Tools - how to equip a basic workshop and assemble your kit - BASIC
Posted: Sat Nov 07, 2015 12:16 pm
Armortek models are intended to be assembled with the minimum of simple hand tools. The humblest of tools are often the most effective.
The fits of Armortek parts as designed are very precise on tolerance and as manufactured are very accurate. It's generally the case that if an Armortek part appears not to fit, it's either been fitted incorrectly, or it's not been cleaned up mechanically. It's highly unlikely to be a manufacturing or design issue but see below under Preparation for further advice on assembling your model.
Tools fall into two categories, those for preparation and assembly.
Assembly
The majority of fasteners are set screws and nuts.
Fasteners are:
CSK SKT - countersunk socket scew (driven with a hex key)
CAP HEAD - Cylindrical head screw (driven with a hex key)
CSK SLT - Countersunk screw with a slot key (driven with a plain screwdriver)
SKT SCR - Headless screw (grub screw) (driven with a hex key)
SHD SCR - Ground and stepped precision screw (driven with a hex key)
The fasteners are all metric and the nut sizes relate as follows:
M3 = 5.5mm across the flats
M4 = 7mm
M5 = 8mm
M6 = 10mm
Split pins are used in some track assemblies.
These require spanners, Allen keys and screw drivers:
Spanners (wrenches) 5.5mm, 7mm, 8mm, 10mm for hex head set screws
Allen (hex) keys 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm for cap head and socket countersunk set screws
Screw drivers small flat blade 3mm and 4mm.
Small adjustable spanner (monkey wrench) for tightening nut and bolt combinations and making minor adjustments to components
Long nosed pliers for holding nuts and bolts in awkward places
Engineer's pliers for general use
Some components such as bearings are an interference fit. Hand assembly will usually be all that is required, a rawhide and brass faced hammer is useful in some cases:
For work holding, a small engineer's vice is useful but not essential:
or
Some components require precise setting square or at a specific angle (such as axle arms). A combination set square will be very useful:
Preparation
Components are finished to a very high standard but assembly will be made much easier if some final preparation and trial fitting is done. Although parts are deburred mechanically in manufacture, there may inevitably be some remaining burr to remove. Straight edges, sockets and bush seats need particular attention as do any surface witness marks where a close or interference fit is required.
If you're having difficulty getting parts to fit, bear in mind that the all the parts fit in the virtual CAD model. It is in the machining process that small inaccuracies are inevitably introduced. These are known as tolerances. Each part will have a specified tolerance, the amount of deviation which is acceptable without making it impossible to fit. This is where we hit a problem well known by engineers. Tolerances can cancel each other out or if, you're unlucky with your assembly sequence, they can build up cumulatively, which engineers call "compounding of tolerances".
If you find you're having problems with assembly, here are some things to try:
- Leave fasteners loose in the first stages of assembly and only tighten once the parts are lined up. If you tighten fasteners as you go, you may find parts misaligned. Wait until you're satisfied with the overall assembly before applying threadlock.
- Clean out holes and de-burr edges. Some parts may need to be dressed with a file to ease the fit.
- Start with the machined parts and add the sheet metal parts last.
- Try to rearrange parts or change the assembly order. This will allow you to get most parts close to fit and you will then be able to see which parts need to be adjusted for a good overall fit. If you start adjusting the wrong things, you may well compound the problem and end up in a vicious circle.
- The easiest things to a adjust are the angle brackets which join machined parts. They may require easing or fastener holes may need to be moved slightly. This is perfectly acceptable and won't affect the rigidity of the structure. The holes may have ended up slightly off because of the tolerances in the bending process but this is easily fixed.
- Final word: It's best to fix problems at source rather than reshaping the last piece which refuses to fit.
