Stuff I shouldn't have to do..

I try to buy higher end tools not just because I like using them, but you usually get what you pay for.
I really can't afford to spend over $1500 on a fancy rotary tool such as an NSK electric or similar. So I did what most modellers do and bought a Dremel.

The basic thing any rotary tool should be able to do, is spin true. Well my most recent Dremel purchases, fail in this regard.  I bought one of the new Dremel Micro's a year or so ago and a Dremel 7300 a bit after, because the Micro had terrible run out. The 7300 was better, but still not what I was expecting.

The run out was so bad on the Micro, drilling with it was impossible. (which is what I bought to do)   I ended up leaving a wire brush in it, to clean paint off wheel sets.  The 7300 was better, but still not what I would call acceptable.  One day I got pissed off and took them apart.  The problem was easy to figure out.  Inside the motor shell halves, is a groove for the spindle bearing.  Well the groove  is much bigger than the bearing diameter. The bearing can be moved by hand about 0.010" in its bore in each direction. The pocket is basically 0.020" to big. I fixed it by adding styrene shims to the bearing pocket in the motors shells. The green knife is pointing at one of the shims.

Problem fixed.  I did this to both.  The Micro is still not as good as the 7300, which I account to the the 7300 having a shorter shaft which means less vibration from flex or whatever..

Now why Dremel can't make the bearing bore close to the right size is beyond me. The parts are injection moulded with glass fiber filled thermoplastic.  This process can yield highly accurate parts. So much so, that the bearing pockets shouldn't need 0.020" clearance, may be 0.002 tops..

I broke at least a few $20 drill bits because of this manufacturing issue.

About the chuck and drill bits I use.

I use the Dremel keyless chuck (not shown in the picture), so I can hold 1mm shank Cobalt drill bits from Richards Micro Tool. These are higher end drill bits, much better than any wire drill bit you can get from a hobby supplier. I get mine from McMaster Carr.  Here is a link..

Cobalt Inch Size Drill Bits with 1mm shank

With this combo I can drill hundreds of holes in resin in a fraction of the time I can by hand.

Don't try it on styrene though, the Dremel's lowest RPM is still to fast, to not melt the plastic with a #79 drill.

RPO Part 5

Well here it is CN RPO #7810.

I used ScaleCoat CN Olive Green Paint for the body. Tamiya Flat Black for the roof and under frame bits.  The decals are from Microscale, the CNSIG set in particular.

The rivets are a combination of MicroMark and Archer.  There's at least 2500 of them on it!

It sounds like a lot, but it was only three evenings work to put them all on. One evening for the ends and then one for each of the sides, spending about two hours or so per.

The Mail room windows are Tichy Work Car frames, with the sill removed.  Using 0.010" x 0.030" styrene, a frame was added to the top of the outer portion to make these into single hung windows.  The Tichy muttons were not used. Clear styrene representing glass, was slid between the new upper framing and the rabbet in the Tichy window frame.  It would normally receive the muttons.

The Bars are brass wire held in some styrene blocks that I milled grooves into. The grooves space them correctly. The assemblies are then simply glued to the inside of the car.  The mail room windows, got a coat Testors Dullcoat to frost them.

The roof is held on with magnets, a method I will be using again.

I am very happy with how this car came out. It's the first passenger car I have modelled and I can't wait to get started on some more.  It really pushed my modelling skills up a notch. Here is my lessons learned.

Being a more complex build, it forced me to slow down and put more into the planning before each step was taken. 

At a minimum I have new found skills in working with styrene and decal rivets.  I also have a better understanding of passenger car details, and figured out a method to reproduce roof panel lines.  

All of these new skills will make tackling other projects easier while resetting the bar for what I can achieve.  

I even spent some time figuring out the white balance settings on my camera, so I can take better pictures.  Hopefully this has removed a road block, in me submitting a magazine article in the future.

RPO Part 4

Trucks

The Branchline under frame is designed to work with the kit supplied 3 axle trucks.  ACF built these RPO cars with short wheel base, 2 axle trucks.  The Walters 8'6" passenger car truck was selected as the closest to the prototype.  In order to mount these trucks, the under frame was modified in the following manner.

1. Mill off the bolster even with the surounding material.

2. Install a block of styrene for the truck to rest on, that provides for the correct coupler height.

3. Drill the truck mounting screw on center and the correct distance from the car end.  To ensure the screw is centered, I coloured the block with some pencil graphite and then used my dividers to scribe two arcs using the moulded holes near the end of the car, on either side of the coupler.

4. The smaller piece of styrene helps to keep the Branchline swinging coupler box wiskers,  flat against the under frame, improving the coupler mounting box angle.

5. The openings were filled with sheet styrene from the inside.

The trucks were modified by adding a small washer to fill in the large hole to size it for a 2-56 screw.  These were glued using ACC.

 The underframe was detailed the best I could figure from my reference photos and a photo supplied by one of the blogs readers, of his Bethlehem Car Works kit of this car.

 The Sill steps were formed from Details Associates flat stock in a simple wood jig and soldered together.

