Previously when milling in the lathe I’ve just put the milling cutter in the jaws of the 3 jaw chuck. This is not idea as it may slip and could damage the chuck jaws if it does so. A better solution would be a collet chuck which are designed to hold round items more securely as they are effectively a close fitting multijaw chuck.
My little Saupe MD200 (Prazimat) lathe has a M14 x 1.0mm spindle with no taper and also has 3 M5 bolts arranged in a circle. Luckily that spindle size is the same as the Sieg C0 lathe, EMCOs Unimat 3, and Cowells 90ME lathes so there are plenty of components availble for it.
Collet chucks come in different series which determine the shape of the collets needed and the range of sizes of material that the collet can take. The ER16 (also known as ESX16) range can take 1mm to 10 mm in increments of 1mm which is ideal for this size of lathe.
I’ll be looking at this weekends model engineer exhibition to see if I can pickup a cheap ER16 collet chuck, £22.95 is the price to beat. The collets are sold individually or in sets of 10 for around £70. I’ll probably just get a couple with suitable sizes to match my end mills. I’ve seen individual ones for around a £5 each so it should not be too costly.