Scratchbuilding Workshop

The Environment

Just to start: I am not lucky enough to have a real workshop, a room dedicated only for my hobbies and the tools needed for them. But I have a corner with a working table usually used by me. As this table was always in the living room, even if in its dark corner, I was always oblidged to clean the desk after work and I cannot leave all tools, models and parts lying around until the next model building session. I think this is still better than for many fellow modellers, who perform their scratchbuilding activity at the corner of the kitchen table.

The Working Table

I think the Working Table for scratchbuilding should be large enough to accommodate a small clean surface besides the vise and place for the power unit for soldering and other tools, and some surface for these tools as well. It should be rigid enough to withstand smaller hits by the hammer and filing jobs with parts fixed in the vise. It is very useful if the table is long enough to build a short test track on it, but I don't think this has a very high priority. In my opinion the running tests require a very small portion of the model building and for that time one can build a test track elsewhere - on the dining table for instance. More important is, however, to have enough place around the working table for filing and cutting jobs. An electric outlet is necessary as well.

It is useful to have the tools, parts and models on shelves around the working table. It can be very annoying to search all these items in different corners of the house while building a model.

The Lamp

I found the best way to have two at least 60W lamps, as this ensures shadow-free visibility. I used so called architect's lamps for a long time, those desk lamps with long pantograph levers to move them into the position of the best visibility. One thing was, however, very annoying with these lamps. The best visibility could be achieved, when the lamps were closed to my eyes, above or beneath my head. Unfortunately it was almost unavoidable that I touched the lamps' cover with my forehead. And they were HOT. Thus I was happy to buy an architect's lamp with fluorescent tube. This has all the benefits of a usual lamp, and being a not concentrated light source one needs only one to get shadow-free light. The lamp was of Chinese origin and its ballast coil burned out after two months of use, but I replaced it by a usual fluorescent tube coil. The only drawback of this lamp, that sometimes its light is not intensive enough for very small scale jobs. I plan to add a small 12V halogene lamp with concentrated light for such cases. But I recommend the architect's lamp with fluorescent tube for all scratchbuilders.

The Vise

I purchased a small parallel vise with ball joint and I have never regretted this. The large ball joint allows tilting the vise in all directions. Although the vise body is from Aluminium, its faces are from steel and they have a V-slot for fixing round pieces, like rods or tubes. The body is probably not the strongest one and combined with the ball joint it is probably unsuitable for heavy jobs. But for filing and sawing small brass parts it is strong enough.

The vise originally had a rubber vacuum fixation. This was its weakest part: it released just when one needed most. Thus I removed the rubber with its lever and screwed the vise fix on a piece of thick particle board. This board is fixed on the Table with C-clamps.

The Soldering Surface

The Table is flat enough for most jobs, but the plastic surface does not withstand any soldering activities. They require a surface that is heat resistant. Unfortunately metal surfaces aren't ideal, as they conduct heat well. As a first approach I casted a plaster tile. It was flat and heat resistant but not really strong. After a while it was scraped and once, when soldering with the propane torch it brake into several pieces. I found, however, a special tile from Italy, a very strong and flat version, very popular nowadays, called "porcelain" tile. I use smaller piece of this as working surface. Unfortunately it also did not withstand a concentrated flame of the propane torch and brake into two, but avoiding such harsh handling it works well. It even withstands smaller hits by the hammer. You can see on the picture of the Working Table near to the vise. I also have a larger, apr. 30x30cm (12x12") piece of the same tile and I use it as surface when making pictures of my parts and models. You can see this grey textured flat surface below many of my models here.

The Power Source

Although all HO DC modellers have a 12V DC Supply, this is not the best for Scratchbuilding: usually the power of 30-50 Watts is not enough and most such supplies cannot even deliver it for longer time. I've built my Power Unit from a scrap 100W 2x12V transformer. I made an aluminium box for it with switch and fuse for the primary circuit. There are basically two outputs. One 2x12V AC, I use as 24V for the Weller soldering iron and the 12V side for Resistance Soldering. The other output is a non-regulated 12V DC output. It is not filtered intentionally as the speed control of the Proxxon Motor tool needs rectified but unfiltered (pulsed) DC. The DC part is protected by a 5A fuse and the DC current is measured by an old analog meter. In order to have low internal resistance the analog meter is powered by an amplifier. Its range can be switched for 1A and 5A. Both the AC and the DC outputs are connected to banana sockets but the 12V DC output comes also on a 2-pole AMP Mini-Module© socket. This is a cheap and safe solution. I mounted this type of plug on all of my tools requireing 12V DC.

Tools

Measuring Tools

Scriber

I use a simple scriber with replacable pin. This allows to change the pin if becomes dull. I often paint the brass surface black before scribing on it for better visibility. The easiest way to do it to use black marker pen. It is easy to remove, but admittedly not really durable.