 The roof was sanded of all detail including the panel lines, as they were in the wrong location for this car.  The panel lines were recreated, by first priming the roof, then masking off the half of the panels, followed by adding 4 more coats of primer.  The masking tape was removed shortly after the last coat, while the paint was still soft, so that it would not chip.

The roof was detailed with Custom Finishing Vents, brass bar stock for the drip rails above the doors and a brass wire with mounts for the Gas Lighting Pipe.




In the next installment I will show the final car so Stay tuned.....

RPO Part 3

These CN RPO's feature an Arch Style roof with rounded ends.  An Athearn 70' Round Roof Coach was sacrificed to provide the roof.

First the roof was separated just below the upper rivet strip using a large razor Saw.

Next I scraped and sanded the roof even with the rivet strip.

It was determined that this point the roof was too wide to mate with the RPO body.  I calculated the point at which the roof narrows along the arch profile where it would be the correct width.  I used my height gage and scribed a line around the roof at this point.

Then I used a small modelling plane and my plexiglass mounted sandpaper to remove this material.

I now had an Arch roof of the correct profile and width to match the car.

The forth step was to shorten the roof to the correct length.  A razor saw and miter box were used to cut out a section from the middle of the roof.  I then used my milling machine to end mill the roof sections to the correct length to match the RPO body.   These were glued together using Testor's model cement, as it has a slow cure time compared to MEK.  I used my machined gluing jig to keep things lined up.

The final step was to reinforce the joint from the inside with some sheet styrene.

Next steps will be to detail the roof correct for the 7810-7812 series RPOs.

Crapola!!

Well I screwed up.  I did exactly what I was being so careful not to do.

 I knocked the glue bottle and some MEK escaped. 

I ended up melting about a third of one of the RPO sides. The glue hit the back side and I thought I could save it but......... I finally admitted to myself it was gone.  I had put this much work into it I had to make it right.

 So I cut it off, just to the right side of the baggage door and spent the evening remaking the mail room end of the side.  I'm going to leave it  for a day or so now and go watch hockey highlights instead..

RPO Part 2

Over the weekend I made substantial progress on the RPO.

I scratch built new sides from Evergreen styrene sheet and strip.  Commercial sized strip was used to keep things simple.

In the first photo you will see some finger clamps I constructed to assist in the process of making the sides. I saw these over on Joe Smith's Blog and thought they were just great.  Mine are made of mild steel with a piece of Tig welding wire pressed into a drilled hole.  They are basically a mini finger to hold things while your gluing etc.  What great idea and now that I have them, I can't live without them!!  Construction is done on plate glass set against a metal scale.

The first layer is made of a piece of 0.010" thick material with 0.060" quarter round on either end. The second layer is all made from 0.010" strip of varying widths.  A piece of 0.100" and 0.080" strip is attached along the top and bottom of the sides respectively.  The top and bottom of the three doors are made with 0.080" strip centered on the pencil lines.  These are made longer than actually needed.

Here is a close up of the side as described above.  The strips are set 0.010" off of the top and bottom strips to leave room for upper and lower door sills.  The top of the side is against the scale in this photo.

Next I applied the mutton's to the upper half of the door to frame door window openings.  The mutton's are 0.040" styrene and the outer edge is 0.080" which will be covered with a 0.040" quarter round door jamb that will leave a 0.040" door boarder to match the mutton size.

Here is both sides with the doors and windows all framed up. 

Next the remaining areas were filled with 0.010" sheet to complete this layer.

The third layer starts by adding 0.040" sheet on top of the second layer using individual pieces followed up with 0.010" x 0.040" strip set vertically at the top and bottom of the door openings.
Unfortunately I didn't take a close up photo. Finally I added the 0.040" quarter round on either side of the door to form the door jamb.

Next up is to cut out the window and door window openings, followed by adding the belt rail and letter board using 0.010" strip.  I will fill any seams with putty and sand if needed before mounting on the car floor.

Railway Post Office Service on the Grand Trunk NEL

The Grand Trunk (NEL) rostered  three Railway Post office Cars #'s 7810-7812.  They were built by ACF in 1929, possibly for subsidiary GTW and transferred at a later date.

The Canadian National Historical Society magazine CN lines Volume 9 Issue 1 has a article pertaining to these cars and similar RPO's used on the Central Vermont and Grand Trunk Western.  Here is a picture found in Morning's Sun Colour Guide to Northern New England Cars.

I am going to kitbash one of these cars using a Branchline Coach as the base model.

I recently discovered Joe Smith's Blog "Signal Station 199" regarding his efforts in building a New Haven themed layout. He has a set of blog entries showing his techniques to kitbash a similar RPO for the New Haven.  Go take a look, but I warn you Joe's modelling and blog are top notch so your  going to be there for a while.  Here's the link...

https://signalstation199.blogspot.ca/search/label/RPO

Now that your back, here's where I'm at with this project. Follow along as I put what I learned from Joe to good use.

First off I enlarged a drawing provided in the CN lines issue and copied the dimensions over from the soft copy, that were blurry when enlarged.

Next I cut the floor and spliced it back together to give an length over the couplers of 66' - 61/2".

The floor is braced with a sheet of styrene and some square stock.

The second photo shows the floor sections I removed.  I also removed the side vestibule doors and walls on either side of the end doors.