I have the Tree 325 with the Delta 20 controller. I have to use the tapping holders that have a little spring play to them. They work fine . If you just put a tap in a drill chuck or holder alone , for me it seems to get alittle off coming back out. The speed and feed stay the same but on reverse out it sometimes gets off the same pitch going in. The tap holder with play solved that problem . Tap size was 1/4-36 through 1/4" alum.
Hope this helps.