Files and the 2mm Modeller

by Andrew Webster

Let me convey some conventional wisdom about files and filing which has not penetrated deeply into modelling circles. I was originally in watchmaking. Now I am a financial analyst but also I assist my wife with her goldsmithing firm. Between goldsmithing and modelling benches we have about 700 files. I therefore write this article from the optic of someone who uses files to generate revenue, but also bearing in mind a 2 mm modeller's needs.

Quality of files. Many of us use cheap files for general work. Some (like me) keep them for jobs requiring cheap files (viz. to save the good ones). Excepting the latter need, always buy the best tool you can afford. Tooling up is costly and a true craftsman can do wonders with primitive tools. My aim here is to educate you about the advantages of gradually building up a modest collection of really good and appropriate files, and to help you avoid buying poor quality when better is within your means. Good files are not only nicer to have, but they do the job quicker and more precisely.

Most files sold today are truly vile Chinese (or other Asian) efforts, sometimes even sold under well-regarded UK brands. Don't get me wrong. I've just bought Chinese and Indian groceries for supper this weekend. But their files are garbage. Their cost has doubled and tripled over several years while their quality remains dismal. The ones at £1.99 (or cheaper) for 12 are the same as those £1.49 apiece in the bin on the hobby shop counter. For £1.99 a dozen they are a worth having for cleaning up solder and filing those stainless steel coupling rod etches. The teeth soon break off when used on steel but your good files are not blunted. Moreover, a terminally dull Chinese file becomes a splendid scraper or lathe graver.

What really sets me off is when this nastiness is sold as Swiss pattern files. Swiss pattern files comprise a large group of tough, chrominum-steel, precision fine-cut files 6-8" long and needing fitted handles. The type originated in Switzerland and most come from there. The tips are small and the tapers particularly long, except for the flat and pillar shapes of course.

The best Swiss files, pattern-type or other type, are marked Vallorbe or Grobet. You cannot buy better and they cost accordingly. Swiss pattern cost £10-15 apiece; escapement files (high-grade, delicate needle files) two-thirds apiece; and a set of six Swiss needle files normally cost £20-25. You can sometimes get sets of six or twelve Swiss needle files for a downright good price, but otherwise it is best to systematically build up your collection of Swiss files one at a time, as finances permit. All Swiss files should be considered lifetime investments and candidates for the birthday and Christmas lists. They are thus affordable.

File terminology. The measured length of a larger file length is usually that of the cutting portion, exclusive of the tang. The tang is the tapered, rough end meant to fit in a handle. Some files, like needle files, have integral handles. For these files the measured length includes the handle. Files are usually single- or double-cut. Single-cut typically have their teeth cut in rows 25° normal to the axis of filing. An example is the mill file, named after its origins in sharpening large mill saws. A big, sharp mill file is ideal for chamfering 45° edges on plastikard building sides, à la Iain Rice. In this case you place the file flat on the bench and rub the work along it. However, single-cut files of any size can will give a smooth finish, hand-held or flat on the bench.

Double-cut files have two rows of teeth: one at 25° degrees and the other, a finer cut, crossing at 40-45.° These are used with heavier pressure. The triangular teeth cut faster but the finish is rougher. So, we see that single- or double-cut, angle of tooth-row, and fineness of the teeth (i.e., number teeth per inch) are important selection criteria.

Do not confuse single- or double-cut with grade. The former refers to number of tooth rows. The latter means fineness of the teeth. Besides a slightly different grading system, German tooth-rows are cut on a more extreme angle relative to the axis of filing. This theoretically makes for smoother cuts, but I doubt you could tell the difference. In either grading system, the higher the number, the finer the teeth, down to dead-smooth #8.

The table shows the Swiss grading system & approximate German grading equivalents:
General Type
German Cut
Swiss Cut
Teeth per inch
4" - 8" long, less tang
#00
Extra-coarse
30-38
ditto
#1
Coarse
40
ditto
#2
#0
50
ditto
 
#2
79
ditto
#4
#3
117
Needle & Escapement
 
#00
51
ditto
 
#0
64
ditto
 
#1
79
ditto
#3
#2
97
ditto
#4
#3
117
ditto
#5
#4
142
ditto
#8
#6
213
ditto
 
#8
260

The Swiss system seems to apply to files originating in Britain, Italy, France, and most other countries. Alas, few decent files are made in the UK today. I treasure my ancient Stubbs and Bedford needle files. Not as precision-cut as Swiss, but representative of the former, good quality norm. German made files normally conform to German grading. They are very good quality, albeit not the absolute best, and fairly easy to find. Note that some German-grade files, like Friedrich Dick, are actually Swiss made!

