Distance between HO turnout points?

Distance between HO turnout points?

Post by Mr. Bl » Fri, 19 Jan 1996 04:00:00



What should the distance between HO turnout points be?
I'm using sheet brass soldered between the rails and want to
know how long I should make the strip.

How does one use the "points" section on the NMRA gague?
What should I be measuring with it, exactly?

 
 
 

Distance between HO turnout points?

Post by ernfi.. » Tue, 23 Jan 1996 04:00:00



Quote:

>What should the distance between HO turnout points be?
>I'm using sheet brass soldered between the rails and want to
>know how long I should make the strip.

>How does one use the "points" section on the NMRA gague?
>What should I be measuring with it, exactly?

When the points are against one rail the distance between the other point and
other rail must be at least equal to a flange way.  If you make it any wider you
will probably require excessive point throw.

ernie fisch

 
 
 

Distance between HO turnout points?

Post by Charles A Dav » Tue, 23 Jan 1996 04:00:00


Quote:


> Date: 22 Jan 1996 05:04:36 GMT

snip
> >I'm using sheet brass soldered between the rails and want to
> >know how long I should make the strip.
snip
> When the points are against one rail the distance between the other point and
> other rail must be at least equal to a flange way.

AS A MAXIMUM DISTANCE --- Even then you may have problems. Consider,if
you use the 'flangeway' distance, then any correctly gauged wheel set can
rub the back of the point that it is passing, IF it is a metal wheel, and
you are using a piece of brass soldered between the points, and the other
point is snugged up to the other rail, you have what is commonly
referred to as a SHORT CIRCUIT. That is why commercial turnouts that
have electricly bonded points, use a much WIDER than 'flangeway' spacing.
If you desire to use the 'flangeway' distance as your controlling figure
(It WILL look better), you then need to go to the trouble to solder an
'ear'/'tab' to the bottom of each point, through which you can run a
screw/rivet into an insulated throw bar.
Failing to go this route, means that you need to use a brass piece
SHORTER than what would give you a 'flangeway' width gap.

Quote:
> If you make it any wider you
> will probably require excessive point throw.

> ernie fisch

Most switch machines are capable of throws of 1 1/2 to 2 'flangeways'.

Chuck D.

 
 
 

Distance between HO turnout points?

Post by john purbri » Tue, 23 Jan 1996 04:00:00


Quote:


>>What should the distance between HO turnout points be?
>>I'm using sheet brass soldered between the rails and want to
>>know how long I should make the strip.

>>How does one use the "points" section on the NMRA gague?
>>What should I be measuring with it, exactly?

>When the points are against one rail the distance between the other point and
>other rail must be at least equal to a flange way.  If you make it any wider you
>will probably require excessive point throw.
>ernie fisch

I don't think this is true. If you use the bare minimum separation along
with points electrically connected together, as Mr Blue suggested, you risk
getting a wheel flange bridging between the point and the stock rail as it
passes through the gap. Since the point is connected to the other point
and that is in contact with the other stock rail, you'll get a short. But
the switch will look better with the smaller gap and as Ernie said, the
points don't have to move as far. Many people who make their own switches
figure out other ways to move the points (without using a throw bar) or
make the throw bar out of an insulator such as PC board material. If this is
done, you can have each point permanently connected electrically to the
adjacent stock rail.

John Purbrick

 
 
 

Distance between HO turnout points?

Post by Andy Sperande » Fri, 26 Jan 1996 04:00:00


Hello Mr. Blue,

The instruction sheet that comes with the Mark IV NMRA gauge -- the
first to have the "points" prongs -- shows how to use it to check point
spread and gauge from one point to the opposite stock rail.  You
probably don't have that or you wouldn't be asking, but check inside the
envelope the gauge came in just in case.  Otherwise you can ask the NMRA
for a replacement.

However, the NMRA deliberately makes the spread rather wide (points
closer together than in the prototype) to prevent short circuits from a
wheel touching a point of opposite polarity.  If you're building your
own turnouts, you can easily insulate the points from each other and
hard-wire them to the nearest stock rail.  Then there's no danger of a
short and you can have the open point rest closer to the stock rail for
a more realistic appearance and a shorter, easier point throw.  See Tony
Koester's article on handlaying turnouts in the December 1989 MODEL
RAILROADER, and page 23 of my book, "Easy Model Railroad Wiring"
(Kalmbach).

