Wobble on Nova G3 chuck

Signed-In Members Don't See This Ad

billgtx

Member
Joined
Aug 9, 2019
Messages
3
Location
Spring, TX
Hi all. I have a Nova Comet II lathe bought a little over a year ago. Bought the Nova G3 chuck, drill chuck, etc at the same time because I didn't have a drill press. Have probably made 50 or so pens and my wife has probably made 20 or so. We use a typical pen mandrel for the pens although I've recently moved to turning between centers.

Recently I tried my hand at making some rings. Was using the G3 chuck to hold a 2x2 piece of wood to turn a ring mandrel and noticed there was a slight wobble in the chuck. Since I'm not sure if this will cause issues when I remount the ring mandrel after taking it off, I decided to run some tests. At first I was just using eyesight and there is a barely noticeable wobble in the body of the chuck but the jaws seemed to have a noticeable wobble.

So I bought a dial indicator and took some measurements. If my descriptions aren't clear I'm happy to post some pics or take video.

Dial indicator at the body of the chuck (between the tightening holes and the jaw slides. I get about 5-6 thousandths of movement. If it matters, the peak and valley are right near the #2 and #4 slides.
Dial indicator on the jaws fully closed - right at about 9 thousandths.
I have a spur center that came with the lathe. Put that in and measured the runout at 2 thousandths. Does this indicate the spindle, bearings and morse taper are OK?
Put in my drill chuck and measured at the jaw housing - I get 4 thousandths.
I also bought the Patrick Adair ring mandrels and put one in the drill chuck and measured 5 thousandths at the ring furthest out.

How do you read this information? Any other tests I can do? The only other thing I have that screws on to the spindle is the face plate that came with the lathe. Wasn't sure if it was constructed with enough precision to do a runout test on the body.

Thoughts? Do I have a bad chuck? Can it be improved?

Many thanks!

PS. Apologies on this as my first post. I joined after buying my lathe but was more of a lurker than anything. Again, thanks.
 
Signed-In Members Don't See This Ad

MPVic

Member
Joined
Dec 23, 2011
Messages
319
Location
Hamilton, ON, Canada
No apologies necessary - everyone on this forum learns something from one another's experiences, whether good or bad. I am not knowledgeable about diagnosing your problem but I'd bet the farm someone here will be able to help you. Good luck.
 
  • Like
Reactions: DrD

monophoto

Member
Joined
Mar 13, 2010
Messages
1,734
Location
Saratoga Springs, NY
There have been several similar threads on this subject. One point that I found interesting is that while 0.001” might be considered a nice target for runout, that might actually be a illusive target in that wood can move more than that much in response to changes in temperature and humidity.

Seems to me that your real concern is the increase in runout with the chuck in place relative to the runout of the lathe spindle. I suspect that some increase is normal. so the issue is whether the increase you are getting is reasonable. Presumably you were satisfied with the chuck and its performance, so the question is what has changed.

Do you have a washer on the spindle? Washers are notorious for increasing runout. But the same effect can be created if crud builds up on the mating surfaces, so maybe you just need to clean the chuck and lathe spindle. It is also important to confirm that the chuck jaws are on the correct sliders, that there is no crud between the jaws and the sliders, and that the jaw mounting screws are tight.
 
Last edited:

Mortalis

Member
Joined
Aug 19, 2013
Messages
394
Location
Rochester, Mass
I've heard some woodworkers that are trying to square a cross cut sled say that 1/32 is good enough and some that strive for less. It all depends on what your tolerance level is for what you are making. I typically look at 1/32" = .030 for even numbers. I know it is not exactly .030 but for easy math and the fact that wood can move more than the difference I use it for easy calculations.
Back to the OP question.
Seeing how 1/32 is close to .o3o and you are seeing .009 max runout....is that a true problem? .009 is a bit more than 1/128th". Will someone you sell a ring to be able to tell if the ring is off by .009"?
 

Charlie_W

Member
Joined
Nov 16, 2011
Messages
5,710
Location
Sterling, VA USA
Louie already mentioned build up of crud where the chuck tightens up against the shoulder of the spindle. If it doesn’t snug up tight to the shoulder, there can be wobble/run out. Also check the Morse taper for accumulation of crud or eve galling if a Morse taper fixture has spun inside the spindle.

