Jet 1442 Headstock and Tailstock Alignment

[Ken]

I've heard that it's common for lathes with a swiveling headstock, for the headstock and tailstock center lines to be out of parallel ... the center lines run at an angle to each other. Is this true and if so ... has anyone experienced this problem with their Jet 1442? If you had the problem ... how did you fix it?

Thanks!

Ken

 

[Mark Mandell]

Here you go, Ken,

http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=lathes-acc-mrstool


Fix you right up.

 

[Ken]

I shoulda known there'd be a tool for this ... go figure!

If the factory set indexing is out of alignment ... is the indexing bracket user adjustable to bring it back into alignment.

I haven't bought the 1442 yet. I just wanna make sure I know what I'm gettin' into.

Thanks!

Ken

 

[Bill Boehme]

When I first got into woodturning, I thought that the double ended Morse tapered insert was a great idea, but now I would be very hesitant to use one on my lathe for fear of damaging the sockets on the tailstock and headstock. The mating surfaces of the socket and insert fit together with a precision on the order of 0.0001 inch. Now imagine what might happen if you have a lathe that has a misalignment between the headstock and tailstock that is two or three orders of magnitude greater than the fit between the socket and insert. First you loosen the locks on both the headstock and tailstock and then slide the tailstock up to the headstock so that the tapered insert fits into both the headstock and tailstock. The lateral component of the misalignment may not be too much of a problem since there is probably enough play between the ways to allow for some amount of shifting of the headstock. But what is going to happen when the locking lever is tightened? Most likely the headstock will want to rotate just slightly which will cause some lateral binding force. That part is not too bad, but what about the vertical component of misalignment? No matter how good your lathe may be, it is unlikely that the vertical misalignment is on the order of 0.0001 inch. In fact, it is considered pretty good if it is 0.01 inch or less which is just barely discernable to the unaided eye. So when you fit everything together and there is some vertical misalignment, one of the two ends will get lifted off the bed of the lathe (in actuality, there is usually enough mechanical play and flex so that neither end will actually lift off the bed -- it will just result in all of the mechanical compliance being loaded up like a large stiff spring). OK, so now you lock down the headstock to hold it in place and at the same time put a good bending moment on the double ended insert (not to mention what it is doing to the Morse tapered sockets on the headstock and tailstock). So now my question is, how much damage have you caused to the Morse tapered sockets on your lathe in the name of aligning things? I can't think of any instances where the headstock and tailstock are (or need to be) rigidly coupled during turning. When you are spindle turning, the connections to both ends of the wood act as flexible couplings in which there is very little angular displacement. The end result will not be any different between perfectly aligned centers and those that are off by even as much as 1/16 inch. What will, however, cause a problem is when the point of the center at either end inscribes a small circle rather than running perfectly true. And, I suspect that use of the double-ended tapered insert could eventually become the root cause for a spindle socket that doesn't run true.

Bill

 

[MichaelMouse]

So now my question is, how much damage have you caused to the Morse tapered sockets on your lathe in the name of aligning things? I can't think of any instances where the headstock and tailstock are (or need to be) rigidly coupled during turning. When you are spindle turning, the connections to both ends of the wood act as flexible couplings in which there is very little angular displacement. The end result will not be any different between perfectly aligned centers and those that are off by even as much as 1/16 inch. What will, however, cause a problem is when the point of the center at either end inscribes a small circle rather than running perfectly true. And, I suspect that use of the double-ended tapered insert could eventually become the root cause for a spindle socket that doesn't run true.

Of course, if you're using something besides a point in the tailstock, it makes a big difference if the two are out of alignment. Inscribing a circle is from misalignment at the tail, though it may be runout at the headstock which causes it as well. Snubbing up to hold the top on a box to match diameter and grain is one place where you don't want that blunt end scrubbing, trimming the bottom of a reversed bowl, and there are many more. So alignment is important, and should be checked regularly, especially if you're blessed with that spindly POS tailstock on a Nova 3000, where you have to make the alignment true in the direction the base rotates as it is tightened, since there's slop in the block.

If you're convinced by the above that the double-ended morse taper - here referred to as a "biological impossibility," fitting - may cause damage even if you're gentle, then you might also go the way I use to check. Take the point of choice out of your center and sneak the blunt ring up against some trued thing rotating at the headstock. If it doesn't scrub and deflect the quill at good extension, you've got it right. Juggle until it doesn't, if it does. Method two is to make a hole in your rotating piece and ease the tapered nose in while it's not running. Touches at all places around the edge, working great.

