Lens coding with a Dremel - notes

[RichC]

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Reading this thread gave me the impetus to code my lenses using a Dremel this afternoon.

 

Total success - and my lenses didn't end up looking like a dog had chewed them. either! So, thanks for your post, Tom.

 

I practised on a bit of scrap brass, and, like Tom, found that a spherical engraving bit worked best - it was easy, with a bit of care, to create oval pits with a nice regular shape. The spherical bits did not create any burrs, though I did run a piece of 1200-grade wet-and-dry paper gently over the pits, to take off any sharp edges.

 

After practising, I found the best technique for me was to draw lines accurate lines where the pits are to go, using a fine indelible marker. I then set the Dremel to its lowest speed (setting 1), and ground shallow indentations at the start and end of each line, marking the ends of each pit. I then connected the pits, holding the Dremel steady but without too much pressure - pressing too hard made the Dremel more likely to slip, and not much pressure is needed to grind brass anyway.

 

I used the smallest bit (0.8 mm ball diameter) initially, and the resulting pits were about 1 mm wide.

 

After a few dummy runs on the scrap brass, I was ready to attack a lens. I decided to do my Voigtlander 25 mm lens, since it cost a lot less than my other lenses!

 

I've got Tim Isaac's M-Coder Kit, so marking the pit positions was a breeze. After masking off the rear of the lens with masking tape and paper, to keep out swarf, with trepidation I then started grinding... All went well, and, feeling pleased, I filled in the pits with Humbrol matt paint (as used for Airfix models), using the Leica lens code table for the lens codes. I chose this paint as it's easy to clean off with common solvents like lighter fluid or white spirit.

 

Then I took a photo: lens not recognised!

 

I Googled, to look at lens coded by Leica, and decided the problem was that the pits were too narrow. Back to the scrap brass for more tests. I used the 1.6 mm diameter spherical bit, mainly because that was all I had. It was perfect: gently running it up and down the existing 1 mm pits enlarged the pits in a well-controlled manner. I did try cutting pits from scratch with the 1.6 mm bit, but the bit was harder to control, and the pits looked a bit ragged. So, using the 0.8 mm bit followed by the 1.6 mm bit gave the best results: the 1.6 mm bit was easier to control, and created pits with nice regular edges.

 

I repainted the pits, and took another photo: it works!

 

Flush with success, I engraved pits in my Leica lenses (and, yes, I was nervous!), and an hour later, all my lenses were neatly coded, and recognised by my M8.

 

I'm attaching a photo of my Summilux 35 mm pre-aspherical lens. The pits aren't totally identical, since I'm not a machine, although some of the irregularities you can see are actually from careless painting of the pits - I was in a rush to try out the lens, so just slapped the paint in (I'll repaint it later)! Personally, I think it looks pretty damn tidy, even if I say so myself!

 

[As an aside, the shroud protecting the rear element fouled the M8 lens throat, preventing the lens being focused at infinity: to fix this, part of the shroud has been removed (the portion at "five to four", if you imagine a clock face). The portion removed was 1 mm deep and 7 mm inwards from the shroud edge. Also, I'm using a Summicron hood (with a hole cut in one corner for the viewfinder), as the original round one is hopeless at preventing flare.]

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[leicanut2]

Good job, I will have to pick up the coder and think I will try it on the Voighlander first to.

 

Cheers Jan

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[alex7075]

RichC,

 

What you did looks excellent to me. A bit scary maybe, but I would try it if only I was competent as you are in using a Dremel; always loved this kind of self-made fixes!

[RockyIII]

I am new to Leica, and the lenses I bought were already been coded. What you did looks very neat though. I am not sure I would trust my hands to attempt it

 

Rocky

[RichC]

What you did looks excellent to me. A bit scary maybe, but I would try it if only I was competent as you are in using a Dremel; always loved this kind of self-made fixes!

What's the worst that could happen ... no, don't answer that!

 

The Dremel rarely comes out of the cupboard, so I was unsure about whether I'd be able to do a neat job - practising on waste brass I picked up at the junk shop put my mind at rest, though I was still nervous.

 

Actually, the worst that could happen is cosmetic damage to the bayonet ring - unsightly and affecting resale value: irritating but not disastrous. Preferring the look of older Leica lenses like the pre-aspherical Summiluxes, self-coding was my only option since Leica won't code my lenses and I know of no one who mills coding pits in the UK.

