UPDATED  22 April 2021

Modelling Hints

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Tips to help build an etched kit, for all scales


There are many different ways of assembling etched kits.  The methods I use are shown here.  They are quick, effective and use simple tools.

These tips work on N Brass kits, they may not work on other kits with a different design  approach and using thicker metal.



Using a model knife to remove parts from a fret.



Removing parts from a fret

The fret is a way all of the parts of the kit are kept together for easy handling.  Small tabs of metal hold the parts to each other.  The tabs are half the thickness of the other parts and can be cut with a modeling knife.  (Note the fret in the pictures has been painted to get better photographs, work with an unpainted fret.)

Take a knife where the blade is firmly held, the one in the picture is a Swann Morton brass handle with a No.1 blade (the plastic handled version is as good so is an Xacto knife).  Do not use a scalpel the blade can flex and snap.

Place the fret on a cutting mat with the detail and text showing.  Rest the tip of the blade on a tab and move the blade sideways until it touches the edge of the part (not the edge of the waste).  Angle the blade into the part and press firmly down.  In most cases no cleaning up of the tab is needed.  Work round the part and cut all the tabs.

N.B.  It is good practice to leave parts on the fret until they are needed.



Tidying up a rough tab



If one of the tabs has not been cut cleanly it can be taken off with a needle file.  Use a triangular needle file (a flat one will easily bend).  Stroke the needle file along the length of the edge, not across the edge.  If the file is worked across the edge it is possible to go to far and create an unwanted notch.






Opening out a hole with a tapered broach.



Opening out holes in a fret

Holes are purposely undersize so that they can be opened out to be a tight fit for the wire or part that fits into them.  As long as there is a hole right through the etch they can be opened out using a tapered broach as above.  (If the hole has not etched through drill it out with a suitable sized drill.)  A set of broaches gives you all the hole sizes between the smallest and largest broach, the equivalent of a lot of drills.

Put the broach in the hole and with gentle pressure rotate it a couple of turns (broach can be rotated either way).  File a crude taper on the end of the wire or part that is to fit the hole, this helps locate it in the hole and makes checking the size easier.  Try the part in the hole, if it does not go in open out the hole a bit more.  Cut little and check often until the part fits the hole.



Opening out a hole with a rat tail needle file.



Open out the holes while the part is still on the fret and hold the fret between two strips of wood so it cannot distort.  An alternative to a tapered broach is a round rat tail file with a fine cut.  Rotate the file anticlockwise, if rotated clockwise it will jam in the hole.







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