Removing and re-installing headstock

[Jamie Straw]

I'm still having problems with alignment of the headstock and tailstock on my Jet 1236. One of the guys who installed the new spindle feels certain that the source is the headstock -- gunk throwing it out of whack, for instance. He indicated it's easy to take them off, but hard to put back on. I've cleaned the heck out of it, short of removing it. Anyone out there care to comment? I'm not in a big hurry to do this, but the darned thing has to get fixed or I'll be condemned in spindle work to nothing longer than wine stoppers.🙁
[Oops, proofed everything but the title😛]

 

[Bill Boehme]

I used my super powers to fix the title for you. 🙄

It's hard to imagine that there could be enough gunk to have an impact on alignment unless the lathe is unimaginably filthy. How bad is the alignment? Horizontal? Vertical? Both?

Turning between centers isn't a problem regardless of alignment. Turning with a mandrel ( pen mandrel, for example) can be a problem. Since no lathe has absolutely perfect alignment and many mandrels aren't perfectly straight, I think there is a better way ... don't use a mandrel. Instead, turn between centers.

 

[john lucas]

Does it have the rotating headstock. My Delta and my Nova did and here's the solution I used. This is only for the swinging alignment, won't work if they are off up and down. I used a drive center and tailcenter and aligned it as accurately as I could and locked it down. then I drilled a hole at the junction of the headstock and lathe bed. Not deep, about 3/8". Now all I had to do when I rotate the headstock is to rotate it back to the normal position, insert the tail end of the drill bit into the hole I drilled and then lock the headstock down. Perfect alignment. Of course this doesn't work if you slide the headstock to the middle of the lathe. for that you need to buy one of the double morse taper adaptors. I believe it was Nova that sells them but I never bought one.

 

[Charlie Knighton]

Jamie....can you show a picture of the two points on headstock and tailstock close together.....drive center to revolving center

 

[robo hippy]

If it is a fixed headstock rather than a sliding or pivoting headstock, then that should not be the problem, unless it was there to start with. Not sure what is happening with that lathe. The only pivoting headstock lathe I have seen that meets my criteria for being good and solid is the Vickmark one. Built like the brick outhouse..

robo hippy

 

[stu senator]

Alignment consists of two parts, the head stock and tail stock.

Are you sure that the head stock axis is not parallel to the lathe ways?

This can only be determined is by dial indicators as the lathe turns. It must be done in two planes.

Perhaps the tail stock can be shimed to align properly.

On my lathe I only tighten the tail stock as I push the center away from me. This keeps the horizontal alignment. The vertical is good.

I could add a shim but this works and I am lazy.

Stu

 

[Jamie Straw]

Replying to everyone...

Rather than respond individually to your posts, I'll do it all here.

• Headstock swivels, but does not slide. Original symptoms were somewhat improved by locking it down much more firmly. My AAW chapter buddy is thinking along the lines of some paint or rust between the headstock and the base. Wouldn't take a whole bunch, perhaps, to throw things off 8-10" away.
• No way to know if the problem's been there forever, and I do not know if it actually is in the headstock. I just haven't removed it to check anything, hence my original question. The problem showed up when I started turning spindle stock longer than 2". Though the lathe is chronologically pretty old (blue Jet), it has very few hours on it, and the guys who put the new spindle in (installed because old one had gotten scarred inside) were really impressed with how it runs. Misalignment was a problem before and after the new spindle, no change whatsoever.
• No pictures, but I have the Teknatool double-ended mandrel, and when I install it in either end, as I am advancing into the opposite taper, the free end is not aligned. As it enters the taper, I can see that the gap closes unevenly and it stops "early." For instance, if I install it into the tailstock and advance it toward the headstock, it will enter low and to the right a bit. The end that's going into the headstock will not go in as far as it will when I just hand insert it. Reverse the description for anchoring in headstock and inserting into TS.
• I beg to differ with the notion that if one is turning between centers, it doesn't really make a difference if the centers are in alignment. If one spindle is dead on center, and the other one (head or tail) is pointing NW or SE or whatever, there is going to be a problem when turning stuff that's 7" or 8"+. I can feel it as I go up a spindle from the head to the tail. And no matter how nicely I'm turning, the far end will insist on chattering and will not turn true. Have varied TS pressure, to no avail.
• If I take various mating parts and check alignment even further away than the double-ended taper reaches, the alignment is worse, which makes sense if there's an angular problem here.
• Thank you, John, for the tip on how to provide alignment when the head's been turned. If need be, I'll give that a try. Stu, my lathe is the opposite, I pull the tailstock toward me when locking. I have used shims, and they help with the vertical, but it's fairly apparent that there's some lateral mis-match also, and the vertical isn't getting totally corrected with the brass shims I used.
• I have a dial indicator, cheap though it may be. I'll see if I can figure out how to set it up for a test. I have put a machined straight-edge on the lathe ways/rails, and they are not perfectly flat, but the symptoms don't correspond to the very slightly high point (less than .015", which is the thinnest gauge I have).

