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PostPosted: Sun May 09, 2004 6:51 pm 
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Cutting Those Pesky Gaps!

By Tim Warris (This newsletter was originally published on February 1, 2004)

Every hand built turnout needs isolation gaps to electrically isolate the frog from the rest of the turnout. Without them there would be a dead short in the turnout.

Commercial ready-to-run turnouts provide isolation by using an all-plastic frog, or by using the switch points to route power to the frog. This not only leaves a very unsightly gap in the switch points, but also relies on the points to route power to the closure rails and the frog, which can be a constant source of trouble.

Hand constructed turnouts or crossings on the other hand need to have the isolation gaps manually cut into the rail. There are a couple of ways to do this.


Why I Hate Dentists

The simplest and most common method of cutting isolation gaps is to use a cut-off disk with a Dremel Moto-Tool.

Image

Image


There are two types of cut-off disks that you can use. The first is a ceramic disk; a very thin cutting wheel that will cut a clean, discrete gap. The downside to using this type of wheel is that they are VERY fragile and will break very easily. Twist the wheel even slightly while cutting the gap and BOOM! It will explode! So safety glasses and great care are essential.

Personally I prefer to use ceramic wheels, as I like the thin gap and the smaller diameter of the wheels are less likely to nick the stock rails. Fortunately they are sold in packages of 25, so blowing up a few wheels is not hugely expensive!

The second cutting wheel option is a fiberglass reinforced cut- off disk. These wheels are very durable and long lasting, and short of taking a hammer to them, very resistant to breaking.

The downside to fiberglass wheels is that they are a bit thicker than the ceramic disks and are usually only available in larger diameters.

Fiberglass wheels do work well for larger scales (HO and up), but in scales where there isn't much space between the rails, like N or narrow gauges, cutting gaps on a finished turnout can pose a bit of a challenge. Dual gauge turnouts are even more of a problem as the rails are very close together, which can prevent your from using a cut-off wheel at all. I have several times "nicked" the guardrails while trying to cut the gaps for the frog with fiberglass wheels.


Why I Like Jewelers

So for these types of turnouts there is a third method - the Jewelers Saw.
Image

We offer these on our site here.

This nifty little tool is very handy for all aspects of model work, but are particularly useful for cutting isolation gaps. By opening one end of the saw the blade can be passed through the ties to cut the rails at the frog, even in the tightest of spots!

The completed trackwork is mounted into a vise, clamping onto the ties sticking out on the side of the rail. After threading the blade through the ties, start cutting with a long even stroke until the blade bites into the rail a bit, and then short back and forth strokes. Rail being very soft will cut quickly and cleanly. You might break the odd blade, this is not unusual as they are very small and fragile, after cutting a few gaps you will get a feel for how much pressure to apply.

Image

This is one of the handiest methods I have found yet to cut the gaps in tight spots. Of course this will only work with a "bench built" turnout, like the turnouts and crossings produced in a Fast Tracks fixture (shameless promotion!)

Once the gap is cut, carefully inspect the gap for any burrs that might be crossing the gap, as these will cause a difficult to find short in the turnout.

A video documenting this process can be found on our main site here.

This requires a high speed connection. If you have a slower connection, a smaller version is available here.

A through collection of videos is available on our site here.

- Tim

----------------------------------------
Have a question or comment about this issue of the Fast Tracks newsletter? Then post a reply! I will be happy to respond to any posts. - Tim


Last edited by Tim Warris on Mon Mar 12, 2007 4:43 pm, edited 1 time in total.

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PostPosted: Sat May 15, 2004 6:02 am 
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Joined: Mon May 10, 2004 4:02 pm
Posts: 52
Probably a lot of us like the disk when cutting gaps, problem is the fibreglas reenforced one is to big and too thick. the smaller disk is thin enough but fragile. but most of us would like something thinner and more robust. Well micro mark has the answer.

Check out the saw blades made out of stainless steel that mount on mandrels that fit dremel or sear units. They are very thin, thinner than the fragile disk we normally use, and very sharp, the diameter is very small too,
Now heres the hitch, the diameter, (you get two sizes) is so small that you'll have to use either the 90 degree angle converter for the dremel or the shaft unit. control is very good, the blade cuts very cleanly.

It may have other uses that I haven't explored yet.

Rob de rebel
Custom track builder

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Rob de Rebel


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PostPosted: Thu Sep 23, 2004 9:42 am 
Hey, go easy on the dentists. Someone has to do the work. Dentists are always "down in the mouth" because people hate them.
Tim Warris wrote:
Cutting Those Pesky Gaps!

