Saturday, September 25, 2021

SPMW 7021A (Part 5) Wrecker - Rail & Tie Car

Ok, time to wrap up this build.  In SPMW 7021A (Part 4), I finished most of the fabrication of the plastic parts of the rack and painted it.  Now it's time to build the wooden parts and install the last grab irons.

Let's work on the running boards!

Staining & Fabricating the Running Boards

I decided to build the top running boards from strip wood 1x8 boards.  The boards are cut into shorter sections which land on the support frames, which are only 0.040" wide.

Top boards coming together.

The stain were primarily made from AppleBarrel (20366E) Dark Gray in water.  I stained full strips of wood.  This required me to come up with a way to stain the full lengths of strip wood.  I ended up wetting the board with water, then applying the paint with a brush.  Quickly, I then reverted to "finger painting" pulling the paint down the board between two fingers.  Then some light blotting with paper towel.

Third running board on the left side of the rack installed

I also painted the inboard sides of the tie-rack end bulkheads, which are plastic 2x6s, the same rough color as the board stains, so that it looks like any paint on those boards was knocked off and roughed up from the ties shifting around.

Canopy glue drops ready for the last board on the right side of the rack.

I used canopy glue throughout the process of attaching the boards to the roof.  This works pretty well, I did weigh down some of the board joints with a piece of 1/4x1/4" steel bar until the glue set.

Completed high-level running boards.

I was hoping that the wooden running boards would add structural strength and rigidity to the model.  Thankfully it did just that.  I can now gently pick up the car from the rack frame without the rack flexing like it did before having the running boards installed.

B-end running boards.

I had to patch a little bit of paint on the end of the right side running board where I trimmed it short and nicked the frame's FCR paint.

Cropped end of running boards.

There was a slight distance mismatch on the B-end, resulting in the end walkway couldn't be made with 1x8 boards, but they had to be cut down to 1x6s.  I still need to fabricate and install the hand brake staff and install it on the B-end.

Running boards over the frame truss structure, possible storage racks?

I'm still debating if there were any boards under the running boards.  Some of the prototype photos show what might be some form of crane cables layed under the running boards, over the main deck.  I may fabricate some cables and see if they can be made to fit in the future post on building the load.  If there were boards forming additional rack storage space there.  The flip side of that is, would they have had "head-klonkers" there or did they keep the space clear if a crewman had to climb into work on the rails and frogs, etc on the main deck.

Fabricate Tie Rack Floor Boards

I decided to make the tie rack boards removable.  The prototype photos don't show if there are floor boards forming a bottom to the tie area, but it seems logical that the wrecker crews wouldn't want to have ties dropping down into the truss if they were shorter than the spacing of the cross beams, or if they shifted with slack.

I am planning to make the tie load removable as well, so there's also some factor of "I want to be able to see all the cool cross bracing of the truss.

Random bits of stained 1x8 strip wood cut to length of the cross frames

I decided to build the tie rack floor with more 1x8 strip wood.  0.010"x0.060" plastic strip and some split 1x8 (down to 1x4) wood strips are also used to supplement the cross pieces.  I don't want any adjacent board joints at the same frame.  The under cross ties are going to be slightly offset from the rack frames.

Mixing up the stained boards to make the floor obviously made from different boards.

I mark the underside of the boards with mechanical pencil, so that I can apply the canopy glue to precise locations.

Floor coming together.

I liked that a couple of these pieces of strip wood have chips out of the side of the boards.  I decided that I wanted a couple of "missing boards" to show the rack frame structure.

Here's the first shot of the rack installed.

I had to cut about 0.015" off the edge of the floor to fit into the rack.

Nail/bolt heads marked with mechanical pencil.

The floor boards are getting wrapped up at this point, I decided to do the pencil tip nail marks on all the boards.

Corner Grabs

Custom bent corner grab irons.

Bent wire grab irons using rems of 0.009" PB wire.  These are custom measured to fit the A-end of the rack.

0.015" holes drilled for corner grabs.

