DK Pilot 01: Introduction to the pilot model

Introduction to the pilot model:
The Dick Kerr "pilot model" is a kit of parts that build a Dick Kerr petrol locomotive.  Two versions of the pilot model have been designed, an as delivered version and a contemporary version.  The pilot model is largely a body kit, with brake details and other accessories.  Other versions may be produced.  These instructions are being provided as an aid to those building the pilot model. Subsequent versions (if produced) will incorporate enhancements and attachments for a mechanism based on the experience of the pilot builders.  Brake shoes for the pilot model have been designed to fit a Hollywood Foundry drive, details of which will be provided after testing.  Final installation of the provided brake details will be left to the model builder in this pilot phase, as the nature of the installation depends on the chosen mechanism.

Selecting glue:
The kit consists of 3d printed acrylic parts, many with very fine sections.  The best glue to use for these parts is a 2 part epoxy.  Thin cyanoacrylate glue (CA), a.k.a. super glue, is also useful for mating brass parts to 3d printed parts.  Although CA will bond the acrylic pieces to each other, the bonds are easily broken: epoxy should be used for best result.  Solvent glues will not work with the type of acrylic used to produce the model.

Tools required:
The kit can be assembled with a minimum of tools, including:

• A selection of fine files, preferably dedicated to working with resin to avoid contaminating material with brass or other metals.  These should include rounds and flats in a few sizes;
• Flat and round files for brass.  The flat file will be used to shape the horizontal cross pieces that hang just above the rail.  The pointed round file will be used to open the 1/16" tube used for the exhaust pipe;
• A razor file for cutting the flat rafts off the sprues;
• Sprue cutters;
• A #17 X-acto blade for cutting sprue nibs from flat surfaces;
• A fine philips screw driver for the coupler screws;
• Wire cutters;
• A pair of chain nose pliers to form the lift rings;
• A pair of flat pliers to form the hand grabs;
• Steel blocks and angles to brace and align assemblies for gluing;
• A piece of glass or flat work surface for assembly;
• Tooth picks to aid with glue application;
• A pin vise and a set of miniature twist drills to open or enlarge holes if needed;
• A small piece of 400 grit sandpaper for smoothing some surfaces and rounding rivets.

In the box:
The pilot model is hand packed, and includes all of the necessary acrylic parts.  Also included are springs to be used for the journal boxes, and brass pieces that interface with 3d printed parts, such as the cross pieces and the exhaust pipe.  You will need to provide fine wire for the lift rings, and music wire for the hand grabs unless otherwise noted.  Holes are provided for these.

Removing the parts from the carrier:
Parts are hot glued to cardboard carriers on their sprues so that all of the parts can be removed from the box in an organized fashion.  As these are very much one of a kind kits, the exact arrangement may vary.  Be careful removing parts from the cardboard.  The support rafts are stronger than the parts they support.  When prying parts from the cardboard, handle the rafts.

DK Pilot 02: Preparing the major parts

Freeing the parts from the rafts:

The acrylic used to print the model is very strong, but can also be brittle.  Printed on tabs that aid assembly are easily broken off if care is not taken.  Fine details are similarly vulnerable.  The best general procedure is to begin by cutting the raft off the vertical support sprues, and then gradually removing the sprues, working towards the model to better see what is being cut.

Freeing the raft from the vertical supports by gently cutting with a razor saw.

Work toward the part with the sprue cutter, removing small sections at a time.

Begin with the hood top, sides, and small end piece:

• The hood top has four downward pointing tabs.

Four downward pointing tabs on hood.

• Some of the sprues attach to the horizontal trim at the top of the side.  Note that there are two rivets at the front of the trim to be careful of when smoothing the trim piece.  These rivets are very faint.

The intersection of the hood and radiator with the side removed.  Notice the two fasteners on the trim, and the recess in the radiator to accommodate the trim attached to the side.  Although the trim is not free standing, recesses are deep enough to make it appear as if it is. 

• Note the chamfer on the trim requires that the side be installed to the hood from below.
• The inner surface of the sides have two tabs on the cab end, and two braces/tabs on the front where the end piece attaches.  

