Instead of screws I used Liquid Nails and clamped the backdrop in place until the glue set up -- No matter how carefully you countersink, putty, sand, and/or fill in over screw heads, they will usually still show through.
jbinkley60 wrote: I used 5/8" drywall screws, carefully countersunk them, then spackled and sanded them.
I used 5/8" drywall screws, carefully countersunk them, then spackled and sanded them.
I agree and would add to double fill the holes. Fill and sand and then fill and sand again.
Guy
Our backdrops are all sheetrock/drywall, even the curved corners. But we did use masonite for the valances and fascia. We countersunk drywall screws with a countersinking bit, then filled them with joint compound. You have to be careful with sanding the masonite, unless you have the good, dark, tempered stuff. The regular stuff gets fuzzy when you sand it and will show under the paint.
Drywall screws have a bit shallower head than regular wood screws, so they should work with your 3mm thick masonite.
Are you glueing the backdrop to something, or relying solely on the screws? If you aren't glueing, be careful how deep you countersink or the masonite will pull right off the screw.
Good luck.
I spent twenty years in construction. I would strongly suggest using a countersink bit first to make a neat hole for the screw head. If you are using a screw gun, set the screw tension setting really light to begin with or you are likely to run the screw right through the masonite. Normal drywall screws will work fine. They are 1 1/2 or 1 5/8 inches long. The black ones are the least expensive. The silver deck screws are more and the self tapping with a little drill bit on the end are realy expensive and not necessary.
If you ever lose a screw you need to remove after filling and painting use a stud finder to tell you where it is. Even a normal magnetic compass will point to the metal screw. Just don't use aluminum screws.
Wish I were at the point you are but it will be a year probably before we get started on a room addition for trains. TARP
In my case the backdrop was over drywall, not bare studs. I didn't want to glue the backdrop to drywall and then have to replace a bunch of drywall if I ever tried to pull it off.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
The viability of countersunk, patched over, drywall screws can be questionable, depending on how much change in humidity, temperature, and jostling the backdrop has to endure. Over the years I've seen many patched spots over screws break out on backdrops and it can be difficult to cleanly fill the cracks or holes back in and blend (sanding, paint, etc.) them back into the scene without a mess. It's a much better choice, where possible, to glue the backdrop to something like 1x2 uprights attached to the rear of the layout...and it saves a lot of damage to the walls.
CNJ831
A tip on positioning the screws: place the screws consistantly and at uniform distances. Log the dimensions (say, 2" up, 2" down and 8" on center). If you ever need to remove a backdrop you will be glad you did. There's always those couple screws you can never find to dig out the joint compound or spackle.
Modeling B&O- Chessie Bob K. www.ssmrc.org