Of course, you could always use the method in the book, aligning points.

Quick hint, a mirror is nice to have for alignment. The dentist kind you use to find those "easy access" bolts on your alternator is great.

 

[Bill Grumbine]

Hi Ken

I have owned three swivelling headstock lathes of various levels of quality. Those indexing pins never seem to quite line up, so I gave up on that early on with my Jet 1236. For 11 of the 12 years I have been turning, I just brought the points of the centers together. On my latest lathe, a Poolewood Euro 2000, they sent a cheesy spur center with a bent point, so my first purchase was a better center from Packard. Just last year I bought a double ended MT, and use judicious pressure when lining things up with it. I don't think you really need one, but I was in the store with money in my pocket.

In practical matters, the further away the centers get from one another, the less critical their alignment becomes. In my own experience, the longest I have taken this principle was when I turned the mast for my sailboat. The centers of two lathes provided 14' 2" of turning space. They were at 48" and 47" high respectively, and I eyeballed lining them up by sighting through the headstock and tailstock holes of the smaller lathe. I had a few eccentric lumps in my mast, and that bothered me for a while until I examined a few commercially turned wooden masts, only to discover that mine was just as good if not better than theirs.

Bill

 

[Mark Mandell]

Ken,

Poolewood and Silverdrive, probably the two premier swivel-head lathes, supplied that double end taper specifically for positive realignment of their high-end machines. Now, a $900 JET lathe is not built to the standards and tolerances of those $6,000 lathes, but the tool works just fine with no damage to the machine PROVIDED that the tool and the morse tapers are cleaned before the taper is inserted; something many turners never do.

Note, however, that if the 1442 JET, like the 1236, uses mechanical detents for alignment, the tool won't do you any good because the lathe will only lock at points where the machining will allow. I don't know if there is adjustment on the 1442's detents (if it has them); there wasn't on my old 1236.

Mark

 

[Bill Grumbine]

Note, however, that if the 1442 JET, like the 1236, uses mechanical detents for alignment, the tool won't do you any good because the lathe will only lock at points where the machining will allow. I don't know if there is adjustment on the 1442's detents (if it has them); there wasn't on my old 1236.

Mark

Yes and no. Mark is right that the Jets as well as other machines have detents in the swivel mechanism, and the lathe will stop at each detent, and it is the manufacturer's intent that you use the detent. However, you can lock the headstock down at any point in the arc. With both my Jet and my Nova TK 1500, which has the same headstock as the Nova TK 3000, the alignment detent was just a hair off. I would align the headstock according to the centers, but it required frequent readjustment, since any pounding at all caused the headstock to slip into the detent. My Poolewood has no detents, and is only subject to moving when very heavy pieces are turned aggresively or if someone has a large catch - a real large catch.

Editorial note: my comment about frequent readjustment is not contradictory to my statement in the previous thread about distance and such. I was doing production pens at the time, which requires a high degree of accuracy. I just thought I would put this in since I have a detractor who seems to follow me around (and it ain't Mark).

Bill

 

[Mark Mandell]

Ken,

I think it worthwhile to drop a footnote here on morse tapers. They are not, unfortunately, all created equal. I found this out when I bought my JET home only to find that the TS taper had a slight bump in the interior that prevented the live center from seating properly and aligning with the drive spur point; they [the points] were off by a good .004. Now when spindle turning between centers, it's not that big a deal because you'll turn away the ghost of the slight eccentricity, but with a faceplate mounting, the TS live center point will scribe a circle and its bearings will wear much more quickly. The cure was a No. 2 morse taper hand reamer. A [nuther] tool, about $26 from ENCO, that you'll rarely use after the initial application if you do things right. Looks like a 6" long, 6-fluted router bit that is CAREFULLY inserted into a morse taper and LIGHTLY & GENTLY turned by hand (and wrench) to remove ANY bumps, galls, and other imperfections in the female taper's surface. DO I need to say that the LATHE MUST BE TURNED OFF when you do this?

I judiciously applied a reamer to my JET (1236), and the points met to less that .001; way good enough for a wood lathe. I also found a stray burr on the TS taper of my Stubby 1000 that prevented the live center from seating properly; taper applied and the points (after truing) match to less than .0002.

The reamer is not for frequent use however, as it will tend to bore out the taper. You should use a rubber taper cleaner (Packard sells one) that removes a dust or grit from the taper before an appliance (center, etc.) is inserted to prevent scoring or galling of the taper. Do NOT use abrasives to ream or clean a taper because the fractured grit bits will imbed in the metal surface and cause further damage.