Filter Ring Dent Removing Tool
by Henry Taber

Bet you have at least one lens with a dent in the filter ring. And probably you’ve been living “filterless” for some time on that lens because the dent removing tools you’ve seen are so pricey. Well...wait no longer! Here is a simple method and the “tools” won’t cost anything if your garage is as junked up as mine!

Material:

Find a scrap piece of wood for the base. I found a used (painted on one side) piece of 1 x 2 (actual size is ¾” x 1-3/4”) that was formerly an outside door jam. Size is not really that important although too thin and it may fall over during use and too wide, it’ll be more work cutting the crescent.

Next find another piece of wood for the punch. Here I used a length of 3/8” round dowel. Using a round is not that important. It was just what I found under the workbench. Any piece of wood long enough so you won’t thump the lens with the hammer yet thin enough to only contact the dented area will do. But I favor the round. Wal-Mart sells a 3 foot length of various diameters for under a buck... if money is no object.

Hardwood would be better but the soft pine I used works fine. The tip of the punch piece will smash easier being softwood versus hardwood. It will simply need to be reshaped more often.

Making the tool:

To make the crescent shaped cutouts, first trace the outline of the outside diameter of an undented section of the filter ring onto the side of the board. Then cut it out. A jigsaw will work but you’ll need to smooth and shape with a quarter round file afterwards. Or a rotary tool and long mill cutter would do nicely. A router with circle jig would be even better. But being lazy, I went over to my neighbor’s and used his scroll saw. Ron got to clean up the sawdust.

How you get the hole isn’t as important as how snuggly it fits the filter ring. You could even whittle the crescent with your Barlow pocket knife! Too large a diameter is better than too small. Also I found that the crescent need not be as big as I cut it. An arc just big enough to support a little more than the length of the dent is adequate. Of course the larger arc makes the lens easier to position and hold

The tip of the punch tool must be shaped so when struck it won’t slip into the front element glass yet concentrate the force of the hammer blow in the required area. On the round dowel piece I used, this entailed beveling at about 30 degrees from flat (square?). On larger dents I’ve had to reshape the tip a couple times.

Using the tool:

I use a helper to seat the lens securely in the crescent’s center with the center of the dent centered in the center of the crescent. (Just checking if you are reading this out loud...it made me stutter too.) In the picture you see a blue washcloth holding the lens, that was just for the picture. An unheld lens WILL fly off the bench! I draft my 16 year old son. But I have this theory that wives may work in a pinch. I’m not sure of this, mind you. It is just a theory...

Hold the punch as vertical as possible. You’ll have to strike harder than you think to get the ring perfectly round but start with much smaller “love taps” to initially bend the lip in small increments. Too large a localized movement in a large dent might crack the ring. Save the hard whops for the final shaping when the ring is near perfectly round. The filter threads sink into the wood, distribute the load and are unharmed.

No lenses were harmed in the making of this article...