By Tim Warris (This newsletter was originally published on February 1, 2004)

Every hand built turnout needs isolation gaps to electrically isolate the frog from the rest of the turnout. Without them there would be a dead short in the turnout.

Commercial ready-to-run turnouts provide isolation by using an all-plastic frog, or by using the switch points to route power to the frog. This not only leaves a very unsightly gap in the switch points, but also relies on the points to route power to the closure rails and the frog, which can be a constant source of trouble.

Hand constructed turnouts or crossings on the other hand need to have the isolation gaps manually cut into the rail. There are a couple of ways to do this.

Why I Hate Dentists

The simplest and most common method of cutting isolation gaps is to use a cut-off disk with a Dremel Moto-Tool. (Photo 1)

There are two types of cut-off disks that you can use. The first is a ceramic disk; a very thin cutting wheel that will cut a clean, discrete gap. The downside to using this type of wheel is that they are VERY fragile and will break very easily. Twist the wheel even slightly while cutting the gap and BOOM! It will explode! So safety glasses and great care are essential.

Personally I prefer to use ceramic wheels, as I like the thin gap and the smaller diameter of the wheels are less likely to nick the stock rails. Fortunately they are sold in packages of 25, so blowing up a few wheels is not hugely expensive! A good description of ceramic wheels and places where you can buy them can be found here.

The second cutting wheel option is a fibreglass reinforced cut- off disk. These wheels are very durable and long lasting, and short of taking a hammer to them, very resistant to breaking.

The downside to fibreglass wheels is that they are a bit thicker than the ceramic disks and are usually only available in larger diameters.

Fibreglass wheels do work well for larger scales (HO and up - Photo 2), but in scales where there isn't much space between the rails, like N or narrow gauges, cutting gaps on a finished turnout can pose a bit of a challenge. Dual gauge turnouts are even more of a problem as the rails are very close together, which can prevent your from using a cut-off wheel at all. I have several times "nicked" the guardrails while trying to cut the gaps for the frog with fibreglass wheels.

Why I Like Jewellers

So for these types of turnouts there is a third method ? the Jewellers Saw. (Photo 3) There are a number of places you can purchase Jewellers Saws and blades on the web. Here is one.

This nifty little tool is very handy for all aspects of model work, but are particularly useful for cutting isolation gaps. By opening one end of the saw the blade can be passed through the ties to cut the rails at the frog, even in the tightest of spots!

After threading the blade through the ties, start cutting with a long even stroke until the blade bites into the rail a bit, and then short back and forth strokes. Rail being very soft will cut quickly and cleanly. (Photo 4)

This is one of the handiest methods I have found yet to cut the gaps in tight spots. Of course this will only work with a "bench built" turnout, like the turnouts and crossings produced in a Fast Tracks fixture (shameless promotion!)

Isolation Insulation

To keep the gaps from closing up due to expansion of the rails or the bench work shifting (which can happen!), you may want to fill in the gaps with small pieces of styrene.

The gap cut with my jewellers saw is about .01" thick, which just so happens to be one of the thicknesses that styrene is available in. I hold the styrene in place with a small drop of CA adhesive (crazy glue or Zap!) applied with a toothpick.

Once the glue has cured I shape the styrene to match the rail and after the rails have been painted the gaps will be virtually invisible.

- Tim

----------------------------------------
Automatically receive each new issue of the Fast Tracks newsletter in your email inbox as soon as it is released.

<a href="http://www.handlaidtrack.com/bulletin-subscribe.php">Click Here</a> to subscribe now.

Have a question or comment about this issue of the Fast Tracks newsletter? Then post a reply! I will be happy to respond to any posts. - Tim
:wink:


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 Post subject:
PostPosted: Fri Sep 24, 2004 11:06 pm 
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Joined: Fri May 07, 2004 11:22 pm
Posts: 311
Location: Port Dover, Ontario
Quote:
Hey, go easy on the dentists. Someone has to do the work. Dentists are always "down in the mouth" because people hate them. Tim Warris wrote:


Well of course we ment to say "we hate visiting dentists..."

Naturally we have a deep respect for dentists and all their "cool" tools and skills.

Tim

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Cheers!

Tim Warris
Fast Tracks
http://www.fast-tracks.net
service@fast-tracks.net


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 Post subject:
PostPosted: Wed Sep 29, 2004 5:25 am 
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Joined: Wed Sep 29, 2004 1:44 am
Posts: 4
Location: Melbourne, Australia
Thanks Tim,

Best thing I ever did was to buy a jewller's saw after reading this newsletter.

