/ ice screw - bent tooth
Now I've got a screw with two teeth damaged - one burred and one burred and bent a little inwards. I'm looking for some advice on my options - is there a good service which will be able to reshape the teeth?
A set of cheap diamond coated needle files and a bit of care will sort the burr. The bent one probably needs straightening. Ordinary files, especially blunt cheap ones may struggle if the teeth are hardened. A Dremmel type tool will make light work of the burr too if you have one (goggles, those disks explode!).
The grivel machine works by shortening the teeth, this is particularly detrimental to BD screws and / or screws with a lot of damage to the teeth. I suggest if the you have shortened / damaged the teeth by more than 1-2 mm this may not be a good idea.
I think if the top part of the tooth is bent you will probably need to sharpen it down beyond this, if its more damaged than 2-3 mm perhaps a pic would be worth posting up.
BD recommend this way
I can do it without needing a vice and also I have a technique that maintains the tooth length.
First I sharpen the dead teeth using a small flat file working the slanted flat edges. Once these are sharpened I place the screw on a flat surface (like a frying pan) teeth down and work out which teeth are too long, I then lower these by filling the slanted edge. Then using a small round file I file down the grooves to maintain tooth length and roughly measure them to make the all the same length as a new screw (time consuming!), note as you will be effecting the cutting edge you need to file in at an angle to maintain this, also keep an eye on what you are doing to stop the tooth edge becoming too rounded and adjust angle pressure accordingly. Finally I sharpen the nearly vertical cutting edges in using a small flat file (note these come in at quite a sharp angle and are used to cut the ice). For screws that are not badly blunted this takes about 5 - 20 mins per screw (depending on how blunted they are and if the grooves need deepening) and needs down about once per year at the end of the season. For badly damaged screws this can take over an hour per screw. Its not a bad idea to spray the screws with WD40 inside and out after doing this as it helps prevent corrosion and aids the ice removal when they are placed. The end result is screws that are not noticeably different to place than brand new ice screws.
One tip I can give is never leave screws in a wet bag overnight as the sharpened teeth tend to start corroding a bit and loosing their sharpness.
I've done all my ice screws with just one file, it being the one I have http://instagram.com/p/XPRY2BLvLx/ http://lightfromthenorth.blogspot.fi/2007/02/ice-screw-sharpening.html
To the OP; just get a file and sharpen it. The top 'point' of the tooth needs to be pointed to get a bite, get ride of any burrs, but after sharpening my own screws for 15 years I'm pretty unconvinced when people say the teeth all HAVE to exactly the same level, or that the tooth HAS to be "sharks tooth" shape rather than having a vertical or only just overhanging edge etc etc. I reckon my self sharpened screws are now 5 to 10 mms shorter than they were new because I've need to sharpen them lots over the years, but my BD screws are all from 2001 or earlier and still get used every week through the winter. I reckon they work 90% as well as brand news ones, and I can't afford to buy news ones regularly, so that's fine for me.
There is now a local engineering ice climber where I live who has written a programme to have his works fancy cutting machine re-cut screws to their original shape, and I might have that done to my oldest 4 screws at the end of this winter - but at 10 euros a pop it's not a cheap option! Self-sharpening isn't really that hard and the results are just fine.
Toby, climbing in Finland do you very often find your screws hit rock? In Scotland this was definitely less of a problem for me than climbing in the lakes / snowdonia.
I think you are probably right that having the teeth all the same length and maintaining the precise geometry of the tooth isn't necessary, it MAY make the screws work a bit better (after all BD have designed the profile specifically) but how important this is, is another matter. I know from quickly sorting out screws whilst on trips that its not all that necessary.
One thing I do notice is my BD screws that have shorter teeth and especially the ones I badly damaged and got sharpened in the grivel machine do not bite as easily as the ones I've maintained the profile of from the off (although once started they are just as good). Unfortunately on one or two of them the teeth are now pretty short (just slightly shorter than new grivel screws) and reshaping the teeth by hand to the as new BD profile is now not practical :(.
Thanks for the replies, I'll have to invest in a couple of files it would seem.
I have just tried to photo but can't get my phone to focus on the end of the screw, so useless images.
The BD vid is useful, thanks. Hopefully with a vice, files, and some patience I can bend the tooth back - I've got another 9 months or so to find some time!
How much of the tooth is bent?
