View Full Version : Drilling that Big hole in lens board yourself

Dan Kowalsky
24-Mar-2000, 10:10
I sure would like to know if any of the seasoned large format hole drillers out there ever drilled your own lens board holes, in my case it would be a wood 6" r ounded corners deardorf board drilled for a copal 3 size. My questions would be 1- is copal 3 a 39mm hole or not? 2- What is your home brewed recipe for puttin g that Big hole right in the middle , thanks Dan

24-Mar-2000, 11:08
Umm I might be wrong as I didnot quite manage to copy the correct information off some post months previously, but I'd hazard it and say that it might be 61.9mm. As for making the hole, first draw lines from the very middle of each side to the opposite, then draw out a circle to just under the size you wantdrill small holes in the center, and the points near the circle that you just drew, carefully cut out with a fret saw. I'd not recomend power tools as they may use too much force and you may not have enough control over them (If you've never used them much like me anyway), then use a file to widen out the hole as required.

Bruce Schultz
24-Mar-2000, 11:25
Drill that sucker! After paying a machinist $25 to drill a very precise hole, I decided to do it myself. I don't remember the dimension, but I drilled a plastic lensboard for a Copal 3 using a hole saw. As I remember, the hole was a bit too small, but I filed it out. It wasn't pretty, but it worked without any light leaks. And if you do have light leaks, a little tape and putty will work fine. To test, Put the mounted lens/lensboard on the camera and remove the back. Shining the light around the outside of the lens should reveal any problems.

Pete Andrews
24-Mar-2000, 11:28
According to the excellent Mr.Grimes web-site (http://www.skgrimes.com/products/cobig/copal3.htm) a No.3 shutter is a 61mm (2.4 inch) mounting hole. Not owning anything in that size shutter myself I'm unable to verify that, but it sounds about right to me.

You can easily find the centre of the board by laying a straightedge across the diagonal of the panel, from corner to corner, and marking a line with a fine drawing pencil or suchlike. Then lay the straightedge across the diagonal at right angles, bi-secting the corners and draw another line. Where the lines cross is the dead centre of the square or rectangle. If the corners are too rounded to make that method accurate you'll have to resort to a ruler or vernier calipers and an engineers square.

Once you've found the centre, mark the diameter you need the hole opened up to with a divider or compass, then you can drill a small pilot hole in it (about 1.5~2mm), and this'll make drilling a larger hole much easier. Access to a drilling or milling machine with a fly-cutter makes the job a doddle, but the home workshop usually doesn't boast such luxuries.

You can get things called Cone-cutters which are basically large cone-shaped drills that you push through the panel until the hole is the right size. For a thick panel you need to turn the job over and open out the other side with the cone-cut as well. It sounds complicated, but once you've seen the cutter you'll quickly get the idea. Best option is to rent or borrow a Cone-cutter tool, since they're quite expensive to buy. However, you do need a sturdy drill-stand and be able to clamp the job securely to use one, otherwise the hole will wander miles off centre.

One other thing, watch your fingers! A job where you can still count up to twenty with your shoes and socks off at the end of it, is a job well done :^)

Paul Schilliger
24-Mar-2000, 15:03
According to Schneider's spec. sheet, lens boards holes should be: 34,8 mm(35) f or Copal #0, 41,8 mm (42) for #1 and 65,3 mm (65) for Copal #3. The 62 hole is for Sinar DB lenses. Older Compur have different sizes!!! Lens board thickness should be for #0 1,5-4,0 mm, for #1 1,5-3,0 mm and for #3 1,5-4,0 mm, but depends on the lens. (Be careful to remove the small positioning screw on the Copal flange -if still there- before you mount the shutter). A hole saw is the way to go. The hole saws usually make a slightly larger hole than their given size. I have used a 41 mm for metal recently and the hole was 42 mm . Best is to have a column drill but not indispensable if you work careful ly. Take a larger board about 12 x 12" and place your lensboard in the middle after you have marked and drilled a small centering hole . Place four nails around it, one on each corner, to keep the board tight a nd from rotating, respecting the rotational direction of the drill (to the right). If your wood is soft and you want to preserve it, nail a piece of wood on each side. Drill carefully and slowly with the hole saw keeping it as perpendicular as you can. (If you work with a hand drill, you may want to mainta in the larger support board on the floor with your feet)... Enjoy your good job! Same process can be applied to aluminum lens boards but with a metal cutting hole saw only. (They work well for wood too). It is possible to enlarge an existing hole by using a large washer, or two concentric washers that fit tight in your existing hole ( the hole saw centering bit should have no play). Make some trials before you go on t he good plate and good luck!

