Ok I will have enough foam to work this weekend. I will also be buying my homasote tomorrow.
So now I have a couple of questions, I think I have read the answers on here but I can’t find them.
What is the smallest track radius for HO 19 inches?
When I get ready to lay out my turn radius, what is a good way to cut it out and have it the same width all through the curve?
Thanks
Baker
The radius you’re asking about is 18" and it’s not the smallest. The range is 15" 18" 22" 26" 30" and 36" that I know of. I wouldn’t recommend 18" unless you’re pressed for space. The recommended minimum radius is 22". Thsi will allow operation of large locomotives and rolling stock. An 89’ flat car would look like a toy on an 18" radius curve and would probably be derailed because of the tight radius.
On your other question, my answer is this. if you set your curve radius down for 22", find where the centerline of the track will be. Mark that centerline on your foam, then measure how wide your track section is. mark this on your foam with the centerline being the center of the measurement. This may help. I’ll use a + as the centerline and a - as the track edges. - + -. Trace out the radius of your curve on the foam using this method. When you cut this out, leave an edge about 1/16" to 1/8" on either side. This will be your roadbed edge. Hope this helps.
Jeff
Just out of curiostity, why the foam and the homosote? Most people go with one or the other.
See RP-11 (recommended practices) at NMRA’s website for recommended minimum radius for different sizes/types of locomotives and rolling stock. Recommended HO minimum radii range from 5 to 40 inches, and turnout frog angles from 2.5 to 8.
Baker: Are you the former Secretary of State?
Seriously, in addition to the above reccs., after you’ve layed your roadbed over your radius compass marks, I think it’s probably a good idea to lay your track with radius guages (Ribbonrail, ? other brands) to insure smooth radius curvature throughout the whole curve as you mentioned in your last point.
Jim
I am not a 100% sure to be honest with you. I am just following what my good friend told me works best. Here is what he has always told me for my set up.
Here is my set up and then what he told me.
I am building a 6’ x 16’ lay out. It is made up of (12) 2’x4’ tables. They are squared up and lined up to the T, then Clamped together very well. The table tops are made up of 3/8" ply. I have layed down 2" foam clear across the whole thing. I have now cut out my river that runs through it and I am sure I will cut something else into it. Such as ditches and what not once I get a couple of weeks ferther down the line.
Ok so now I have my base. Now it is time for the homosote, and the reason be hind it.
“I am by no means knocking ANY ONES way of doing things by my next statement.”
My friend owns his own trains shop and he has a couple chunks of track hung up in the store. One was a chunk of track that had been glued down and has been pulled up. The owner wanted to change something. So any way the track was trash, you could not flex it at all.
Have seen this, I know that my truck would never hold true just being nailed to the foam or cork. It would sooner or later work its way loose.
So if I lay down the foam then homosote then cork then track, the homosote would hold it all true for longer then I am going to live.
Baker
I am not a 100% sure to be honest with you. I am just following what my good friend told me works best. Here is what he has always told me for my set up.
Here is my set up and then what he told me.
I am building a 6’ x 16’ lay out. It is made up of (12) 2’x4’ tables. They are squared up and lined up to the T, then Clamped together very well. The table tops are made up of 3/8" ply. I have layed down 2" foam clear across the whole thing. I have now cut out my river that runs through it and I am sure I will cut something else into it. Such as ditches and what not once I get a couple of weeks ferther down the line.
Ok so now I have my base. Now it is time for the homosote, and the reason be hind it.
“I am by no means knocking ANY ONES way of doing things by my next statement.”
My friend owns his own trains shop and he has a couple chunks of track hung up in the store. One was a chunk of track that had been glued down and has been pulled up. The owner wanted to change something. So any way the track was trash, you could not flex it at all.
Have seen this, I know that my truck would never hold true just being nailed to the foam or cork. It would sooner or later work its way loose.
So if I lay down the foam then homosote then cork then track, the homosote would hold it all true for longer then I am going to live.
Baker
James,
I will be building a layout before long and so have an interest in this topic. Pray tell, what is “homosote”? Pardon my ignorance. We are a bit behind the latest material technology out here.
The other possibility is that it is something I know by another name.
Here you go!
