Wednesday, October 7, 2009

Bull Frog point controller and installation notes

A typical installation of a Bull Frog point controller, from Fast Tracks. It's an all-wood structure, laser-cut and glued together (or, you and purchase them pre-assembled). I've cut away a portion of the fulcrum to allow a nylon R/C aircraft clevis to attack the throw-rod to the mechanism. . .

I've just finished installing nearly 40 switch point under-baseboard controllers on the upper level of the Narrabri layout. The majority of the controllers are the New Rail Models Blue Point controllers reviewed in a previous posting. Six are Fast Tracks' offering, the Bull Frog.

I decided to go with the Blue Point units for a couple of reasons:
  • Cost: Though Fast Tracks offers the Bull Frog in kit form for $6.00 unassembled, the prospect of assembling more than 50 of these (at a minimum 15 minutes each) made the assembled version more attractive. But the assembled units are $9.00. And the only place you can get these is through Fast Tracks, so no discount there. I found Charleston Digital Trains offering 10 packs of Blue Points for $79.95--20% off list. Their service was first-rate, and delivery was quick--just a couple of days with priority US mail.
  • Availability: While I can save a good amount ordering mail order on the Blue Points, a local hobby shop stocks them at 10% off--so if for some reason I need a couple in a hurry, the option is there. That isn't the case with the Bull Frog.
  • Length of mechanism throw: Though the controllers only have to move the throw rod on the points five millimeters or so, the length of throw out the front of the layout differs significantly. A "full stroke" of the fascia rod on the Blue Point travels only 5mm. A "full stroke" of the Bull Frog travels 26mm, a big difference when you're considering how far an extended fascia knob will stick out from the layout edge (and, Murphy's law being what it is, snag clothing, etc.). To be fair, it doesn't take the full stroke, though, to move the points a sufficent amount to change a route with the Bull Frog--8mm will do it.

Biggest difference to layout users between the Blue Points and the Bull Frogs is the disparate length of the throwing range. On the left, the Blue Point rod at full extension; on the right, the Bull Frog fully pulled out.

With knobs in place, there's little difference between the two with the mechanisms in the "full forward" position. . .

. .but there's quite a difference when the mechanisms are pulled outward. I'm guessing the Bull Frog knob will be inadvertantly snagged a few times each operating session!

Dimensionally, the Bull Frogs are smaller in height (49.5mm vs. 60mm for the Blue Point), a consideration if you're building a multi-deck layout where a thin profile upper deck is important. Distance from bottom of the baseboard to the center-line of the actuating rod from the fascia of the layout is 43.9mm for the Bull Frog and only 20mm for the Blue Frog--a chief factor in the length of the throw of the unit. The big throwing range results in crazy torque--if your turnout isn't secured to the layout, the Bull Frog will try to move it out of the way!

The big throwing range also makes installation easier than the Blue Point. By comparison, the Blue Point's throwing range is much narrower, so one needs to be much fussier lining up the unit just so when installing it to the underside of the layout baseboard.

I do like the "feel" of the Bull Frog as it throws--it doesn't "snap" over like the Blue Point, as the throwing function is a spring-mounted ball-bearing rolling along a tapered groove to a larger laser-cut detent at each end of the throwing range. The Blue Point uses an off-the-shelf mini electrical switch set inside a plastic casting.

While the Bull Frog is a nice unit, the lower price and shorter throw at the fascia front made the Blue Point the preferred mechanism for my layout.

A typical Blue Point mechanism installed under the layout. It can get busy in there with bus wires and throw-rods!

Additional support to the tube-in-tube is given on long (over 9") runs by simply hot-gluing a short section of L-shaped wood molding in place.

A few notes on installation:
  • Tube vs. Rod: Most of the controllers are actuated using tube-in-tube tubing, made for R/C aircraft. It can easily snake around obstacles and allow you to position the throw rod anywhere on the layout front. While a solid, threaded rod is easier to install, the tube-in-tube offers much greater flexibility. Another plus is the physical flexibility of the nylon tube itself: snag it with your belly or a sleeve, and it won't bend out of shape, as is a concern with a metal rod.
  • Under-layout support: I've found that tube-in-tube can run around 8" before you want some sort of support between the mechanism and the front of the layout. New Rail will be glad to sell you a stamped metal bracket to hold the mechanism and the tube-in-tube for $7.50 for three. . .I just chopped a 2" long piece of L-shaped wood molding, drilled a hole in it, and hot-glued it to the underside of the layout. Ain't pretty--but it's cheap!
  • Pricing the Parts: Buying the mechanism is just the start, of course, of what you'll need to make the installation. You need the clevis to hold the rod or tube to the mechanism, the rod or tube itself, and a knob for the front of the layout. All these parts can be sourced cheaper through your local R/C aircraft store--for instance, I purchased 2-48" tube-in-tube plus hardware to attach it to the mechanism for $6, quite a savings from what New Rail or Fast Tracks is offering.

So, the trackwork on the upper level is just about done. All powered up, point controllers in place, and just about ready to host the first "shake down" operating session, hopefully before the end of the month. It's exciting getting to the point to actually invite friends over to operate trains! Of course, before that happens, there's some tuneup of trackwork, a little troubleshooting here and there, preparing the "operating aids" for the layout (track diagrams, station names on fascia fronts, etc.). There's still lots to do, but getting the point controls checked off the list really moved this project ahead!

1 comment:

Ray P said...


Good to see you back on line, now I know why you have been a bit quiet.

Well done, a very good comparison and critique on the merits of each mechanism.

I look forward to hearing about the lead up to your operating session and the actuality.

I have had two operating sessions since you were here and I would have to say that the last was worse than the one you attended. It's amazing how you can forget what needed fixing between sessions.

Ray P