Any suggestions on a better way of cutting curved roadbed?

Hi Steve,

How about something like this? http://www.leevalley.com/US/Wo...42936,42938&ap=1  I use this arrangement to cut plywood sub-roadbed ( I use Fastrack).  It works quite well.  The bad news is you're still gonna have to use some type of Jig Saw to do the cuttin'.  Good luck on the new lay out and the new location!!

Chief Bob (Retired)

If you're good with a table saw, you can make spline roadbed -- a series of strips of material laminated to form a thick roadbed. Each spline can be separated by space pieces. Here's a link that gives a good description: http://s145079212.onlinehome.us/rr/howto/splines/

Curves have natural easements when spline roadbed is used, plus creating turnout splines is very easy -- split the spline for the diverging and non-diverging routes, fill the gap and keep going. The spline doesn't have to be solid. You can put a spacer between each spline and top the roadbed with Homasote. It will be quiet, will support the track well, and when creating a grade the transition from level to grade will be smooth (you can't make sharp vertical bends).

Another option is "Ladder" roadbed. This is what I refer to as a spline variant but it has the same positives as spline with a slightly easier (albeit tedious) construction. You can make ladder roadbed using PVC from Lowe's (see Ron Karlsson's video here: https://www.youtube.com/watch?v=NvXzN2vz2OU). It's available in 1.25"x1/4" strips (sides) and in "1x4" (actually 3/4"x3 1/2") which you can chop into 3/4" square stock to make the "rungs". The build is a bit tedious but you get an open, quiet, well supporting road bed. For more information you can go here:  http://familygardentrains.com/.../roadbed/ladder1.htm

Note that they used HDPE, which is sometimes hard to get. PVC works just as well. The article is for G Gauge, but can be done with O gauge (our viaduct on the club layout is done with HDPE ladder roadbed to which we glued bridge girders.)

Good Morning Steve.......I have only used the cookie cutter plywood type of construction. To cut the curved pcs. I would make a large compass out of tempered Masonite wide enough to mount a router with a spiral straight bit, on one end. then make holes for a bolt pivot point at the desired radius. The 4x8 plywood was laid down on the shop floor on top of 4x8 extruded foam(not white bead board) another sheet was laid down at right angles making a T for the pivot point. I made 120" dia. curves. I cut more than I needed but I wanted plenty, so I would not have to do this again. I sold my extra's on this forum. The waste pcs from cutting out curves from a rectangle where used for flat scenery base or mountain forms. The router cuts cleaner and smoother, the curved pcs also make a good jig for bending Gargraves track. Next time my curves will be larger. With plywood laid flat on styrofoam the router cuts right through it, the router bit only sticks out of the plywood a fraction of a inch. also you don't have to worry about the cut off piece falling or binding, you also don't have to layout your curves, I cut my curves out of the long side of the plywood. I make all my plywood cuts laid on top of styrofoam even with the Skill saw. the styrofoam is then used for scenery. A one armed person can make these cuts by himself.

Clem 

I just lay it out and cut it with a jig saw. if the curves are wide enough you can use a circular saw but the blade will be junk when youre done

Matt Makens posted:

I just lay it out and cut it with a jig saw.

Yup.  Right tool for the job.  No sense in overthinking this exercise.

Find a sign company with a large 5X9 bed cnc router table , have them cut the desired radius , get a lot of perfect curves and some of the in between remains can also be utilized , see PDF ,

If it was fun it wouldnt be called work

This is my next project. I have a lot of concentric curves O-90, O-81, O-72, O-63. I plan to make a 48" long compass that I will attach to the mid-point edge of the long side of a 4 x 8 sheet of plywood with a pivot hinge. I may even, attach my jig saw to the compass at the different cutting radii. Out of each sheet, I can get a half circle of all 4 different curves. 

I rounded the corners for my layout using the router and Masonite "compass" method.  Worked great.

I can't vouch for any of this techniques -- but the tips on this webpage seem to be good ones:  http://www.familyhandyman.com/...ves-in-wood/view-all

Steve, I know what you mean about curves being a pain to cut. Here's what I use:

My compass is just a 6' long, heavy gauge, perforated steel strap, most commonly used for hanging garage door tracks and openers. Get it at any home improvement store.  Doubles as a straight edge.

