Atlas C55 switch question

[mike_lawyer]

My dad is working on building a small N-scale layout using Atlas C55 flex track and Atlas C55 number 7 switches.  He has all the track installed, but then he realized he forgot to drill holes through the plywood base below the switch throw bars for Tortoise switch machines.  Anyone have any ideas on the best way to drill a hole through the plywood base with the switch installed?  My first thought was to drill a small pilot hole from the top next to the switch throw bar, then drill a larger hole directly under the throw bar up from the underside of the table.  Any suggestions would be helpful.  Thanks!

[shark_jj]

I haven't forgot to drill the hole but I have had to enlarge a hole with a switch installed.  I put my tortoise machines in the centre of the throw bar so it is even more difficult.  I slide a thin piece of metal under the throw bar so it protects the portion of the turnout over the hole.  I have a small metal ruler that I use for this.  I mark the drill bit with masking tape for the depth I want to go as a guide.  I have 3/4 inch plywood subroadbed, so I place the masking tape at 3/4 inch.  I then drill up from the bottom carefully.  The metal ruler protects the turnout, the tape tells me how deep to drill.  The issue you have with not having already drilled any hole is locating the point under the layout to begin the drilling process.  Unfortunately I have no ideas on that other than a pilot hole near the spot you want to drill and then measuring from the pilot hole.  When you locate the point you want drill another pilot hole and check the location.  If it is accurate, then drill the size hole you require.  I really do recommend sliding a piece of metal under the turnout, don't risk drilling from underneath into an unprotected turnout. 

[robert3985]

If I were in your place, first, I would tape the closure points on your turnout's switch to be centered...equal spaces between both closure point toes and the adjacent stock rails, then take a sharpened pencil and insert the lead into the hole in the Atlas throwbar, marking on your plywood the exact place the throwbar hole is located, and where the hole through your plywood is to be located.  If your throwbar is high enough over the plywood that the pencil lead's taper won't allow the lead's tip to reach the plywood, then chuck up a drill bit in a pin vice that's the same size as the throwbar hole, run it through the hole and lightly twist your pin vice to put a shallow hole in the plywood directly under the throwbar hole.

Then, take a sharp X-acto #17 narrow chisel blade, grind it down on either side so it's just a little narrower than the space between the two headblock ties, and cleanly and squarely cut off the throwbar about .175" (no less than that) from the outside of the straight stock rail, with the throwbar thrown for the straight-through route. Save the piece of throwbar you've just cut off.  If your turnout is glued to cork roadbed and you haven't extended your cork roadbed under the throwbar and headblocks, insert an appropriately thick piece of Masonite or hardwood under the throwbar where you'll be cutting it to support the throwbar and facilitate a clean cut.

Next, take an ice-pick or sharpened nail, and press a significant dimple in the center of the pencil mark or little drill bit hole where the hole in the throwbar was located that you've previously marked on your plywood...this will help you precisely locate your drill bit when you drill through your plywood, or you can drill a pilot hole with a 1/16" bit.

Then, chuck in a new 3mm high speed steel saw drill bit that not only drills a hole but will cut side to side...(like this:  https://www.amazon.com/Titanium-Coated-Twist-Drill-Bits/dp/B08NY8G25Z/ref=asc_df_B08NY8G25Z/?tag=hyprod-20&linkCode=df0&hvadid=476529449663&hvpos=&hvnetw=g&hvrand=6882807288952895993&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1016367&hvtargid=pla-1197414852956&psc=1 ) ...these are also called "side cutting drill bits"....Harbor Freight has them but the smallest is 1/8"...slightly bigger than 3mm...would still work, but not be ideal. Get the metric set if you can find it.

Next, carefully drill a hole through the plywood, trying to keep it as perpendicular to the plywood surface as possible...then slowly, with your drill at its highest speed, make the hole into a slot that's perpendicular to the straight stock rails, being careful to not cut or destroy your two headblock ties on either side of your slot.

I like to taper the slot so the bottom of it closest to my Tortoise is wide enough to not interfere with the Tortoise throw wire.

Since the total throw of the throwbar on an Atlas #7 is only .054", the slot doesn't have to be very long, but it should be spaced equally distant on either side of the initial hole you drilled.

Time to put your throwbar back together.  I would probably drill a .020" hole in each piece of the throwbar...the one still attached to the switch, and the one I just removed, bend up a small piece of .020" brass rod into a shallow "U" shape with a flat bottom, and insert it from the bottom of the two pieces of throwbar...clean the assembled throwbar and brass "U" with Heptane/Bestine or 90+% isopropyl alcohol to remove finger grease and mold release...then, glue the assembly together with 5 min Epoxy, making sure to get Epoxy on both the "U" shaped rod, the bottom of the throwbar and also the top of the throwbar...especially in the line between the two pieces and the protruding legs of the "U".  Let that cure, then snip off the protruding legs of the "U" up top of the throwbar not quite flush with the top surface of the throwbar with your flush-cutters.

