Mark V vibration while turning bowls

[RFGuy]

Thank you both for your responses.

The vibration occurs constantly whenever I have a bowl mounted without support from the tailstock. I use a Nova G3 chuck with a worm drive screw to turn the outside of bowls and to put a tenon on the bottom. Then I flip the bowl around and mount it with the tenon in the chuck jaws. I double checked and the jaws are installed properly (the numbers line up). I do use an adapter to attach the chuck. The adapter has a cylindrical hole on one end that is slid onto the mark V's shaft (and secured with a setscrew), and a threaded section (male) that the chuck can screw onto on the other side. I guess it could be possible this is the cause of the problem, but it does not account for the play I feel in the main shaft when the adapter is not installed. I do have a faceplate, so I could see if the vibration is still present once a bowl is turned round on it.

RFGuy,
You are exactly correct, the only time I get vibration is when a bowl is mounted without tailstock support. I will have to try that trick with the pencil on a bowl blank. I also know it doesn't have anything to do with me making cuts with my chisels because the vibration occurs without my touching the wood with a tool.

Hugh,

Thanks. Again I still consider myself a newbie woodturner, but I will share one experience that I had that may/may not help. I also have the Nova G3 chuck. I had a few experiences with concentric errors while learning to make salt & pepper mills on my 520. I made all the tenons to the best of my ability and chucked them in the G3. The challenge with salt & pepper mills (for me), was that you start with one long blank, then create tenons and separate the blank into two blanks, i.e. one for the top and another for the bottom of the salt/pepper mill. The chucking & re-chucking proved a little problematic for me. I believe the chuck jaws can obtain a different bite on the tenon each time you re-chuck the blank and this can be exacerbated if you don't keep the same clock orientation (lack of a better term) of the blank mating with the chuck jaws, i.e. rotation of the blank in the jaws. To correct my mistake, I found that I often had to take my turning down in size a bit, i.e. losing more material to create a new rounded blank after I had already started profile shaping - because the concentric error from re-chucking had changed the axis of my workpiece. At times, I also found that I had difficulty getting the Nova G3 to tighten enough on my tenons. I think I even found a woodturning forum or two that discussed this and some preferred other more pro level lathe chucks for their work over what Nova provides because they keep a death grip on the woodturning. I debated getting some of the different vise jaw options that Nova sells to see if one of the others might work better at holding the workpiece without any slippage, but got sidetracked with other projects at the time. Anyway, I hope this helps...by the way, can you share what size your blanks are for reference?

P.S. I believe more serious woodturners than myself typically keep multiple lathe chucks in their shop so that they can readily switch between projects if necessary and to minimize concentric errors due to re-chucking I believe.

[hugh556]

RF Guy,

That is an interesting thing to look out for. I have considered my chuck jaws being the cause of my vibration issue, but I am still getting the vibration using a worm drive screw. While the jaws do secure the screw, I think the metal-on-metal contact between flat surfaces would be consistent. The most recent blank I was working on was 7 inches in diameter once round.

Thanks,
Hugh

[hugh556]

Update: I tried to attach my chuck/adapter setup to the aux spindle, but the shaft is slightly larger than the main shaft on my machine. This prevented the adapter from sliding over the aux spindle. I am not sure if that is typical for mark v machines or if it is a defect in my machine. I ordered new bearings for my quill. I will see if replacing them resolves my issue. If it does not, I am not sure how to proceed. Once I get the bearing installed in the quill, I will post another update.

Thanks again to all those who have shared their perspectives with me. Please feel free to leave additional comments if any other ideas for fixing the vibration come to mind.

Hugh

[RFGuy]

RF Guy,

That is an interesting thing to look out for. I have considered my chuck jaws being the cause of my vibration issue, but I am still getting the vibration using a worm drive screw. While the jaws do secure the screw, I think the metal-on-metal contact between flat surfaces would be consistent. The most recent blank I was working on was 7 inches in diameter once round.

Thanks,
Hugh

Hugh,

Again I am a newbie and it has been at least a couple of years since I researched the worm drive screw. I saw varying opinions on them online. Like many things in woodworking, or other endeavors, there are often many different methods to accomplish the same thing. So, of course opinions will vary on which method is better. I seem to remember some commenting about difficulties with using wood worm screws in lathe turnings, but I can't remember which forum I read it on. I tried it once with my G3 and it didn't go exactly as planned, but I chalk that up to user error on my part. I found a good YT video on making salt & pepper mills that got me started and I copied their technique which was to chuck a square blank like a spindle between a spur drive center and a live center on the end. I rounded the blank and then cut tenons on it for chucking it in the G3. Then I had to re-round again, slightly, because of the small concentric error offset between my spur drive and the G3. To me, wood worm screw drives are popular with very experienced woodturners who make a living doing this stuff and need the fast on & off of a blank/turning IMHO. IF you are hobbyist like me, I would perhaps consider trying other methods like I suggest here or even a waste block/faceplate mounted option to start with before moving to the chuck jaws. Just to see how they compare. Again none of what I describe may be causing your vibration...just trying to help. Good luck.

P.S. JMO, but a 7" round diameter is a good size mass, particularly if it is long/deep hanging off of the G3, and/or heavy hardwood - so any concentric error or off-balance issues with the blank will cause vibration. Many add some kind of weighting to the lower half of their Mark V to reduce vibration with woodturning and that may be your only option. Unfortunately the lack of a cast iron bed as a traditional wood lathe has makes the Mark V a little more prone to vibration issues compared to its competition.

[larryhrockisland]

viewtopic.php?p=305437#p305437
The tenth post down has a picture of the “drive & ring”. Sometimes it gets worn. Sorry, I cannot get a specific page in a topic to show up.
Below are screenshots from the parts diagrams on SS.

IMG_0784.jpeg (113.28 KiB) Viewed 1515 times

IMG_0783.jpeg (151.76 KiB) Viewed 1515 times

[rpd]

Also check that the insert is fully seated in the back of the chuck. As I recall there have been reports of people having vibration issues due to that.
The G3 manual I found on the Nova web site is pretty sketchy on mounting the insert, it is covered in more detail in the SuperNova2 manual

SuperNova2 Manual full version_10 October 2016.pdf

(89.46 KiB) Downloaded 147 times