Wooden lens board question

[Jmarmck]

I have a Zone VI and several lenses. One lens came with the camera as well as an undrilled board. I need 3 more. I am not sure of the hole size on some.
I was looking at the supplied board and saw that two sides are joined with another piece of wood in a simple lap joint. Very well done, I might add.
I understand that they are probably there to prevent warping as the wood grain is not continuous across the board.

The question is, are these lap joints necessary? Can I use some high quality ply form a craft store? Or even some cherry form another source. Maybe even some maple or walnut, oak? (My brother has a wood mill shop and collects downed trees)

Thanks

[Dan Dozer]

I've used the wood from the craft store before and not had many problems. Sometimes the boards did warp a little, but those seemed to be the ones that I left unfinished as bare wood. Make sure that the wood isn't already warped before you buy it. Also, don't leave the wood lying around in your house for a long time before you cut your lens boards. I've done that before and the longer boards seem to many times warp with time. Cut the boards out when you purchase the wood adn finish them right away and you probably won't have any problems.

[goamules]

I've used plywood, one square smaller than the outside square (to make the light trap) then laminated the outside with thin mahogany and glue.

But then I learned from Mark Sawyer to use those psuedowood square floor tiles you can get at Home Depot. They are remarkably flat and warp resistant, and come in many wood styles that look quite real. All you do is cut a rim around the edge to make the light trap, cut your hole, paint the back black. I've got a dozen in 9" and 6" for future lenses.....

[Jac@stafford.net]

But then I learned from Mark Sawyer to use those psuedowood square floor tiles you can get at Home Depot.

Very good idea!


paint the back black

Black flocking paper (http://www.edmundoptics.com/lab-production/general-tools/light-absorbing-black-out-material/1502) is even better.

[Jmarmck]

Well that is certainly some good advice. Thank you all. Don't know if I would try the flocking paper but there are a couple other ideas that could benefit from it. Thanks.

Guess I need to get the router and table saw in working order.

What finish on the front, a polyurethane on the front (if needed) and a coating or two of flat black on the back?

[EdSawyer]

I use HDF (masonite) sometimes too - it machines very well (avoid the dust though), has no grain = no warping. Seal it up well with paint and it will work well. Not as pretty as wood but faster and cheaper sometimes. I use the black self-adhesive flocking too, it's great stuff.

re: finishing wood - generally you want to have a balancing finish on the back that is the same as the front side - so that the wood gets pulled equally by the finish contracting and doesn't warp as a result of the finish. Paint/Poly might be close enough for that to work. Mostly it's an issue on larger panels, and even then, probably a fringe issue. in a 4" board it's not going to matter very much to have a perfect balancing finish.

[Steven Tribe]

The original idea of using 3 - piece lens boards was to secure the board against cracking down the grain. With the 3 piece idea, the grain runs in both directions - otherwise you have to remember to mount the board with the grain vertically. The quality of wood used made these tiny miracles of tongue and groove joinery possible. Later boards, from the continent at least, had 2 grooved pieces with a darker (not mahogany) locking strip.
Derelict furniture often provides a good quality walnut/mahogany veneer on (early) plywood.

[Mark Sawyer]

But then I learned from Mark Sawyer to use those psuedowood square floor tiles you can get at Home Depot. They are remarkably flat and warp resistant, and come in many wood styles that look quite real. All you do is cut a rim around the edge to make the light trap, cut your hole, paint the back black. I've got a dozen in 9" and 6" for future lenses.....

Actually, I use a wood-finish composite flooring material very much like Pergo, but without the foam backing that Pergo has. That foam is tough to get off so look for the stuff without it. It usually comes in strips 7 or 8 inches wide and about 3 feet long. Great stuff for lens boards, it looks good, never warps, and it's tough enough to walk on!

[Jmarmck]

Thanks, I will look for some tomorrow. I gotta go to one of those home improvement places and see if I can find some calipers. They don't carry spanner wrenches. SK Grimes I guess.

[Mark Sawyer]

The best spanner wrench is a home-made one. Get a piece of wood that fits in your hand nicely and drill a couple of holes through it. Run screws through the holes until the points are half an inch to an inch out the other side. Angle the holes outward at about 30 degrees, and the size will be adjustable by changing the amount the screws stick out. If you want to get fancy, you can file or grind the tips of the screws to blade shapes or whatever; I just barely take the sharp points off them. I have a set of "real" spanner wrenches, but the home-made works much better. Very solid, lots of leverage, easy to adjust, and they stay at exactly the size you adjust them to.