Yeah, it tends to be a tad jumpy but when I was going really slowly I managed to keep it in a straight line. Also, what was quite interesting at least for me personally
, I discovered that I could avoid edmill jumps by moving the vice in different direction. If I remeber correctly by moving the piece towards the column bit was biting to the left hand side and since I was removing stock making a cavity I managed to get a very nice and clean edge on the right hand side. When I got to the other end I simple moved the vice away from the column giving me good results on both sides.
As far as mills are concerned... yeah, welcome to the rip-off Britain LOL!
The cheapest new I saw were Clarke mills ant Machine Mart and Axminster stuff - roughly £275 a pop. The downside of 'em was quite weak motors - 150 watters...
My one is Clarke CDP210B if I rember correctly with 370w motor.
I think I'll skip barbs in the block I am currently making and simply braze 1/2"pipes - not nuff thickness to get any half decent thread going... - otherwise rswww are quit handy :P