Work Holding?

[Mark Jundanian]

My wife has renewed her interest in turning after a couple of years hiatus, and I would like to encourage her. However, we share the lathe and she (well both of us, really) can take a long time (weeks) on a project. So we need to be able to dismount and remount projects. To that end I have 3 chucks. Problem solved -- mostly. She was doing a second turn on a rough out and had the bowl between centers. But after a few days she was still truing up the outside so we rounded the tenon and put the bowl on a chuck.
But with the chuck on the HS spindle the rim will be towards the TS, which is kinda backwards for her. Then it occurred to me that this arrangement might work:

The chuck is mounted to the live center with an adapter. At the HS there is a friction drive (Rubber Chucky). I've run it for several minutes at 900 and I don't see anything wrong with the plan, but I'm interested in other's opinions.

 

[Ron Solfest]

I don't see why it wouldn't work. Typically when I start a bowl blank up to ~14-15" I use the tailstock to push it tight into a flat 5" friction drive disc, with rubber drawer liner, on the headstock. I've spun ~10" bowls up to ~1200 rpm this way (~5-6" bowls up to 1500-2000 rpm) while cutting the outside clean and putting a tenon on before reversing it into a chuck mount to turn the inside. Similarly when second turning twice-turned natural edge bowls I use the same flat friction drive (with larger rubber drawer liner extending over the drive edges) to drive, again just using the cup center on the tailstock to apply pressure. Your Rubber Chucky would give lots more drive surface area than the perimeter of my disc.

If you have a center point on the base I'd just use the cup/point center on the tailstock instead of the heavy chuck.

 

[Mark Jundanian]

If you have a center point on the base I'd just use the cup/point center on the tailstock instead of the heavy chuck.

That's how I would typically go about it, but I would get the outside trued up and reshaped in one or two sessions. She will be 5 or 6 sessions over a week or more, and I think this will be a more repeatable mounting (and there was no dimple).

 

[Jim Reynolds]

An alternative would be a wooden disk / wooden faceplate (larger than the diameter of the bowl) threaded on to the headstock and using hot melt glue and shims / wedges to secure the warped bowl to the disk. I’d use tailstock support (because I’m cautious) but remounting should be very reproducible. This would free up the chuck.

 

[Michael Anderson]

I don’t understand why it matters which direction the rim is facing. She will need to turn in both directions at some point anyway, right? Maybe I misread something though.

Alternatively, you could just have her use a faceplate, so there would be no need to turn the bowl around until finishing the bottom. Depending on the blank, this might not be ideal. But, it would keep everything trued up until the end.

And in jest, sounds like you need a second lathe. His and hers

 

[Leo Van Der Loo]

I use something similar when mounting a natural edge, but use the centerpoint in the tenon and a wooden cup held in the chuck against some wetsuit foam to drive it, works for me.

 

[JeffSmith]

I typically turn a very shallow recess inside and turn the bowl to grip the recess with a chuck (ala Richard Raffan) true the tenon and turn the outside to the final form except for removing the tenon or finalizing the foot. It helps to have a set of tower jaws for this. Sand outside, turn bowl and grip with the tenon to hollow, then use the vacuum chuck to finish the foot.

 

[hockenbery]

The chuck is mounted to the live center with an adapter. At the HS there is a friction drive (Rubber Chucky). I've run it for several minutes at 900 and I don't see anything wrong with the plan, but I'm interested in other's opinions.

Should be fine. I assume you’re doing this to turn the outside with the right hand forward.

I often finish turn the outside with the chuck on the headstock this I do with the left hand forward

I also reverse turn bowls rim facing the headstock I just put the tail center in the same hole where it was when I turned the tenon.

 

[Mark Jundanian]

I did a bad job posing the question; I should clarify.

What I want to know is whether folks here see any obvious problem/risk with spinning the chuck on the live center. Not so much looking for alternative mountings, etc.

Should be fine. I assume you’re doing this to turn the outside with the right hand forward.

Yes, that's how we began this turning. Hopefully she'll stay interested long enough to try turning left handed.

 

[Ron Solfest]

@Mark Jundanian - no reason you can’t spin the Chuck on the live center, but I don’t like the idea of that much weight metal to metal on the soft aluminum cone on the live center by friction as I think it shows. If I wanted to do that I think I’d be more comfortable with a thread adapter taking the live center threads to the chuck threads. You probably are OK, but not what I’d do.

Why aren’t you taking the Chuck off and pushing just with the cup center? Assuming you have a center point on the tenon would give you much more clearance to shape the outside of the bowl without worrying about the jaws swinging around.

 

[Clifton C]

I see no danger in this set up. I read this "The chuck is mounted to the live center with an adapter.", to mean, a threaded adapter to the 3/4 x 10 tpi live center threads.
I've used the same setup with no issues. But... check the HS to TS alignment with two good centers bringing them point to point to check for lateral alignment, adjust by raising or lowering a leg. If not, you will get friction burns inside the bowl. Might not be an issue since the inside is still to be turned but sometimes the out of alignment can cause a most irritating noise. If horizontal alignment is off, that's another topic indeed.

 

[Ron Solfest]

Missed the adapter comment, my bad - ignore my prior concern; but I still question why you don’t get rid of the Chuck on the live center and make access to more of the bowl easier

 

[Mark Jundanian]

Because it will be dismounted and remounted multiple times before she gets the bottom trued up and then shaped and I want to use a work holding device that can be remounted accurately. Good news, no one seems to find the method unsafe, and I don't think it's unsafe either, so we'll proceed, with caution of course.

 

[Doug Freeman]

There is no problem with the TS chuck setup, and it probably has an advantage for repeated mount-dismount and when the bowl is turned around for hollowing.

I assume the chuck is left on the piece, unthreaded from the live center. Reseating a threaded steel joint is more accurate vs a center hole in the wood. Also when the bowl is turned the od will run true.

I typically use the tenon center hole for the TS. When the bowl is flipped and tenon mounted in a chuck it is not unusual to get a bit of wobble. Already having the tenon seated in the chuck over the days/weeks the piece is worked on will provide the best realignment during repeated mountings and flipping the bowl position.

 

[Mark Jundanian]

There is no problem with the TS chuck setup, and it probably has an advantage for repeated mount-dismount and when the bowl is turned around for hollowing.

I assume the chuck is left on the piece, unthreaded from the live center. Reseating a threaded steel joint is more accurate vs a center hole in the wood. Also when the bowl is turned the od will run true.

I typically use the tenon center hole for the TS. When the bowl is flipped and tenon mounted in a chuck it is not unusual to get a bit of wobble. Already having the tenon seated in the chuck over the days/weeks the piece is worked on will provide the best realignment during repeated mountings and flipping the bowl position.

Yes, that was my goal, and my thinking.

 

[Dean Center]

Mark,
Good problems to have.

A. She needs to make a bunch of bowls so she can get faster.
B. As Michael pointed out, you are really lathe deficient. Maybe give her one for Valentine's Day.