Good luck,

Andy Sperandeo
MODEL RAILROADER

 
 
 

Distance between HO turnout points?

Post by Mark Johns » Fri, 26 Jan 1996 04:00:00


Let me echo Chuck's comment - with a conductive throwbar connecting the
points, they must move far enough away from the stock rail to avoid
short circuits with the backs of metal wheels.

I use HO Shinohara code 83 and code 70 turnouts, which have a metal
throwbar.  The gap between the point and the stock rail is the most
unrealistic part of the turnout, but I still get shorts on 3-axle
trucks and long-wheelbase steam engines.  I've taken to coating the
backs of the offending wheels with nail polish.

--
Mark Johnson                       http://www.arc.ab.ca/~johnson/
Alberta Research Council           http://www.arc.ab.ca

 
 
 

Distance between HO turnout points?

Post by RickSter » Tue, 30 Jan 1996 04:00:00


I'd suggest making the points electrically the same as the stock rails.  I
do it as follows:
1:  Make a hinged point.  Drill a hole in the benchwork and insert a brass
tube.  Then insert brass rod and solder the heel of the point to the top
of the rod.  You can connect the point to the stock rail electrically by
soldering a wire to the tube where it sticks through the benchwork.
2.  Use PCboard for the tie rod.  Cut the foil cladding to prevent short
circuits.  Drill a #76 hole through the point and into the tie rod.
Insert a short length of wire and solder to the point rail (be careful not
to solder to the pcboard tie rod).  

This whole arrangement is very flexible and mechanically sound.  If you're
really ambitious you can use the brass rod to throw the switch from the
heel.  This makes for a totally invisible throw mechanism.

Best Wishes
Rick Stern

 
 
 

Distance between HO turnout points?

Post by Andy Sperande » Tue, 30 Jan 1996 04:00:00


This thread has drifted away from the original question, which concerned
hadlaid turnouts.  While the NMRA's Mark IV standards gauge has
point-spacing prongs which can help to avoid shorts through the wheels
between stock rails and points, this results in a noticeably
wider-than-scale space between the open point and the stock rail.  For
this reason many who build their own turnouts prefer to insulate the
points from each other (and the frog) and hard-wire them to the adjacent
stock rail, so the open points can lie realistically close to the stock
rail.  This does make for much nicer looking trackwork, in my opinion.  
As a side benefit, close spacing reduces the distance the points have to
move, easing the load on switch motors or other operating mechanisms.

Andy Sperandeo
MODEL RAILROADER Magazine  

 
 
 

Distance between HO turnout points?

Post by Don Mitche » Tue, 30 Jan 1996 04:00:00



Quote:

>This thread has drifted away from the original question, which concerned
>hadlaid turnouts.  While the NMRA's Mark IV standards gauge has
>point-spacing prongs which can help to avoid shorts through the wheels
>between stock rails and points, this results in a noticeably
>wider-than-scale space between the open point and the stock rail.  For
>this reason many who build their own turnouts prefer to insulate the
>points from each other (and the frog) and hard-wire them to the adjacent
>stock rail, so the open points can lie realistically close to the stock
>rail.  This does make for much nicer looking trackwork, in my opinion.  
>As a side benefit, close spacing reduces the distance the points have to
>move, easing the load on switch motors or other operating mechanisms.

>Andy Sperandeo
>MODEL RAILROADER Magazine  

Andy's right about appearance, and his described method is what is used on
the Tehachapi Pass layout of the La Mesa club.  When using this method, though,
make sure you are adhering to back-to-back wheel spacing standards appropriate
to the point to stock rail spacing you've chosen.  Otherwise, you can
get derailments from mechanical interference.


 
 
 

Distance between HO turnout points?

Post by Andy Mill » Tue, 30 Jan 1996 04:00:00



Quote:

> I'd suggest making the points electrically the same as the stock rails.  I
> do it as follows:
> 1:  Make a hinged point.  Drill a hole in the benchwork and insert a brass
> tube.  Then insert brass rod and solder the heel of the point to the top
> of the rod.  You can connect the point to the stock rail electrically by
> soldering a wire to the tube where it sticks through the benchwork.
> 2.  Use PCboard for the tie rod.  Cut the foil cladding to prevent short
> circuits.  Drill a #76 hole through the point and into the tie rod.
> Insert a short length of wire and solder to the point rail (be careful not
> to solder to the pcboard tie rod).  