As a rule, anything sold as a minifile or microfile is just a short, #2 cut Chinese needle file being sold for far too much. Short length does not a useful file make. Fine teeth and delicate profile are what you need. The handle can and should be relatively long for reasons of control. What you therefore need (nay, what you dream of) for tiny work is the genuine Swiss escapement file. We shall return to these.

Inspect before purchasing. Do this whenever possible. Inspection is less important if you buy from a watchmakers' or jewellers' supplier. Most only sell the best. Nonetheless, nowadays many of these firms carry the nasty stuff for their miserly clientele but, fortunately, they label and price them as economy. Unfortunately there are some US distributors of professional tools (i.e., in California) who market completely unusable Indian-made files in a misleading manner. I know a Canadian supplier who gave away the files he was shipped because they were too bad for his most penny-pinching customers. The samples he was shown were not what he was shipped and no refund was possible. Beware.

Parallel surfaces should be parallel; teeth should not look worn or chipped; teeth should be fully cut rather than just burred up; edges and corners should be sharp; the cut indicated should be the actual cut of the teeth; see how well the file cuts your thumbnail; and ask about the origin.

Building up your collection. First off, let us stick with the Swiss grading system. You need two genuine Swiss-made Swiss pattern files, starting with a #2 cut flat for general work, 15mm width. I cannot imagine coping with a far coarser mill file for general modelling. This would be hell to finish a footplate edge with. Hats off to those who can. The ideal for thin sheet work is a #4 cut flat, your next purchase. Flat means parallel on all sides, not wavy or curving down towards the tip. Half-rounds, rounds, barrettes, and other shapes are hardly essential.

A few words on big, coarse files. A second-cut axe-file is essential for ripping out material and saving your Swiss pattern files. Quality is less important here. Even a really cheap one will do if it passes inspection. Incidentally, Axminster sell a reasonably-priced Swiss-made Farmer's file which is just the ticket. You may want a second axe-file strictly for plastikard. It is damnable frustrating to cut plastic with a worn file. Soft materials usually need the sharpest teeth. I also have a really coarse brute 14" long less tang. It powers through aluminium angle-iron 50 by 50 mm. These, and a 6mm round chain-saw file, do most of the support tasks.

A set of six tanged files, half-way between needle and hand size but coarser (say, cut #0), is very useful. These are often sold as warding files although the name technically refers to a thin, wide, flat file with tapered edges used for entering and enlarging slots and notches. The set you want has one of these and five other tapered shapes. These sets often have come with an interchangeable handle. The set should be good but not necessarily Swiss. Also get a tungsten point file, available from all ironmongers. These are thin, flexible, flat files about 5" over the integral handle. They are inexpensive, handy, and tough.

Most needle files used by modellers are cut #2. These are too coarse for much 2mm work so also get a set of six #4 cut at your earliest opportunity. Eventually you will want one set of needle files in all shapes. For our purposes, my first choice would be a dozen-set of number fours.

Swiss needle files make others look and work positively primordial, so save up. The small file I use most is a Swiss #6 cut flat needle file, 5mm wide and 1mm thick. Special order one, if necessary, as a priority. Superb on etches. Now to escapement files. Fortunately only several of these costly items will do wonders. A #6 cut square will get you into intricate tender frame cut-outs. A #6 cut rat-tail, with a very fine point, will let you enter holes smaller than #70. Don't use it as a reamer! Keep that delicate point for drifting holes sideways by in-and-out filing. A #6 cut extra-thin flat is invaluable for cutting slots, i.e., on the rear buffer beam of Bob Jones' J72! A makeshift is to grind a cheaper #4 or #2 cut needle file very thin.