Yes, from time to time. It happens both early season when the ice is still thin. Then additionally, most of the climbing is "crag style" i.e. a number of lines next to each other as you go a long a crag. Invariably this means people have climbed thin ice pillars and weeps as independent lines, stuff that might just be seen as 10 mtr dribble of ice in Norway if it was next the start of 30 mtr wide, 300 mtr high massive icefall! But here, that's a route and hence you are often not very far from rock, even if the tree trunk sized pillar you are on is good quality ice - this sort of thing (where you can see a screw in front of me): http://4.bp.blogspot.com/-vdQWIJy2DIk/UTXQBx45-xI/AAAAAAAAGC0/GxTptFARdNw/s1600/rajis-20.jpg
I've also climbed skinny ice in Wales, I guess it just come into nick less often than the high routes in Scotland so everyone is inclined to get on it sooner than you might in colder climes, on the basis it might melt again in a day or two!
As mentioned the needlesports grivel machine does not produce as good a result especially on screws that are not grivel and / or have more than 1-2 mm of damage as my 'DIY solution'
Top 2-3mm curving inwards, badly burred on the edges. I found it quite difficult to screw into ice that didn't already have a hole available (thankfully not many spots around Cwn Idwal this weekend).
which brand screw?
Interesting. I had mine done on a similar machine in Rjukan, perhaps not a Grivel. The teeth if anything were longer than previously and the profile was perfect when compared with a new screw. The teeth were sharper than the new screw too and were amazing to place.
Like I say, couldn't tell you who the manufacturer of 'the machine' was though. They were BD Express screws.
some of the teeth on the BD screws I sent in to needlesports came back literally half the length.
Interesting x 2! Must have been a different machine I guess. Like I say, great results. Expensive Norwegian prices though!
Watching the video perhaps the machine does deepen the grooves / lengthen the slanted flat edge, but on BD screws this doesn't work as expected because of the changes in geometry between grivel and BD, in any case I wouldn't send my BD screws in for sharpening on a grivel machine again because the teeth can end up about 2/3 as long as a new BD screw after sharpening whilst hand sharpening I can maintain the original geometry.
Perhaps I just got unlucky and the machine wasn't set up right or wasn't being operated optimally. Anyway YMMV.
You need to assess how close the geometry of these screws is to the Grivel screws, by the looks of things the more similar the better result the machine will give you. From the video it looks like the machine will approx ensure that Grivel screws maintain the manufactured profile after sharpening. It will likely be a long job to hand sharpen that screw and maintain the profile and I wouldn't try bending the tooth back myself.
I guess from looking at the video that if they took a cm or so (ie a tooth length) off most tubular screws it would have the profile of a Grivel screw (if the operator does a good job), not that you'd want to take that much off a screw IMO.
The grivel machine sharpens the vertical "cutting" edge of the screw, so shouldn't have a major impact on the overall length of the tooth, maybe loosing 1-2 mm at most.
Because the post 2008 black diamond screws have a tapered tube, there's anissue with using the gtivel machine which changes the pitch of the cutting edge, making them less effective.
Prior to 2008, the black diamond screws had a straight tube, and can be happily sharpened on a grivel machine.
"The grivel machine sharpens the vertical "cutting" edge of the screw"
Yes I already mentioned this
"so shouldn't have a major impact on the overall length of the tooth, maybe loosing 1-2 mm at most."
Yes as mentioned above, the OP has bent 3mm of his tooth this is quite a lot of the tooth to loose. However looking at the video on the needle sports site posted above the grivel machine does cut in at an angle so does actually lengthen the teeth as well.
"Because the post 2008 black diamond screws have a tapered tube, there's anissue with using the gtivel machine which changes the pitch of the cutting edge, making them less effective."
Logically I'm not sure why having a tapered tube would effect the pitch of the cutting edge using the machine. Although I would hazard a guess that the differences in pitch between BD and grivel teeth is one of the factors which effected the length of the teeth on the screws I got sharpened.
"Prior to 2008, the black diamond screws had a straight tube, and can be happily sharpened on a grivel machine."
So you say but one of the screws I sent in that came back very short was a prior to 2008 screw. This one in particular was a bit shockingly short and was a fair bit shorter than my new grivel screw. I have since attempted to lengthen the teeth somewhat by hand, but it's too long a job to bring back to the original geometry.
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