Holes are drilled above the inboard end posts and on the last horizontal brace under the longitudinal running boards.

Grabs installed with small drops of ACC glue.

The corner grabs are last non-standard detail I'm planning to put on the model.  The brake staff and linkages will be the final parts, but that will take a bit more to do and I'll probably hand paint touch up those when it's in place.

In Closing

Lower angle photo of the nearly finished car.

In the next post on this topic I'll be getting into building the load for the tie rack and the main deck load of rail, points, frogs, etc.

Jason Hill

Thursday, September 23, 2021

SPMW 7021A (Part 4) Wrecker - Rail & Tie Car

During the last three parts of SPMW 7021A (Part 1), (Part 2), (Part 3), construction and kitbashing, the rack and bulkheads have been fabricated.  It's time to finish one of the my most concerning details and get the new rack ready for paint.

Time to finishing painting the rack in this post!

Fabricating the "Hanging" Grab Irons

SPMW 7021A post-1958 photo - Eddie Sims collection

Looking at the prototype photos, there is a huge gap between the grabs on the side sills and the grabs at the frame level of the rack.  On the prototype car, there was an additional set of grabs suspended from the rack frame, which will allow rails to be pulled from the main deck of the car, yet will still be the correct height to allow easy access to the running boards on the top of the rack.

Grabs and Styrene Hangers

I decided to use 0.015"x0.040" styrene strip for the vertical hanging structural pieces.  The grabs are formed with OMM jig using 0.012" PB wire, to the "long" jig setting.

Marked hole, calipers and carbide scribe to mark hole center

I drilled the hole in the styrene strip 0.125" from the lower edge of the rack frame (same as the top of the hanging styrene strip).  The prototype steel piece has the grab at the very bottom, however I want to have a small amount of plastic around the grab iron, so I left it about 0.015" longer than where I drill the hole.

Completed grab irons and hanger strips

I inserted the wire grab into the hole in the styrene, then applied a drop of ACC glue to the back of the styrene.  With a small piece of scrap wire, I transferred a bit of ACC to the front side to finish securing the grab at a square angle to the styrene.  Note that I made two "Left" and two "Right" configurations of this assembly.

Completed A-end right side grab iron and hanger

The holes in the bulkheads were predrilled during Part 3, in anticipation of this coming step.  I apply a small amount of ACC to the remaining wire end of the grab iron.  With my favorite Leatherman pliers I grab the grab and press it into the hole in the bulkhead.

B-end right side grab iron and hanger

B-end left side grab and hanger, top grab is a little off level - oh well.

A-end left side grab and hanger

Next, the styrene strip is rotated up against the bottom surface of the rack frame.  Tamiya liquid glue is used to weld the styrene pieces together.  As it starts to weld the joint, I make sure to press it flush with the outside edge of the rack frame.  Often I used handles of metal tools, such as my tweezers, which can be used to align the plastic parts, but will not be effected by the liquid plastic glue.

A-End Additional Supports

New horizontal supports installed on each side of tie rack bulkhead.

I decided to put in two more 0.020"x0.040" styrene pieces between the upper rack bulkheads and the flat steel gussets to support the A-ends of the running boards.  These two pieces were a bit tricky to install, but with a bit of pre-softening with Tamiya liquid glue was easier.

Stanchion Top Cables

New 0.009" top cable threaded through stanchions

The top cables (0.009" PB wire) are now fitted through the tops of the H-column stanchions on the rack.  One end is bent over and secured with drop of ACC.  The other end is also secured with a small drop of ACC on the wire, then pulled into place and allowed to dry.

Masking & Painting

As with all things SPMW before 1958 and that wasn't a crane or a snow plow, SP Freight Car Red (FCR) is the color of the day.  The main body of the car would have already been painted FCR from the revenue service days.  The conversion date in 1939, I'm not 100% sure if the new tie rack was welded directly to the frame as it seems, but in any case, it was then painted overall FCR according to the 1950s photos I have of the adjacent cars from Bob's Photos.