Thanks for brainstorming on this. If push comes to shove, I have a line on a machinist I can take it to. Somewhat concerned any time there would cost half of what the lathe is worth.😛

 

[Michelle Rich]

what kind of surface is the lathe on? is the floor flat? so many times it is just this simple..the legs are not on a flat surface & it will twist the bed just a bit and cause misalignment..something simple to consider

 

[Jamie Straw]

what kind of surface is the lathe on? is the floor flat? so many times it is just this simple..the legs are not on a flat surface & it will twist the bed just a bit and cause misalignment..something simple to consider

It is on a shop-made "mobile" base made of 4x4's and Baltic birch plywood. A few months ago, I loosened the bolts in case the wood was moving and pulling the lathe out of whack. I don't think the bed is twisted -- the aforementioned test with straight-edge and feeler gauge didn't show much, and (as mentioned) the symptoms don't mesh with what little lack of flatness there is (near as I can tell).

 

[Charlie Knighton]

as I am advancing into the opposite taper, the free end is not aligned

you have 4 legs to adjust with shims......the bed can be adjusted that way.......if you can borrow 2 foot level and 4 foot level those will probably show which leg is out of wack.........u may have to adjust the legs over a period of time.....sounds like the ways are out of wack and you will have to adjust more than once......sort of like weighing a rough out till it achieves equalization .....good luck

 

[Bill Boehme]

.... I beg to differ with the notion that if one is turning between centers, it doesn't really make a difference if the centers are in alignment. If one spindle is dead on center, and the other one (head or tail) is pointing NW or SE or whatever, there is going to be a problem when turning stuff that's 7" or 8"+. I can feel it as I go up a spindle from the head to the tail. And no matter how nicely I'm turning, the far end will insist on chattering and will not turn true. Have varied TS pressure, to no avail.

To make sure that we are on the same page, turning between centers means that you are NOT using a chuck or a mandrel to rigidly hold a piece in the headstock. The headstock will have a spur drive or a stebdrive or a safe drive or some type of drive that is holding by virtue of the pressure applied by the tailstock. An analogy of turning between centers is the drive shaft on an automobile. There is a universal joint at the transmission and another at the differential gear case. The transmission and the differential are never in alignment with each other as the vehicle is traveling because of all of the dynamic forces acting on the rear axle, yet the drive shaft turns just fine without any binding. Another example that is a bit closer to home: a simple foot powered wooden lathe works just fine turning spindles even though they don't have the high tech precision alignment that we believe is essential for turning between centers. When we turn between centers, the axis of rotation is NOT the boresight centerline of the spindle ... the rotation axis is the line that connects from the center points of the of the drive center and the tailstock live center (or dead center, in the case of more rudimentary lathes).