Chris Partti
24-Mar-2000, 15:26
I recently did this, and, being a tool klutz, feel very proud of myself. My camera takes 6x6 Burke & James style boards which complicated the problem because the retaining ring threads on the Compur shutter I was mounting were not deep enough to fit through the quarter-inch plywood board. I therefore had to cut a recess into the back of the board as well as drill the hole so that the retaining ring could reach the threads and be screwed on. I bought two hole-cutting bits for my small hand power drill, one about the right size for the hole (in your case, I guess diamerter 2.5 inches) and the other with a diameter about a half inch larger. I marked the center by placing a straight edge from corner to corner, as described above, and drilled about halfway through the board from the back with the larger diameter bit. I then turned the board around and, using the same center hole, drilled entirely through the board with the smaller diameter bit. I then carefully chipped out the remaining wood between the smaller hole and the half-drilled larger hole.

___________ _________ |___ ___| | |

Robert A. Zeichner
24-Mar-2000, 20:15
I just manufactured 4 lensboards for an old Century Grand. Here's how I drilled the holes: Take a straight edge and align it across the diagonal corners of the board. Mark a fine line at the center. Switch the straight edge to the opposite corners and mark the center again. The intersection of the two marks is the center. Get yourself an adjustable fly cutter from some place like Sears. This is the type of device that has a 1/4" pilot drill in the center with a sliding blade that locks down with an allen set screw. You'll have to make a couple of test holes (actually don't have to cut entirely through) to check your diameter. You'll need to use a drill press for this, of course. Drill slowly and back up your work with a nice hard piece of lumber to prevent chipping on the exit side. Clamp the whole mess to the stage of the drill press to keep it all from moving. This method worked well for me. Good luck. I'll try and draw a fly cutter for you:

xx This part gets inserted in the chuck xx of the drill press xxxx xx xxxxxxxxxx xxxxxxxxxx xx x This is the cutting tip xx This is the pilot drill xx xx

Robert A. Zeichner
24-Mar-2000, 20:16
Guess that didn't work!

Tony Brent
24-Mar-2000, 22:13
Most of the time I use 4 jaw chuck in the lathe and check for size often. I think that a GOOD quality hole saw (Starret, etc -- not a cheap import) that is close to but not larger than the required size would give the cleanest result in the wood board.

This is a round tube with saw teeth on one end that mounts in an adapter with a pilot drill. Put the whole works in the drill press, center up the board, clamp it firmly and cut slowly.

Dont use the version that has a number of different rings in a slotted base. They are flimsy and wont work cleanly.

David F. Stein
25-Mar-2000, 00:28
Great question and answers. Thanks.

Bruce Pollock
25-Mar-2000, 14:56
I can't help you on the correct size question, but here's another method that worked OK for me. I had a lens board already drilled out for a #0 and needed to fit a #1 into it. I looked at the hole boring idea with a fly cutter drill bit, but it will only work on a blank board - you need material at the center of the board for the drill to start in.

My solution (albeit primitive) was to trace a line around the existing hole to the correct size using a fine pointed awl. Then I got a small "sanding drill" which is like a drill bit, but it's about 1/2" in diameter and has sand paper around the outside. I put this in a drill press and slowly, carefully sanded out the inside of the opening until I reached the scored line. The finished opening was not a perfect circle (it's hard to exactly meet up with your scored line everywhere) but the lens fits just fine.

Dan Kowalsky
26-Mar-2000, 18:00
Thanks loads for this ton of information on this topic , Dan

Darin Cozine
14-Oct-2003, 15:45
If you are using wood, I have an alternative way to cut the hole if you have a dremel, router, or similar rotary tool.<br/><br/> 1. As said above, use a ruler to mark the center of the board. 2. use a compass to draw the correct diamerter hole. 3. drill a pilot hole near the edge. 4. Use a rotary cutting bit to cut the rough hole. 5. Use the barrel sanding bit or rough sandpaper to finish the hole. 6. Use fine sandpaper to smooth the edge.