plywood

[zahc]

I want to buy some good material for making a large-format camera. Plywood means I can cut the standards out in one piece instead of having to join pieces of hardware at the corners. Important since I don't exactly have a wood shop. But I need much better plywood than the stuff used for flooring or roofing. More like the stuff skateboards are made out of. Is there a name for this stuff?

[Perd Hapley]

I think Home Depot has better grades of plywood. Don't know about skateboards. When I was pimping lumber, we called it hardwood plywood, I think. Maple, oak, etc.


Here's a company down the road from me, and their plywood selection:

http://stcharleshardwoods.clickforward.com/hardwood-plywood.html

[Triphammer]

Do you need a higher strength per thickness or a better (read smoother) surface

[RoadKingLarry]

Cabinet grade will have at least one pretty face. Marine grade will be free of voids.

[Triphammer]

MDO is another choice for dead smooth. If this is going to be stationary so that weight doesn't mater, MDF, high density fiberboard is great & cheap. MDO is an outdoor grade plywood covered with a phenolic paper - used mainly for roadside billboards.
 If you need a higher strength to weight ratio, go aircraft grade. This is the more but thinner layer stuff you referred to for skateboards.

[bedlamite]

http://www3.towerhobbies.com/cgi-bin/wti0093p?&C=RCC&P=ML

[rcnixon]

Bedlamite for the win. Birch aircraft plywood.

Russ

[zahc]

MDO is another choice for dead smooth. If this is going to be stationary so that weight doesn't mater, MDF, high density fiberboard is great & cheap. MDO is an outdoor grade plywood covered with a phenolic paper - used mainly for roadside billboards.
 If you need a higher strength to weight ratio, go aircraft grade. This is the more but thinner layer stuff you referred to for skateboards.

I don't think I want MDO since I plan to round the edges. I need 1/4 or 3/8" thick. I didn't think of MDF. I think that would work. I would have to paint it good for looks and for weatherproofing. Both options make me nervous since MDF doesn't take screws that well and crumbles when wet.

I'll check out a hobby shop.

[dogmush]

MDF shaped, resin coated, then painted will last for years in the weather.  My parents still have some stuff on their deck I made in the mid 90's.  They live in Alaska.

[Tallpine]

You're going to have to have some framing for the corners.

[Triphammer]

I'll check out a hobby shop.

Hobby shop? How big is this thing? I'm thinking you need 4x8 sheets.

I don't know your lead time but these guys are great.

http://www.aircraftspruce.com/menus/wp/plywood.html

[zahc]

I'm building a 6x9 view camera so I should only need maybe a 2x2 ft. piece even if I screw up a lot.

With a coping saw I can avoid framing anything. I will just cut the standards out whole by cutting concentric squares.

[zxcvbob]

I think what you want is called "Baltic" plywood.  (or Baltic birch plywood)   It is free of voids and made with exterior-grade glue.  It's not cheap, but a 1/4 sheet shouldn't be too bad.

[tokugawa]

Baltic birch is good plywood, but it will not stay flat- most plywood will not- I would recommend a place that sells to boat builders, see what they have.

[dogmush]

Just to confuse the issue, are you sure you want wood?  UHMW comes in sheets up to an inch thick, is shapable with a router, holds screws and comes in colors.  Marine Starboard does the same thing.  A thick sheet of black plastic might be a better option here.

[zahc]

I've considered ABS. Also solvent weldable, but I think heavier for a given stiffness. 1/4 ply is probably enough but ABS plastic would be too floppy. Plexi would be stiffer but not good for a camera. I didn't think of uhmw sheets. I'm not familiar with the properties. I'm thinking it's prrobably like Corian.

[K Frame]

Sheets of marble.

[zxcvbob]

Sheets of marble.

That's an interesting idea.  12x12" tiles are cheap.

[mtnbkr]

no shutter shock with all that weight.

Chris

[K Frame]

That's an interesting idea.  12x12" tiles are cheap.

Exactly. And slabs aren't much more expensive. Plus, it's relatively easy to cut with a grinder or even a hacksaw.

The only problem you might run into is joining it for long-lasting durability. An internal wooden framework might be a good idea. it would give the ability to either glue or screw into.

There might be a problem of light porosity, but a coat of paint would take care of that.

[CypherNinja]

I've considered ABS. Also solvent weldable, but I think heavier for a given stiffness. 1/4 ply is probably enough but ABS plastic would be too floppy. Plexi would be stiffer but not good for a camera. I didn't think of uhmw sheets. I'm not familiar with the properties. I'm thinking it's prrobably like Corian.

Those cheap white plastic cutting boards are UHMW.

Also some (30%ish of them) Lowes carry a product a called ApplePly. It's a real nice high layer count hardwood plywood like the Baltic Birch. Generally Maple all the way through and choice of outside veneer (if your ordering it). Lowes carries pieces rather than full sheets, but they and any decent plywood place should be able to order it for you. It's nice stuff.

http://appleply.com/

[tokugawa]

Apple-ply is very similar to Baltic birch- it will also tend to warp some- I don't know anything about cameras but  I do know a lot about wood, so enlighten me- what is it exactly you are building?
 If it is a box type structure, and the edges are joined, then the warp will be confined to a shallow bow between the corners , if it matters. Or it could twist slightly.
 
 Thicker ply will be easier to join with a rabbet , glue, and pin nails , or thin pieces can be joined with a cleat , box joint, or stitch and glue- ( wired corners with epoxy fillet
 
For staying flat, it is very tough to beat MDF, it is not the strongest however. -but that may not matter for your application. It also paints well. If you need a flat, rigid, smooth, non resonant material this would be the ticket.

[zahc]

I haven't decided if the standards shall be partially boxed or simply flat plates. Either way using plywood is simplifying because I can cut the film-hole and lens-hole out instead of having to build a frame out of pieces. Although I believe I've seen 8-inch poplar board at LowesDepot, and that would be wide enough.

[tokugawa]

The originals of this sort of thing would most likely be Honduran Mahogany, for stability purposes. It was the wood of choice for most scientific instruments. Quartersawn white oak was also used a lot. But with any solid wood it takes some work to build something that will not tear itself apart with movement.

 MDF will be pretty stable, easy to work (although wear a mask)available in  a wide variety of thicknesses, it will not fasten well on the edge "grain", - Unless there is some reason why not, I would be tempted to make this from MDF with a hardwood frame around the edge-say, for example a 3/4" thick MDF and a 3/4" thick by 2" wide frame with the MDF and frame at right angles- dado the wide side of the frame 1/4" and glue in the MDF panel- That will make a stiff and rigid shallow box.
 
 A couple of pieces of MDF with a spacer for the glass could also be glued up as one unit- these have some metal spring clips to hold the glass plates?

 Are there not plans available? 

[zahc]

Found birch plywood at Michaels, made camera. It uses a rotating back from an RB67 that I bought on ebay. The moving bits are linear sliders I got as free samples. It has full front movements and rear swing. Uses 90, 127 and 150mm lenses I had anyway, and folds completely with any of them. The bellows was the hard part.