You didn’t mention whether your G3 has an insert or is a fixed 1” thread type. A turner in our club found runout in his Nova Chuck even though the spindle ran fine. He bought another insert....worse. He ended up at Woodcraft with his chuck and dial indicator checking the several inserts they had in stock and picked the best one. This tells me that these chucks /inserts are not machined to the best tolerances. You should not have this issue with quality chucks. Of course with run out at the spindle, it gets magnified the farther you move away from the spindle towards the tail stock.

Another thing to consider is the quality of the lathe itself and that many lower priced wood lathes are not machines to the specs of a top quality machine...or a metal lathe. There is slop where the tailstock fits between the ways. There is often play in the tailstock quill when the quill lock is loosened such as when drilling or turning for that matter....always lock the quill lock. It is there for a purpose. Manufacturers can keep the costs down when tolerances are not as tightly machined.

As for chuck jaws, I would expect to see variances in tolerances as scroll chucks have multiple moving parts and the jaws are not machined on the actual Chuck you receive. They are machined separately. Some jaw sets are machined and cut into quadrants and numbered so they can go back together the same way. Non numbered jaws may have more variances.

Hope this helps!
 

billgtx

Member
Joined
Aug 9, 2019
Messages
3
Location
Spring, TX
Thanks for all the responses! I know you don't know me from Adam, just a guy posting a question on the forum. And I support business users in a technical setting, so I understand asking all of the basic questions. I have searched the forums and found all of the suggestions posted elsewhere. Here's the bullet point list:

No adapter as the chuck is 1 x 8 and my spindle is 1 x 8.
No washer.
Jaws are seated in the corrects slots - checked over and over.
Read the manual for attaching the jaws just to make sure. But I must say, that wasn't all that clear.
Everything cleaned as well as I can do. I don't know how to look for damage/galling. Things look and feel OK.

I'm content that this is not an expensive lathe and there will be looser tolerances. I do get a little nervous when I can visually see mandrels / hardware moving around. I had found out of round issues turning pen blanks for various reasons so when I can see the wobble I get nervous.

I guess the underlying question in my OP is the procedure for troubleshooting and acceptable tolerances vs expectations.

Thanks again for the responses. I'll go back to turning things and see what results I get.

Last question(s) - what are some better quality chucks to look at? Better drill chuck?
 

monophoto

Member
Joined
Mar 13, 2010
Messages
1,734
Location
Saratoga Springs, NY
I guess the underlying question in my OP is the procedure for troubleshooting and acceptable tolerances vs expectations.


Last question(s) - what are some better quality chucks to look at? Better drill chuck?


I think the procedure is correct. The problem is that there is no real standard for what is acceptable - it really is a matter of what kind of tolerances you put on your work. 0.001" is tight - that's less than 1/64" which is actually hard to measure.

The other question that I kind of mentioned, is what caused you to become concerned about runout? Did you have an actual experience in which runout was a problem, or was it more of a curiosity thing -" I saw it wobbling and measured it and wow it didn't know it was that sloppy"? I've often thought about buying a dial indicator, but then it occurs to me that maybe I'm better off not knowing how sloppy my tools are, and just doing the best job I can with what I have.

As to your second question, the old saying is 'You get what you pay for'. In other words, price may be an indicator of quality. That said, even the 'best quality' sometimes either has a bad day (think 'Monday' cars) or is used in a way that leads to substandard results.
 

Dehn0045

Member
Joined
Mar 19, 2017
Messages
1,362
Location
Houston, Texas
I use a brass brush to clean the mating surfaces really well. A couple of times I have placed a piece of 2000 grit sandpaper on a flat glass surface (granite surface plate would be better) and lightly sanded the mating surface on the chuck. It has helped a little. I have been wandering into the metal lathe corners of the internet where tolerances are a bit tighter, but 1 to 2 thou on the body of the chuck is pretty common even with higher quality metal lathes. These machines also tend to use more exotic methods for mounting/centering the chuck (1x8 tpi threaded is cheap and super simple but not the most accurate). The runout of the spur center isn't great, but easily could be the center - maybe try a dead center as they are probably more precisely machined (a dial test indicator on the inside of the morse taper is probably the correct way to check).

