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Grill Cloth Cardboard Backing - Printable Version

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Grill Cloth Cardboard Backing - Joeztech - 12-18-2013

Does anyone know of a source for the type of cardboard that Philco used for grill cloth backing on their radios in the late 30s and early 40s? My 40-201 will have to have the two pieces on either side of center replaced and the one in the center also. One side piece is crumbling away and the center piece is warped at the top from moisture exposure.

Joe

RE: Grill Cloth Cardboard Backing - Eliot Ness - 12-18-2013

You might want to try a craft store and buy some of the matboard they use for matting prints. I've found some at a local craft store called Michaels:

http://www.michaels.com/24%22-x-36%22-Matboard/fr0725,default,pd.html

RE: Grill Cloth Cardboard Backing - Joeztech - 12-18-2013

Eliot Ness;

OK thanks for that suggestion. We don't have a Michael's store nearby, but we do have Hobby Lobby. If the material is not the right thickness, I guess I can use some spray adhesive and build up layers to approximate the original thickness. Some of the plywood wall paneling is about the right thickness, but would not be as dead to vibration as cardboard would be. That is probably one reason Philco used cardboard. The speaker mounting baffle board is plenty sturdy being about 3/4 inches thick. The speaker grill cloth was attached to the cardboard backing and then stapled into the cabinet. I am glad that I bought an electric stapler years ago. It is much easier to get consistent force using an electric one. It is also easier on my arthritic hands!

Joe

RE: Grill Cloth Cardboard Backing - jerryhawthorne - 12-18-2013

Joe, your right, tough to staple inside a cabinet. Tougher to find staples short enough! I discovered that when one went in and came out slightly on the front of the radio. Be careful.
Jerry

RE: Grill Cloth Cardboard Backing - Joeztech - 12-23-2013

Jerry;

Thanks for that warning! I had not thought about the staples going all the way through the wood - not good. I will have to pay close attention to the grill panel build-up and the thickness of the wood. The right length of staple is critical to getting it right. I will try some experimenting first to see how it goes. If I can not find staples that will work, I might find some small wood screws that would not go all the way through the wood. I would also imagine that some sort of solid backing needs to be in place on the front as stapling is done from the back to keep from causing any splits in the wood. There is more to this than meets the eye at first glance.

Joe

RE: Grill Cloth Cardboard Backing - Joeztech - 01-01-2014

Yesterday I picked up some 1/8" thick MDF wall panel to use for the grill mounting board. A 4' X 8' sheet cost just under $10 at Lowe's and I will have plenty left over for more radios! I first had bought some posterboard at Walmart, but soon realized that even if I did a build-up stack they would never be stiff enough to do justice to holding grill cloth without warping. The MDF panel material is very similar to the OEM board material. This is a separate piece from the baffle board that the speaker mounts on. I believe Philco used this approach on most of their radios in the 1930s and into the 1940s. It actually makes repair and replacement of grill cloth easier.

Since there is no current source for grill cloth that looks like the original, I picked a repeating brocade cloth with a brown tone that has a nice pattern to it to replace the old cloth. The old cloth was worn through completely in a number of areas and had to go.

Joe

RE: Grill Cloth Cardboard Backing - jhgrahamjr - 11-28-2014

Joe--How did you cut the wall panel to the shape of your grille cloth mounting board? I found a "Tempered Harboard 1/8 in. x 2 ft. x 4 ft" project panel available through Home Depot for $5.97. I was searching under MDF and also under Masonite. Would this work? I suspect it's too hard to use an Exacto knife or similar. Would one use a manual coping saw, or what would be your best suggestion? Here is my broken backing board, and a sample of the deteriorated grille cloth with the amazing metallic copper sheen which doesn't show in the photograph.

RE: Grill Cloth Cardboard Backing - tab10672 - 11-28-2014

A perfect match I found when throwing away some of our daughters old school supply's, the fiber board used in the covers of cheap 3 ring binders appear to be the same material and thickness. But if the grill is fragile like in a 20 cathedral I use wood paneling with construction paper glued to the front and back to help hold the weight of the speaker from pushing through.

I cut either with a jig saw and scroll blade, and paddle bits for the larger outer holes.

RE: Grill Cloth Cardboard Backing - JimZ - 11-29-2014

I wonder how this stuff might work. I know guys that buy the black color to make dust/back covers and Ill bet it might work

http://www.perfectfit.com/15347/154532/Chipboard-Car-Panelboard/Kraft-Tan-Waterproof-Panelboard.html

I had to make a speaker board for an old Truetone that had typical cardboard that ripped in half so I made one out of 1/8" birch ply. I got abit carried away and actually created the cutouts that matched the front grillwork exactly because I was concerned about it not fitting exactly and getting wrinkled fabric. Worked out fine but probably 3 hours wasted.