The reality is that you need a set of different designs for different situations. The divider-style ones are good for working in smaller spaces and deeply set parts and on rings that are not too badly stuck, but they do succumb to twisting of the legs under a lot of force. I have resorted to clamping a long-nosed pair of vise grips across the legs to reinforce them when I needed a lot of torque, with limited success. I also have three different versions of the crossbar-style spanner that hold up better under higher torque applications but have the tendency for the set-screws that lock the points to the crossbar to fail and the points slip out of place as I'm trying to turn the thing. This was a problem with the ones mentioned in post #24, as well as the springs that hold the points letting go under a lot of force (and in one case, scratching a lens for me.) The real test was trying to release the retaining ring for a taking lens on a Mamiya C-series TLR that was stuck on the mounting plate. All the above-mentioned tools failed and I finally had to drill out the attachment ring and split it by inserting a large screwdriver blade into the hole and twisting it until the ring broke.
So with that experience in mind I bought one of these spanners that I mentioned above: https://www.ebay.com/itm/2554024228...d=link&campid=5338260023&toolid=20001&mkevt=1
Got it from Japan Hobby Tool, who seem to be the people who make them. $30 plus shipping, delivered in two days from Tokyo, though as I mentioned above you can get it from B&H and possibly save money on the shipping. Looks very sturdy, seems to be well engineered, and the side orientation of the handle and the attachment method of the points look promising. But it clearly isn't going to be terribly useful for working on parts that are deeply set. would have been handy working on that Mamiya TLR lens, though the corrosion that was preventing that ring from turning was the toughest I've ever seen and I'm not convinced that any of the spanners we've discussed would have loosened it. (I did try all sorts of solvents and a heat gun to no effect...)
UPDATE: Yesterday I dug out an old Mamiya lens assembly with a deeply-set internal retaining ring that I had been unable to move with any of my many spanners. I set up the new spanner for the correct distance between the points for this ring. (This was a bit fiddly to adjust but with a little patience do-able.) I put a little downward pressure to make sure the points on the spanner were engaged with the slots on the ring and began to turn it--the ring moved immediately and extracting it was easy. Having the additional leverage of the offset handle, rather than having my hand smack on the rotational axis of the ring made a huge difference; I think this is going to be a very useful tool.
So with that experience in mind I bought one of these spanners that I mentioned above: https://www.ebay.com/itm/2554024228...d=link&campid=5338260023&toolid=20001&mkevt=1
Got it from Japan Hobby Tool, who seem to be the people who make them. $30 plus shipping, delivered in two days from Tokyo, though as I mentioned above you can get it from B&H and possibly save money on the shipping. Looks very sturdy, seems to be well engineered, and the side orientation of the handle and the attachment method of the points look promising. But it clearly isn't going to be terribly useful for working on parts that are deeply set. would have been handy working on that Mamiya TLR lens, though the corrosion that was preventing that ring from turning was the toughest I've ever seen and I'm not convinced that any of the spanners we've discussed would have loosened it. (I did try all sorts of solvents and a heat gun to no effect...)
UPDATE: Yesterday I dug out an old Mamiya lens assembly with a deeply-set internal retaining ring that I had been unable to move with any of my many spanners. I set up the new spanner for the correct distance between the points for this ring. (This was a bit fiddly to adjust but with a little patience do-able.) I put a little downward pressure to make sure the points on the spanner were engaged with the slots on the ring and began to turn it--the ring moved immediately and extracting it was easy. Having the additional leverage of the offset handle, rather than having my hand smack on the rotational axis of the ring made a huge difference; I think this is going to be a very useful tool.
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