wobble

[fredbelknap]

How much wobble is tolerable. Pic may show what I mean.

[fredbelknap]

Guys I forgot to say this on my Grizzly lathe. Time ran out to edit.

[TDHofstetter]

Lots more than six thousandths.

Now... is that LOOSENESS (you can shake the spindle & get six thou deflection) or RUNOUT (solid, just not perfectly true)? If it's RUNOUT, don't worry at ALL. What you turn will always still come out as round as your skills permit. If it's LOOSENESS, it's prob'ly time to tighten (or replace) bearings at one end or the other... 'cause that's quite a lot of looseness & it won't get better over time.

The faceplate is tight on the spindle nose?

[fredbelknap]

Apr 3, 2010 10:32:54 GMT -6 TDHofstetter said:

Lots more than six thousandths.

Now... is that LOOSENESS (you can shake the spindle & get six thou deflection) or RUNOUT (solid, just not perfectly true)? If it's RUNOUT, don't worry at ALL. What you turn will always still come out as round as your skills permit. If it's LOOSENESS, it's prob'ly time to tighten (or replace) bearings at one end or the other... 'cause that's quite a lot of looseness & it won't get better over time.

The faceplate is tight on the spindle nose?

There isn't any looseness. When I reverse ends with a piece I always have to allow thickness to true it back up. It seems like a lot of difference. I normally use a Talon chuck, I just put the face plate on to check for runout. The problem might be in my chuck. I have a center spur that I can put in the chuck and it will work in only one position. All the other positions the center makes a circle.

[TDHofstetter]

Hmmm... I'd really think it SHOULD be a little more true than that. The faceplate is about a 6"? So... we can figure 6 thou at 3" radius would be about 1 thou at .5" radius (outside of the thread) or 1/2-thou at the inside of the bore. Roughly. That's not bad, but I'd think it'd be better.

The spindle nose might have gotten bumped someplace along the line - in manufacturing, in packaging, etc... I'm sure that'd be within tolerance per Grizzly's policy, and I wouldn't blame 'em too much.

You might run a couple of tests with that chuck - once with the chuck snugged down on the spindle nose and once with the 1/16" spacer inserted behind the chuck to rotate it 180 degrees. If you have to allow MUCH thickness when you reverse the workpiece, that sounds like it's a lot farther out than six thousandths, though - that's just about exactly the thickness of a playing card. We all have to allow SOME because it's impossible to get concentricity back when you reverse a workpiece... and the wood will tend to move a little while we're doing it.

So... let's check runout on the outside of the chuck body at 0 and 180 degrees, then again on its face (with no jaws attached) at 0 and 180, then clamp a scrap block in your biggest jaws & turn it VERY smooth, true, & flat. WITHOUT LOOSENING THE SCRAP, space the chuck out with your 1/16" spacer and indicate against its face.

[monty]

Take the faceplate off and see if the spindle runs true using the gunge to measure the runout.. That will tell you if it's the spindle or faceplate that's off.

[fredbelknap]

Tim I have already checked the side and the face of the chuck and the deflection was about half what it is on the faceplate. Which makes sense. I have been using a plastic washer because the chuck is the devil to get off. I have to use a strap wrench. Tomorrow I will check it some more. Tim I'm not following you very well about chucking up a piece and turning it flat. Will that tell me if it is the chuck or the spindle. I'm guess the larger a piece would give better reading.
Monty not to sure how to get a reading with my set up. The spindle threads kinda throw off the reading. It's workable but aggravating. Maybe it's just me.
Thanks for the help

[TDHofstetter]

I was thinking... mount the chuck with your plastic washer, without the spur center in it. Use it to chuck a piece of wooden scrap, then face off the scrap like you were making a plate. Make it as flat & smooth as you can.

Then don't loosen the chuck jaws at all... just unscrew the chuck and take the plastic washer off. Screw the chuck back on without the washer - I figure the washer's about 1/16" thick, which is half of one thread on the spindle nose; when the chuck is screwed on, it'll screw on one-half turn farther than it did with the washer in place. I just want to see if the faced-off wooden scrap indicates true (on its face) or a long way off.

