Yes, there is a “short” reason

https://www.handlaidtrack.com/FTV-Turnouts-12

If you don’t gut the caps, all the rails are electrically connected (assuming you’ve built the turnout following their directions up to this point).

Yes!

You definitely need the gaps to avoid a short circuit. The frog is where a positive polarity rail and negative polarity rail meet. There must be gaps on either end. It is also a good idea to power the frog once the gaps are in place to avoid short wheel base engines stalling on the frog.

You can slide some styrene between the gaps and glue it in place with cyanoacrylic adhesive, then file it down to the same profile as the rail. Once the rail is primed and weathered you won't be able to tell that there is a piece of styrene there and you've created a bullet proof way to avoid a short circuit due to rail expansion or movement.

I understand the gaps on the

Yes your overlooking

Yes your overlooking something,,,,, gap each side of the frog. 

There is an option for no gaps…

Tommy:

If you use Iowa Scaled Engineering's MRServo-3 to switch the points there is no need to gap the point rail side. 

http://www.iascaled.com/store/ModelRailroad/MRServo

The MRServo-3 changes the polarity at the mid-point of the travel of the points thus eliminating the need to gap the frog on the closure rails. Of course, you would still need to cut two gaps on the opposite side of the frog. 

Iowa Scaled discontinued the MRServo-3, but there still may be some stock, or if you contact them they may make enough for your layout. 

Hope this helps.

You have a short unless you cut something

If you assemble the turnout per the fasttracks instructions, you have to do something to avoid a short.  You have two options - the preferred way that doesn't risk shorts with metal wheels running through the turnout is to gap both sides of the frog.  But instead of putting gaps in the closure rails (on the point side of the frog) you could cut the copper traces on the pc ties between the points and stock rails so that the points are isolated from both stock rails if you center them.

 "But instead of putting gaps

If I was going to do that I'd use screws or pins to attach the points to the throw bar. Cutting the copper so close to the solder joint would leave a weaker throwbar/point connection( not as much surface area holding copper to fiberglass)......DaveB 

To clarify, the terminology I

But but DaveB,

But I thought the points rails were only soldered on the inside and there should be no solder on the stock-rail side of the points rail because that will interfere with the points fitting into the filed-out part of the stock rail. 

I must be misunderstanding the less-recommended option.

"I thought the points rails

   There's no solder on the stock rail side but the PC board extends under the rail so power will feed back from it. If you gap the copper on the stock rail side of the point you'll only have a small piece left holding the point to the throwbar so that's why I'd screw or pin the point to throwbar joint.....DaveB

If I'm understanding

I think I understand

I think I understand your point. "by a small piece left" you mean a small piece of the copper top pcb layer attached to the pcb substrate - and your point is that the copper might detach from the "plastic" layer because it's only a small piece of copper (having been gapped both between the point rails and between the point and stock rails).

I hope the OP still has the option to take up the turnout and make the gap with a jeweler's saw instead of a cutoff wheel. From the video that does seem to make a finer gap. 

I wonder if anyone building turnouts tries to hide the gaps by filling them in with plastic or something and how they do that and how well it works.

"If I'm understanding

  You'd have to eliminate all the copper from the throw bar from the points to beyond the stock rail so no power can come thru the open side of the points. Power routing turnouts had insulated throw bars with the points riveted on them instead of soldered to PC board. You also have to make the point to stock rail clearance wide enough that  the back of the wheels can't contact the open point. These type of turnouts went out of style as DCC became popular as the electrical contact was poor than points wired to their adjacent stock rails. Gapping before the frog is simpler and better performing.....DaveB

"I wonder if anyone building

  The common method is cut the gap with a dremel disc then glue in a small piece of plastic and when it dries trim the plastic to give a smooth wheel passage( takes a few seconds with an exacto knife and a file). I use black plastic and don't bother painting it but any rail weathering will make it disappear....DaveB

I'm coming to this party really late Tommy but

I do understand your original question regarding the necessity to gap the point rail before the frog.  As you suspected the answer is NO.  Let me go on a little...........At this point you will have to feed this segment of track comprised of BOTH point rails and the frog itself with a wire that changes polarity depending upon the position of the turnout.  So far OK.  Where the problem arises is one of the points will be the opposite polarity to the outside stock rail which is only a sixteenth of an inch away.  When your train rolls through there any wheel that accidentally contacts both rails at the same time will cause a short circuit and I will not go into the possible troubles that will follow.  This is why EVERYONE gaps all four rails going into the frog.  Keep thinking outside the box, that's where great ideas come from.

And get an ohmmeter or

And get an ohmmeter or continuity checker so you can buzz it out and see for yourself why it won’t work.  Or alternitively if you try the power routing turnout option, so you can see if you’ve gapped the copper on the pc ties that you need to.  Much quicker, easier, and less potentially smokey than hooking it up to your track power and seeing it anything runs on it.

Being an electrician I have

So as I now see it, the best

Yup.  Of course there are

Yup.  Of course there are variations on that theme too...

If your shortest wheelbase loco is long enough to not have more than half of it's pickups between the gaps around the frog, you might be able to get away with leaving the frog unpowered.  But solder a feeder to the frog just in case you decide you need to power it later.

If you weren't otherwise planning on using a switch machine, or your machine of choice doesn't have handy contacts, you can use one of the DCC frog power gizmos like the frog juicer to power the frog.

"If your shortest wheelbase

  I'm leaving the frogs unpowered on my new layout. I'm counting on keep alive capacitors in the engines to prevent any stalling . For unpowered frogs it's best to cut the gaps as close to the frog as possible. For powered frogs the gaps can be anywhere between the frog and the point hinge and any where between the frog and the fouling point on the diverging side( so the turnout to flex track joint in practice).

If one really wants power routing it's not hard to do. Just solder the points to a solid throw bar ,leaving a bit wider clearance so the wheel backs won't touch. The problem is the contact from stock rail to point is the only electrical connection so if it gets dirty the engines will stall.If you use switch motors they can feed the frog /points assembly and solve the stalling. Look for an old brass switch on ebay or a swap meet to see how they did it.My first layouts used Atlas brass switches with power routing as that's all they sold in those days......DaveB

My frogs will be powered and

i don't gap the closure rail

yes, you need to cut any PC ties between the closure and stock rails

yes, you need to make sure the rails are properly gauged and there is adequate space between the closure and main rails so that the wheels don't short between them