Best Of Scratchbuild Project - Van Iron Woodchip Cars

[Angus Shops]

Tim, how do you consistently cut the tapered cross members? I like your method of using 2 pieces of .040 x .040 on either side of the centre line rather than trying to centre a single piece of .040 x .080.
Geoff

[BCR 570]

Tim, how do you consistently cut the tapered cross members?

For this test section I simply marked the tapered end with a pencil using a .030" piece as a guide, and then chopped them freehand with a #11 blade (#17 not quite long enough).  So they are likely not quite as consistent as you might suppose.

For the actual underframes I will either lay a strip of .030" along the top edge of the cross-members (the edge against the floor) or I might try and make a styrene jig.

I like your method of using 2 pieces of .040 x .040 on either side of the centre line rather than trying to centre a single piece of .040 x .080.
Geoff

Exactly.  I may not have explained clearly why I do this in my post but you have correctly surmised the reason for the method.


Full size test underframe now in progress.


Tim

[jpf94]

.

[x600]

"Patience Grasshopper"

I too look forward to progress, but can't rush creativity. 

I'm sure Tim is busy with non-train related items, like being outside. maybe.

Greg O.

[BCR 570]

I'm sure Tim is busy

Quite so, with all of the year end school activities (graduation, awards, report cards, yearbooks, locker clean-out, etc.), all of which had to be organize differently this year.  Hopefully back to some modelling soon.

Tim

[craigolio1]

Quite so, with all of the year end school activities (graduation, awards, report cards, yearbooks, locker clean-out, etc.), all of which had to be organize differently this year.  Hopefully back to some modelling soon.

Tim

No one wants to hear your whining Tim. Get back to work on those chip cars!  Haha.

[BCR 570]

Underframes (Part 2)
Back to work on this project after a hectic month at work.  My next task was to build a complete test underframe.  This was done to test the interface with the other parts and to test it on the layout for performance.  Specifically, I wanted to ensure that the bolster design resulted in acceptable performance of the trucks.  The same construction methods were applied as on the previous test section, resulting in this:




I mounted a pair of Micro-Trains trucks for testing the underframe on the layout:




I loaded the underframe with weight to simulate a completed car.  Here the underframe is seen traversing through switches at the Chetwynd Yard throat:




The side view shows a comparison with the Micro-Trains coupler gauges, indicating that the bolster construction results in a correct mounting height for Micro-Trains couplers:




The next question to resolve was whether to build these underframes prior to adding the ends and sides, or afterwards.  I had planned to add the sides to the floor while upright, so that I could shim the floors up .040" in relation to the sides.  However, the tapered cross-members make this impossible.

I eventually came up with another way to assemble the cars which would allow for assembling the underframes prior.  It involves adding the ends to the floor first while on their side edges.  When both ends are on I will then be able to add the sides with the car upside down, resulting in a matched height around the top of the car and the desired offset at the bottom.  The .040" thick plank is acting as a shim to ensure that the .040" difference between the bottom of the ends and the floor.  Here is a mock-up of how I will add the ends to the sides:




Now to build six better underframes . . . . .


Tim

[BCR 570]

Underframes (Part 3)
Installation of the underframes begins with marking out the centreline, centre of car and locations of bolsters on the floors.  A scale rule is used to locate a centre mark toward each end of the floor:




A longer scale rule is positioned on these two centre marks, and the centreline is drawn along the length of the floor:




The floors are a scale 58 feet long, so the centre of the car is measured off and marked 29 feet in from one end:




The distance between truck centres on these cars is 46'-3", so the locations for the bolsters are marked off at 23'-1 1/2" from the centre mark:




A thin set square is then used to draw the locations for the centre of car and the bolsters across the floor:




At each end of the car, the end of the centre sill is marked 4'-6" in from the end of the car to clear the couplers:




At the intersection of the centreline and bolsters, a pin is used to create a pre-drill for the bolster pin holes:




A #80 drill bit is used to precisely drill the bolster pin holes:




This is what the floor looks like with everything marked and drilled:




All six floors are now ready for the installation of underframes:




Installation of the centre sills is next.

Tim

[Philip H]

Where did you get that thin square?

[BCR 570]

Hi Philip:

It is one of a series of thin metal precision tools made by Creative Horizons.  They are listed on a number of vendor websites as sold out so perhaps they are no longer available.  I believe I got mine during a show down in the U.S. some years ago; I have had it a long time and I use it constantly.


Tim

[philippe.whyte]

Micro-Mark sells what they call a "thin beam square".  The description says it is for material down to 1/16" thick.  Not sure how that compares to Tim's.

https://www.micromark.com/Thin-Beam-Square

[Jim Costello]

Try Zona Tools, Item 37-434 a 3"x4"  L Square Rule @10.92.  In stock at Walthers.

Jim

[BCR 570]

I may have misunderstood Philip and was referring to the L-shaped N Scale rule.


The thin set square is indeed from Micro-Mark and is also very useful.


Tim

[BCR 570]

Underframes (Part 4)
The first component of the underframes to be installed is the centre sills.  In order to be able to centre these accurately, I begin with two strips of .040" x .040" styrene which will be installed on either side of the centreline:




To locate the first half of the centre sill, I place a steel ruler on the centreline and then place a large steel block on top of the ruler to keep it in place.  The strip is then brushed with glue and set in place against the steel ruler:




After setting the strip in place, additional glue is applied with a small artist's brush to lock it in place:




After it has dried, the underframe is turned around and the second half of the centre sill is set in place on the other side of the centreline:




Again, additional glue is added to lock the strip into place:




The flanges for the centre sill will be made from strips of .020" x .080" styrene:




An aluminum track alignment tool is used to ensure that the flange is perfectly upright, as the cross-members will butt up against it and a nice solid joint is required when we get there.  Here is the first flange going into place, using the same procedure of initial tack down and a second application of glue once in place:




After the first flange has dried in place, the underframe is turned around so the second one can be installed:




Here is a single underframe after completion of the centre sill:




And here are the six underframes after completion of the centre sills:




The next task is to cut, taper and install the cross-members.  With a total of 30 per car, this will take a while . . . . . 

Tim

[BCR 570]

Underframes (Part 5)
This instalment will cover fabrication of the tapered cross-members and installation of the centre pair.  The cross-members are cut to a length of 3'-9" from .020" x .080" styrene strip:




With six cars requiring 30 cross-members each, I needed a way to taper these accurately and quickly.  For the test underframe I measured and marked the shallow end and then cut them freehand with a #11 blade, but the measuring, marking and cutting took time.  I decided to try and fabricate a cutting jig which would eliminate two of the steps.  The jig is made from two pieces of .020" thick styrene which are offset by .040" (the depth of the taper at the shallow end).  A stopping guide is attached to the top of the jig.  It is seen here with the first set of 30 strips to be tapered:




This photo shows the underside of the cutting jig shows the .040" inset and the stopping guide:




The strips are placed into the cutting jig and a #11 blade is placed against the corner of the jig and the corner of the stopping guide.  I then press down to make the cut:




Here is the first strip and its offcut after making the cut:




With the cutting jig, I was able to taper a set of 30 cross-members in ten minutes:




I start installation of cross-members with the centre pair, applying liquid cement and placing the part on my pencil mark at the centre of the car:




I then use the thin square to ensure that the part is perpendicular to the centre sill:




I then make a second application of cement to lock the part down in place:




Here is the first underframe after installation of the centre cross-members:




I elected to do this for all six underframes at this point, and am now moving on to the bolsters.

Tim