I keep a length of brass rod to wack it down the quill.

Machine tools often use tapers to attach chucks and other accessories. They wedge into a socket and grip tight enough not to spin or fall out. (We hope!). As the taper angle effects the grip, they can be made self-holding or self-releasing. (See Machine Tapers on Wikipedia).

Tapers work well, but sometimes they come apart by accident, and sometimes they stick solidly together. David's chuck has come off the arbour unintentionally: no problem, it's allowed. When the time comes just push it back on firmly.

The other end of the arbour is stuck in the tailstock spindle. Five common causes:

• The taper was wedged too firmly in the past by applying excessive force, perhaps a hammer! (Don't.)
• A cold male taper was pushed firmly into a hot female (yikes!), forming a shrink fit when the lathe cooled down. This can happen when a lathe is thoroughly warmed up and a cold tool is pulled out of storage. More likely to happen at the headstock end because the bearings warm up, and cutting heats the chuck.
• The taper was lightly oiled and gummed up over time.
• The taper wasn't lightly oiled and corroded.
• The taper was inserted dirty and is jambed by a bit of swarf.

You might like to soak the stuck parts in penetrating oil for a day or two. It removes gum and loosens corrosion.

Normally, winding the tailstock spindle back beyond zero will cause a tongue to press on the taper and eject it. Not all tapers fit properly, so this may not be working on your lathe. Try inserting a rod through the hole and, gripping the spindle in one hand, rap it sharply on a wooden bench to push the taper out. Nice thing about owning a lathe is the rod can be turned to fit, if necessary.

If that doesn't work, try supporting the shoulders of the spindle in a vice (with the chuck hanging freely below), and tapping the rod with a hammer. Note a sharp tap is essential because prolonged slow pounding will damage the spindle. Don't overdo the violence!

Heat is the most certain way of loosening a stuck joint. Apply a blowlamp or electric paint stripper to the spindle and heat gently : not red heat or anything like it because that will damage the metal, hot enough for spit to dance on the surface. Let it cool down and try rapping again. The metal expanding and contracting causes enough movement at the joint to gradually loosen whatever is jambing the wedge. Several cycles may be necessary. Not tried it myself, but some report success by cycling with boiling water and a deep-freeze. As the temperature swing is smaller than can be done with a blow lamp, I guess more cycles might be necessary, and the process will be slower because the freezing part must take a few hours. No need for a blowlamp, and no risk of damaging the metal by overheating.

After separation, give both genders a good clean. As they are a precision fit, nothing aggressive. Ask again if the problem was corrosion or the tapers are obviously damaged.

Dave

Forget WD40 get some Plusgas ideally the liquid not the spray

Roy

I might try cleaning up the bore with a piece of hard wood / 'coarse rag on a stick & vinegar' or similar before resorting to the reamer – the spindles and shafts are of very soft steel on the Hobbymat. If you do need to ream, go very lightly, just the tiniest skim. The size is 1MT.