I am thinking possibly BA)
[quoted text clipped - 32 lines]
>>
>> Alan
JG - 25 Jul 2008 20:51 GMT
from "David"

> 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?)

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
JG - 24 Jul 2008 11:46 GMT
from "David"

> 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.

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
David - 24 Jul 2008 18:49 GMT
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.

Signature

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

> from "David"
>
[quoted text clipped - 54 lines]
>
> JG
JG - 25 Jul 2008 03:53 GMT
from "David"

> 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.

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.

> 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.

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

> 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.

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 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.

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
David - 25 Jul 2008 17:26 GMT
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.

Signature

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

>
> from "David"
[quoted text clipped - 60 lines]
>
> JG
JG - 25 Jul 2008 19:19 GMT
from "David"

> 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.

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.

> 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 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.

> 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.

That could be your next 'Project' :)

> 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,
[quoted text clipped - 5 lines]
> guess I could paint the upper thicker portion as if anything is exposed, it
> will only be this part.

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
David - 25 Jul 2008 22:08 GMT
Well, most of it machined now. All machining ops in the lathe done except
for chamfering and parting. Looking nice apart from the inside of the thin
wall where vibration marks have set in.

I have been taking pics of it as it goes. Will put them online when I have
the job complete.

I have made the thin wall 7.5 mm deep and a step of just 0.5mm. The step is
really only a clearance step anyway. (however, I will double check in the
morning...

Thanks for the help, advice and drawings. :-) (Oh, I did note on the
drawing, the inner diameter of the spigot. I had to go back to my drawings
to double check the dia.)

Signature

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

> from "David"
>
[quoted text clipped - 71 lines]
>
> JG
David - 26 Jul 2008 19:05 GMT
Well, all done now...

Photos here...
http://www.revilloc.com/camera_repair

(the last 2 are the photos using the lens at each end of its zoom)

Had a few probs that I had to iron out, but I suppose that is the
prototyping.

I had to skim more of the inside of the thin wall, then turn more off the
hieght of the thick piece (after filing the spigot lower due to it
interfering with the inner barrel.)

I also had to trim the inside of the zoom barrel to fit the piece into.

The screws, I couldn't get hold of an M1.6 tap so used 10BA instead. Screws
fit quite tight and well. (see pic 19)

A number of times, the damn thing kept moving when I kept having to trim
extra bits off it. I thought I was going to have to make the whole thing
over again a number of times. Luckly though, it didn't bend.

The only problem I have now (2 probs). 1. I didn't glue the ring in place.
Mainly due to the really tight gap, but I thought then that there is enough
friction to keep the ring in place. However, I can adjust the ring position.
2. The barrel is way to tight to turn naturally. I think the height of the
ring is still too much and the cover (cover with orange ring on, photo 20)
is tightening down onto my aluminium ring and effectively locking it. (I can
move it, but it is really tight.)

Signature

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available

> Well, most of it machined now. All machining ops in the lathe done except
> for chamfering and parting. Looking nice apart from the inside of the thin
[quoted text clipped - 87 lines]
>>
>> JG
JG - 27 Jul 2008 11:47 GMT
from "David"

> Had a few probs that I had to iron out, but I suppose that is the
> prototyping.

> I had to skim more of the inside of the thin wall, then turn more off the
> hieght of the thick piece (after filing the spigot lower due to it
> interfering with the inner barrel.)

Just goes to prove that no matter how much you think you've researched a
reverse engineering project you never get all the details right first
time!

> I also had to trim the inside of the zoom barrel to fit the piece into.

> The screws, I couldn't get hold of an M1.6 tap so used 10BA instead. Screws
> fit quite tight and well. (see pic 19)

Looks as if you had to make a packing piece as well   -   why are the
two screws different?

> A number of times, the damn thing kept moving when I kept having to trim
> extra bits off it. I thought I was going to have to make the whole thing
> over again a number of times. Luckly though, it didn't bend.