Steel Ruler

I have a 300mm (12") steel ruler. One side with mm scale, the other one with 0.5mm scale. Very useful tool, but to use the 0.5mm side one needs good eyes and should keep care of the parallaxis errors that might be considerable as the ruler is 1mm thick!

Digital Caliper

I have a 150mm (6") Mitutoyo digital caliper. It is very exact, but in my opinion one cannot rely on its 0.01mm (0.0004") scale: these values depend very much on the pressure you apply while measuring and also on the distance of the measurement point. You will measure less length or diameter when putting the workpiece at the end of the faces than close to the ruler part. I used for a long time a Russian 1/10 mm vernier caliper too. Although a tool of lower quality, it was quite exact. I've cannibalized it to make my home made Height Gauge.

Height Gauge

This height gauge was made by myself. I needed a height gauge but found the price for the industry quality items extremely high. Thus I made one from an old Russian caliper. The brass block was milled to shape and a slot was milled in the top. The outer jaw of the caliper was grinded away. A small brass rod with a marking needle forms the height gauge.

The only problems arise because of the brass rod fixing. It is fixed by two M2 screws on the back side. If these screws bacome lose, the height will be uncertain. Thus it is necessary to check both the brass rod and needle fixation before using the gauge. Of course a professional height gauge usually has anothe nice fitting, the set screw. That allows exact positioning up to 1/20 mm. This solution lacks of the setscrew, but with some patience it can be set according its accuracy level.

Cutting Tools

Piercing Saw

I could never understand why the so called jeweller's piercing saws cost much more than a usual fret-saw used by woodworkers. After all it is a similar construction, just the piercing saw is smaller and easier to use. Thus instead of buying an expensive jeweller's saw I made a piercing saw from a cheap $3 metal saw.

The main job was to replace the blade hooks by a similar piece with screw fixation. It was made by a lathe, but the head that secures the part against turning was a hexagonal one with a rather unusual 7mm distance between flats. This was made by filing it to size.

I use for sheet cutting the finest blades I could get, they are 00 size. This means the pitch is 0.4mm (0.016") thus it is possible to cut 0.5mm (0.02") brass sheets. Unfortunately no blade is available for the 0.3mm (0.012") sheets, even the finest standardized size, the 000 has 0.35mm (0.0138") pitch, larger than the sheet thickness. With enormous care it was possible to cut thinner sheets than the saw blade pitch, by keeping the saw slanted, but usually I cut thin sheets by scissors.

Universal Scissors

I use universal scissors to cut thin brass sheets and in case if the flatness is not very important. Unfortunately the metal scissors bend the sheet while cutting and I found it difficult to align it again. The best results show if one side is narrow, than the other one and the narrow side will bend, but the wide one not so much, just at the end of the cut.

Motor Tool

I have a small but quite high quality motor tool from Proxxon. It has a 12V 100W motor, roller bearing close to the chuck and a fixation with 34mm diameter. When fed with 12V unfiltered DC the speed can be regulated with a turning knob on the head. There is a small chuck available that accommodates drill bits and other tools with up to 3.2mm (1/8") diameter. I also have a collet set for it, but the maximal diameter of the largest collet is the same as the chuck. As the chuck is quite exact, I rarely use the collets.

I made an aluminium block with 34mm hole that serves as fixation for the drill. The CNC-Drill uses this fixation too, but I often fix the motor tool horizontal into the vise. This is the usual position for grinding. For simple drilling I keep th etoll by hand, as except the CNC unit I have no drill stand.

The drill set I use for most jobs with the motor tool contains the following drill bits:

0.4mm (0.016")
0.5mm (0.02")
0.6mm (0.024")
0.8mm (0.0315")
1.0mm (0.04")
1.2mm (0.047")
1.3mm (0.051")
1.5mm (0.06")
1.6mm (0.063")
1.9mm (0.075")
2.0mm (0.079")
2.4mm (0.095")
2.5mm (0.098")

The 1.3mm drill bit is necessary for drilling core holes for M1.2 threads. The 1.9mm is very useful to get exact and round 2mm holes for shafts.

I often use abrasive disks for with the motor tool. When centered well, they do a much mor exact job than the files. For rough grinding I also have a set with emery paper glued on the surface. The usual problem with these tools how one can keep the piece without getting the nails grinded too.

Reamers

I have a few reamers to make exact round holes. The sizes I use are 2mm, 2.5mm and 3mm diameter. Unfortunately these reamers finish a bit larger hole, thus the shafts rotate freely in the holes - perhaps too free.

There is another set of conical reamers available. It contains a set of thin rods grinded to a five-angle cross section. Being conical they allow to enlarge holes in a fine way. Unfortunately this only works for thin material. The five-angle cross section does not allow to remove larger amount of material.

