Georgetown Branch - 2010: CNC on the GTB

Monday, September 12, 2011

CNC on the GTB

I know it has been a while since I have updated or even worked on the railroad but I have a good excuse!

Over the summer I converted one of my old mill/drills to CNC and I have really been having a blast making parts and learning the software for programing and control of the machine. If you are interested I have posted a few video's on YouTube. Like this one

So tonight I started drawing up the Dalecarlia tunnel entrance in the cad and cam software. I have generated a simulation of the tunnel opening (pictured below) and it says over 2 hours to mill.

I have no idea how this will turn out . I still need to tweak a few things in the software before I give it a test cut but if it works out Ben will get on for his railroad also!

The bricks/mortor joints will have to be cut with an engraving tool. I am not sure how I can engrave the motor joints in the recessed area's without the body of the tool hitting the sides. I am also not sure how to approch the letters. I could engrave the area and then place the letters on top of skip the engraving and carve the leters into the portal as shown.

The engraving bit it a 1/4" V shape and it will only be cutting .001 or .0015 inches deep.

I will report back soon with the results.

2 comments:

SlugSep 13, 2011 06:40 AM
WOAH!!! THAT LOOKS AWESOME. This is definitely one of the stumbling blocks for that area of the RR; the custom portal. VERY nice work. I can't wait to see how this turns out! :)
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SlugSep 13, 2011 06:49 AM
Here are some photos for reference (remember to click the little enlarge button above each photo for a hi-res version, if available):

http://gallery.sluggyjunx.com/main.php?g2_itemId=63007
http://gallery.sluggyjunx.com/main.php?g2_itemId=63010
http://gallery.sluggyjunx.com/main.php?g2_itemId=65975
http://gallery.sluggyjunx.com/main.php?g2_itemId=65978
http://gallery.sluggyjunx.com/main.php?g2_itemId=62566 (four of them here)
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About the Georgetown Branch

Located on the Metropolitan Subdivision of the Baltimore & Ohio Railroad the Georgetown Branch line was started 1892. By 1910 the line was completed to Georgetown with regular service starting in July of that year.

The Georgetown Branch parts from the Baltimore & Ohio main line in Silver Spring, Maryland. The branch runs 13 miles to Georgetown located in Washington D.C.

The branch served as a minor freight spur carrying coal, building materials, flour and other goods to local outlets in Silver Spring, Chevy Chase, Bethesda and Georgetown.

The ruling grade was 1.51 percent for a short distance near the Dalcarlia Tunnel. The tunnel passed under the Great Falls conduit that carries water from Great Falls on the upper Potomac River to the water treatment plants just inside the Washington D.C. line.

The branch was home to several unique features such as the Rock Creek Trestle that was 1400 feet long when it was first built in 1892. A site dedicated to the restoration of the Rock Creek Trestle can be found here Rock Creek Trestle Restoration.

The line also passed under a large office building creating a second tunnel on the branch. The Air Rights Building was built in the early 60's.

The branch was in operation until 1985. It has since been been converted to a hiking and biking trail. A complete history of the branch and trail can be found at the Capitol Crescent Trail Web Site.

Ben Sullivan has done extensive research on the branch and has some great information and pictures on his site. Ben is also building a model railroad based on the Georgetown Branch and we have been sharing our information along the way.

Operating the Branch

The B&O had two crews working the branch most week days in the 40's and 50's. One crew worked the Georgetown Branch local out of Eckington Yard in Washington D.C. Another crew worked the the switcher engine that was house at Georgetown Yard.

Prior to 1963 the local train working out of Eckington Yard would push it's train caboose first up the EAST bound track of the double main line until it reached Georgetown Junction in Silver Spring. It would switch the junction tracks and a few other industries there and then continue pushing its train down the branch working each industry along the way until it reached Georgetown.

Once in Georgetown it simply dropped any in-bound cars pick up the out-bound cars and headed back to Eckington Yard, engine first. Trailing point sidings on the branch where switched on the fly!

A switcher engine based in Georgetown would work all the sidings in Georgetown.

Switching cars on the fly poses a problem on a model railroad. It is almost impossible to recreate the rolling characteristics of a real rail car in HO scale and un-coupling on the fly is just as hard to model.

With that in mind I have decided to operate the model railroad with 2 daily runs to Georgetown. Local train #1 will operate as the prototype did pushing its cars toward Georgetown. Local #2 will pull its cars toward Georgetown and switch the trailing point sidings at the Water Treatment Plant and Army Map sidings. Train #2 will then push its cars back toward Ekington yard (staging).

Local trains will consist of 1 locomotive and a maximum of 8 cars and 1 caboose.

Operations on the model will be conducted using the Protrak operations software.

Georgetown Branch - 2010

Monday, September 12, 2011

CNC on the GTB

2 comments:

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