To read the spindle directly, reach barely inside the hollow spindle, crosswise so you're reading the FAR side of the hollow socket. Rotate the spindle and see if the socket is running true.

[monty]

Thanks Tim. Beat me to it.

[fredbelknap]

Been doing some checks this morning.
The spindle seems to be pretty good, like less than a thousands.
I placed the chuck on the TS surface and measuring on opposite sides and it is out by .004, thats like 3" apart.. I'm thinking that is where my problem is. The part of the spindle that the chuck butts up against is dead on like less than .001.

There is a space between the spindle adapter (1"x8 tpi) and the rear of the chuck of about 1/16". Is this normal, it looks like it should fit snug. The adapter has three machined screws that appear to hold it to the chuck, i was wondering if that is all that holds it on or if it also was threaded. If someone would check there Talon chuck and let me know it would be much appreciated. I hope I explained that ok.

[TDHofstetter]

That's a taper-fit adaptor:





I wonder if there's a bit of crud inside the taper...

EDIT: There SHOULD be some gap between the adaptor's flange and the back of the chuck. That's just the taper not be seated quite all the way in. Different chucks & adaptors will have different gaps there. It's crazy difficult to get a taper like that inside the tolerances it'd take to make it seat JUST FULLY and still snugly so it doesn't flop around.

[fredbelknap]

Apr 4, 2010 12:29:47 GMT -6 TDHofstetter said:

That's a taper-fit adaptor:





I wonder if there's a bit of crud inside the taper...

So far I haven't been able to get it apart. The screws were just finger tight. There is enough space between the shoulder of the adapter and the back of the chuck that I can see the threads on the screws.

[TDHofstetter]

That sounds about right... except... I'd sure hope they were more than finger-tight! I'll bet some sanding dust worked its way into the taper.

Try this:

Unscrew each screw fully, one at a time. Screw each one back in about four full turns. Now mount the chuck on the lathe. With your hands, yank the chuck toward the tailstock. The screws, with their four full threads each, should keep you from yanking it completely off the adaptor... but should provide enough looseness to allow the taper to come apart.

Once it's apart, clean the inside & outside of the taper really well. If you HAVE to (but ONLY if you HAVE to!), touch it up with VERY HIGH-grit sandpaper (1000 or higher) or #0000 steel wool - the steel wool's preferable because it's not as abrasive.

Once it's well cleaned, put it back together and tighten the screws. They don't need to be break-your-wrist tight - that'll just make the taper harder to take apart next time. They SHOULD be snug-Allen-wrench tight, though. Use the long arm of the Allen wrench in the screw's socket; it's really hard to overtighten 'em with the only short arm for leverage...

[fredbelknap]

Tim I got it apart. Used a small cole chisel with a dull angle on it and a light tap with a small hammer and it came loose. Checked the chuck without the adapter and it checks dead level. I then put the adapter back in and it is out .004. Same amount. It looks like I got a bad adapter. Oneway has them on their website for $25, shipping probably as much, it in Canada.

[fredbelknap]

Tim I sanded down the adapter as you suggested and it helped some. It looks like it has been rejected a few times and thrown back in the bin, got quite a few dings on it. I put it back in the lathe and tried it on a piece around 4" long. The wobble is still about 1/8" when I turn the piece end for end. If I keep trying different positions I can get it down to about 1/16". Sorry to bore everybody to death with my small problem.

[TDHofstetter]

Na, I doubt you're boring anyone with it - everybody's tucking this whole issue away in their noggins for later reference, in case they ever should run into a "need for know" about it.

If the adaptor's really very dinged, you might be able to true it a little more, VERY carefully, with a very fine file while the lathe runs. I can't stress "very carefully" enough here, though - that taper is so shallow that if you take a thousandth of an inch off, the adaptor will seat a LOT deeper into the chuck. 2000-grit sandpaper held tight against a flat stick of steel (like a straightedge) would be safer; it'd cut more slowly, and take off very little except the real high points.

[fredbelknap]

Thanks Tim I like your idea to sand it will it is on the lathe, better control. The finest paper I got is 1000 grit. I'll stop by NAPA tomorrow and get some. Really appreciate all your help.