> This whole arrangement is very flexible and mechanically sound.  If you're
> really ambitious you can use the brass rod to throw the switch from the
> heel.  This makes for a totally invisible throw mechanism.

> Best Wishes
> Rick Stern

We have been building switches this way at the the Tech Model RR Club of
MIT for a long time.   They work very well and as Rick says, the throw
mechanism remains invisible.  We don't even use a tie rod between the
points.  We throw the 2 points in unison by connecting the wires from the
heel rods together with a plexiglass block, and connecting the plexiglass
block to the switch thowing mecanism.  This leaves us with no visible tie
rods at the "toe" of the points.  But this is visually better than the
usual oversize tie rod, be it PC board or brass.

--
Regards,

 
 
 

Distance between HO turnout points?

Post by Terry Fly » Wed, 31 Jan 1996 04:00:00


Quote:


>>What should the distance between HO turnout points be?
>>I'm using sheet brass soldered between the rails and want to
>>know how long I should make the strip.

You are better of using a PCB strip the length of your sleepers (ties)
and solder directl to the top.

Quote:
>>How does one use the "points" section on the NMRA gague?
>>What should I be measuring with it, exactly?

>When the points are against one rail the distance between the other point and
>other rail must be at least equal to a flange way.  If you make it any wider you
>will probably require excessive point throw.
>ernie fisch

Earnie,
            your statement is untrue.  The  distance between the point
and rail must be larger than the largest check rail gap . Both these
deminsions can be determined by adding the minium back to back
dimension and minium flange thickness of the wheel and subtracting the
result from the maxium track gauge . In relality you  should make it
larger as wheels do not necessilary approach  the points square on. I
make the gap about 0.5mm wider than my maxium flangeway gap.  My
maxium flangeway gap is 1.3mm. You will need to increase this
dimension if you do not make the polarity of the point blade the same
as the rail next to it.

Terry Flynn.

 
 
 

Distance between HO turnout points?

Post by john purbri » Thu, 01 Feb 1996 04:00:00



Quote:



>> I'd suggest making the points electrically the same as the stock rails.  I
>> do it as follows:
>> 1:  Make a hinged point.  Drill a hole in the benchwork and insert a brass
>> tube.  Then insert brass rod and solder the heel of the point to the top
>> of the rod.  You can connect the point to the stock rail electrically by
>> soldering a wire to the tube where it sticks through the benchwork.
>> 2.  Use PCboard for the tie rod.  Cut the foil cladding to prevent short
>> circuits.  Drill a #76 hole through the point and into the tie rod.
>> Insert a short length of wire and solder to the point rail (be careful not
>> to solder to the pcboard tie rod).  

>> This whole arrangement is very flexible and mechanically sound.  If you're
>> really ambitious you can use the brass rod to throw the switch from the
>> heel.  This makes for a totally invisible throw mechanism.

>> Best Wishes
>> Rick Stern

>We have been building switches this way at the the Tech Model RR Club of
>MIT for a long time.   They work very well and as Rick says, the throw
>mechanism remains invisible.  We don't even use a tie rod between the
>points.  We throw the 2 points in unison by connecting the wires from the
>heel rods together with a plexiglass block, and connecting the plexiglass
>block to the switch thowing mecanism.  This leaves us with no visible tie
>rods at the "toe" of the points.  But this is visually better than the
>usual oversize tie rod, be it PC board or brass.
>--
>Regards,


One note along the lines of "don't try this at home": you have to use
silver solder if you throw the points via the vertical rods. A ***joint
with the area of the cross-section of the rod will be too weak to survive.

An alternative approach which we use at MIT (Andy, you're a bit out of date)
is to saw a slot into the heel end of the point, then bend over the end of
the vertical rod, hammer it flat and solder it into the slot using regular
solder. This works fine and has the huge advantage over silver solder that
you can heat it up and re-align the points right on the spot. Because silver
solder needs a propane torch, that method requires the removal of the points
every time an adjustment is needed, unless you wish to make the acquaintance
of the local fire department.

John Purbrick

 
 
 

Distance between HO turnout points?

Post by ernfi.. » Sun, 04 Feb 1996 04:00:00



Quote:


>block to the switch thowing mecanism.  This leaves us with no visible tie
>rods at the "toe" of the points.  But this is visually better than the
>usual oversize tie rod, be it PC board or brass.

Yes, but the prototype has a visible tie rod.

ernie fisch