I don't want to risk the deck weathering putting any masking tape down directly on it at this point in the painting and finishing stage of construction.  So, I need to make a non-sticky mask to keep my nicely weathered and distressed deck from getting any over-spray.

The main desk mask is cut from some standard paper scrap.

My mask is made from a scrap of standard 8.5x11" paper.  Two creases are formed for the width of the deck.  The paper is cut to the internal distance between the bulkheads.

Slipping the mask into place.

The mask is carefully slipped in between the main deck and the hanging grabirons.  A couple pieces of 3M Scotch tape are used to secure the paper around the body of the flatcar.  I needed to tighten up the paper, so I added a small amount of extra tape to cinch it a bit tighter.

Partly painted rack.

My finger grip would help bias the mask and pull it tight at the lower edge of the interior bulkheads when I was going to use the airbrush.

Painted rack completed and mask removed.

It looks pretty good.  It took two loads of SP Freight Car Red StarBrand paint in my airbrush to cover all the nooks and crannies of this complicated structure.  Best to just do light coats and keep going around the various areas, hitting all the angles you can see.

In Closing

Now the rack just awaits the wooden parts.

Well, this pretty well finishes the construction of the SPMW 7021A.  In the next post, I'll be building the running boards for the rack.  These will be made using pre-stained wood for those parts.

I'm also planning to build a load of rail and a frog for the main deck and ties for the rack of the car.  I hope you'll come back again to see the next post in this series.

Wednesday, September 22, 2021

SPMW 7021A (Part 3) Wrecker - Rail & Tie Car

I decided to do another few steps on the since SPMW 7021A (Part 2).  It's time to dive into the more delicate details of the rack.  

Installing Stringers

Since the last time I cut and installed 0.040"x0.060" styrene strips to fit between the vertical posts.  Specifically I wanted these to be wedged slightly longer thank nominal space so that the rack will put these stringers in compression to keep the rack from sagging.  Later I actually decided to insert a 0.010"x0.040" strip in between the frame rail and the A-end end sheet to force the floor to have a slight crown in it.

0.040"x0.060" Styrene strips cut and fitted between vertical H-posts.

Supporting the upper rack with a section of 1/4x1/8" styrene, I started drilling the marked center points for the grab irons with a No.78 drill bit.

Center stringers wedged in place.

Side grabs bent using the longer grab jig on the OwlMtModels F-50-series sprue, which is about 0.250" long.

Cutting Running Board Supports

NWSL Chopper used to cut up supports for running boards.

The Northwest Shortline "Chopper" is used to cut exact length pieces of 0.020"x0.040" styrene strip for the support frames.

Vertical and horizontal running board supports. (Vert supports above, Horiz. below)

I decided to fabricate the running board supports from four 0.020"x0.040" styrene strips, this allows a lapped joint at the corner.  The running board support needs to be 0.215" higher than the rack frame, and 0.315" wide for the horizontal support.  The alternate piece is cut 0.040" shorter, allowing for the lapped corner joint.
Pile of cut materials for running board supports.

Installing the Running Board Supports

Running board supports installing against gusset plate.

The first several supports I glued up and kept square against a metal square.  Once dried I installed them to the gusset (A-end) of the car.  

Running board support being installed - Right side

Running board supports being installed - Left side

3/4 end high view of running board supports and stringers

Later I went to installing the vertical pieces with Tamiya liquid glue, and then installing the horizontal pieces after the vertical had dried.

All running board supports installed.

Completed running board supports.

B-end close-up of running boards installed.

Structure of the rack coming together.  A piece of 0.009" PB wire will be strung through the top of the vertical rack.

Rack Bulkheads & Tie Fitting

2x6 rack end boards installed and ties piled in rack.

The next step is to fabricate the bulkheads in the end of the tie rack.  These were made from seven 0.020"x0.060" styrene strips with 0.015"x0.040" strips vertical on the exterior of the panel, glued together with Tamiya liquid glue.

