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If a vernier caliper is not available it is possible to measure card thickness using a standard ruler. Hold a
full deck (52 cards) and measure thickness as shown below. Then divide the result by 52. This gives the
thickness of a single card.
If card thickness is known the correct gap size can be calculated by multiply card thickness by 1.2 to 1.4.
For example: Measuring the full deck gives a result of 15.5mm. Divide it by 52 gives thickness of the
single card equal 0.298mm (rounded to 0.3mm). This value multiplied by 1.2 gives 0.36mm – this is
minimum gap size, multiply by 1.4 gives 0.42mm – and this is maximum gap size. In this case use a
0.4mm gap. It is not necessary to set the gap with accuracy greater than 0.05mm. It is enough to use
0.25, 0.30, 0.35, 0.40, 0.45 or 0.50 sizes.
3.1.2 Measure existing gap size
A Feeler Gauge is required to measure the gap size. A Feeler Gauge can be purchased in any tool shop.
Feeler gauges can cost from $4 to more then $200 for the high precision, high quality ones. For the gap
measurement and adjustment the cheapest one is enough. Feeler gauges should have blades with 0.20,
0.25, 0.30, 0.35, 0.40, 045, 0.50mm sizes. Some cheaper ones have blades every 0.1mm (0.05, 0.10, 0.20,
0.30, 0.40, 0.50mm). These feeler gauges are OK to use if they have a 0.05mm blade – thus to get e.g.
0.35mm two blades need to be used together.
Note: New Feeler Gauges usually have blades covered by oil or grease to prevent rusting.
Please wipe each blade with dry cloth to remove any oil or grease to prevent transfer to the
machine parts.