Graham :D

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Graham S
Modeling the MN&S and SOO LINE in the 1970's

http://soors27.fast-tracks.net/index.php


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PostPosted: Thu Jan 06, 2005 2:42 pm 
Anyone bothering to handlay thier own, more than likely is going to power the frog too.

I myself don't bother with cutting gaps past the frog. why bother. the section of turnout is very short, another 1/2 to 3/4 of an inch isn't going to do anything to stall the train if the frog is powered-- it will also get power. Another thing is the short exit rails are not past the clearance point, so locomotives shouldn't be stopping their anyway. Of course theres the occasional bloopers, but I've seen them run into the frog area too.
The lack of gaps past the frog, increases the overall strength of the turnout by not having the rails gapped. it looks better, runs smoother. and saves a few steps because now you don't have to solder two short feeders (4 solder joints) to connect what would have been two dead short sections of rail.

The exit rails of course should be isolated from the connecting track, and plastic railjoiners fit the bill (Micro engineering makes excellent ones as does Atlas) I put four on the exit rails, to isolate the turnout, The power feed to the point area stock rails takes care of the stock rails, and the frog switching circuit takes care of the frog and exit rails. If theres a short, its confined to the turnout most of the time.
On very long turnouts, or curved turnouts where the clearance point is questionable, I do gap beyond the points, but I do way past the frog and use insulated rail joiners to keep the rails aligned.

Rob

Your thoughts on this? anyone!


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 Post subject: rail gaps
PostPosted: Thu Jan 06, 2005 3:01 pm 
Just for general info this came up when I started using Atlas's code 55 turnouts, (which I already had prior to obtaining my jigs)
It seems the Atlas turnouts ocassionally had a contact problem on the exit rails that developed after I layed the turnout down. So to make the fix quicker and easier, I soldered the two inner exit rails to the frog with a wire bridge. I removed the connecting track beyond the exit rails, placed the isulated rail joiners on the exit rails, reconnected the track beyond the exit rails, and reballasted the exit rail section. Works just the same, only difference is the frog section is longer, it recieves power along with the frog, so thier wasn't any problem or operational difference.

Now obviously this isn't going to work for you if you don't power the frogs. but then again your missing the increased performance of having the frog powered.

Rob


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 Post subject: Gap cutting
PostPosted: Thu Feb 15, 2007 5:23 pm 
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Posts: 84
Rob's note mentioned the gaps need not be cut past the frog. Is this the side closer to the throwbar?

How does this change affect the wiring process?
Are there any concerns about short circuits/stalling?

I would like information from which I can learn more about the electrical side of a turnout.

Thanks,
-Sambear

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PostPosted: Sun Jun 15, 2008 2:01 am 
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Posts: 3
The link aren't showing up right now so these may be what your talking about. I use Dedeco ultra .009" wheels:
http://www.dedeco.com/cart/products.asp?grouping_id=96

I cut from the bottom so not to nick the surrounding rails.


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PostPosted: Thu Jun 19, 2008 12:03 pm 
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Posts: 52
Hello Sambear,
No these are the second gaps past the point of the frog, the ones on the two exit rails.
If you leave those rails connected to the frog, the frog powers the exit rails of the turnout.

There are three advantages to this:

1. It uncomplicates the wiring. put two insulated rail joiners (I use four) on the exit rails (for signaling reasons) Now the you don't have to run two feeders to the dead rails past the turnout. This area has no clearance for trains. So why have the gaps there?

2. It makes the turnout stronger, why? because now there aren't any breaks (gaps) on the two exit rails.

3. It eliminates having to cut that pesky gap in the turnout just past the frog, (where fast tracks has the two ties) Your gaps would ordinarily go between the two ties, and on the second tie, (towards the ends of the turnout) you have to gap the pc tie otherwise you'll have a short.

If your having trouble following me pull up one of the templates, and look at the turnout. The first gaps are in the two rails just before the rail pinch before the point of the frog. The second gaps are past the frog right inbetween the two pc ties. The pc tie gap is the second of those pc ties going in the direction of the exit of the turnout.

Rob

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PostPosted: Thu Oct 23, 2008 7:58 pm 
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For cutting gaps I have found the diamond Dremel wheel to be much thinner than the regular cutting wheels. The diamond wheels are more expensive at around $15 at Home Depot but for me they are well worth it.

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PostPosted: Sun Feb 06, 2011 12:58 pm 
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Posts: 51
Location: Rotterdam
Proxxon sells (diamond coated) disks (at the bottom of the page) of 0,6 mm thick

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Everybody can shovel, firing is an art

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Firing this train was more fun then hard labor :-) © R. de Water


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