> The only problem I have now (2 probs). 1. I didn't glue the ring in place.
> Mainly due to the really tight gap, but I thought then that there is enough
[quoted text clipped - 5 lines]
> (I can
> move it, but it is really tight.)

As long as it does the job !

JG
David - 27 Jul 2008 13:29 GMT
> from "David"
>
[quoted text clipped - 8 lines]
> reverse engineering project you never get all the details right first
> time!

Still having to mod it... (done now). I had to shave some off the height to
fit the cover with the orange band on. I then forgot about the chamfer. The
lens became really tight to turn when that cover was screwed down. This
morning, I discovered that the cover actually has a machined / moulded
chamfer, so I had to strip the lens again to chamfer the ali ring. It is
MUCH better now. Still a little tight, but nowhere near like it was before.

>> I also had to trim the inside of the zoom barrel to fit the piece into.
>
[quoted text clipped - 4 lines]
> Looks as if you had to make a packing piece as well   -   why are the
> two screws different?

No, that is actually from the original piece. The spigot on my piece is
effectively the black broken piece in photo 1. That has a small steel 'arm'
that is screwed to the spigot. Is that what you mean by a packing piece?

All I made for it was the aluminium ring. (I had to make some clamps
(basically just a lump of metal with a hole drilled in) in order to fasten
my lathe chuck to the rotary table)

If you look at photo 19, the inner ring where the actual lens is, you can
see a slot. That piece where the screws are rides into that slot, so when
the ring rotates, it drives the slot round which has a (VERY) course thread
to drive the lens forward (downward in this photo) to zoom..

The two screws were like that when I took the lens apart. Because of the
head size,  I had to measure both screws just incase they were different
threads. They are both the same thread, just different sized heads. (I
thought it was odd as well.)

I quite pleased with it. I only bought the rotary table a few weeks ago.
That has just paid for itself. The only real cost was my time. (At my hourly
rate as a computer programmer, I could have bought two lenses, but what I
thought to myself is why waste a perfectly good piece of equipment due to
the failure of something I could very easily manufacture to fix it.) It is
just a shame that the cost to have something fixed by the manufacturer is
almost the same as the cost to buy a new item, which makes such things now
just throw away.

Best regards,
Dave Colliver.
http://www.AshfieldFOCUS.com
~~
http://www.FOCUSPortals.com - Local franchises available
JG - 27 Jul 2008 14:55 GMT
from "David"

> I quite pleased with it. I only bought the rotary table a few weeks ago.

That - complete with dividing plates - was one of the first things I
bought after the lathe itself. Wanting to cut gears I thought I couldn't
do without one.

> That has just paid for itself. The only real cost was my time. (At my
> hourly
> rate as a computer programmer, I could have bought two lenses, but what I
> thought to myself is why waste a perfectly good piece of equipment due to
> the failure of something I could very easily manufacture to fix it.)

Don't ever consider your time !!   It is always a shock to realize what
the part has really cost you :))

I needed an M3 x 4 grub screw yesterday and by the time I'd made a
fixture to hold a cap-screw, cut off 4mm and saw a slot in it I'd spent
nearly an hour (being in IT support I would be on similar remuneration
to yourself )

> It is
> just a shame that the cost to have something fixed by the manufacturer is
> almost the same as the cost to buy a new item, which makes such things now
> just throw away.

I don't see any way out of that mentality for the vast majority of the
population who no longer have the opportunity to get into manufacturing
in this country :(

JG
_ - 21 Aug 2008 16:34 GMT
> Further to my last message re this problem...
>
> I am going to machine a component. I have done a drawing...

Why not cut it out of sheet and bend and silver-solder it?
 
Sign In
Join
My Latest Posts
My Monitored Threads
My Blog
My Photo Gallery
My Profile
My Homepage

Start New Thread
Enable EMail Alerts
Rate this Thread



©2008 Advenet LLC   Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.