Removing the drill chuck from a HF Mini-mill

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Don't hit the drill chuck or the taper shank (which is an R8 taper). Instead, after you loosen the drawbar half-a-dozen turns (such that it still has numerous threads engaging the the R8 shank of the drill chuck, and still has the 19mm nut on top) tap or rap the top of the drawbar. One sharp tap should loosen it, and having the drawbar still engaged keeps it from moving more than about 1/8" in this initial loosening step. After it's loose you shouldn't need to tap it any more. (But if the keyway in the R8 shank wasn't aligned with the alignment pin inside the spindle, but incorrectly forced into place, it might not come loose that easily.) Note, place a 6" cutoff of 2"x6" lumber on the table below the spindle when changing collets or chucks. Engage the crown nut and lock the clamp below the head to keep the head from moving when you tap on the drawbar.

Look at around 3:40 in this youtube video?

Rap the top of the drawbar sharply with a small hammer or a wood mallet . Be sure you have the drawbar threaded well into the chuck taper so you don't bugger up the threads on either . Once the taper pops loose you can unscrew the drawbar . Be aware there is a locater pin in the spindle and a matching groove in the collet or drill chuck adapter .

This. Unscrew the drawbar a few turns and tap on it until the R8 taper releases then finish unscrewing it and catching the released drill chuck with R8 shank.

This is the key thing here, the HF mini mill is R8 taper, not the MT3 taper of some other brands of the mini mill (all made by Sieg). You can not install an MT taper drill or the like in the HF mini mill spindle, you have to use tooling that is R8 shank or that will fit in an R8 collet. The only exception is if you buy an R8 to MT adapter.

================= Nice looking unit

You may have to reinsert the draw bar, finger tighten, and back off about 1/2 turn and smack the end of the draw bar to break the collet/shank loose. If you have one use a brass hammer to give a shaper rap than a rubber one. Bridgeports have a special wrench/hammer for this.

I am not familiar with this unit but similar units have a #2 Morse taper spindle which is a common drill chuck shank size, and these are available threaded for a draw bar, as are #2 Morse taper collets.

These are also available in the Weldon style.

When you extend the spindle are there slots on each side? If so, assuming the drill shank is long enough to be seen in the slot, you may need to use a wedge to pop the shank loose.

For completeness there are also wedges to remove the shank from the chuck.

FWIW -- a reminder that because of the side loads [and tendency to loosen] you should never use an end mill except as a drill in a drill chuck, but always use a collet.

George , the HF website says this unit has an R-8 spindle . But your advice about a half-turn loose then smack it with a mallet or hammer is spot-on . I keep a 12 oz ball peen hammer on my mill bench for this and tapping pieces down in the vise (as when using parallels) as I tighten it .

Some people argue that a lead hammer is better for setting things in a vice as it is said to be a "dead blow" whereas the steel hammer has a certain amount of bounce back.

Quite possibly true , too . I'd guess the "dead blow" comes from the lead deforming when you strike . I think I'll cast up a couple of lead slugs for the plastic mallet with replaceable faces . If it doesn't work out I can always recast it back into ingots until I need it for bullets/balls . Hmm , make that one from pure lead and one from wheel weights .

If you haven't rounded the top end of the drawbar on the grinder yet, do it now!

In my mill if I have a stuck R8 I back off the drawbar maybe 1/8". Keeping a long threaded section into the chuck or whatever. I snap it with my black plastic hammer and the rod goes down 1/8 and the R8 is free. Doesn't take more than a little downward direction to get it out.

Martin

Lead is also better than brass, as brass can work harden. Not that the occasional tapping on a draw bar would cause it, but one shouldn't be complacent about using a brass hammer. This one of those DAMHIKT things, that happened to involve a stuck lathe spindle. Fortunately the damage did not affect its functionality.

Bob

I worked one place that had a "lead hammer mold". They had cut up some

1" tube to make handles, drilled one end and pressed in a cross pin to hold the head better and just cast the heads onto the handles. Every year or so they'd get all the shop's old battered lead hammers and melt them down and recast new hammers.

Back in the late 50s when I started working in a machine shop, several of the old timers had babbitt hammers for this that they swore by. Seemed to be even softer than lead. Every so often they would melt and recast their hammer. Big complaint was that it was getting hard to find babbitt. I just checked and new tin babbitt is available, but is expensive

IIRC the aerospace industry does not allow the use of lead/babbitt hammers as this contaminates the metal. They have special soft aluminum mallets. Anyone know if this is true?