Best Of Scratchbuild Project - CC&F Twin Trailer Flat Car

[DKS]

Funny, I was just about to bump this thread. Good to see it back.

[sirenwerks]

Bump?  How's this project going?  I was on the edge of my seat when you solved the weight issue.

[BCR 570]

Resurrection
While searching my stock of decals for a project which I could see through to completion, I came across a set for the PGE 7100 series trailer flat cars and was reminded of this project I had started years ago.  It fell by the wayside as layout construction ramped up, but someone (  ) had the presence of mind to store all of the parts carefully in plastic bags and label them accordingly.  I located the project components and decided to see if I could get back to work on these cars.  While some warpage of parts has occurred during the interim, everything is accounted for including my detailed build notes.  I am not sure if I will still get a decent car or two out of this project, but the build experience will still be educational.

I recalled that I had started a build thread on them and was able to locate it; however the posts preceded the great Photobucket f*ck-up and the pictures were no longer there.  Fortunately someone (  ) had the presence of mind to save all of the build photos in a separate file folder so it was not much work to upload and reinstate the photographs.

So, nine years later (  ), here is what I got done tonight:


Assembly
Up until now each car has been built in two halves comprising centre sills, bolsters, cross-members, stiffeners, and runway plates.  It is now time to join the two halves together to form a single carbody.  Two bolster beam centre blocks and a series of tungsten weights will go between the two centre sills to act as spacers and to provide the much needed weight.  The styrene blocks and tungsten weights will be added to the first half of the car, and the second half will then be added to the assembly.

Prior to assembly, the tungsten weights wee laminated with .005" sheet styrene on one side as they came out a little thinner than specified.  The weights were coated with CA on one side and then laid down on the sheet styrene:




After the CA had dried, the excess styrene was cut away and the styrene attached to the weights was filed and sanded to match the outline of the weights:




This photograph shows the styrene bolster centre blocks and the tungsten weights ready for installation:




The addition of the styrene layer actually proved helpful as it allowed me to install the weights into the first half of the car with styrene cement instead of CA:




When the styrene cement had dried, CA was applied to the tungsten weights, styrene cement to the bolster blocks, and the second half of the car was added.  After checking the alignment, the assembly was placed between angle blocks to keep the two halves together during the curing process:




For the first time, the two cars are now a single assembly.  This photograph shows the top and bottom of the cars after joining the two halves:




On the prototype cars, the space between the twin centre sills was hollow and they were held together by a series of straps welded across the top and bottom flanges of the centre sills.  The next step will be to cut these from strip styrene and add them to the models.


I am not sure how long this new flurry of work will last (no promises), but I am motivated by the need for additional trailer flatcars on my layout, and with capacity for two trailers each, these are essentially two for the price of one.


Tim

[craigolio1]

Tim I’m super excited that you are working on these again.

 I will encourage you with threats. If you stop working on these I will text every night, when I am going to bed, to remind you to work on them. And I’m three hours ahead of you. Do you want me texting you at three in the morning? Haha.

All jokes aside, this is an awesome project and I hope you can find the energy to complete it. You are so close.

Craig.

[randgust]

So DKS was concerned about the solvent cement warping the styrene.   I've certainly found that to be a problem - and CA doesn't do it.   Because CA has such horrible shear strength, I'm still conflicted - but on long laminations I've gone over to CA.

Most recently - on that EMD SW9 shop job project, I used solvent to join up all the .040 x .040 'frames' for the open doors on the hood, and wow, they really wanted to warp.    Back in the day I stripped the decks off of Trix container flats and made them into Piggybacks using scratchbuilt styrene decks as none were available, and while they looked great they warped like crazy.

So this has had plenty of time to either prove or disprove some of the warp issues.....what do you see?

[peteski]

I have laminated 2 strips of Evergreen sheet styrene.  0.020" as I recall. One was white, the other black styrene. Used Testors liquid cements (basically MEK).  I needed short pieces of it for the projects - they seem to look fine.  But I had about 4" strip leftover, and after some time (several weeks weeks) it developed pretty severe bow.  I don't like solvent cement.  Not only bowing, but I have seen it soften and develop slight depressions at the glue seam (of items such a s halves of a cylindrical shape) after weeks or months. If I can, I avoid liquid cement, and I use CA.

[BCR 570]

So this has had plenty of time to either prove or disprove some of the warp issues.....what do you see?

Hi Randy:

I would say that the parts have held up petty well in storage for nine years.  i am seeing some distortion where the runways go over the diaphragm plates.  For all I know this could be due to a slight discrepancy in height between the diaphragm plates and the cross-members - this has been entirely hand-assembled. 

My scratch-building experience tells me that one has to be careful with repeated applications of liquid cement to an assembly as there is a chemical or heat build-up which magnifies with successive applications.  I apply hte liquid cement with a fine paint brush to control the amount used and get it exactly where it is needed.

CA is not practical for large joints due to the limited working time.

I recall from seeing the prototype twin trailer flatcars that there was lots of bumps and curves on them as they aged, so perhaps a less than perfect model won't be too out of place . . .