A-end close-up with end boards and ties in rack

Installing the grab irons, the end grabs are using the standard F-50-series short grab jig.  The top corner of the A-end of the rack will have corner grabs on top of the running boards, like a boxcar have.

B-end close-up with end boards and ties in rack

The inside of the rack a longitudinal stringer on the inboard side of the H-columns is fabricated from 0.015"x0.040" styrene strip.  I may decide to fabricate a very small stringer to go between the flanges of the H-columns about halfway between the running boards and the top cable.

In Closing

SPMW 7021A at Bakersfield, post-1958 gray.  D.F.Willoughby collection

I'm saving installing the vertical structures hanging off the rack frame which the intermediate side grabs were hung from.  They will be pretty fragile, so I'll add them right before painting.  Most of the stake pockets had short stakes to help contain the rails and switch frogs, so those will be fabricated at some point soon once I get the rail & frog load built.

Finishing up this car should be pretty fun as this project is entering the home stretch.

Tuesday, September 14, 2021

SPMW 7021A (Part 2) Wrecker - Rail & Tie Car

The previous post on the SPMW 7021A (Part 1) covered my first go at building the bulkheads and rack.  However, after looking at the prototype references closer, the bulkheads were too short.  It would have been easier to cut them down, but not so easy structurally to raise them.


I took some time to draw up the car in my CAD software and get the proportions worked out. Much of the internal structure is guesstimates and logical design based on what is visible in the photos.  I have a couple other photos from Bob's Photos, which I don't have permission to publish here on my blog.

SPMW 7021A stripped of original bulkheads sitting on top of 1:87.1 scale rack plans.

I printed out my CAD drawings and then double checked them against the model that the printer scaled the drawing correctly to match the SPMW 7021A physical model.

Ok, everything checks, time to start!

So, after a break of about 6+ months and now armed with a good set of drawings... I'm looking forward to diving in and finishing this crazy looking project!

Fabricating the Rack

The first step in fabricating the rack was deciding how I was going to model the 6" main span beams.  I have some 0.060" C-channel styrene shape, but I need more like 0.069" tall beams per the scaling off the photos.

I decide to use the 0.060" C-channel stock and glue a 0.060" x 0.010" strip along the bottom, creating a bit of a flange to the inside of the C-channel for the cross pieces to attach to.

I start by gluing the 0.060" I-beams to the 0.060" C-Channel/L-girders.

The end beams are also formed from 0.060" C-channel stock.  I'm using a section of plywood with square marks and basic dimensions transferred over from the drawing so that I don't get Tamiya glue on the paper print.  Later on I get more adventurous about doing this!

Cross frames are glued in place.

The cross frames are made from 0.06" x 0.04" strip styrene, this will allow them to match height with the main frame beams.  Once they are tacked in place at the marked points, I add an additional 0.06" x 0.01" styrene strip to the bottom, inboard of the flange, forming a larger gusset plate.

All cross frames in place with gussets.

Now it's time to make the diagonals.  I would have liked to use 0.04" x 0.01" strip, but I only had 0.04" x 0.02" on hand... oh well.  

I cut and fitted the diagonal bracing

At this point, it is critical to ensure the rack is square before installing the diagonal pieces!  I did all the braces in one direction on the top, then flipped the rack over and did the other direction on the bottom.

Bottom of the "flat" rack frame

Top of completed "flat" rack frame

The process of cutting and fitting all the diagonal pieces is complete.

Fabricating the Bulkheads

Marks for collision posts on bulkheads.

After reviewing the previous material on how I built the first set of bulkheads 6 months ago, I should have used the same spacer method on these when attaching the collision posts to the bulkhead sheets.

Mismatch in height of bulkheads.

I marked the A-end bulkhead on the interior side with pencil to help me align and set the height of the rack frame.

Pair of styrene bulkheads completed.

The top of the bulkheads are finished off on the exterior with a strip of 0.060" x 0.010" styrene strip, which actually helps the 0.010" bulkhead sheet keep from rolling up during handling.

Joining the Rack and Bulkheads

Rack frame with offset end sub-beams.

