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seanmckinney
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 01, 2006 - 02:56 pm: | 
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I received an ebay lense, a 400mm, which has a substantal dent in the filter thread. It wasnt advertised as such and compensation has been agreed. It looks like it might be around a 70mm filter thread. The dent will be at least 1mm deep and there is no way a filter will go on to that.
Are wood and pliers or gaffa tape etc and pliers etc bad ideas and can I place tape on the glass to protect the lense?
I have seen mention in one thread from 2003 about a page of undenting instrustions on here but I havent found that page yet. |
Ringo
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 01, 2006 - 03:05 pm: |
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One might read Henry Taber's article:
https://kyp.hauslendale.com/classics/filterringtool.html
as a place to start ... but i've always had touble with accomplishing it myself. itz e-z 2 overdo |
seanmckinney
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 01, 2006 - 04:44 pm: |
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Read and saved, ta. |
rick oleson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 01, 2006 - 06:35 pm: |
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I have managed it by tightening a radiator hose clamp around the lens with a thin sheet of rubber to protect it from scratches, and then using a plastic bar (with one end shaped to match the filter ring radius) as a punch, hammering the dent out. The basic method is similar to Henry's.
I have one of those "Filter Ring Vise" tools, but I can't recall ever having gotten good results with it. |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 01, 2006 - 06:35 pm: |
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There are three types of tool sold for filter mount reshaping; a shaped wooden block like Henry's self made item, a pair of 'pliers' with curved male/female forms attached at right angles to handles or a set of small vice like expanders. Microtools sell all three at a price.
I purchased a set of the expanders - covers 40mm to 120mm in two separate tools - off eBay. Came from one of the many Indian providers of camera service bits. They are well made and work well, the only fault is that the nickel plating is utter rubbish(now removed and chemically blacked). However at £15.00 including postage, they were a bargain and are very useful for reforming the edges of the fitted lens hoods on FD telephoto lenses. |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 02, 2006 - 05:36 am: |
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In many cases not only the shape of the filter thread is damaged but also the single threads. Also, since most filter threads are made of soft aluminium in most cases the thread itself gets damaged when undenting it. To make it perfectly usable again you have to recut the thread. Unfortunately metric handheld thread chasers are hard to locate even in metric Europe. |
WernerJB
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 02, 2006 - 08:20 am: |
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After reading all available inputs on the matter I "invented" my very own method. The first step I usually take is similar to what is described in Henry Taber's "Filter Ring Dent Removing Tool" in this forum's article section. I followed his advice, with minor changes. Instead of a wooden tool I use the stem of a plastic toothbrush like a chisel when I hammer out the dents, as this material is hard enough to transmit the punch and soft enough not to scratch aluminium surfaces.
The most important thing when undenting is that you work carefully and slowly, step by step. A repair like the one you describe, seanmckinney, cannot be done in a minute. The first lens I undented had dents facing off-center because I had used too much force and first and foremost because I thought I could do everything in a hurry. |
seanmckinney
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 02, 2006 - 02:01 pm: |
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Winfred, re a chaser, its going back a few years but I think I remember draper doing a chaser with across-the-file 'teeth' at the ends (sold as for female or pipe threads). I dont know if they still do them nor do I remember the pitches, would Snap On etc sell them? but then you would have to mortgage the house. If the pitch was available, the danger with that would be the rest of that end of the chaser touching the lense.
Other thoughts might be a set of thread gauges possibly from Moore and Wright, I havent tried that but the actual gauge does taper and would probably be a better and less dangerous fit than a proper general purpose chaser, they might be hard enough to gently scrap clean an aluminium thread with out damaging the gauge. I have also used a tap of the correct pitch but much smaller diameter to clean up or out the threads inside such as motorbike axle nuts. However for a lense it might be advisable to grind most of the tap away and leave only one flute with a carefully dressed end to the modified tap. I wouldnt buy a cheapo tap from the likes of B&Q even if they did carry the right pitch, I would have a hunt at a jumble or car boot for some old high speed steel taps HSS that some one is selling. I have bought 2nd hand HSS sets for £1 or £2 especially at the small sizes you are talking about the get the correct pitch, a normal bench grinder will grind an HSS tap but cool the tap frequently and wear eye protection.
Last way I have cleaned female threads in aluminium, get a allen key bolt (socket cap) = high tensile and generally harder than you general bolt. With a fine toothed and sharp junior hack saw cut a notch up the length of the threads of the bolt cutting into the core of the bolt, the cut must be clean and have a clean sharp edge. You would probably have to dress, with a 60 degree needle file, the threads of the bolt where the meet the cut but used with care this tool will clean up aluminium threads |
seanmckinney
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 02, 2006 - 02:06 pm: |
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Oh sorry I forgot to say thanks to every one else and I better say sorry to Winfried for Winfred. |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 02, 2006 - 03:00 pm: |
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Interesting thing about my cheap set of expending dent removers, the curved forming jaws are cut with the correct pitch thread and hardened. If you put a light smear of tapping compound on these threads before you attach the device, all you have to do is rotate the tool back and forth as you expand the 'jaws'. No deformed or crushed threads, just re-usable filter mounts. |
Jack
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 04, 2006 - 11:04 pm: |
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Glenn, do you remember the name of the eBay seller? I'd be interested to see what other tools they might have as well.
Jack
remove underlines and "nospam" to send e-mail |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 05, 2006 - 02:59 pm: |
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Jack,
It was Active Industries, but go to their web site as this has much more in the way of tools.
www.activeindustries.com.
Their eBay ID seems to have been Active 21 when I dealt with them.
Glenn |
rick
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 06, 2006 - 06:34 am: |
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I've used all of the methods Sean described to chase filter threads: a stainless steel thread gauge, a tap, and a bolt with a flute ground in it to resemble a tap..... all of them work well.
Come to think of it, all of them work well enough that at the moment I can't think why I didn't just stay with whichever one I tried first.... the tap was the best cutter though. I think I used a broken one so that it didn't have any unthreaded material at the end.
 = |
Arnold Harris
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 09, 2006 - 07:23 pm: |
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I bought a filter ring vise tool last summer. So far, I've straightened out two previously dented filter rings on more than 20 Voigtlander Vitessa-Ts that I've acquired since then. I'm doing CLA/refurbishing on all of them, and I now own 26 of these, all the same make and model.
It is important to fit the threaded edges of the convex jaws into the threads on the lens rings.
In some extreme cases, I think Rick Oleson's suggestion to use a rubber-padded radiator hose clamp would be very useful in conjunctin with the filter ring vise. It should help keep the ring round while you are squeezing parts of it outward.
If it comes to a choice of saving the lens filter ring as opposed to saving the filter, obviously you will want to save the lens and all its parts. Filters in various sizes a lot more easily replaceable.
I sometimes wonder why people drop lens, and when they do, why they always seem to land on the filter ring. But that's another forum topic.
Arnold Harris
Mount Horeb WI |