Cab end tabs and interaction of side and hood top tabs.

• The detail at the radiator end of the left side also includes an extremely fine internal support between the vertical post and the adjacent flange that can be knocked out with a file.

Note the small white internal support (side shown in blue, supports in white).

Pointing out the small internal support.

• The end and sides have extremely fine fingers that interlock and form a brace,  Be careful of these, as they contribute to the strength of the assembled unit. 

Note the interaction between the printed on fingers of the end beam (yellow) and sides (green).  Note the shape of the nut-holder for the coupler nut and box.  Also note the indentation in the side just behind the exhaust pipe; this indentation accommodates the cross brace/muffler assembly.

• Take care with the channels extending downward from the end.  The channels fit into the provided brass channel to make the cross piece just above the rail.  A chip to the end of the channel will be hidden by the brass should it occur.  
• When dressing the sides, not the unique profile of the mitre joint at the end, with a small scale thickness section at the end.  Subsequent versions of the model may add more chamfers to the top of these sections in order to simulate scale thickness at the top.

Note the scale thickness section at the end and be careful not to sand this off.

After cleaning these parts the hood and sides will friction fit to one another using the tabs, with the cab side of the assembly lining up.  Before beginning assembly, prepare the cab.

Preparing the Cab:

• The cab is provided as one piece.  Supports attach to both flat surfaces and to rivets.  Using rivets to accommodate supports minimizes clean up of scars on the surface. The underlying rivet can be dressed with fine sandpaper after sprue removal.  Better to cut the sprue high, and sand to the rivet.  Where supports are attached to smooth surface, they are made to be as obvious as possible.  Smooth surfaces can be dressed with the #17 blade.  Refer to drawings if in doubt of any rivet.

Cab support attachments.

• Internal supports attach just inside openings.  Openings are chamfered so that they appear to have scale thickness.  These attachements are easy to remove if you align the tool with the chamfer.  Take care not to chip the fine edges of the openings.

Attachments, just inside the door.  Note the holes adjacent to the door and side of locomotive where hand grabs attach.

• Use 400 grit paper to round any rivets where attachments were made.
• Use files to clean internal attachments.
• Use 400 grit paper to smooth the curved roof or flat expanses.  Minor diagonal lines from the printing process generally fill with primer.  Touching up sanding after primer will take care of any issues, extensive pre-sanding is not necessary. 

DK Pilot 03: Assembling the hood

Assemble the hood:

• Once the parts are cleaned and attachments are removed from the inner surfaces, test fit the parts. The hood pieces will friction fit together.  

Parts friction fit.

• After test fitting, sparingly apply epoxy to the joining surfaces and assemble with the end up, using blocks to keep all square.  Apply epoxy towards inner surfaces to prevent epoxy from seeping onto the external surfaces.  Test fit the end section to ensure the parts are aligned.

Glues pieces held in alignment by steel blocks.

• Test fit and glue the end in place.  

Test fit the end to verify alignment.

• Install the coupler nut in the end beam, using a drop of CA to hold the nut in place.

End glued in place, note the faintly visible brass nut in the coupler assembly.  Glue the nut sparingly in case it needs to be adjusted.

• After sides, hood and end are cured, test fit to cab.  The hood tabs will fit inside of the cab tabs.  Do not glue the cab in place, as the cab interior is much easier to paint with parts disassembled.  

Test fit of cab.

DK Pilot 04: Coupler boxes, cross brace, and muffler

Prepare and install the coupler boxes:

• Remove coupler boxes from the sprue. Note that there is an internal support inside the coupler box print that is easily removed.  After minor prep, the boxes will snap together similar to a Kadee draft gearbox.  The model will accept many Kadee or similar couplers. File the sides, top, and bottom of the box so that it slides in and out of the holes in the end beam and cab easily.  

Assembled box shown adjacent to boxes on the sprue.

As with other parts, separate the raft first, then cut the attachments to the angle iron portions.  Note the internal support in the left side of the coupler box as viewed from this angle.

The box will be a tight fit as supplied (there is a small tolerance built in).  File so the box slides in and out easily but does not wobble.

