HLV-H Tailstock Questions

Hi,

I recently "inherited" an HLV-H in fairly pristine condition (as well as a similarly pristine Bridgeport and a whole raft of tooling for both.) Nice first machines on which to learn, to be sure. I'm now spoiled.

In any event, I'm having an issue with the HLV-H's tailstock.

Much of what I do on this lathe involves drilling holes using a drill chuck mounted in the tailstock. What came with the machine is a nice Albrecht model with an MT shank. The challenge I'm facing is that the MT shank will regularly break free and spin. I've tried degreasing, scuffing, and a whole raft of other possible "fixes" but nothing works. I'm no machining expert and don't really have anyone to ask, so I'm hoping someone here might suggest a fix for this.

Also, I'm a bit surprised this is possible in the first place. The chuck's taper has a tang on the end of it. Why doesn't the tailstock's female taper have a slot that the tang slips into to keep it from spinning? (As I said, I'm new to all this.)

Anyway, I'd appreciate any suggestions / info you've got. I'm sure this problem only gets worse every time it happens so I'd like to find a real fix.

Also: I'm wondering if it's possible to use MT collets with this tailstock? I'm not sure how that would work since I don't suspect there's a way to install a drawbar, but again, I'm new to all of this.

Thanks,
-Ben

Can you take a photo of the chuck Morse taper and post it? If it's a cheapo import adapter, it may be mis-ground. Roll a clean shop rag into a taper and "screw" it into the tailstock taper, being sure to go as deep as you can. I like to use paper towels as they're easier to check for debris (or lack of it). Then insert the chuck into the tailstock (tang aligned) and, with the jaws fully wound back into the body, tap the end of the chuck square on axis with a large, soft faced dead-blow hammer. A few solid taps and it's not coming out until you back the tailstock quill all the way into the tailstock housing.

I like to leave at least 1/2" of extension on the quill to avoid accidentally winding the quill to far back and releasing the chuck.

Most machines do have a slot in the tailstock quill to accept the tang of a drill or drill chuck. I have run a HLV-H, many years ago but I don't remember if it had one. It may have been removed by a previous owner who repaired the taper, or Hardinge may have figured that machine doesn't need it because it doesn't have enough power to be an issue, although I would think that is unlikely. There are plenty of Hardinge owners in here who can tell us if it should be there or not. Either way, if the taper fits correctly you shouldn't have a big problem with things spinning. I would cover the taper of the drill chuck with blueing, magic marker, or lamp black, and lightly fit in to the tailstock and rotate it a bit and see where the contact is happening. It should show pretty even contact the entire length of the taper. If its not, try the same test with several other taper shanks to try to figure out if the error is in the taper on the drill chuck, hopefully, or in the internal taper of the quill. If its just the drill chuck, you can probably polish it out using the marking as a guide. If the error is in the quill, you can buy a morse taper reamer and very carefully ream it. You are right when you say the problem is getting worse every time it happens, not good to have that happen.
There are collet chucks made that have morse taper shanks, or that could be adapted, they use a nut on the front side instead of a draw bar. You don't see people using this kind of set up on manual machines except in rare specialty set ups because that stuff is expensive and not usually nesessary. I've never done it, never needed to.

I have many Hardinge tailstocks and none are slotted for removing tapered shanks. Note that the slot is for removing tanged MT shank tooling, not to keep them from spinning. All drill presses have the slot and some lathe tailstocks have the slot. Hardinge provides a loose piece of steel inside the tailstock bore behind the taper, that ejects the tool if it is the correct length. I have a couple of non-tanged tools on which I had to drill and tap the small end and install a socket cap screw to make them long enough to eject.

Once you spin a tool, you probably have welded some steel from the shank into the tapered bore of the tailstock. Doesn't do the tool any good, either. Nothing you can do then but carefully apply a hand MT reamer, so you remove the welded metal but avoid enlarging the original taper. The tool shank can usually be repaired with a fine file anywhere there is a raised bump.

I have a nice German tool for cleaning chips and dirt out of tailstock bores. It is made of wood, tapered, and has three strips of leather glued on lengthwise. Insert, twist, remove and use a toothbrush to clean the chunks off the leather. It is a good idea to clean the tailstock before inserting a tool, and clean the tool shank, too.

As was said, a Morse taper drill or drill chuck should be struck with a lead hammer or a deadblow nylon mallet. Morse taper tools are meant to self-lock against spinning, but need a good bump to seat properly.

You should not bump a live center, which has precision ball bearings. A live center will not try to spin in the tailstock. Just bang them into the tailstock by hand to seat them.