The Nova G3 is a well respected wood scroll chuck, I doubt you'll find a woodturning scroll chuck that performs significantly better. In metal turning they often use a 4-jaw independent jaw chuck. With this style each jaw is manipulated independently which allows you to compensate for some of the errors and get bang on. I haven't seen any woodturners use them, but I don't see why it wouldn't work for holding mandrels and such. I imagine they are not very effective for holding softer workpieces (like wood). https://littlemachineshop.com/products/product_view.php?ProductID=1175&category=566826475 (note that these are often "plain back" and require a back plate, I suspect with a little searching you can find a chuck/backplate combo that works without additional machining. Also may be able to find one on ebay used that is already set up 1x8 tpi).

Use some caution with holding the drill chuck in the MT of the headstock. Radial forces will pop the MT out and the chuck will go flying (super not safe - don't ask me how I know). You can use a draw bar to secure it in place, but I've never done this so can't offer any details.
 
Last edited:

monophoto

Member
Joined
Mar 13, 2010
Messages
1,734
Location
Saratoga Springs, NY
Use some caution with holding the drill chuck in the MT of the headstock. Radial forces will pop the MT out and the chuck will go flying (super not safe - don't ask me how I know). You can use a draw bar to secure it in place, but I've never done this so can't offer any details.
Very true.

A drawbar is nothing more than a piece of all-thread rod that screws into the end of the morse taper on the drill chuck. Typically, drill chucks have a threaded hole to receive either a 1/4" or 3/8" rod (and perhaps other diameters) - you have to examine the chuck to determine which you need. The drawbar extends through the headstock and is secured with a nut outboard of the handwheel. You can buy them, but they are really easy to make. In mine, the securing nut is a t-nut embedded between two blocks of wood that I glued together and then turned into a smooth knob. I also covered most of the shaft of the drawbar with a plastic sheath - I slipped some pieces of heat-shrink tubing over the rod, leaving about 3/4" of threads exposed at the end that goes into the chuck, and then blasted it with a heat gun to shrink the tubing. That prevents the threads from scoring the inside of the headstock spindle.

But beware - a drawbar is not a perfect solution. The drawbar does effective trap the morse taper on the drill chuck and prevent it from coming loose as Sam describes. But some jacobs chucks consist of a chuck head that is mounted to a double-ended mandrel - with a morse taper on the end that fits into the lathe, and a JT-33 taper on the end that fits into the chuck body. That's a good arrangement in that it allows you to upgrade the mandrel without changing chucks - for example, when I moved from a small MT1 lathe to a midi lathe with an MT2 spindle, I didn't have to replace my drill chuck - I just replaced the mandrel. On the other hand, that arrangement also means that there are two tapers between the lathe spindle and the chuck body, and the drawbar will only secure the MT end. So it is still possible for the chuck body to separate from the mandrel at the JT-33 end, and as Sam said, that can be dangerous.
 

robutacion

Member
Joined
Aug 6, 2009
Messages
6,494
Location
Australia - SA Adelaide Hills
Many of us have experienced that same issue, I certainly did with a Nova G3 and after a number of inserts, all seem to have some "slack" none was unable to stop the wobble, however, someone mentioned proper nylon buses made for the purpose of been inserted between the spindle and the chuck no stop chuck from getting such but also to reduce the amount of wobble in question, these are buses that I have use since and replace as soon as I see an increase of the wobble, this works for me as I don't require extreme precision if you do, you may need to invest in higher-end equipment and accessories for a high cost, unfortunately.

For the price of these nylon bushes is well worth to get a couple and try them out.

Cheers
George
 

monophoto

Member
Joined
Mar 13, 2010
Messages
1,734
Location
Saratoga Springs, NY
Many of us have experienced that same issue, I certainly did with a Nova G3 and after a number of inserts, all seem to have some "slack" none was unable to stop the wobble, however, someone mentioned proper nylon buses made for the purpose of been inserted between the spindle and the chuck no stop chuck from getting such but also to reduce the amount of wobble in question, these are buses that I have use since and replace as soon as I see an increase of the wobble, this works for me as I don't require extreme precision if you do, you may need to invest in higher-end equipment and accessories for a high cost, unfortunately.

For the price of these nylon bushes is well worth to get a couple and try them out.

Cheers
George
Ideally, when installing chucks on a lathe spindle, they should be tightened until the machined face on the back of the chuck is dead flat against the machined shoulder of the lathe spindle. Often, you see demonstrators on YouTube who wildly spin a chuck when installing it on the lathe, with the result that it jams in place. When that happens, subsequently removing the chuck is difficult.

