Oscillating Spindle sander build

[jonnydot]

Hi Guy's I could use some help with connection devices For the main shaft I am thinking of this ....20mm Linear Optical shaft held by 2 Ball bearing blocks.The shaft will have a pulley on it and a belt drive to a motor to spin the shaft at around 2300 rpm.I wish to have a collet at the top and don't know how they mount to shafts nor do I know what collect to buy so help there would be great.... I think I need a Motor shaft collet chuck ER20A-20mm and collets to suit Here is an ebay link for what I think I need but I don't fully understand the terminology and I'm not sure if it will fit over a 20mm shaft https://www.ebay.com.au/itm/Motor-Sh...m1438.l2649The collets will need to be able to handle a range of sizes from 3mm to 10mm.At the bottom of the shaft I was going to use a windscreen wiper motor and a crank system turning an offset wheel,this will give the shaft vertical rise and fall,I need the shaft to move up and down approximately 40mm @ around 75-100 rpm. I would also like to have a button to push to lock the shaft to change collets again not sure what to use ? Many thanks for reading ...dropbox drawing for explaination https://www.dropbox.com/s/nh359qla57...ander.pdf?dl=0