I think that the double ended Morse taper tool is a diabolical device with the potential for damaging the Morse taper sockets on on a lathe. Morse tapers are machined to a precision on the order of ten thousandths of an inch. There is no woodturning lathe in existence that has the precision such that the headstock and tailstock will align to that accuracy. This means that you could wind up getting things is a bind if the parts were very close and a little excess force were applied to force then together. Also, I'll be tarred and feathered as a heretic, but the standard practice of matching points is no assurance of alignment-either. If you were able to get the points "eyeball" perfect, that only says that the headstock spindle and tailstock quill are in radial alignment, however, in all likelihood there is still some angular misalignment ... and if you were holding a long spindle rigidly in a chuck, it would be the angular misalignment that become the most significant alignment error. The good news is that most of these errors are not important when it comes to woodturning because we have ways to deal with them. And, turning between centers is the oldest way of dealing with alignment.

 

[hockenbery]

When turning between centers the tailstock and headstock each have a center point and two points are always in a straight line.
A small angular difference is not a problem. Obviously if the angle is big like 90 degrees the centers won't hold.

With a bowl blank or a pen Mandrel the center of rotation near the tailstock center moves in a circle.
When the circle gets bigger than an 1/8" or so the tailstock cannot be used effectively.
With a pen mandrel the pen barrels will get sort of oval or thinner on one side a bit like doing an off center turning.

Any easy way to test the alignment is to put a block of wood (bowl blank) on a screw center.
Face of the side near the tailstock. (New turners may have to sand it) Put a center with a center point in the tailstock that you can keep from rotating.
Bring the point up to the wood and turn the wood by hand and advance the center slowly so that the point scores the surface.

The diameter of the circle will be half the off center distance of the two centers.


Al

 

[Doug Rasmussen]

"double ended Morse taper tool ".....? That's a new one for me, it would be an alignment tool I assume. My experience is with high precision metal working machinery so it's easy to visualize the tool, but to apply that to a basic wood lathe doesn't make sense to me. I have doubts that such a tool would "validate" the headstock and tailstock alignment of my CNC lathe costing 50 to 100 times the price of a Jet wood lathe. Yet, my lathe is capable of repeatable work to a fraction of a thousandth in diameter.

There must be other issues at work here beyond headstock alignment.

 

[Bill Boehme]

... Any easy way to test the alignment is to put a block of wood (bowl blank) on a screw center.
Face of the side near the tailstock. (New turners may have to sand it) Put a center with a center point in the tailstock that you can keep from rotating.
Bring the point up to the wood and turn the wood by hand and advance the center slowly so that the point scores the surface.

The diameter of the circle will be half the off center distance of the two centers.

Jamie, when I use Al's method of aligning the tailstock, there is enough "wiggle room" between the tailstock quill and the body of the tailstock to take care of any misalignment when doing faceplate turning. Obviously, this won't work if the misalignment is large. Fortunately, on my lathe, it's barely more than a gnat's eyelash difference.

I don't have much confidence in pen mandrels being straight. I have two of them and neither is perfectly straight. I can tap on them to improve the alignment a bit, but that also tells me the Morse taper isn't perfectly seating ... c'est la vie. It might be my fault because in my early days of turning I probably applied too much tailstock pressure. I've noticed that some pen turners are now turning the pen blanks between centers rather than using a mandrel. This solves a bunch of problems such as going oval because of a bowed mandrel.

"double ended Morse taper tool ".....? That's a new one for me, it would be an alignment tool I assume.....

I'm sure that there's a special place in Purgatory for whoever invented that tool.

 

[Jamie Straw]

To make sure that we are on the same page, turning between centers means that you are NOT using a chuck or a mandrel to rigidly hold a piece in the headstock. The headstock will have a spur drive or a stebdrive or a safe drive or some type of drive that is holding by virtue of the pressure applied by the tailstock.

Yeah, got that (several years ago).

(Snip)
I think that the double ended Morse taper tool is a diabolical device with the potential for damaging the Morse taper sockets on on a lathe. Morse tapers are machined to a precision on the order of ten thousandths of an inch. There is no woodturning lathe in existence that has the precision such that the headstock and tailstock will align to that accuracy. This means that you could wind up getting things is a bind if the parts were very close and a little excess force were applied to force then together.

