How much is too much pressure?

[Sam Fleisher]

When starting to finish turn a bowl sometimes I've employed the technique of starting out with placing the inside of the bowl over the four jaw chuck instead of using a friction chuck, bringing up the tail stock and applying pressure to start truing up the tenon etc. before turning the bowl around and putting it in the chuck properly.
I've noticed that sometimes the inside is warped too much to get a good flat surface for the jaws to ride against and I get some noise. (usually 2 of the 4 jaws being loose) So I tighten the tail stock some more. Is there a rule of thumb so I don't wear out the bearings prematurely in the spindle or tail stock by over tightening?

 

[hockenbery]

I've noticed that sometimes the inside is warped too much to get a good flat surface for the jaws to ride against and I get some noise.

Try opening or closing the jaws. There is often a better seating with a different opening on the jaws.

As far as pressure from the tailstock. This would be a function of the lathe.
A ONEWAY or a Robust - you probably can’t wear out anything.
I turned a lot between centers on a woodfast before I got my ONEWAY. The bearrings were still good after 30 years when it found a new home. It spend the last 12 years used by little old students

 

[Dean Center]

You might want to look into Glenn Lucas' solution for remounting warped bowl blanks. It's a plain backing board with 2 rails, sometimes with padding, which can be mounted on a faceplate or in a chuck. It's simple but effective for the oval shaped dried blanks.

View: https://www.youtube.com/watch?v=LUKPO_MNn-w


As for bearings, at our high school shop, we have no center points that have a point, I have to re-sharpen live center chisel points every year, the chuck jaws look like someone took an angle grinder to them, and I regularly have to get some moving part unstuck that you wouldn't think could be stuck. In short, the lathes get abused, but we've never had to replace any bearings in 10 years.

 

[Sam Fleisher]

You might want to look into Glenn Lucas' solution for remounting warped bowl blanks. It's a plain backing board with 2 rails, sometimes with padding, which can be mounted on a faceplate or in a chuck. It's simple but effective for the oval shaped dried blanks.

View: https://www.youtube.com/watch?v=LUKPO_MNn-w


As for bearings, at our high school shop, we have no center points that have a point, I have to re-sharpen live center chisel points every year, the chuck jaws look like someone took an angle grinder to them, and I regularly have to get some moving part unstuck that you wouldn't think could be stuck. In short, the lathes get abused, but we've never had to replace any bearings in 10 years.

I usually don't use the jaws backwards mount but I have the big jaws on at the moment which don't fit my face plate ring that holds my friction chuck. I'll take a look at the video later though. I have to get going to my first paid for lesson. He said he would work with me since it's "turning a wood bowl class". (beginners, which I consider myself) I just want to work on my technique.

 

[Marc Banka]

With the jaws significantly open you have four rounded points. To put a little pressure with tailstock, spindle locked, rotate the bowl back and forth as you advance the tailstock. You’ll find the point that naturally fits. Then with moderate pressure, rock the bowl back and forth again so the jaws bite in a bit. Once it’s really seated I back off the pressure to something reasonable.

 

[Steve Chaplin]

I usually put a foam pad against the chuck jaws. A 5-6" pad for polishing cars works well because it has a tough fabric backing for hook and loop, place that side against the jaws.

 

[Sam Fleisher]

I usually don't use the jaws backwards mount but I have the big jaws on at the moment which don't fit my face plate ring that holds my friction chuck. I'll take a look at the video later though. I have to get going to my first paid for lesson. He said he would work with me since it's "turning a wood bowl class". (beginners, which I consider myself) I just want to work on my technique.

Just got back from my class, there were three of us. The other two didn't have lathes. They just wanted to make a bowl to see how they liked it I guess.

The hardest part was the teacher did things differently than I do them. I would have used a short worm screw or one of my face plate rings. He used a forstner bit to drill a mortise initially to hold the blank. Then another mortise.

The forward and reverse switch was opposite on a jet lathe than mine. I could see where I could have easily gotten in trouble with that.

So my take away was practice- practice- practice, learn to sharpen better and remember not all wood is green and turns fast. Slow and steady wins the race. (if you're a turtle)

Working on technique not form. I made a maple dog dish. (that cost plenty)

 

[Sam Fleisher]

You might want to look into Glenn Lucas' solution for remounting warped bowl blanks. It's a plain backing board with 2 rails, sometimes with padding, which can be mounted on a faceplate or in a chuck. It's simple but effective for the oval shaped dried blanks.

View: https://www.youtube.com/watch?v=LUKPO_MNn-w


As for bearings, at our high school shop, we have no center points that have a point, I have to re-sharpen live center chisel points every year, the chuck jaws look like someone took an angle grinder to them, and I regularly have to get some moving part unstuck that you wouldn't think could be stuck. In short, the lathes get abused, but we've never had to replace any bearings in 10 years.

I should have tried that technique with the mdf the other day with the bigger elm bowl (red one). It ended up too thin and eventually several pieces. What was the apparatus he had mounted on the live center? I thought it was some kind of gauge but he used a pencil to mark the spigot. Maybe it still is and he just didn't use it?
I'm also dealing with mortises but I suppose the procedure is the same.

 

[Doug Freeman]

The hardest part was the teacher did things differently than I do them.

That may well have been the most important turning lesson you will ever get - there are many acceptable ways to do various things (plenty of unacceptable ways as well). The challenge is finding which ones fit for you, your lathe, your overall process - have logical reasons for why you do what you do, vs “I was taught this way”. Seek out other methods and try the ones that appear could be helpful.

As for Glenn’s method in the video, its a great way for flat rim bowls, but won’t work for natural rims. I do both, and wanted a single process. An internal friction chuck (lots of different ways to do them, including chuck jaws) works for about any bowl.

 

[Gord Cameron]

I should have tried that technique with the mdf the other day with the bigger elm bowl (red one). It ended up too thin and eventually several pieces. What was the apparatus he had mounted on the live center? I thought it was some kind of gauge but he used a pencil to mark the spigot. Maybe it still is and he just didn't use it?
I'm also dealing with mortises but I suppose the procedure is the same.

Yes, that apparatus mounted on the live centre is used to set the size of the tenon; he did use it to size the tenon, though he made a marking with a pencil, perhaps for clarity in the video. Glenn sells this jig on his website ("tenon sizing indicator").

 

[Dave Landers]

What was the apparatus he had mounted on the live center? I thought it was some kind of gauge but he used a pencil to mark the spigot. Maybe it still is and he just didn't use it?

Yeah, it's a tenon sizing gauge. Not used as a scribe. But the tips are pointers to various sizes so they can be marked with a pencil or just turned to size without marking.