Threading Taps and Dies

The modeling in HO scale needs taps and dies that are too small to find in usual DIY shops, they offer M3 as smallest size. I purchased my sets of M1.2, M1.4, M1.6 and M2 taps and dies at small specialized mail order companies. I did not buy the smallest ISO standardized size, the M1.0. The price of M1.0 tools and hardware is considerably higher than even M1.2 and does not offer too many advantages. Of course I have the core drills for these taps as well, except the 1.15 needed for M1.4. They are those the 1.0 mm diameter for M1.2, 1.3mm for M1.6 and 1.6mm for M2. I use 1.2mm diameter for M1.4 tap; this results in a bit lose threads, but still acceptable.

Forming Tools

Files

I think for scratchbuilding the most important tools are the files. In small scales one does not need larger files anyway, I have only one single 200mm (8") long flat file, which is used for longer edges. For smaller scale jobs there are two sets of Swiss files available, one 140mm (5.5") set containing flat, square, half-flat, round and spade form files. In order to access very thin slots I grinded down the back of the spade form file in a length of 10mm (0.4") thus it is only 0.6mm (0.024") thick. The other set of Swiss files is 10mm (4") long and contains the same shape files, but in a finer version. Besides this I purchased two so called "rat-tail" files on the Geneva flea market. They are round having a minimal diameter of apr. 0.5mm (0.02"). These are ideal when small holes should be enlarged with an offset. They are also very sensitive.

Grinders

Basically I use the motor tool's abrasive disks to grind. If possible I fix the motor tool in the vise and keep the piece to be grinded by hand. I find this safer than keeping the motor tool in hand.

To make flat surfaces or straight edges I use emery paper on the flat tile, and move the part on it.

Soldering Tools

For doing all possible soldering tasks on an optimal way, the scratchbuilder needs three different tools. The soldering iron is perfect for soldering small items together. The butane torch is the best tool for soldering large sheets of metal, while th eresistance soldering unit performs best there, where the other two do the job with compromise: when one wants to solder small items on a large sheet of metal.

Soldering Iron

As the quality of the soldering iron is cruicial for both electronics and scratch building work, I decided to buy a high quality temperature controlled soldering iron. These tools are usually sold as kits together with a transformer, that also includes the temperature control circuit. I considered as wasted money to buy an extra transformer, if I already have a Power Source on my table. The extra transformer would need extra place too.

Thus I decided to buy the Weller 3001 type iron. This is a 50W temperature controlled tool, where the control electronics is integrated into the iron's handle. This way the soldering iron needs only simple 24V AC, that is anyway an output of my Power Source.

I also purchased a range of different soldering tips. One thin for electronics jobs and soldering handgrabs. A medium for usual work and a thick one for the case if more heat should be applied.

Butane Torch

I consider the butane torch as a necessary tool for scratchbuilding. It allows to solder metal sheets, parts of a cab or boiler to each others resulting in an almost invisible joint. There are several torches available on the market. For small scale modeling, however, the large ones, using an external gas tank, are unusable. They deliver so much heat, that the thin brass sheets melt, or at least will be annealed immediately. Even the smaller vertical types are a way too big. I use two types, both pencil like ones. The smaller sometimes cannot heat up larger sheets, the larger is sometimes too hot. Unfortunately the smaller torch is hard to regulate. It is very important when doing soldering jobs, that the torch gives constantly the exact amount of heat what we want. A torch that suddenly changes the gas flow while soldering can destroy our model.

Resistance Soldering Tool

The resistance soldering unit was the last one I started to use. For long time, when it came to jobs where a small item was to fix on a larger surface I used epoxy glue. A resistance soldering unit does this job better. I've built my unit from scratch.

I salvaged a carbon rod from an AA size battery. It was cleaned and fixed inside a brass tube that had 4mm bore. As during not only the carbon rod, but also the brass tube becomes hot, I mounted them inside a wooden file handle. The thick stranded cable is screwed to the end of the brass rod and has a hole at the upper end of the wooden handle. The other pole is connected to the workpiece using a strong clamp.

I use as transformer my Power Source. It gives the required 80-100W on its 12V AC output. A very important part of a resistance soldering unit is the foot switch, thet switches the primary voltage of the transformer. I constructed my switch from a standing lamp foot switch. I mounted the switch on a piece of plywood and mounted a foot pad below. This is very important: the foot should be placed conviniently while the modeler sets up the parts for soldering. If you need to keep your foot above the switch for a long time, you become tired and you will switch the soldering current in an improper moment. This can destroy the model.

Other Soldering Tools

One needs a few other tools for unsoldering soldered joints. In a simple case it is possible to unsolder just by heating the parts and wait until it falls apart. Sometimes this is not possible because the parts are mechanically fixed. In these cases the tools, that remove excess solder, can be very useful. Basically one can use two tools for this purpose. One is the stranced unsoldering copper cable, that sucks up excess solder. The other is the solder pump. This has a preloading spring that should be pushed. The tool's teflon tip will be positioned very close to the soldering joint and the joint will be heated by the soldeing iron. Triggering the spring the pump removes the excess solder.

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