36 38 40 42 secured respectively thereto by rivets or screws 44 the support handles 36 38 40 42 are manually engageable for applying compressive forces to the printed circuit board support 10 during installation in the positioning device 97 of the screen printer station a portion of a screen printer station 70 is shown in fig7 and 8 with a cover not shown removed the positioning device 97 includes opposing step like spaced surfaces 90 92 94 91 93 95 formed from sheet metal each one of the shaped surfaces has a leg 92 93 connected to and extending upwardly from a steel plate 96 and an upwardly extending portion 90 91 spaced outwardly by horizontal portion 94 95 internal conveyor belts 72 73 are spaced above horizontal portions 94 95 respectively as shown in fig8 the lips 13 15 of the outer rails 12 14 are in abutting engagement with the step like spaced surfaces 92 93 when the support 10 is released with reference to fig7 and 8 the support 10 is positioned on the steel plate 96 and is held thereon by magnets 50 which are positioned in recesses 52 located in the underside of the mid block 16 printed circuit boards 80 81 82 are sequentially supplied to the screenprinter 70 by a pair of feeder conveyor belts 85.