Anniversary bridge rack reproduction

Boxcar

AzB Silver Member
Silver Member
Great historical reference. Thank you.

I was an AWI affiliate back in the 70s, 80s, and 90s. Seeing your shop makes me homesick. I still have your scraper(the one on the right)in my tool box.

We did an awful lot of circle head sash and door frames for one of our well known period restoration contractors. We bent a lot of NE WP and some Hond Mah and we had a steam chamber that was very helpful. I'd have to say that 100% of our bends ran the grain long. We mixed waterproof brown powder so it was easy to set the viscosity and cure time.

A major ship builder near me used miles and miles of Hoover laminated wood fire retardant scaffolding. The scaffolding was load bearing. My memory is that all of the plys ran long. There was no loss of lateral or longitudinal integrity. My point, of course, is that laminated products which lay up parallel grain components are suitably strong. It would seem that post-formed components layed up with their grain running parallel would be more than suitable for these bridge racks. Even if Martin went from a 3 ply to a 5 ply build, things should work well. We always felt that glue was stronger than wood. Please share your thoughts.

Best regards,

BOXCAR
 

Ssonerai

AzB Silver Member
Silver Member
Boxcar-

Running all the plies longways is both stronger, and nicely more convenient for many items. Certainly most of my architectural millwork was run long grain. I had a small milllwork and installation business/crew, and we worked in DC & Manhattan. Lot's of arch windows, replica or new work, lots of doors of all shapes. Some curved both ways.

Seats and "thin" stuff or other 3D bends, it is usually best to have a cross ply or more for shape stability & to prevent cracking.

It is good you continue to "press" ;) on the immediate subject, the triangle rack. I was taking it as 5 ply. Often on constructions like that, the face is thin and with the edge beveled or rounded, it is not really perceptible on a stained part. But studying the eBay item, i think you might be right that it is 3 ply.

Doing it that way should certainly be easier. My only minor concern would be that the part should be over-bent, it will have more springback with only a few thicker plies. However, Martin (IIUC) was initially speculating that it could be 1/2" or 3/8" thick. Studying the eBay item, it seems about 1/4" thick. 3/32"-1/16"-3/32"? The eBay item also seems to have a continuous round section where the above drawing shows the 1" radius 90° bend with a short straight. Those differences for all parameters start to suggest a very easy vacuum bend.

Further speculating or testing without some assured numbers seems pointless. :smile:

smt
 

Boxcar

AzB Silver Member
Silver Member
SMT,

Excellent post!

So now, the mission may well be one of creating an authentic period replacement part. Brunswick was in a roaring, post war footing in the mid to late 40s. They were trying to make up for war time losses, which is to say they weren't worried about competing with Steinway. These racks were entirely utilitarian, and were surely designed to be CHEAP, cheap to build and built of cheap materials. If I had been the design engineer on that part, I would have made it 3/8" thick and out of three 1/8" plys fresh from the plywood mills. The core and the bottom would have been trash and off-fall and the face would have been the prettiest piece of trash left in the bins. I'd have slapped those muthas together in a press that anticipated an acceptable amount of recoil, made 500 at a pop on the clamp carrier, pulled them, shaped them on a template running against a ball bearing collar, sanded them, stained them, shot them twice with cheap lacquer, and shipped 'em.

Whatdya think?

Better yet, Martin, what do you think?

BOXCAR
 

martin35

AzB Silver Member
Silver Member
Hello Guys

I'm back, sorry to be long to answer. This thread is getting out of hand but in a really good way. Thank you SMT for the ptototyping and testing, it will really save me a ton of beginner's trial and error.

It make a lot of sense that the long radius at the top is continious and do not have any flat surface, I understang that is makes the form a lot easier to build and fit together. I also agree that something around 1/4-5/16 thick should be enough and easier to build.

The more I think about it , I will probably try to build a form and some kind of little flat press with one or two bottle jack to make some trial, may be this winter.

I found some cheap veneer kit that will allow me to make some experiment without breaking the bank.

Guys (SMT and Boxcar) thank you again for your expert experience.

I'll keep you informed of any progress.

Martin
 
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