question on headstock / tailstock alignment

[Jesse Tutterrow]

I just got my new lathe. After assembly I notice that the drive center point and the tailstocks live center are about a 1/32 inch off horizontally. Vertically they are perfect. I did level the ways before making the measurements.

Should I be concerned about this?

What are the ramifications in spindle turning with the alignment being off?

 

[Bill Boehme]

Generally there is enough side to side play in the tailstock fit between the ways that it can be shifted to get a better match before locking the tailstock down. On my lathe I get perfect alignment when I push the tailstock towards the ways on the back side. If you are turning between centers then all this is meaningless anyway and there is no downside. Think of it being like the universal joints at each end of the drive shaft of an automobile. It becomes more important when something is held rigidly by a chuck or mandrel on the spindle.

 

[Mike Johnson]

Some lathes will have a little bit of play when setting the head-stock on the ways.
When you lock the head-stock to the ways you may gain some of the 1/32" distance
by adjusting the head-stock in the needed direction to correct the issue. Depending
on the make of the lathe will determine the options you can employ.

 

[Jesse Tutterrow]

I already took the headstock play into consideration and pulled the drive center toward the front of the lathe to minimize the gap.

 

[Jesse Tutterrow]

If you are turning between centers then all this is meaningless anyway and there is no downside. Think of it being like the universal joints at each end of the drive shaft of an automobile. It becomes more important when something is held rigidly by a chuck or mandrel on the spindle.

Bill I should have been more specific, I plan on doing spindle turning including using a chuck on the headstock with the tailstock providing support (think jam chuck with the tailstock providing support).

 

[Bill Boehme]

Something that I didn't mention about getting the points to touch is that only gives a partial solution. Suppose, for example, that the headstock and tailstock axes were both angled towards you by 30° (an absurd exaggeration, but for illustration purposes it is easy to visualize) and the points touched. In this scenario neither the headstock axis nor the tailstock axis is parallel to the axis of the ways. This illustrates that there are two components to alignment ... radial and angular ... and when touching points we don't know if there is still radial misalignment, angular misalignment, or a combination of the two that allows the points to touch. The only correct answer would be to use the gap between the ways as our absolute alignment reference. I haven't seen a tool that does that so we make do with what we have.

I have seen double ended Morse taper tools, but scare me because of the risk of damaging the Morse taper sockets on the spindle and tailstock quill and still not really determining if the axes are the same when you move the tailstock or headstock.

 

[Lamar Wright]

Hi Jessie, I had the same issue on my new Jet 1640 lathe. What kind of lathe do you have? Is the headstock capable of slide sliding on the lathe bed and does your headstock rotate? I fixed my problem by resetting my headstock to the lathe bed.

 

[Jesse Tutterrow]

Hi Jessie, I had the same issue on my new Jet 1640 lathe. What kind of lathe do you have? Is the headstock capable of slide sliding on the lathe bed and does your headstock rotate? I fixed my problem by resetting my headstock to the lathe bed.

Grizzly G0766 lathe. The headstock does _not_ rotate. There are cast nibbs that protrude from the bottom of the headstock into the slot on the ways. I tried pulling on the headstock but that only changed things by a couple of thousands.

How can I determine if the headstock is angled or if the problem is the tailstock?

I will be using a chuck in the headstock and a live center in the tailstock.

 

[Richard Coers]

I'm curious about how you leveled the lathe. Did you put the level on both ends of the bed, perpendicular to the ways? You want to check twist, and make sure the lathe is in one flat plane. Level is not that critical. Try putting a twist in it to align the points? Who cares what the level says, if the points line up perfectly.

 

[Jesse Tutterrow]

I'm curious about how you leveled the lathe. Did you put the level on both ends of the bed, perpendicular to the ways? You want to check twist, and make sure the lathe is in one flat plane. Level is not that critical. Try putting a twist in it to align the points? Who cares what the level says, if the points line up perfectly.

I assembled the legs and ways, placed it in the final position, added banjo and tail stock, lifted the headstock into place. I then used a 3 foot level to level. Along the ways, perpendicular to the ways, and finally diagonal. One problem with the Grizzly is the legs are not threaded so I had to mess with using nuts to raise and hold the leg.

 

[Lamar Wright]

Grizzly G0766 lathe. The headstock does _not_ rotate. There are cast nibbs that protrude from the bottom of the headstock into the slot on the ways. I tried pulling on the headstock but that only changed things by a couple of thousands.

How can I determine if the headstock is angled or if the problem is the tailstock?

I will be using a chuck in the headstock and a live center in the tailstock.

Jessie if you have a fixed headstock then I would look at the tailstock and make sure it sets flat on the lathe bed and there are no burrs or any obstructions on the tailstock. Make sure that when you check the lineup with headstock to tailstock make sure both centers are in tight and secure. Like Richard said I'd check for any twist in how the legs sit on the floor/concrete.

 

[Gary Beasley]

No twisting! That will result in a structure that lines up at one sweet spot and nowhere else. You might try putting a long rod in the chuck, spin it to be sure it's centered then check its alignment to the bed. If the head needs adjustment it may take judicious filing of the tabs to bring it in line horizontally, shims for vertical. Just remember not to go overboard trying to get perfection!