The prototype photos show that on both ends there's a I-beam installed inboard from the bulkheads, under the frame.  I'm not sure why these are mounted below the rest of the rack, but they certainly are.  I fabricated them out of a couple of 0.060" I-beam stock, cut to the width of the rack.  The lower corners are cut off at a chamfer, so I was sure to do that before installing.  I added a short piece of 0.04" x 0.02" strip between the frame beams and the I-beam sub-beams to account for the thickness of the diagonal bracing.

It was also at about this point that I realized that I would need to cut off the end C-channels from the rack frame, as I had accidentally made the bulkheads too thick, using the 0.06" collision posts, instead of the planned 0.04" strips.

Rack prepared to be installed on the bulkheads.

I slightly miscalculated and used 0.040" x 0.060" styrene strips on the bulkhead collision posts, which pushed them in an additional 0.020" on each end from the CAD drawing, which was expecting only 0.040" x 0.040" strips.  I had hoped to use the C-channels to create a larger bonding surface to the bulkheads... but I guess that's not going to happen!

Rack frame installed.

At this point I start gluing the rack to the bulkheads.  I was double checking the space from the deck to the bottom of the rack main span beam at 0.305" with my calipers before the Tamiya glue fully hardened.

Checking the rack for square and level.

I may still add another 0.060" x 0.040" strip across the ends at the bulkhead to reinforce the inside of the joint before I paint the rack and install the running boards.

Fabricating & Installing the Gussets

I fabricated the two large gussets on the A-end of the rack from 0.010" styrene sheet using the CAD drawing to help get the size right.

A-end gusset plates are cut and installed from 0.010" sheet.

The anti-shear gussets are useful to have, oddly they're only installed on the A-end of the rack.  Funny enough, it actually does make the joint much stronger, forcing the 90 degree angle between the rack and the bulkhead to be fixed.  However the middle of the rack is still quite flexible and able to sag.

Second gusset installed.

Around this time I also marked the centerlines for the various grab irons which will need to be drilled.

Close-up of A-end bulkhead

Grabiron hole marks are also put on both bulkheads, which I'll need to drill out soon.

B-end bulkhead with grabiron marks.

The B-end will also need to have the extended brake staff and rigging installed to the left of the coupler.  I'm not sure how high the brake wheel was above the upper running boards on this car.

Installing Vertical Rail Rack

I predrilled the top of the rail posts with a 0.015" drill bit about 0.04" below the top end.  This will be for the cable "hand hold" between the posts.

The outer edge of the posts are marked on the horizontal frames

I mark the horizontal frames with my mechanical pencil 0.315" inboard from the edge of the rack.  This will be the mark for the outer edge of the vertical rail posts.

The vertical posts are glued in place with Tamiya glue.

The posts are attached with butt-joint connections to the horizontal frames using Tamiya liquid glue.  The glue welds the plastic together, creating a fairly strong joint.  Later on I'll put some splice plates or additional supports in there to beef it up a bit.  The prototype photos show at least some angle-iron or other bits which should support and form a partially open box for the ties.

Using a 1/4"x 1/8" strip of styrene as an alignment guide.

One of the challenges of actually gluing these posts on free-hand is getting them properly aligned. To help with this, I glued the end posts first.  Then I'm double checking the alignment with a straight edge (heavy styrene strip) to see that the posts are still in a good line.

The rack is still rather flexible, so putting the heavy styrene strip inside for support.

The model rack's coming together nicely, but it is still rather flexible in the vertical axis across the span.  I'll be putting in more spacing structure higher up between the posts, but for now I want to put some support in under the middle of the rack to keep it from sagging.

In Closing

The rack is mostly installed now with the vertical posts.

This is where I'm going to wrap it up for now.  Upcoming steps will include fabricating the supports for the running boards, putting in spreader pieces between the vertical rails.  I'll be using 0.009" PB wire for the top cable between the posts.

I'll then mask the main flatcar and paint the bulkheads and rack before installing pre-stained basswood running boards around the top of the rack.

Jason Hill