That would be the user's stup... -- no sorry, bad judgment.

Also, I'll be tarred and feathered as a heretic, but the standard practice of matching points is no assurance of alignment-either. If you were able to get the points "eyeball" perfect, that only says that the headstock spindle and tailstock quill are in radial alignment, however, in all likelihood there is still some angular misalignment ... and if you were holding a long spindle rigidly in a chuck, it would be the angular misalignment that become the most significant alignment error. The good news is that most of these errors are not important when it comes to woodturning because we have ways to deal with them. And, turning between centers is the oldest way of dealing with alignment.

I'm in the "whatever helps" camp. Perhaps you could share said "ways to deal with them" besides defaulting to between-center operations. I have learned to use the TS point to micro-adjust a spindle put into a chuck. May not be aware of other tricks.

After being chastised so thoroughly about this between-centers thing, I went through all the various tailstock apparatus I have. Turns out the Nova live tailstock system, most especially the miniature extension center because it's so long, describes a circle as it turns. After I shimmed the TS last night (whatever helps, right?), I went back to the PSI live center and turned an 8" spindle. Things went much, much better. Teknatool is sending me a new set this week.🙂

 

[Jamie Straw]

When turning between centers the tailstock and headstock each have a center point and two points are always in a straight line.
A small angular difference is not a problem. Obviously if the angle is big like 90 degrees the centers won't hold.

With a bowl blank or a pen Mandrel the center of rotation near the tailstock center moves in a circle.
When the circle gets bigger than an 1/8" or so the tailstock cannot be used effectively.
With a pen mandrel the pen barrels will get sort of oval or thinner on one side a bit like doing an off center turning.

Any easy way to test the alignment is to put a block of wood (bowl blank) on a screw center.
Face of the side near the tailstock. (New turners may have to sand it) Put a center with a center point in the tailstock that you can keep from rotating.
Bring the point up to the wood and turn the wood by hand and advance the center slowly so that the point scores the surface.

The diameter of the circle will be half the off center distance of the two centers.

Al

I learned to hate mandrels after my pie-knife experience. The only one I've used since is Ruth Nile's wine stopper mandrel. Thanks for the tip on testing alignment. That I can do. I used what I thought was a fairly clever idea the other day for getting an idea of how far off things were over a long distance. I screwed the long Beal buffing holder onto the spindle, and put the short taper-mounted holder in the tailstock. They have the same diameter on the outside. Made it easy to see both vertical and lateral relationships. I know they're not precision machined, but still, it helped. Here's a picture before the two mating surfaces are closed up:

 

[Jamie Straw]

Jamie, when I use Al's method of aligning the tailstock, there is enough "wiggle room" between the tailstock quill and the body of the tailstock to take care of any misalignment when doing faceplate turning. Obviously, this won't work if the misalignment is large. Fortunately, on my lathe, it's barely more than a gnat's eyelash difference.

I don't have much wiggle room in the quill, but there's lots between the body dovetail and the ways (lateral only, of course).

I don't have much confidence in pen mandrels being straight. I have two of them and neither is perfectly straight. I can tap on them to improve the alignment a bit, but that also tells me the Morse taper isn't perfectly seating ... c'est la vie. It might be my fault because in my early days of turning I probably applied too much tailstock pressure. I've noticed that some pen turners are now turning the pen blanks between centers rather than using a mandrel. This solves a bunch of problems such as going oval because of a bowed mandrel.

As mentioned, I've learned to hate mandrels, or at the very least be picky about which one's to use.

I'm sure that there's a special place in Purgatory for whoever invented that tool.

Surely the inventor should be spared when his tool is used unwisely. It was not produced for what I used it for (simply to check alignment, since there's no aligning I can do on my lathe other than shims), nor was it produced for some Sasquatch turner who jams it into a taper and messes things up.😀