Be cautious to center the .020" hole in the throwbar pieces and don't get the hole too near the throwbar pieces' cut ends.  You want the ends to ideally be touching each other, so be careful when bending up the brass rod to get it as perfect as you can.  Filing the ends of the brass rod "U" piece to get rid of sharp edges will facilitate inserting it easily into the holes in the two throwbar pieces.

As an aside, maybe just Styrene or brass plates on the bottom & top Epoxied to the throwbar might be enough...but, I'm not sure how well Epoxy will stick to the plastic Atlas uses for their ties.

This should leave the stock hole in the throwbar pretty close to the center of the slot when the point toes are centered on the stock rails.

When you put the throw wire on your Tortoise, center it up...then insert it from the bottom through the turnout's throwbar hole and mark with your pencil where to drill a couple of shallow pilot holes centered on the mounting slots of the mounting base of the Tortoise underneath.  To be clear, I usually just mark two holes...drill shallow pilot holes and mount the Tortoise using those two screws, check the Tortoise/Throwbar alignment, then drive in the other two screws without needing any pilot holes.

I'm pretty sure this will work for you and should be fairly easy to do.

Cheerio!
Bob Gilmore

[pedro]

Geez, lol.

I guess simply cutting the switch out and replacing it after you drill the hole isn’t an option? That’s what I would do, assuming it wasn’t glued and ballasted in place. (The OP didn’t specify)

[djconway]

What I have done in cases where the hole was "off" spot was to use a Dremil tool with a 1/8 or 3/16 ball cutting bit and hog out enough for the throw bar.
If there is no hole at all - using a small pin drill drill the hole in the throw bar and through the sub roadbed, push a length or brass wire through the hole and mark the underside of the subroadbed then make the hole with the Dremel tool.

[fire5506]

What I would do is push the points to one side and drill though the hole in the throw bar through the plywood. Then push the points over the other way and do the same. Then you have marks underneath for the throw. I would then use a Dremel with the router attachment and route a slot from underneath about an 1/8 in past the holes going a little at a time until you just clean the plywood out from under the turnout. Be careful when you are getting to the depth of the plywood.

And for safety sake wear goggles and hearing protection.

Richard

[NDave]

Here's my thought...
Tape the turnout so that is is in between the straight and diverging routes...

From above: Drill two small holes (small enough to easily cover later, large enough to find from underneath) that precisely flank/bracket the hole in the throw rod that you will use to throw the switch...  OUTSIDE of the ties that serve to guide the throw rod. These holes should go all the way thru any roadbed and sub-roadbed.

From beneath: mark a point precisely between the two holes you drilled from above. This point SHOULD be now be directly under the throwbar hole you plan to use. Now, either use a drill with a mark or drill stop to drill up from underneath, til you just barely break thru the sub-roadbed and roadbed (a thin piece of metal under the throw bar as a shield is a good idea). You could use a bit with sufficient diameter for the amount of throw you will need... or use a smaller drill bit, and then enlarge the hole as needed with a micro router bit in a Dremel.

[peteski]

The small pilot hole sounds like a good idea, but I would not trust a piece of metal under the throwbar to prevent the large drill bit from coming through.
When drilling using twist drills, when the bit comes through the surface it tends to grab the material end pull itself out through the hole with quite a force.

I recommend restraining the drill bit from doing that.  I have a set of metal collars with aset screw which can be installed on the drill's shank to control how deep the drill bit will go into the material. Using something like that, and adjusting it to just barely go through the surface should make the drilling safer.  Even if the hole is not all the way through, it can be opened up by trimming the hole's edges with a hobby knife.

[wazzou]

I’m reminded of the installation of a lightbulb. 

[Jim Costello]

I have had to do this twice, when drilling from underneath use a Brad Point  or dowling drill bit, These have an outside cutting edge that  cuts the hole fairly clean
and helps by not pulling through the baseboard as does a twist bit drill.  A sharp exacto pointed blade will help clean out a hole.

[peteski]

I’m reminded of the installation of a lightbulb. 

I see what you did there. 

[wm3798]

I doubt I can put my finger on a photo of it, but I've dealt with this issue by simply drilling the hole just beyond the end of the throw bar, so the drill can't damage it.  Then run your wire up, and bend it into a suitable shape to effectively actuate the throw. A bend toward the switch, and a short bend up from below the throwbar.  A little scenery magic to camouflage it, and you're in like Flynn.

Lee

[wm3798]

This isn't an Atlas switch, but this stunt also works.


This is on my hollow core door layout.
I didn't want to have the machines hanging down below the bottom, so I laid them on their side and worked the wire as needed to throw the switch.  It works remarkably well, but will require some creative scenery, which I have not yet worked out the details of...
It turns out the depth is perfect to hide in 2 inch foam.
Lee

[nkalanaga]

Put a piece of plastic tubing around the large drill bit, leaving just enough to drill through the plywood.  Try it first to make sure it's right!

I'd use Plastruct's ABS tubing if possible, as it's thicker than Evergreen's, and probably more durable.

This idea has been used for at least a century in industry, where a drill bit can't be allowed to go too deep, and a drill press won't work.

[John]

I've actually just lifted up the throw bar and bent it back enough to get a small drill into the area it needs to go .. then get underneath and drill back up .. don't overthink it ..