 

[Mike Johnson]

There are several good videos on YouTube that detail several methods that can be used for
leveling a lathe. A dial indicator on a magnetic base is a good tool to measure the run-out on
a lathe when you have a shaft installed into a chuck to determine the alignment of the head-stock
to the ways. You could also locate and mark the center-line between the ways and measure the
width of the ways on both ends of the lathe to determine if there are any differences. You will be
moving the tail-stock on a regular basis so concentrating on re-positioning the head stock is your
best bet. With a dial indicator you can quickly determine after installing a shim in any location if you
are gaining or losing ground in aligning the head stock. This process can take time and can get
frustrating if you have not done this task before. You could also install a jacobs chuck in your tail-stock
and install a straight steel rod into the chuck and measure the run-out on the tail-stock alignment to
the ways. This would give you a better idea of where the problem is coming from.

Your 2nd option would be re-centering the tail-stock this would require considerable modifications or machining on the tail-stock. Some metal lathes have adjustment screws on the tail-stock that allow for alignment. You could install a set of gibs on the tail-stock to re-align the center point. This would require machining the tail stock and drilling and threading or securing the gibs to the tail-stock in some fashion. The gib is basically a long hardened steel shim that would provide the surface that would ride on the ways and keep it aligned. You could possibly get by with one gib installed on one side of the tail-stock after it was machined on a mill. If you have some slop between the ways and the tail-stock you could temporarily glue a shim stock on one side or the other on the tail-stock to see if you can gain any distance on the alignment.

 

[Bill Boehme]

Jessie if you have a fixed headstock then I would look at the tailstock and make sure it sets flat on the lathe bed and there are no burrs or any obstructions on the tailstock. Make sure that when you check the lineup with headstock to tailstock make sure both centers are in tight and secure. Like Richard said I'd check for any twist in how the legs sit on the floor/concrete.

His lathe has a sliding headstock, but it doesn't rotate which is good. My first lathe, a Delta 1440 had a headstock that did both ... Not good.

I've thought about having a laser to boresight the headstock spindle and tailstock quill, but there's a point where we need to stop and recognize we're turning wood ... a medium that moves in response to changes in its surrounding environmental conditions.

Something to consider is that the headstock/tailstock and lathe bed all deflect slightly when the locking lever is locked down and the amount of deflation is influenced by the amount of locking force applied. I almost bought a lathe once until I saw the deflection ... it was a 16" Delta lathe with an inverter and "floating" bed ways.

 

[john lucas]

Bill I tried to build an adaptor to hold my boresight but I'm a really lousy machinist. It seemed to work and when projected 34" to my tailstock the alignment is off a little. It traces a circle around the live center center point. The problem is I don't know whether it's my poor machining skills that are at fault of the the headstock isn't aligned. For the most part having the headstock and tailstock not in perfect alignment doesn't cause a problem. When you drill using the tailstock is when I see it show up but then you also have a worse problem of the drill following the grain which is usually worse.

 

[Bill Boehme]

John, what you need is a Morse taper in the headstock that has a small hole drilled through it and do the same for the tailstock quill so that the beam is projected through the spindle and tailstock and projected onto a target. if you can get a well focused beam to pass through both then you will know that you have a well aligned system. Alternatively, you can do it without a laser. Have a bright light at one end and look through the other end to see if you can see a full circle or not. The holes need to be small and you also should have an insert at the handwheel hole and tailstock crank hole as well. It would be a tough test for any lathe.

 

[john lucas]

I made a morse taper with a hole that accepts the shaft of my Bore sight and is slightly tapered at the front so the taper of the bore site sits in this. Thought that would be pretty accurate, and it may be. Like I said I'm not sure if it's my machining or the lathe is actually off. In reality being off less than 1/8" at 34" is pretty darn close. Of course that still doesn't tell me if it's the tailstock or the headstock that is off.

 

[Gary Beasley]

I would think if you get the same results with the tailstock almost touching you can take that as near perfect.

 

[Bill Boehme]

Of course that still doesn't tell me if it's the tailstock or the headstock that is off.

The only way to determine that is by using the bed gap as the reference. If you could make an accurate fixture that slides in the gap that could be used. Maybe with some modifications a Baxter threading fixture could be used. The boresight doesn't have to be centered in the gap as long as the headstock and tailstock are the same.

Of course you are right that close is good enough. If you're turning something 34" long, it probably means that you are turning between centers and alignment isn't critical at all.

 

[john lucas]

Not turning something that long. Just saying that if it's only off that much over that distance then the headstock and tailstock are pretty well aligned.

 

[Jesse Tutterrow]

Thanks everyone. I got it to about 5/1000s. This is as far as I plan to go.

I wish I had all of the machinist experience you guys have.

 

[Jamie Straw]

I've had problems with alignment on two or three different lathes over the past 2 years, and had a number of people tell me "it doesn't really matter" when you're turning. Uh, yes it does. Always thought it did -- solved the problems -- and had my suspicions confirmed when two different, very experienced, demonstrators came to our Club and part way through commented about the Nova DVR demo lathe not being lined up. They both took the time, right then and there, to adjust them before continuing their demos. Same thing when Stuart Batty demo'd in the area last year on a Powermatic. Vibration in the piece is noticeable when ends are misaligned, whether you're turning bowls or spindles.

The second lathe that developed this problem had developed a twist from not being on level footing. Re-leveled, and it relaxed and re-aligned.

What I do now when working on a new lathe is to put a double-ended Morse taper in the headstock, and a long-pointed live center in the tailstock, and extend the spindle to its near-maximum projection. That gives me as much span as can be mustered cheaply. There is a tiny pimple on the ends of those doulbe-morse-taper things, perfect to eye for alignment.

I would not keep a new lathe that definitely couldn't be aligned properly (when perfectly level, etc.). The Old Blue Jet Lathe (1236) doesn't line up, but the tailstock is low, so that's shimmable. Still not perfect, but works for bowls and short spindle work.