I’m looking to use several inches of foam on top of plywood for my base. However, I’m not sure how I can drop the track (and other) wiring through the foam and the plywood. Does anyone have a technique for doing this?
Any help would be appreciated.
EdW
Not from personal experience, but I’ve heard that others have used a skewer or a pointy stick. A long knitting needle could work as well. If you’ve already put the foam on top of the plywood, you might have to work from underneath. I’ve also seen in MR, someone used straws to push wires through so the ends don’t catch and tear up the foam.
Ed B
I usually just drill through the foam with a wood-type bit, but I never drilled through foam thicker than 1.5". You could try an awl, but the foam has a tendency to close back in if it is just displaced, which thrust-type peneteration tends to do. Ideally, you would have a long thin bit that would actually remove a little of the foam.
Once you have a hole in place, you should have a straight length of wire ready to shove carefully into its length. Ends that have been made sharp, or that are curled will not help. If you can get a length of brass tubing into the hole, that will help guide the wire through it. I read that a plastic straw works, but you’d need a substantial hole.
Our club had the same problem. We used large plastic soda straws ro run the feeder wires through up to 6" of pink foam.
Jim
I’ve used both plastic soda straws (which tend to collapse if the foam is really active) or Evergreen styrene tubes (a bit thicker walls). I use a high speed drill (with a vacuum) to pull as much foam out of the hole as possible and insert the tubing as quickly as possible. A few well-placed tubes will allow you to run wiring from several locations.
Jim
I’ve had success just running a trench across the surface about 1" deep. I slice a channel with a utility knife, then push the wire into the trench, which runs to the outer edge of the layout, where a bus line can run close to the aisle behind the fascia. You can just scenic over the trench. Just make sure you call “Miss Utility” before you dig anything up later!
Lee
We have coffee machines at work. So, we also have coffee stirrers. Sometimes they are short black plastic tubes, and sometimes slightly longer, red plastic tubes. Sometimes we have wooden sticks.
Needless to say, not all of these stirrers make the quick trip from cup to trash can. I find they’re perfect for slipping through the foam, right behind the skewer that’s punching the hole. This will work for 1 or 2 wires, but for heavier stuff I usually use a drinking straw. (The wood sticks become plank fences on my layout, by the way.)
If you can measure accurately enough, you can just drill through the wood from below, and then punch through the foam with a skewer. I’ve even used a pencil to poke through, when I wanted a bigger hole. If it’s tough to locate the right spot to drill from below, you can get long drill bits. I’ve got a quarter-inch bit that’s a good 18 inches long, more than you would need.
Since it sounds like you’re in pre-construction, I have to ask this: Why use plywood at all? 2 inches of pink/blue foam is stiff enough to span 18-24 inches, even with trains on top. You can save on the cost of the plywood, and have a layout that’s lighter without sacrificing anything. If you’re using foam, you’re not going to be able to climb on top of it, anyway.
I have some 12 inch long drill bits. I usually drill a 1/8 hole from the top and follow up with the wire right away. If the hole is too big at the top, I fill it with latex caulk after soldering etc.
Most of the solutions proposed before this one don’t help with getting the wire through the plywood. Most of them work OK for the foam part. I have some 3/32" dia x 6" long bits that I bought through Grainger (they’re called aircraft extension drill bits, I think). These allow me to drill directly down from where I need the feeder, through the foam and plywood. Because it’s a fairly tight fit for the wire diameter, it sometimes takes some twisting and manipulation of the wire to work it through the foam and help it find its way through the hole in the plywood. But, when I’m done there’s no gap to fill.
The only other suggestion I can make would be to drill through the plywood from the bottom, maybe with a large speedbore bit, then try any of the other suggestions to punch a hole from the feeder location through to the area where the plywood has been removed. If the hole in the plywood isn’t directly beneath the feeder location, you can probably punch the hole at an angle to find it. This might even be an advantage if there’s benchwork in the way.
Good Luck,
Tom
I have both 12" and 18" long 1/4" dia drill bits, (bought at Lowes) to drill through as much as 14" of foam and 1/2" ply. I use a stiff piece of wire to pull the new wire(s) through and use a piece of foam to stuff in the hole to close it up.
drill a hole and rune straw thorugh it
You can get bits up to 4’ in the small sizes, they are used for alarm wires and other small wires like doorbell and are available at most electrical stores.
These four footers have a hole in the tip for wire pulling
All good advice so far. I use the long aircraft extension bits to drill a hole then use brass tube inserted in the hole to pass the wire through as the wire tends to try to drill its’ own hole in the foam. Once the drop(s) in I pull the tube through from below and go to the next hole. Hope that helps. J.R.
AKA “Bellhangers bits”.
I was giving it some thought, even tho I’m not using foam. I was thinking about exactly what you posted. Using any kind of rigid sleeve to get the wires through and then remove it for use at the next hole. The trench idea works well in 1:1 as we brought electrical power to my Dad’s garden shed by cutting a very narrow space into the lawn, tucking the cable a foot under ground and then tamping the slight ridge back down. In a week it became invisible. Always test the wire for continuity before committing it to a “permanent” installation. I know, I’m paranoid, but even new, spooled wire can have a break in it(10 years at the shack and yes, I’ve seen it all).
I haven’t tried this but, if you drill up thru the plywood & then heat up a rod of suitable diameter or a piece of allthread & push it up it would act like a hot wire cutter & displace the foam leaving a path for the wire. Probably a hot plate would work. I know a propane torch would, but I would not encourage you to use it in the house. jerry
I made a wire “sewing needle” out of a wire hanger. One end has as loop in it, and the other is has a point ground into it using my bench sander.
I also have plywood bench, 3/4", and 2" of foam glued on top. I use a 12" drill bit. You can get them at Sears, Lowes or Home Depot as well as most Hardware stores. Drill the holes from top down right where you want the wire/s. Then, I release the drill bit from the chuck, and attach the wire/s to the top of the drill bit and push/pull the drill through the foam and plywood exposing the wire/s for removal from the end of the drill bit.
If you are not ready to drop wires yet at the time you drill your holes, then attach a pull wire to the end of the drill bit so that you can later use this wire to pull your electrical wires down through the foam and plywood.