Scrapers provide a finish to the parts removing any manufacturing witness marks and allowing a perfect fit. No self-respecting engineering apprentice would have been without a set of engineer's hand scrapers. They cost very little but are essential for removing burrs, sharp edges and any irregularities in surfaces. They are simple to use, effective and cheap. An example:
Finally, for preparation, a set of files, wet and dry abrasives and a simple deburring tool are useful:
Finally, although not essential to assembling a kit from the box, some personal protective equipment is worth considering later on, particularly if contemplating using rotary tools and or spray equipment. A minimum set would include a respiratory mask and some basic eye protection:
Hand protection is worth considering. Barrier cream and disposable latex gloves protect the skin and help with cleanliness but offer little protection against mechanical hazards such as cuts, abrasion and splinters/swarf (more appropriate to customising a model). Tiger Grip Nitrile gloves are popular:
http://www.eppco.net/tiger-grip-gloves
A new generation of cheap safety gloves tailored to specific ranges of hazards is becoming available from companies such as Uvex. The following cover most of the potential hazards which might occur in model engineering:
http://www.uvex-safety.co.uk/en/product ... ynomic-XG/
http://www.uvex-safety.co.uk/en/product ... uvex-C500/
The fits of Armortek parts as designed are very precise on tolerance and as manufactured are very accurate. It's generally the case that if an Armortek part appears not to fit, it's either been fitted incorrectly, or it's not been cleaned up mechanically. It's highly unlikely to be a manufacturing or design issue but see below under Preparation for further advice on assembling your model.
Tools fall into two categories, those for preparation and assembly.
Assembly
The majority of fasteners are set screws and nuts.
Fasteners are:
CSK SKT - countersunk socket scew (driven with a hex key)
CAP HEAD - Cylindrical head screw (driven with a hex key)
CSK SLT - Countersunk screw with a slot key (driven with a plain screwdriver)
SKT SCR - Headless screw (grub screw) (driven with a hex key)
SHD SCR - Ground and stepped precision screw (driven with a hex key)
The fasteners are all metric and the nut sizes relate as follows:
M3 = 5.5mm across the flats
M4 = 7mm
M5 = 8mm
M6 = 10mm
Split pins are used in some track assemblies.
These require spanners, Allen keys and screw drivers:
Spanners (wrenches) 5.5mm, 7mm, 8mm, 10mm for hex head set screws
Allen (hex) keys 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm for cap head and socket countersunk set screws
Screw drivers small flat blade 3mm and 4mm.
Small adjustable spanner (monkey wrench) for tightening nut and bolt combinations and making minor adjustments to components
Long nosed pliers for holding nuts and bolts in awkward places
Engineer's pliers for general use
Some components such as bearings are an interference fit. Hand assembly will usually be all that is required, a rawhide and brass faced hammer is useful in some cases:
Components are finished to a very high standard but assembly will be made much easier if some final preparation and trial fitting is done. Although parts are deburred mechanically in manufacture, there may inevitably be some remaining burr to remove. Straight edges, sockets and bush seats need particular attention as do any surface witness marks where a close or interference fit is required.
If you're having difficulty getting parts to fit, bear in mind that the all the parts fit in the virtual CAD model. It is in the machining process that small inaccuracies are inevitably introduced. These are known as tolerances. Each part will have a specified tolerance, the amount of deviation which is acceptable without making it impossible to fit. This is where we hit a problem well known by engineers. Tolerances can cancel each other out or if, you're unlucky with your assembly sequence, they can build up cumulatively, which engineers call "compounding of tolerances".
If you find you're having problems with assembly, here are some things to try:
- Leave fasteners loose in the first stages of assembly and only tighten once the parts are lined up. If you tighten fasteners as you go, you may find parts misaligned. Wait until you're satisfied with the overall assembly before applying threadlock.
- Clean out holes and de-burr edges. Some parts may need to be dressed with a file to ease the fit.
- Start with the machined parts and add the sheet metal parts last.
- Try to rearrange parts or change the assembly order. This will allow you to get most parts close to fit and you will then be able to see which parts need to be adjusted for a good overall fit. If you start adjusting the wrong things, you may well compound the problem and end up in a vicious circle.
- The easiest things to a adjust are the angle brackets which join machined parts. They may require easing or fastener holes may need to be moved slightly. This is perfectly acceptable and won't affect the rigidity of the structure. The holes may have ended up slightly off because of the tolerances in the bending process but this is easily fixed.
- Final word: It's best to fix problems at source rather than reshaping the last piece which refuses to fit.
Scrapers provide a finish to the parts removing any manufacturing witness marks and allowing a perfect fit. No self-respecting engineering apprentice would have been without a set of engineer's hand scrapers. They cost very little but are essential for removing burrs, sharp edges and any irregularities in surfaces. They are simple to use, effective and cheap. An example:
http://www.eppco.net/tiger-grip-gloves
A new generation of cheap safety gloves tailored to specific ranges of hazards is becoming available from companies such as Uvex. The following cover most of the potential hazards which might occur in model engineering:
http://www.uvex-safety.co.uk/en/product ... ynomic-XG/
http://www.uvex-safety.co.uk/en/product ... uvex-C500/