 

If Leica gave us users the option to select lenses from the camera options, as requested numerous times, we wouldn't have to resort to such measures...!

 

If you like DIY projects, there's my cheap and minuscule M8 battery charger...

Edited May 12, 2009 by RichC

[sfokevin]

If you could offer a turn around time of less than a month you could put a couple guys out of business

[St Clair]

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If Leica gave us users the option to select lenses from the camera options, as requested numerous times, we wouldn't have to resort to such measures...!

 

But then they wouldn't be getting money for all the lenses sent in for coding...

[chris_tribble]

Full of admiration - well done!

 

re getting this done in the UK - Malcolm Taylor now offers a really professional service for a good price and (in my experience) quick turn round. Did a great job on my 18mm Zeiss + 50mm pre-aspherical lux. So even if we're not bold with the Dremel there's an option for owners of older + non-Leica lenses.

 

(BTW - I have no connection with Malcolm other than being a very satisfied customer!)

[RichC]

re getting this done in the UK - Malcolm Taylor now offers a really professional service for a good price and (in my experience) quick turn round.

 

(BTW - I have no connection with Malcolm other than being a very satisfied customer!)

Excellent - he was still planning to do this when I spoke to him last.

 

Every single second-hand Leica lens I've bought misfocused on my M8 - Malcolm serviced all the lenses, and they focused spot on when I got them back.

 

All the lenses dated from the 1970s (35mm/50mm Summiluxes, 90mm Tele-elmarit) were in excellent condition and had never been opened, so why they misfocused, I don't know... perhaps specs were less stringent back then.

 

Anyway, like Chris, no connection with Malcolm, but I can recommend him. Also, it was he who machined my 35mm Summilux shroud (see my first post in this thread).

[wstotler]

All the lenses dated from the 1970s (35mm/50mm Summiluxes, 90mm Tele-elmarit) were in excellent condition and had never been opened.

 

Never opened from the 70s?! Do you have details on that? Love to hear them.

 

Thanks,

Will

[ken_tanaka]

Nice piece of work there, Rich. I did something very similar, using my Dremel to grind code dimples on three of my non-Leica lenses. My "coding" worked fine, too, although I only dimpled the black spots. Your job puts mine to shame.

[caparobertsan]

Hello, Please take picture of dremel bit and post it here! Please. iwould like to try my zeiss ikon 35/2 lens too!

Thank you.

[doubice]

Hello, Please take picture of dremel bit and post it here! Please.

Thank you.

 

Yes, which drill bit did you use, Rich? As one of my hobbies are also model trains, I am relatively handy with a Dremel as well.... Superb job, just like your Pentax/Leica charger project!

 

I have a Pentax D-BC7 charger on the way, am about to order some Delkin M8 plates and as soon as time permits will embark on an M8 charger miniaturization project, following in your brave footsteps!

 

Best,

 

Jan

[guidomo]

Quick note: those people who had the milling done by John Milich in the US unscrewed the flanges and sent them to him. It is something even the least DIY-abled person can do (as long as you have a decent screw driver) and this way you don't need to send the lenses away.

 

And even if you dremel yourself, would it not make sense to just but the flanges under the Dremel rather than the entire lens? What would scare me most is steel bits scratching the rear glass element.

[RichC]

Will - not as exciting as I made it sound! A better choice of wording would have been "never dismantled" - if was trying to imply that the misfocusing may have been present since the lens' manufacture.

 

Capa - pic attached. Left scale = inches, right = mm. These bits came with my Dremel kit, and are Dremel's standard 0.8 and 1.6 mm spherical bits.

 

Jan - good luck! My modified charger is now the only one I use, and it works perfectly. The Leica brick slumbers in a dusty drawer - a fitting resting place!

 

Guido - I took the flange off my Voigtlander 25 mm, as it's held only by screws; I left the flanges on my Leica lenses as you have to dismantle the lenses to remove them. Working on just the flange is a little more convenient, and you don't have to protect the lens from swarf, but it really doesn't make much difference.

