QT-15 (1988) Tailstock Alignment - How To?

I have a very nice old QT-15. It's had a few bumps over it's life but generally is in great shape. Recently I have been working on some plastic parts and I need some end support for threading. There have been all kinds of challenges to what look like simple little parts. One big one is that my tailstock is not on lined up with my spindle.

I think I saw in a post here where someone said there was some alignment capability in the tailstock spindle. I don't see any such thing on mine. It's just a big solid spindle.

The tailstock is a hydraulic one, both travel and spindle, and it rides on it's own little bed. It's held down with 4 big bolts so I figured the way to do the alignment would be to loosen the big bolts and slide it around to get it aligned. There is not movement to get this to work.

Now I'm thinking what has to be done is to first adjust the tailstock bed to insure it's parallel to the z axis travel of the machine. I need to get a test bar to put in the taper socket to insure I'm checking the taper.

Then step two I think I need to align the head stock so the main spindle is aligned to the tailstock axis and of course the z axis of the machine.

I did have a crash once that knocked the head stock out a little. I got it realigned but never considered the tailstock axis.

Anybody got any experience on the subject?

To align the tailstock you don't move the base of the tailstock, you move the quill. I will have to find my notes, but the quill actually rotates around its centerline and moves the centerline in X. It is fixed in place and after loosening the fasteners holding it in place you can insert a drift or other tool into the slot on the bottom of the quill and rotate the quill. Like I said, I will dig up my notes and get more specific. I think you remove the four screws on the face of the quill that hold the wiper on, and the fasteners that secure the quill from rotating are underneath the quill wiper It is really simple.

Man if that's right you sure saved me a mess. I will need to undo my miss aligning I did by moving the little ways of the tailstock around but relatively speaking that won't be bad.

Here is a photo of what it looks like under there.

This will help, https://youtu.be/tt7gSQpNABM?t=229
Not a Mazak but seems to be the same design, helped me with my QT15 headstock and tailstock alignment.

Pete Deal said:

Man if that's right you sure saved me a mess. I will need to undo my miss aligning I did by moving the little ways of the tailstock around but relatively speaking that won't be bad.

Here is a photo of what it looks like under there.

View attachment 323361

Click to expand...

Yeah, those two bolts will need to be loosened and then just rotate the quill. Probably will want to put an indicator on it first.

That video is exactly where I'm at. I'd say I am going to have to move some things around on this machine. I am out about .02" or so. I think the head stock is going to need to be moved forward some to be able to get what I need.

The machine came from a technical college so as is typical with such machines they aren't worn out but were beat up some.

I did have a minor crash myself but it looks like they had a few into the tailstock.

What contributes to the confusion is that I needed a morse taper extension to be able to reach the part with the center I have. I stupidly bought an extension from Grand Tool Supply on ebay. Probably some Indian made part I suppose. I really don't need precision on these parts at all but this stupid thing has .01" of runout in it.

We use Royal centers with an extended tip. I think they refer to it as an NC center (?). I dont know if that would give you the extension you need, but you might look at it. With our QT15 and the extended point live center we can almost touch the face of our chuck when fully extended.

Yea this has been quite a trip with these little parts.

I got a replaceable tip center to start. It's a Rohm tool and pretty nice. I made a special tip for it. It's 3 MT center and the problem I have with it in this application is that the seals in the center create enough resistance that it slips in the part. Since the part is plastic I can't put much pressure on it.

Then I bought a little Royal 2MT spring loaded live center on ebay with a replaceable tip. Royal doesn't make this one anymore with a replaceable tip. My original plan was to make a tip for it as needed but I found that I could pretty easily remove the whole spindle and make a new one out of 10mm Thompson shafting. The thing here is that the little seals on this center have very little resistance so that seems to be working. Also I blew the grease out of the needle bearings and put some spindle oil in there. But the little bugger doesn't come near being long enough.

I did tweak the tailstock spindle and got closer to where I need to be and rotated the crappy mt extension to my best advantage and It may get me by just for a few test parts till I have a day or so to fix things right.

The whole discussion has been very helpful on direction though. Thanks all.

You should always line up your spindle centerline first, or at least verify it.

The tailstock body is two halves - an upper and lower. They should be bolted together, and there are adjustment pins to push/pull the upper half to get the quill on horizontal centerline.

Vertical centerline is set on the older tailstocks by spacers between the two tailbody halves.

The quill rotation itself is for fine adjustments, if needed.

Oh, and the spindle housing adjusts on the frame in a similar manner for horizontal centerline adjustment. Make sure to re-zero your X-centerline tools, as the value will change if you have to adjust your spindle c/l.

ToolCat