Spindle washers are intended to avoid this problem by providing a slippery and slightly resiliant cushion between the chuck and the spindle, and they do work for this purpose. However, it is critical that they be absolutely flat - if they are not truly flat, then tightening the chuck down on a washer will cause the chuck to be canted to one side, thereby introducing runout. Even a very minute deviation from absolutely flat can cause enough of an angle to create several thou of runout.

A lot of people make their own washer, and one suggestion you will often see is to use material from an old milk carton. My experience is that milk cartons do not have a uniform wall thickness and therefore can't be used to produce a flat spindle washer. I was able to get a reasonably flat washer from the plastic box that originally held a TurboTax software CD,, but it took several attempts.

Expert turners recommend against using spindle washers. They also strongly discourage the practice of spinning a chuck onto a spindle so that it 'snaps' in place. Instead, they suggest carefully cleaning the machined surfaces on the back of the chuck and on the shoulder of the spindle, and then gently rotating the chuck until it is just barely snug. When you turn on the lathe, rotational momentum will tighten the chuck further, but if you avoid that snap action, it won't be jammed onto the spindle and can be easily removed later.
 

Charlie_W

Member
Joined
Nov 16, 2011
Messages
5,710
Location
Sterling, VA USA
As for chucks, most pros use either Vicmarc or OneWay.

I happen to have OneWay Talon chucks as well as their Stronghold for larger work. The Talon is better sized for the mini/midi lathes. These require an insert but the insert attaches differently than the screw in inserts used by Nova.
I’ve never checked run out as I don’t have a dial indicator.....yet😉

When you checked for run out, did you check the face of the spindle shoulder as well as the outer diameter of the spindle?

As for drill chucks, my preference is a keyed chuck. I do have a keyless which is fine for a majority of drilling but my keyed chuck had deeper/longer jaws so the bit is inserted further which I like. This one is 5/8” capacity as on occasion, some pen turning drill bits exceed 1/2” diameter.
I almost always drill with the drill chuck in the tailstock. If drilling from the headstock, I use a draw bar as already mentioned.
 

billgtx

Member
Joined
Aug 9, 2019
Messages
3
Location
Spring, TX
The other question that I kind of mentioned, is what caused you to become concerned about runout? Did you have an actual experience in which runout was a problem, or was it more of a curiosity thing -" I saw it wobbling and measured it and wow it didn't know it was that sloppy"?
Haha. The latter. The longer version...

I had turned a wood ring mandrel using the chuck in the head stock and a live center in the tail stock. But every time I remounted the wood ring mandrel, I had to re-turn the mandrel so that it was round. In other words, I couldn't get the thing mounted in the chuck in the exact same position so that it turned the exact same way.

So, I bought the Patrick Adair steel expanding ring mandrels. These mount in a drill chuck or a collet chuck (which I don't have). I inserted my drill chuck in the headstock and the ring mandrel into the drill chuck. Things seemed to turn round on one ring just fine. A few days later I put in a different size ring mandrel to turn a different ring and noticed it wobbling pretty bad.

So I went back to my chuck with the intention of resuming work on the wood ring mandrel. At least I could turn it so that it was round before working on the ring. But then I started paying closer attention to the chuck itself. I had recently noticed that the jaw sliders rattled pretty good when not securing stock and from an uneducated eye it looked to me like they had too much slop. Went to my local Rockler and tested a few display chucks and sliders. They seemed to be less loose but still moved.

So, now I've pulled a significant amount of thread off the sweater (!) so I wanted to take a step back and just evaluate my setup. Went on a search to figure out what the heck is going on. I ran across topics such as bent/damaged spindle, bad bearings, etc. Finally read a thread on here that said if I didn't have a dial indicator, I'm just guessing. So bought one and started measuring things.

I just went out and remounted the drill chuck and one of the steel ring mandrels. Noticed it didn't noticeably wobble. So now I'm thinking it's a matter of the draw if I get the drill chuck and mandrel installed in the best possible setup.

But I'm still not sure about the jaws on the G3 and posted here in an effort to get someone else to review what I have. I've been meaning to join the local turner's club but just haven't done it yet. So I don't really know anyone that can come in person to evaluate. Your responses are greatly appreciated.

Later today I will measure the inside of the spindle, reevaluate the mounting surface on the spindle/G3, measure the runout on my dead center and work on installing and tightening the jaws again. My feeling at this point, is that the chuck is probably fine (even if the sliders move and rattle), and I need to be more attentive when setting the drill chuck up in the headstock.

