tolerences for lensboard hole size for Copal 0

[David F]

I want to get a hole drilled for my Copal 0 shutter. The info. on this site and at Grimes Co. says that the hole for the no. 0 shutter is 34.6mm, which equals 1.362 in. Another width I've seen (also on Grimes site) is 34.7mm.

The machine shop guy I spoke with said that he could drill an exact 1.362 in. hole with his lathe but it would be very expensive. Or he could use a 1-3/8 inch (= 1.375") drill bit for a more reasonable price. He also said that drilling with the bit would put the hole very very very close to the center of the board, but not as exact as with the lathe.

My question.: is a 1-3/8 inch hole acceptable for the no. 0 shutter? And is getting very very very close to the center of the board, but not exactly center, acceptable? In other words, what is the tolerances and amount of play that's acceptable for mounting on a lensboard? I haven't really seen this info anywhere.

Regards, David.

[John Berry ( Roadkill )]

Worked for me on the wooden lensboards I have made for myself. The difference is only.013 . Lens centered in the hole leaves .006 equal distance clearance, or 2 human hairs average, between lens and hole. The clamping surface of the retaining ring covered that much gap easy. With lenses that are designed with rise, fall, shift, and swing. Very very very close is close enough. In fact very close is close enough.

[Joseph O'Neil]

A friend of mine who is a machinist made me a number of lens boards, same thing - 1 .3/8 hole, and other shutter sizes approx too. Worked just fine.

joe

[Ben Diss]

Machinists are perfectionists. Tell him to drill a hole, centered to a tolerance of +/- .015 with a diameter of 1.362 +.015/-0. If he spends more than 5 minutes on the job he misunderstood something.

-Ben

[Emmanuel BIGLER]

No problem as seen from my metric eyes ;-). As far as I can read on S.K Grimes' web site, 34.6 mm refers to the diameter of the retaining ring of a #0 shutter.
The actual hole diameter is supposed to be .2 mm bigger, i.e. 34.8mm to allow .1 mm of play on each side. 1"3/8 is 34.9mm, you'll get .15 mm of play on each side !! Since the retaining ring has a "safety cap" much broader than .5 mm (it is about 1-2mm wide) there is definitely no problem being light-tight even if you'll be on the high side, close to the unacceptable, of the tolerance interval for a precision machinist ;-);-)
Do not forget that the hole should touch the retaining ring, not directly the lens mounting thread (this, only in case you have to re-fabricate a home-made retaining ring).

[John_4185]

As other's have noted, Yes it's okay. In fact, 35mm will do. You could save yourself some money if you have a drill; just buy a 35mm hole saw. Then you will have it around for any future occasion.

[eric mac]

On my wooden handcrafted ( home made) boards, I just drilled the hole as close as I could to the correct size and then just sanded or filed it up to the correct size. The movement of the wood throughout the seasons is more than these close tolerances dictate.

I wouldn't worry too much about being dead center, I think that you would be close enough for your view camera.

eric

[Ted Harris]

If you are talking a metal and not a wood board then there is one reason to machine the hole rather than drill it and that is the potential stress to the metal from drilling that may (repeat may) cause a very slight (probably less than .001mm) twisting that could do something to the flatness/alignment of the lens with the film plane. Yeah, pickjing nits for sure but wanted to get it said. We work very hard to maintain critical sharpness and resolution throughout our taking and processing and yet some small errors in the euqipoment can undo it all.

[Ron Marshall]

I purchased a used, supposedly, #1 Sinar board that was a couple of millimeters tight, so I widened it carefully with a file, in a couple of minutes.

[Alan Davenport]

If you have access to a drill press, you can go to Sears (or wherever) and get a flycutter for probably less than a machinist will charge to drill a hole. IIRC, I paid about $20. I use the flycutter on both wood and metal boards. I can't seem to adjust it for exactly 34.6mm, but as noted close is close enough. One way to get closer tolerances is to cut the hole slightly small, then finish with a Dremel or similar.

[Stan. Laurenson-Batten]

No problem with the Copal 'O' and a 34.6mm = 1.362" or 1.3/8" I have cut all my own Sinar Metal Boards using a fine toothed hole cutting bit with a hand brace. It pays to get the right tool for the job and gives great satisfaction.

[David F]

Thanks all. I gather from the reponses that I can use a 1-3/8 inch drill, I can do it myself, and that there is a bit of tolerance in the widths -- in other words, not rocket science. The lensboard I have is plasitic, so I don't think that bending or stress will be a factor.

thanks again, David.

[Mike Kovacs]

Luckily at work, I was one of the investigators that put money into a nice little Roland MDX-20 CNC milling machine, which is capable of cutting aluminum and brass but not steel. I just cut out a #1 hole for my "new" Symmar 210/5.6 today in a #0 board from ebay. Really easy software for it - just cut the board outline in a piece of wood, cut the hole in the outline to make sure its centred, double sided tape the board on, cut the hole perfectly centred.

Actually, I was thinking for next time to try and cut an entire lensboard with it from a flat sheet. For a Calumet 4x4 board, it ought to be very simple to mill out an entire square board from a flat sheet. (might take a long time!)

It also has a scanner function - it can scan a part, then import the dimensions into a drawing for refinement/modification, then duplication on the mill.

[Jeffrey Sipress]

The machinist you went to is a loser.

I been a precision machinist for over thirty years and now own a high precision CNC machine shop & manufacturing company. I've made all my own lensboards, and a slew of unique little widgets that assist my photography, and all other parts of my life. Just send me the board, tell me exactly what you want, and I'll do it for you free of charge and it will be right. email me.....

[Mike Kovacs]

My kingdom for a machinist - I used to work at a company that provided me access to a superb light metal fabrication shop and really good people. I miss that!

I gained a lot of respect for those guys - real artists and craftsmen! I still marvel at the thought of the things I built with their help.

[John D Gerndt]

View cameras are 19th century technology. It doesn't hurt to be accurate but there is a lot of room for play, so play!

Cheers!