Often files can be improved by grinding or stoning an edge blind. On a flat file you would make one narrow edge really smooth, assuming it is not so already. Afterwards it will be much better for squaring corners. This treatment will vastly improve a mediocre file. You can slave away with a double-sided India stone and oil, or use a grinder and finish it on a stone. Be extremely careful if grinding to take the lightest of cuts. Quench the very file often in water or the temper will be gone. It must not heat beyond the temperature your fingers can take.

Where to buy good files. I recognise that many members have no idea where to find suppliers of professional tools of this nature. I understand that Nathan Shestopal (Shestos) sells some watchmaking and other tools by mail (website is www.shesto.com). I cannot vouch for their range or quality of products, but they do sell to modellers.

Look elsewhere too. You should find listings in the yellow pages of a big city under headings like watchmaker's and jeweller's supplies. London should have lots. These places normally accept credit cards and ship to anyone. The larger firms have excellent illustrated catalogues which they may charge for. These are worth the price but usually they do not contain current prices. If all they offer is a list of products and no catalogue, then look elsewhere. It seems to me that your local club or group might get these catalogues as a shared resource.

I gather that an annotated list of mail-order suppliers would be valuable to members. I will compile one of a half-dozen firms in Canada and the US, if someone else will do this for the UK. Any takers?

Final thoughts. The catalogue of a professional supply firm will show many fascinating files with obvious modelling application; i.e., bulls-foot, riffler, screw-head. However, stick to your priorities and start off with the basic types, bearing in mind that a few excellent files are better than many poor files.

Part 2 - Care and Use of Files

In the paragraphs above we dealt with terminology and selection of files. This section concerns the lesser-known aspects of their care and use.

Take care of your files. Unless you work in a self-replenishing, file-rich environment, never use new files on hard material like steel. This blunts them quickly and reduces their utility on materials requiring a really sharp edge; i.e., brass. Reserving "seconds" for steel is accepted practice for watchmakers, although really precise steel finishing requires a sharp file. I think it unlikely, though, that you will be making click-springs and balance regulators for your locos! Mark your "steel only" files with paint or a notch in the tang or handle

A few years ago my wife was perplexed that a year of filing wax ring models had dulled a £100 set of 18 escapement files. The problem, I discovered, was tossing them into the catch-tray on her bench. You will swiftly dull files by letting them rub against one another. Now she sets her files down and keeps them tidy in trays and they stay sharp. Make the effort to return small files to their plastic pouch or their box. Avoid storing them on the bench in a can or a wooden block drilled with holes. This may be convenient, but files left exposed to room air are more apt to rust. I do not know why, but fine tools keep better in boxes, pouches, drawers, or cabinets. Vapour-phase inhibiting (VPI) paper or packets help. These are often included in packages of new tools. Certain dried foods (i.e., Japanese seaweed and noodles) contain VPI packets. Packets or paper can be renewed by warming in an oven.

As a rule: never file what you can sand and never file what should be ground. Anneal hardened steel before trying to file it. Heat it to cherry red and allow to cool slowly. Piano wire, which resists annealing, damages even Swiss files and all but the costliest Lindström nippers. Cut it by notching with an unimportant file and then snap. Diamond files, which have dropped greatly in price, are not as handy as you might think. They cut slowly because they are more like an emery board than a file. Most seem to be Chinese or Russian in origin nowadays. The diamond bits tend to be more like dust than chips, and they are pressure-set into imperfect metal. They do not cut well to begin with and soon they break off. Swiss diamond files are far superior in terms of durability but are prohibitively expensive.

On no account should files be on the bench when soldering with acid flux. These fluxes spit and invariably land across the bench on files and on Moore and Wright squares. Soon these tools are stained and pitted. I cannot imagine treating a fine Swiss file this way. A low-viscosity resin flux answers most of our needs without the corrosion. I use No Clean resin flux from the Canadian firm M.G. Chemicals for most of my work. Similar products are available from most electronics suppliers. The residue can be cleaned with a toothbrush and meths.

Oil files when necessary to prevent rust (WD 40 spray is good for preserving tools, and generally great stuff to have around). Never oil over acid contamination. If necessary, scrub the file with baking soda and water to remove the acid and carefully dry.

Oil seldom if ever prevents clogging of files but chalk often works. Do not use steel brushes to clean other than the coarsest of files. They are hard on the teeth and questionably efficacious. Instead, push a piece of brass along the tooth-rows. A strip 2mm by 10mm in section works well for smaller files. A cheap brass brush can also be useful.