Larry

I suspect the taper is buggered up and you need to check the taper as Derek suggests. If you need some help a good friend of mine lives over in Berkeley and is a decent machinist & machine repairman. He also helps hosts the Machine Rebuilding seminars we have in the Bay Area every couple of years He has a small machine shop and probably has a set of tapered reamers and test bars so he could tell you for sure what the problem is and fix it. He goes by the initials of DH and his email is [email protected] Tell him I said hello. Rich

Since the OP says he's new to all this... What is the diameter of the hole you are drilling when it spins? And did you step up in size as the hole gets bigger? Trying to drill a larger hole in one pass is sure to spin a 2MT.

" The chuck's taper has a tang on the end of it."

Most do.


"Why doesn't the tailstock's female taper have a slot that the tang slips into to keep it from spinning?"

Monarch's do.

There are two hardened pins which thread into the spindle and bear against each side of the tang on a standard 2MT adapter (3 MT in a few examples).

In this way, a chuck with its adapter can never spin in the tailstock spindle.

My tailstock taper is a little buggered,and it is hardened too. I just hold onto the drill chuck if I think it's going to spin,pulling it back into the tapered hole. This works fine for the small holes I'm usually drilling.

My larger lathe has a slot for the tang to fit into. But,it also has an opening to insert a tang drift to get the tapered shank loose. And,that slot is needed too.

If the tang isn't to keep the tool from spinning, then why is it rectangular? Think of all the work all the people who have made drills, ever, since the tanged taper shank drill was first made, could have saved if they didn't perform the unnessessary op of milling a flat tang on the end of the drill. Centers don't have a tang, if the tang don't keep a drill or drill chuck from spinning, why aren't drills and drill chucks made the same way? Seems like a whole lot of people have been doing a whole lot of extra work for no reason!

The tang on a Morse Taper tool is solely for ejecting the tool from the taper with a drift. It is rectangular and smaller in width than the section of the taper so that when it gets burred over by the action of the drift, it won't spread out to the point of marking the taper. It is always soft, so that it does not shatter when hit by the drift. If the tool were driven by the tang, it would already have slipped in the taper and be loose. If a tool is driven by the tang with any great torque, the tang will shear off.

From where do people get the idiot idea that the tang has any other purpose than to be pressed by a wedge or hit by a drift?

Milland said:

Can you take a photo of the chuck Morse taper and post it? If it's a cheapo import adapter, it may be mis-ground.

Click to expand...

I'll take a photo when I'm back in the shop tomorrow, but I can guarantee you it's not a cheapo. The chuck's an Albrecht and I would imagine the taper came with it.

Thanks, everyone, for the input. Very interesting data here on a bunch of topics. I'll try putting some bluing on the taper and see what the mating surface looks like. I suspect at this point I'll need to ream the taper lightly to undo past damage, and then maybe replace the taper on the chuck, but we shall see.

Thanks also, Rich, for the pointer to DH. The machine's in Alameda, so a Berkeley based repair guy is a super-useful resource.

"From where do people get the idiot idea that the tang has any other purpose than to be pressed by a wedge or hit by a drift?" [/QUOTE]

I normally try to not engage in petty arguments in life in general as well as in this forum as we are all here to learn and aid others in learning, but if you want to start name calling, I really need to ask, are you simple, slow or stupid? Perhaps all three? Why can you not answer my previous questions then, Have you ever seen a center with a tang? Why not? Don't centers need to be driven out same as drills? Why is the tang rectangular instead of round, but just a smaller dia.? Why is there a rectangular slot made to accecpt the tang inside the tailstock quill? Because this is such an easy feature to make? Seems like it takes a lot of extra effort to machine a slot at the bottom of a tapered hole to me, all major machine builders have been doing this for decades for no reason? The only idiot idea I have is wasting time to set you straight.

I don't care what the tang is "for" exactly, but I sure am glad it's there when I see a big drill try to spin the taper and the tang catches and prevents scoring the female taper.

In the hope of preventing an argument... you are both right.

The traction supplied by a properly fitted morse taper is probably enough to shear the tang off of any drill . The main drive comes from the locking nature of the taper.

However, since drills dont have a draw bar and should not be hammered into the taper, they need a mechanism (the tang) to provide torque (to stop the taper twisting) while the cutting force builds to press the taper home.

The pins in the Chuck fitting and C5 collet do the same kind of job.

Bill

My HLVH tailstock, takes no tooling with a tang. the chuck, or center, seats against the taper. When removing it, the lead screw actuates the quill against a solid stop, which pops the tooling from the taper, I have owned 3 so far, and none of them used a tang.
best of luck,
Chris