Homasote is a gray board that is made out of paper. It comes in 4’x8’ sheets and is 1/2" thick. You’ll find it in almost any school being used as bulletin boards. you can push pins into it with ease.
We call it Pinex or Flameguard over here.
I’m using it too cause I always have, real easy to make changes.
Ken.
Thanks James,
Yes I know it now. Just never heard it called that name. Possibly a US brand name.
May be seems that just about every other place calls it something different.
A few words about track radius. I have about 2/3 of the track put down on a medium sized layout and I can tell you that the principle of track radius is one of those immutable laws of nature that govern this hobby. I’ve made the mistake of trying to ‘stretch’ or ‘fudge’ the law and have been disappointed each time.
Currently my layout has a minimum of 22" on the mainlines and 18" on spurs and in yards. The period I’m modeling is the mid 50’s so I don’t have lots of big long cars or locomotives. The exception is the passenger line that runs through my layout, but it’s minimum radius is 24". The passenger trains run on one track ONLY.
One of my biggest disappointments is my wonderfully detailed BLI 4-8-4. The literature says it will run on 22" radius track. WRONG. It needs at least 30" to be safe. Right now the locomotive is making a really nice wall decoration until I can find a way to run it…
aspenexile: I have a BLI 2-8-2 that runs on my 18" curves without problems, but that may not be a fair comparison.
Hey I for got something about the homasote. I would use it in a 3/8" thickness! It will work better the 1/2" when you have a lay out that has to climes in them!
Baker
If the wheelbase is 4 inches you can get it to go around a 6 inch radius. However for a realistic look then try 18 or more. [:D]
And yes I have done it for a mining RR.
Stephen
I am thinking of using homosote on a layout that will be in my garage. Any problems with the homosote absorbing moisture from the air. Don’t have air conditioning in garage (yet) Live in Georgia
Tom
PLW the MRR Myth Busters – #9 - The Myth is:
Homasote expands during the summer and shrinks in the winter
This one is a Bust as it is not the Homasote that is swelling it is the wood underneath.
I have problems with the layout changing in Western PA in the summer and my swinging bridge at the room entrance swells up so much that it is a real tight fit in summer and a loose fit in winter.
Now if the Homasote was the cause of this problem then the bridge (which is made entirely of wood) would work smooth all year around and the Homasote would be rubbing the Homasote on the solid part of the layout.
I had a problem when I first began building my layout and did not have the dehumidifier set up yet and the wood and Homasote sheared the glue off. In other works the wood expanded so much that the glue left loose from the Homasote. Needless to say I got the dehumidifier running!
All of these techniques have been proven on a HO scale home layout with over 15 scale miles of mainline track and has over 2800 feet of track (42 scale miles) total in place, so far. The layout hosts bi-weekly Operations and yearly OPTUD’s (OP Till U Drop) 12 hour sessions and has had up to 40 operators at some of these sessions. The layout runs Digitrax DCC Radio. All of these so called MRR Myths have been Busted as this layout has been in operation for over 5 years and we have proven these over and over again.<<<
BOB H – Clarion, PA
Thanks for the quick response but I think I lost you about halfway down the page. Do I need a dehumidifier
You will want a dehumidifier - or even better in Georgia - air conditioning. Not so much because of the Homasote, but to keep you comfortable and the wood from swelling so much. Wood - especially lumber - swells mostly across the grain when it absorbs moisture from the air. This swelling and contraction (when it dries) can be as much as 3%, which is far more significant change than any of the other commonly used materials - which is what Bob H was trying to say. The ways to prevent this swelling and contraction are:
control the humidity of the space year round, either with humidifiers/dehumidifiers or humidifiers and air conditioning
use more dimensionally stable materials such as L girders, plywood, OSB, foam
paint the lumber on all sides. Shellac is best, spar varnish is very good, any paint slows the rate of moisture absorbtion/drying out by wood.
provide expanison gaps if construction is done during dry (heating or cold) season.
use a combination of the above techniques
Reality is that you’re not going to enjoy your model railroad much in the Georgia summer without air conditioning. Sweating while you model is not fun in my book, and not conducive to good modeling. The more habitable you make your layout space, the more you will use it - don’t ask me how I know.
Fred W