File handles. Every file needs a handle for control and safety. Many modellers buy plastic needle-file handles with quick-release chucks. Needle files already have handles. The add-on handles are far too big, resulting in loss of fine control and a tendency to overwork and damage the file. However, using a tanged file without a handle is really doubleplus ungood. There is zero control and you are asking for a pierced palm (or worse, if filing in the lathe). Cylindrical wooden handles, with a brass ferrule to prevent splitting, are best for larger flat files. Shaped handles are best for half-round, round, and barrette forms. In this respect the plastic Skrooz-On type are ergonomically sound and easy to attach. Otherwise turned wood is good. Avoid triangular handles completely.

To fix a wooden handle, check the depth of the hole in the handle, deepening if necessary. Use a vice to snap off excessive tang length. The steel is soft there and easily flexed to breakage. Force the tang into the handle (straight!) and fix by striking the handle, never the blade, on a hard surface. This is also how you tighten loose files and hammer heads. If you are good with a torch, quickly heat the tang to red and burn it in, then strike it in.

Filing technique. Files needle-size and above normally require a two-hand hold with the work held down. Often this means clamping the work in a smooth-jawed vice or in a lathe chuck. You can glue it with UHU (or whatever) to a stick, a piece of ply, or the bench edge. You can also file one-handed with the work held in a pin vice.

When filing one-handed, hold the work against the bench edge (preferably a hardwood strip) or a bench pin of the sort jewellers use. Alternatively, a miniature version of a carpenter's bench hook helps secure the work and it preserves the bench edge. This is a piece of 20 mm wood (not ply) measuring 100 mm square. Under one edge screw and glue a wooden strip. This will hook against the bench edge to hold the board in place when you thrust (viz. file forward). Glue a 50 mm by 100 mm piece of 1/8" or 3/16" cork on the top side, to the right if you are right-handed. It is often easier to hold small items down, for filing, on cork rather than a hard surface. Beheaded pins, driven into the cork side, may work better than fingers.

Into the exposed wood half of the surface you can carve latitudinal grooves. Tapered grooves, starting at the left edge, are for filing wire to a taper. Hold the wire in a pin vice and rotate as you file. Longer grooves, of constant depth, are used for filing wire half-round such as for guttering. Another method is to attach the wire to a drawing pin, stretching it right to left with a pin vice or pliers holding the loose end. Then, draw-file with a #4 cut flat. This may be best done in conjunction with a groove.

Always endeavour to use the full length of the toothed portion on each forward stroke. Lift on the pull-stroke or you will find it hard to file flat. You will also wear your files out quickly especially on harder metal. Curved surfaces are another matter; my wife is a master at filing complex curvilinear shapes, and she rocks the file back and forth like most goldsmiths do.

Resharpening files. This is possible by chemical etching. Resharpening is only worthwhile if the file is top quality and the teeth are dulled, not broken by use on something glass-hard. If you come across a collection of intriguing files from some departed watchmaker, the acid treatment can resurrect the lot and set you up proper. They will never be just like new, but they will be perfectly serviceable.

I have resharpened files using sulphuric acid from a car battery, concentrated by heating in a ceramic pot over the stove! Don't think of using such strong acid unless you finished your undergrad chemistry and, please, buy the acid concentrated! A safer alternative appears to be to use common, less caustic, ferric chloride solution as sold for etching circuit boards. You can also, and I am serious, leave files out in the rain to rust. It works rather well. After etching (or rusting) you should remove the oxide chemically. Once again something nasty - potassium cyanide - is best. However, those without chemistry degrees can manage with common rust-destroyer solution (from any automotive supplier) and a brass brush, followed by drying in a warm place and then oiling.

All is not lost if the file is unsalvageable. With the Editor's permission, you can expect from me in the foreseeable future an article on making cutting tools from dead files and from blank steel stock.

 

Website Editor's note, March 2009. This article was written about nine or ten years ago. In March 2009, I was contacted by CORRADI SpA, who were established in 1910 in Italy. They are the only Italian manufacturer of Precision Files (“Swiss Pattern”). The article doesn't mention Corradi, but they might also be worth investigating as a manufacturer of files.