• Install the draft gear boxes in the narrow end and the cab using the supplied screws.  Do not over-tighten the screw as it can distort the box and push it out of level.  The outer face of the coupler box is symmetrical top to bottom, and may be installed with either side up.
• The coupler boxes remain removable for painting and coupler installation.  WDLR style couplers are supplied.

Prepare and install the muffler and cross piece:

• Remove the muffler from the sprue.  Note there is a "lip" on the edge of the muffler to be careful of.  Test fit, but do not glue, the exhaust pipe (1/16" brass tube.  Thin the section of the tube ends using a round tile to make the section appear thinner.

Muffler and brace on the sprue.

• Temporarily remove coupler box.  Apply epoxy to the mounting spaces on the inside of the sides, and slide the brace and muffler into place, aligning the hole with the exhaust ports on the sides.

Apply epoxy to the sides.

Slide brace and muffler in from below.

• Apply a small amount of CA to the brass exhaust pipe and slide it through the muffler from the outside.  Adjust the position of the exhaust pipe so that it is centered in the model, and make minor adjustments to the position of the muffler assembly to center the exhaust pipe on the ports.

Align hole in muffler with port.

Align entire assembly after sliding exhaust pipe into place.  

DK Pilot 05: Install journal boxes, cross members,and radiator.

Prepare and install the journal boxes:

• The journal boxes are designed to accept a portion of Kadee #875 knuckle springs.  Each knuckle spring will yield two springs.  Install springs into the journals with CA, epoxy journals to the provided indentations in the body with epoxy. 

Cut the knuckle springs in half, and then remove the tight winding from the ends of the spring.

Install springs into journals with CA from the back side of the journal.

Epoxy journals to sides in the provided indentations.

Prepare and install channels on the cab:

• Prepare the brass channels by chamfering them to match the cross members.  Drill a hole in the front cross beam to accept the brake rigging.  

Prepared brass cross members.

• Notch the cab end channel part to clear the coupler screw (future versions will incorporate these channels into the cab or include a notched channel part).  The channel overhangs engage with the cab body, tabs are sloped to ensure proper orientation. 

The notched part set in place.

The part is easily notched with a round file.

• Test fit the brass cross beams, note the relationship to the coupler screw.  Create an indentation or a notch to accommodate the screw.
• Epoxy the brass cross beams in place.

Example of an indentation created in the brass channel.

Example of a notch accommodating the screw driver.  The notch is not easily visible from conventional viewing angles (The position of the screw is set to accommodate a standard Kadee draft gear box).

Install the radiator:

• The radiator will press fit in place.  If you wish to permanently attach it, epoxy it in place at this time.
• On the contemporary version, without the radiator cover, it may be useful to refrain from gluing the radiator until after painting.

Contemporary version, left, as delivered right. 

DK Pilot 06: Cab and body detail.

Install hand grabs on the cab:

• Fold grabs from .6mm music wire and install in holes on cab.

Grabs installed on cab. 

Prepare lift assembly:

The lift assembly is only .2mm thick, and replicates the appearance of twisted steel.  It is very delicate, use extreme care when working with it. This step is best attempted when well rested and in possession of an abundance of patience. The assembly will press fit into holes in the body, and does not need to be glued until after painting.

• The assembly may appear wrinkled on the carrier, it will straighten once removed. 
• Begin by cutting the sprues from the raft with a sprue cutter, and then carefully cut the sprues from the part.

Lift assembly on the raft.

• The four pegs on the inside bottom of each side of the part press fit into holes on the side of the body.  Take care to cut the sprue clear while leaving as much of the peg intact.
• The most vulnerable area of the part is the "twist" in the strap.
• The part is asymmetrical.  The twist favors one side to ensure clearance on the hood detail.  The sprue and raft side of the part faces the cab.

Test fit the part, but do not glue until after painting.  The part will have a fine gap on all sides.  

• Form lift rings from .32mm wire.  Holes in the angle will accommodate the rings.
• Install rings when well rested and possessing an abundance of patience.

Form a round split ring.

Installed rings.  Rings may be secured with CA.

Take a much needed break (Bruce W.  I should have sent you two lift assemblies, just because they are easy to break.  If you need a second, please let me know).