The MT in the drill chuck doesn't have a hole for a draw bar. So I'll have to see what my options are there. Is there a way to remove the MT from the drill chuck?
 

Dehn0045

Member
Joined
Mar 19, 2017
Messages
1,362
Location
Houston, Texas
The MT in the drill chuck doesn't have a hole for a draw bar. So I'll have to see what my options are there. Is there a way to remove the MT from the drill chuck?
Most drill chucks are assembled with a head and an arbor. Most have a "JT" or jacobs taper, there are various versions, 33JT is pretty common. The other end is the morse taper that goes into the machine (or various other types of attachment). The "jacobs taper" is possibly an issue as noted by Mal, however I think the risk of popping the head off of the arbor is fairly low, but the risk is non-zero. You can pop the arbor off with a rod/hammer, its pretty straightforward (might need a press, but in my experience a few taps with a hammer and the arbor pops loose).

drillchuck.JPG
 

More4dan

Member
Joined
Mar 17, 2016
Messages
2,031
Location
Katy, TX
It’s your chuck!
Even metal working chucks that self center have about 0.003” runout. Wood chucks are not as precise. Even my expensive Vicmarc chuck has excessive runout and about twice what the company rep told me they should have. The taper is the most accurate way to mount your tooling. However, if you turn you mandrill in the chuck and mark the location so you can remount it in the same place, you should get a much better result. When you turn something the part sticking out of the chuck has almost no runout until you move it in the chuck.

One thing I’ve found that helps some for a sloppy Wood chuck is to loosen the jaws a bit, clamp on a drill bit shaft, then fully tighten the jaw screws. It will help take up some of the runout.

Danny


Sent from my iPhone using Penturners.org mobile app
 

MiteyF

Member
Joined
Jan 27, 2018
Messages
176
Location
Bay area
Scroll chucks are inherently low-tolerance, unless VERY expensive, and VERY worked over, and even then if your work piece isn't perfectly round/hexagonal etc, and you don't chuck it JUST right, you will still get runout. Threaded chucks like the ones we use for wood turning are generally the worst of the bunch, and lower end lathes accentuate these issues.

As a rotating equipment machinist, most of my work days are spent on metal lathes working to super tight tolerances where every thou (or usually tenth) really counts. Runout on my wood lathe makes me cringe a bit, but at a certain point you have to accept the fact that we're not usually making tight tolerance parts, we're making something that looks nice, and (occasionally) "works" well. Add to that, as others have stated, that your work piece is more likely to move far more than your lathe bits are running out, due to movement in grain, water gain/loss, and stress on the part from your chuck, tailstock, etc. Wood is a natural, living (at one point), breathing (yes!) material, and chances are, a lathe chuck with 9 thou of runout will not be your biggest issue. Best tip? Once your part is mounted in the chuck, don't take it out and put it back in. Assuming your wood doesn't move much, and doesn't leave your chuck, and your live center doesn't move, once it's turned round, it will stay round, and will still run true despite your chuck.

Learn to work within the confines of your equipment, and eventually you will either find ways to mitigate the issues you have (either by modifying your technique or your equipment), or you will decide that it is worth it to you and your wallet to upgrade to "better" tools. It all depends on what is "acceptable" to you regarding the end result of your project.
 

Dehn0045

Member
Joined
Mar 19, 2017
Messages
1,362
Location
Houston, Texas
All this discussion got me curious, picked up a cheap dial indicator and stand from Harbor Freight - I know, probably not the most accurate setup, when forced to choose between good and cheap, I went with cheap. Anyway, I have a Jet1013, it has 1x8tpi spindle, I also have a nova g3 with pin jaws installed. Best I can tell the spindle is within 0.001, I measured both the inside of the taper and the outside of a dead center. The outside body of the G3 was also surprisingly basically dead on, maybe 0.001. I mounted a few different things in the chuck and all had about 0.012. I retightened several times with no noticeable change. I loosened and retightened the jaws, again no change. Last I tapped the workpiece in with a hammer, I was able to get down to about 0.003. I then removed and retightened again and I was back out to around 0.010 again.

I checked my drill press, it was at about 0.006 on a shaft in the jacobs chuck.

For kicks I checked out the new bandsaw blade, it was surprisingly dead on except 0.006 near the weld (but not actually on the weld, which I thought was strange).
 
Top Bottom