OcCre San Francisco Streetcar

This is my journey on my build of a "OcCre San Francisco Streetcar".
I will not be bringing you a blow by blow photographic journey (though there will be photos), the OcCre instructions for the build is full of photos, and there are some very useful videos. What I will be doing is describing my thoughts, hints, tips and anything of interest, and where I deviated from the instruction. 

However, the main focus will be on motorization of the Streetcar, and how I got there.  The motorization was carried out in parallel to the main build, but to prevent confusion by jumping from one aspect to another, the details of my motorization journey (including power and control) will be at the end of the blog, with the build of the main Streetcar first.

Six very nicely cut frets, with minimal laser burning, a variety of faced ply wood, also a "bundle of sticks" and a box of metal parts.

Making a start, you really do need to read the instructions and watch the videos, I have been building kits including wooden ones for longer than I care to remember, and IMHO this kit is not for the beginner. My first issue was what adhesives to use, the instructions say: 

• Use white glue for wood, 
• Use fast-acting glue for parts difficult to hold in position, and small parts. 
• Use transparent contact adhesive for window to frames. 

 In the end I opted for OcCre's own white glue, Rocket CA, and Deluxe "Glue and Glaze".

The frets are quite thin and need care to remove, and although this is slot and tab, they are not tight fits so on assembly some "wobbliness" could occur, leading to complications further on, and fine tuning of the parts, especially the wooden strips.  Wanting to motorize this Streetcar I started looking for the appropriate motor not long after opening the box. The Streetcar sits on two bogies, and as I build I am looking at various solutions - more to follow on this.

Below is how I marked out and masked the end panels. After painting around the windows as per the instructions I decided, that rather than just masking the window in two sections, a single set of masking, and mask where the blue is to be painted.  The blue than cut-in by hand.

	Holding the ends and sides in position took both clamps and elastic bands, not enough hands. 😁
With the centre section assembled there were a number of gaps and holes, not mentioned in the instructions, I filled and smoothed these imperfections.
	Painting complete and end panels fitted, minus the glazing.
Final glazing in place, and the roof is next.  The construction method for the roof means that it will not be removable, so any final finishing touches need to be carried out now, especially cleaning the inside glazing of any sanding dust.
	One of the later stages is fixing the bogies to the chassis, however recommended method is a wood screw in to the underside, I felt this may be a weak point, so again before the roof is fitted two machine screws were fixed in place with CA.
The roof is next, the underside stained and varnished, and when dry the outer-side is wetted down to assist with the bending. Lots of clamps, and a few at a time.
	Once the roof has all the sticks fitted and trimmed to length, filling is called for, though the instructions do not advise which filler, so I used a water based wood filler.  Important to mask of the body before starting filling, and more importantly before sanding smooth.
Painting shows up any imperfections, so fill, sand and paint until you are happy with the finish.
	The Clerestory roof is made using the same formula as the outer roof, though the first piece to fit is the central spar with the inside lamps fitted.

Motorization

Initial Considerations

My initial thoughts was to build the motorized bogie using the main kit components, and to be Remote Controlled using a Li-Ion 1S battery 3.7 volts (nominally) and a Deltang Rx45 as the Rx.

Bogie Assembly

As mentioned at the beginning the bogies were assembled in parallel with the body assembly, there were two main reasons for this:

• There is a lot of waiting time between paint/glue/filler drying and this kept me busy.
• Wanting to motorize the Streetcar, but unsure of which specific components I would need, assembly helped to identify where any issue would be.

The axle supports were assembled first to ensure square and the axle holes were aligned.
	Following the instructions the axles' supports were positioned (but not fixed) in the correct position to determine the positioning of the motor drive. The side frames were also temporarily positioned.
The motor was mounted in a Dean Goods gearbox with gearing for a 3 mm axle.
	The issue was sourcing wheels and axles, eventually I came up with IP Engineering 30 mm diameter wheels adjustable to 40 mm B2B, but as can be seen this was an issue for the axle mounts.
New 3D printed axle mounts were sourced, the wheels set to the correct B2B (40 mm) and the axles trimmed to length, these assembles were then fitted to the bogies with packing pieces to ensure the axles positions were as per the originals.
	The motor gearbox was also fitted with a pair of axle mounts, both being PLA, they were glued together to form a single unit.
Bogie side frames fitted, and alignment and clearance checked, before final glueing.
	The meshing of the worm and gear and be clearly seen, power was applied to ensure fault free running.
The finished (except for painting) power bogie, however as a unit I considered this to be very light.
	Not much room for extra weight, the gearbox, and axle mounts removed, and two chambers were formed to hold additional weight (divers ballast).
These were then potted with two part polyurethane resin, however this only increased the weight by about 100 g.

Powering the Bogie

With the bogies now complete, including motorization, the bulk of the main Streetcar complete, time to power up the Streetcar and test.