Tim

[BCR 570]

Assembly (cont.)
A little more progress.  After joining the two halves of the cars together with the bolster blocks and tungsten weights, the joints will be reinforced with straps across the twin centre sills on top and bottom.  (I am not sure of the correct structural term for these parts, so I am referring to them as straps for now.)  From reference photographs I am seeing thicker straps across the centre sills above and below the three diaphragms, and thinner straps across the centre sills below the cross-members.

This photograph of BCOL 7100 shows the thicker straps above the diaphragms:




In this second view of BCOL 7100, the thinner straps underneath can just be made out below the centre sills:

 


For the thicker straps above and below the diaphragms, I used .010" x .040" strip styrene.  This was cut to lengths which would fit across the centre sills between the runways:




We also have the bolster crown plates going across the centre sills above the bolsters.  They are rectangular with the four corners lopped off at 45 degrees.  I had manufactured these earlier so they were all ready to go.  Here are the cars with the bolster crown plates and transverse top straps ready for installation:




This photograph shows the cars with bolster crown plates and top straps installed:




The thinner bottom straps were cut from .010" x .020" strip styrene.  There are twelve per car:




Here we see the underside of the cars with the bottom straps installed:




The addition of these parts has greatly reinforced the joints between the two halves and the cars definitely have a more solid feel to them now.  The next step will likely be to install the centre bearing plates on the bolsters and start drilling the holes for the bolster hubs.


More when I can,

Tim

[mmagliaro]

Tim,
Excellent modeling, engineering, design, and PATIENCE!  Once again, I am impressed by your work.

Nice how those small straps make the car more solid.  You are building it with strength coming
from the same places that it does on the real car.

Do you know how much those custom-machined tungsten weights weigh?  I'm curious.
And are they really pure (well, 99%) tungsten, or are they one of the more machinable-friendly alloys that are
more like 90% tungsten?

-- Max

[BCR 570]

Thank you Max; yes I was amazed at how much structural integrity those tiny pieces actually contributed.

The cars currently tip the scale at 0.70 oz or 20 grams.  of course most of that will be the weights.  And yes, they are 99.99% tungsten (not an alloy).  The advantage is the mass and weight; the disadvantage is the challenge of machining it.  When ordering I have to be very precise with the measurements as there are no adjustments with the tools commonly available to modellers like me.


Tim

[wazzou]

Two comments, well one question, one comment.  How did you take the photo with both of your hands in it?

Get a NWSL Chopper.   

[BCR 570]

Two comments, well one question, one comment.  How did you take the photo with both of your hands in it?

I used a remote switch and the 10 second timer function on my DSLR.  Press the button, get hands into position, wait 10 seconds, CLICK.

Get a NWSL Chopper.

Got one.  I find it better to chop the smallest styrene parts by hand.


Tim

[BCR 570]

Bolster Hubs
This next instalment was both challenging and critical.  Challenging because I needed to drill a 1/8" diameter hole through a delicate styrene assembly, and critical because if the bolster hubs go in crooked, the car will not track well.  I had earlier constructed two test sections including one of the end of the car to work out the process:




The next parts to be added are the centre bearing plates and the bolster hubs, seen ready for installation in this photo:




The centre bearing plates are the surface which will rest on top of the truck when installed.  The centre of the bearing plate is marked with intersecting diagonal lines.  This is where the holes for the bolster hubs will be drilled:



The holes for the bolster hubs must be centred as precisely as possible.  This centering will have to be maintained as we go up through the various drill sizes from #80 to 1/8".  It all starts with a pin prick on the centre mark to locate the drill bit, and then I drill through with the #80, taking care that the drill is upright left to right and fore to aft.  I then work my way up through the smaller evenly numbered drill sizes ie. #80, #78, #76, etc. up to #61, and then the larger evenly numbered drill sizes ie. #60, #58, 56, etc.  Somewhere around size #55, the difference between bits increases to the point where the shearing force on the styrene is more than I would like, so I switch to consecutive sizes all the way up to #41:




At this point I place the model up on the angle blocks to clear the larger drill bits.  The next drill size up from #41 is 7/64 followed by our target 1/8", but these are too big to cut their way through without collateral damage, so at this point the hole has to be opened up carefully with the round needle file.  Here is the set up for this step:




At this point I am monitoring the position of the hole carefully, as the use of the needle file offers the opportunity to move the hole slightly if needed:




After some careful filing, the 7/64" drill bit will pass through the hole.  One more size to go!  Eventually the needle file will clear the hole sufficiently to pass through.  At that stage we are very close to our target diameter, and we can bring in the 1/8" drill bit.  I turn the bit by hand very slowly and go back and forth a fair bit.  The magic moment comes when the bit finally passes through the bolster block:




During this stage I realized that I had made a mistake in installing the bolster crown plates prior to drilling the holes.  The drill bits and the file need to pass through the car, and the hole on the topside of the car is another access point for gluing in the bolster hubs.  I elected to drill right through them and hope they would shear off during drilling, which they did.  New ones were fabricated and will be installed after I have installed the bolster hubs and tapped them, as the tap also needs to protrude through the hubs when doing its job.

Next up is installation of the bolster hubs, tapping for 2-56 screws, and a trial fit of the trucks.  This will allow us to set the cars on their wheels for the first time and get a glimpse of what they are going to look like.


Tim

[John]

outstanding work ..

[basementcalling]

This should be a BEST OF thread.