Unfortunately, the holes aren't at one inch intervals, but it's still easy to work with.

The real key is a good saber saw. I've had this Bosch for over 20 years. I couldn't imagine building my layout without it. Good tools make short work of unpleasant projects, and could even turn them pleasant!!!

MrMuffin'sTrains,

   I use a good Porter Cable industrial Saber Saw for Sawing the 3/4 ply, and I use the Rockwell X2 Portable Table Saw for making Custom FasTrack pieces for close outs, both work great.

PCRR/Dave

Blade and stroke speed are as important as the saw.  Someone at Home Depot or your hardware store should aim you to the correct product.  Things like the length, teeth per inch and type of material you're cutting.  Also, if you cut tight curves you might want a blade that's not too wide.  Wider blades are good for straight and wider radius cuts. 

Last winter I cut up an old oil tank in my basement with reciprocating saw.  I searched the internet and found a guy on youtube who cut up a tank with one blade.  I thought it was proof enough so I found a pack of said blades on eBay and they didn't disappoint.  

Buy the best blade for your specific job, you won't regret it.   

Big_Boy_4005 posted:

My compass is just a 6' long, heavy gauge, perforated steel strap, most commonly used for hanging garage door tracks and openers. Get it at any home improvement store.  Doubles as a straight edge.

 

That is a great idea!  I love it...good thinking.....

Thanks Chris! I actually have two of those. One was used to build both of my helixes. I took a block of wood and screwed an eye screw into the end, then mounted the strap to the block. Then I took a piece of metal conduit and mounted from floor to ceiling, making sure it was plumb.

This picture is over 3 years old.

That is a great bit of engineering there Elliot and a brilliant way of making those helix's....or any radius for that matter.    I like the idea of it being re-usable and as you said doubling as a straight edge. 

N&W Class J posted:

That is a great bit of engineering there Elliot and a brilliant way of making those helix's....or any radius for that matter.    I like the idea of it being re-usable and as you said doubling as a straight edge. 

Everyone who's building a layout should have at least one. If you need a curve bigger than 6' radius, just bolt two together, which would get you almost out to 12'. That's 0-288.

MicroMark Rotape Item Number 82624 and Pencil Lead Item Number 82626, minimum radius 3.5 inches, maximum radius 72 inches, lead is number HB drafting lead, this lead is soft and marks radii with distinctive black lines, chisel sharpen lead to wedge one side at approximate 60 degree angle, cut out curved panel with jig or scroll saw. This method worked quite well using 1/2 inch plywood sheet 4 ft by 8 ft., save sheet drops for deck sheet irregular areas, good luck on new layout, framework was L girder.

If you have access to a CNC router table that for sure is the best method.

Other wise use a trammel to lay out your fixed curved:  

Cut just out side the line with a Bosch jig saw then mounting the router on a trammel run the router directly on the line.  I use a 3/4" bit to just clean up the edge.,  If you use the router w/o the Bosch   jig sawto do the whole job the bit has a shorter life.

For the cosmetic curves somewhat the same

Blocks with lattice strips for cosmetic curves.  I use the lattice to project the lines, then cut just out side the lines,  then use the lattice to guide the router.............

Easiest?  Get someone else to do it for you and watch them work.

mwb posted:

Easiest?  Get someone else to do it for you and watch them work.

  Too funny.

Steve:

Fast and dirty - I agree with previous posts a jig saw with a fine tooth blade. You will have tear out though but it is easily hidden by turning that face down.

Cabinet makers method - a circle cutting jig and a band saw with the proper blade. You will get almost perfect curves and all will be exactly the same. Cut the outside arcs first, reposition the jig and cut the inside arcs. Depending on the blade you may still get some tear out. 

Joe

Don't forget the special blades for cutting circles with a circular saw.  You can use standard blades for wide radius curves.

I have cut circles with a table saw too.

To save the face of any panel you are cutting  from the face side, simply use a laminate blade. 

It cuts on the down stroke.  You need to firmly hold down the Bosch jig saw but there is no need to turn the material over for bottom cutting.

If you sneak a laminate blade into  some one else's jig saw, have a video camera running.