	This is the Battery and Remote Rx for the Streetcar, all fitted in to a small project box and fixed under the main Streetcar body. However on powering up the Streetcar, it became apparent it was far too light to provide any traction, the weight without the bogies was only 450 g.  Applying bags of weights over the power bogies showed I needed at least 500 g additional weight on each bogie.
The only area available for adding that amount of weight was under the floor, but at the expense of the bogie spacers.  I decided that 500 g per bogie (1 kg) would be spread across the underfloor, 2 rows of 3 mm divers lead shot came to 1 kg.  This is all potted in with 2 part polyurethane resin.  When using resin as a "potting" compound for weight ensure there is no area where it can leak through, because, if it can, it will.
	The bogie is now fitted to the chassis, the bolts originally in the chassis to mount the bogies are removed and captive nuts fitted.
Having lost the spacers on the bogies the bogies needed to be angled to allow some lateral side and front and back movement to ensure the bogies remained in contact with the track, and traction is maintained. Weight at this stage of assembly is now 2 kg

If you are considering motorizing your Streetcar, think about adding weight early.  The seats could be filled with weight before assembly, and if you are considering adding weight under the floor, I would advise doing this before adding the roof.

A quick test was carried out on my indoor test track and the Streetcar now runs, with traction, however when placed on my (far from level) Garden Railway, traction was at best intermittent, and almost no traction uphill - time for a rethink.

Motorization -Take Two

After discussions with other modellers, the reasons for the problems were obvious, I just had not seen them, and these were broken down to two main areas:

• Lack of compensation on the axles (minor cause).
• Drive on only one axle (major cause).

These two problems would mean at times only one driven wheel was in contact with the rail, and the main weight could be on the non driven axle leading to lack of traction, the solution is a new power bogie.

After deliberation, I ruled out the axles being hung in the bogie frames due to lack of space, so this would be an "inside frame" with dummy outside bogies frames, trying to ensure as much of the original detail is kept.  Compensated axles, to be used for both axles, driven from a single gearbox and linked by Delrin chain drive.  Also I will build a new non-powered bogie, to allow lateral movement of the bogie.

	The original bogies were measured up, and the sizes for the internal frames transferred to 0.080" thick brass sheet, Gauge 1 Standard Scale frame spacers having already been purchased This will become the power unit.
A new gearbox and motor was bought from Dean Goods, compensation horn-blocks from High Level, Delrin gears and chain from Essel Engineering and Wheels from Slater's, however the wheels were fitted to 1/8" stainless steel rod to allow the components to fit together.
	The 4.5 volt motor supplied (RE280 MM) would not work with the Rx45 (a different tale) and a MFA Como 280/5 was bought and this worked.
The frames were blackened so as to disguise them behind the dummy frames, and the power unit is complete.

	The non-powered bogie was constructed from plasticard both sheet and sectional, a boss placed on top of the frame to allow the frame to move up and down, to enable some compensation.
The wheels, from the Slater's G1 range were mounted in the frame using the supplied bushes, and a coat of paint applied.
	The bogie frames for the powered bogie were constructed in a similar manner to the non-powered bogie, however the wheels are already fitted to the power unit.  This was fitted from the top on to the frame spacers.
However with the power unit in place the screw to secure the bogie to the chassis could not be accessed, so the top frame spacers once fitted to the bogie were removed from the power unit.
	Holes had to be cut in the bogie frames to access the top frame spacers to allow fixing of the power unit to the bogie, and painted.  A bogie that is compensated, with both axles compensated and driven.
The bogie minus the power unit is fitted to the chassis, the power unit is then fitted to the bogie.  The Streetcar with both bogies fitted.  During testing the MFA motor was not fast enough, however a faster RE280MM motor would not be driven from the Rx41, and a Rx65 was used with a satisfactory outcome. A quick test run proves the design, and now to add the last detailing items.

The Finishing Touches

The last few detailing parts have been added, along with the decals.

Conclusion 

Not  a difficult kit to construct, however the instructions need reading a few times, and watching the OcCre videos is very helpful.  Do be aware of painting lots of the parts as advised before assembly, where possible leave the mating surfaces bare, and touch up later.  If you are going to motorise the Streetcar see my mistakes, and try to plan ahead.  If I had gone for the compensated, bogie with both axles driven, I think 1Kg of weight would have been enough, though now I will never know.  As the OcCre website and instructions say "Have Fun".

Main Suppliers used:

•     Cornwall Model Boat Supplies
  
•     Eileens Emporium
  
•     Walsall Model Industries
  
•     RC Trains
  
•     Slaters Plasticard
  
•     Essel Engineering
  
•     Deans Goods
•     High Level
  

 

Components used:

•     OcCre San Francisco Streetcar Kit
  
•     0.080" brass sheet
  
•     Deltang Rx 41and ADD1, replaced by a Rx 65
  
•     1S Li-Ion battery with BMS
  
•     MFA Como 280/5, replaced by a RE280MM
  
•     Slaters 3ft spoked wheels
  
•     Delrin chain and sprockets
  
•     Dean Good 30:1 gearbox
•     Compensating horn blocks