 

As to the Dremel slipping and scratching the glass, you'd have to be really cack-handed! The Dremel is not going very fast, and it doesn't have enough power to catch on something and fly across the lens. And don't forget you have a half centimetre wall on the flange - which I can't see how the Dremel could skip over. The worst that could happen is that you put a shallow scratch in the flange itself - not exactly pretty but without other consequences (excepting resale value - but we bought our lenses as working tools ... right!? <grin>).

 

I've got a broken Practika lens (as a photographer, have you noticed that friends dump unwanted camera gear on you - I must stop accepting it, especially as I don't use film!), and used the Dremel on the glass this morning, out of curiosity: the only way I could mark it was by pressing hard - that multicoated glass is tougher than you think!

 

Lastly, a tip. I held the lens in one hand whilst grinding the pits with other. On reflection, I think I would have found grinding easier to control if I'd taped the lens to my desk with masking tape, freeing both hands, even if I suspect that I'd have to untape and reposition the lens occasionally.

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[cbretteville]

Rich,

Thanks for sharing all of this, I've been meaning to go this route too, but haven't been able to get up the courage to start. One question: these bits look a lot different from the accessories I have for my Dremel, what is the model name of yours?

 

- Carl

[RichC]

these bits look a lot different from the accessories I have for my Dremel, what is the model name of yours?

I've owned it for about a decade - it's a Dremel Multi (says Model 395 Type 5 on the serial number plate).

 

Am attaching a close up of the bit heads - apologies for the quality of my camera phone pic. Leicas may be good for a lot of things, but quick close-ups isn't one! I suspect the smaller bit was once a bit more spherical, but time and use have taken their toll...!

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[cbretteville]

Thanks, that makes it about as old as mine. I'll check it when I get home from work.

- Carl

[Double Negative]

Wow, that came out really nicely! Kudos.

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[RichC]

I've been asked for more detailed instructions, so here they are. If anyone tries this and messes up, don't come round acting like Basil Fawlty and poke me in the eye!

 

Do practice on some scrap brass or aluminium!

 

1. Ideally, remove the mounting flange from the lens. If this cannot be done, use masking tape to protect the lens from swarf. It’s best to have both hands free, so use masking tape to fix the lens or flange firmly to a desk or table. When doing detail work like this, I wear +4 reading glasses (even though I don’t need glasses to read) to magnify the view.

 

2. All six pits should be centred over the sensor: make a template from thin card, using the camera mount as a guide, to transfer the sensor position to the lens flange. Then, draw lines with an indelible marker on the flange, to indicate accurately the start and end positions of each pit. I used match Technical’s Coder Kit template as a guide. If you don’t have the Coder Kit or an already coded lens to follow, the distance between the centres of the first and sixth pits is 10.5 mm, so the centre of each pit is 2.1 mm from its neighbour; each pit is 2.5 mm long (these measurements are taken from the Coder Kit template). Note that the pits are arranged linearly, not along a curve – the sensor is straight.

 

3. The spherical engraving bits used at the Dremel’s lowest speed setting provided good control and gave the best results, creating oval pits with a regular shape and no burring. Dragging the Dremel towards me, as opposed to pushing the bit forwards, gave the most control. The two smallest Dremel spherical bits have ball diameters of 0.8 mm and 1.6 mm: use the 0.8 mm bit to make shallow indentations at the exact start and end points of each pit, then connect these indentations to make a groove with rounded ends; the depth isn’t critical (just deep enough to hold their shape – about a third of a millimetre), and the width of the groove (about 1 mm) should be that created naturally by the bit without moving the bit sideways. Once all six pits have been ground and are identical in shape and parallel to each other, that’s the end of the first stage – the pits now need to be enlarged. Note: don’t be concerned if the grooves vary slightly in shape or have slight errors that can’t be corrected without making them too large – if minor, these will disappear during the next stage.

 

4. Change to the larger 1.6 mm bit, and gently enlarge the pits; very little pressure is needed – pressing too hard makes the grinding process harder to control and takes off too much metal too quickly, and may even make the bit grab and jump (conversely, do hold the Dremel steady enough to have good control!). I did try using the 1.6 mm bit only, but found that without the ‘guide pits’ made using the 0.8 mm bit, the pits were harder to position accurately and their shape more ragged.

 

5. Finally, run a piece of 1200-grade wet-and-dry paper lightly over the pits, to take off any sharp edges.