Not a great result...

[Mr Finch]

So, playing with a piece of oak this afternoon,

"Just one more pass..."

First one I have done this to, although I am sure it won't be the last. Was going to see if I could cut the bottom out and replace it, but managed to tighten the chuck on the tenon instead of loosen it and crack the whole bowl.



Oh, and I broke my drill press so can't currently drill any pen blanks. Not a great couple of days all in all!

 

[paulm]

Easily done, I think most of us have been there !

These days I ten to use a tenon to hold the workpiece for that reason, doesn't need to be very deep, a few mm is usually fine depending on the size of the blank.

It means also that you are not constrained by the size of the chuck jaws when shaping the piece as you just reverse turn and remove the tenon after, which means you can concentrate on the best lines/curves for the finished piece rather than what the chucking recess dictates.

Cheers, Paul

 

[chipmunk]

Take heart. If you're not making mistakes like this then you're not really stretching yourself.

I used to rock climb and there was a phrase that used t come up quite often
- "If you're not flying, you're not trying."

HTH
Jon

 

[Random Orbital Bob]

Easily done, I think most of us have been there !

These days I ten to use a tenon to hold the workpiece for that reason, doesn't need to be very deep, a few mm is usually fine depending on the size of the blank.

It means also that you are not constrained by the size of the chuck jaws when shaping the piece as you just reverse turn and remove the tenon after, which means you can concentrate on the best lines/curves for the finished piece rather than what the chucking recess dictates.

Cheers, Paul

Hi Paul

How do you reverse turn the tenon off when the face you're chucking is now an open bowl? Does that mean you need to build a bespoke friction chuck for each piece? I know what you mean about the tenon method being more convenient than the recess method but I just saw mine off and then sand the base. What am I missing about making the reverse turning easier?

 

[Mr Finch]

Easily done, I think most of us have been there !

These days I ten to use a tenon to hold the workpiece for that reason, doesn't need to be very deep, a few mm is usually fine depending on the size of the blank.

It means also that you are not constrained by the size of the chuck jaws when shaping the piece as you just reverse turn and remove the tenon after, which means you can concentrate on the best lines/curves for the finished piece rather than what the chucking recess dictates.

Cheers, Paul

Hi Paul

How do you reverse turn the tenon off when the face you're chucking is now an open bowl? Does that mean you need to build a bespoke friction chuck for each piece? I know what you mean about the tenon method being more convenient than the recess method but I just saw mine off and then sand the base. What am I missing about making the reverse turning easier?

My guess would be cole jaws or bowl reversing jaws on the chuck. I can't afford them at the moment, hence why I was using the recess.

I agree though Paul, tenon is much easier and you can either completely turn it off or shoe it to a foot to lift the bowl slightly.

 

[Mr Finch]

Take heart. If you're not making mistakes like this then you're not really stretching yourself.

I used to rock climb and there was a phrase that used t come up quite often
- "If you're not flying, you're not trying."

HTH
Jon

I agree entirely, and thanks. Every piece is a practice piece and the outside of this was te best I have turned so far.

 

[paulm]

Usually one of three methods Rob, all of them quite quick and straight forwards to do.

One is to use cole jaws and buttons, I keep a chuck with these mounted permanently to save time and fiddling about. Can be a chore though if the bowl size means moving the buttons around to suit. I've now moved the cole jaws onto an Axi Goliath chuck as recommended by Chas, as that has a wider range of movement that means less need to move the buttons around.

Also use an mdf board with a glued and pinned tenon on the back that fits into a normal chuck. The board has concentric grooves cut into it that aid centralising the bowl, but just locating the tailstock on the centre of the tenon and pushing it up against the board is usually sufficient.

The last method is an extended cylinder mounted in the chuck, with a pad of washing up sponge or similar and covered in rubber friction mat. Again I locate the tailstock in the centre of the tenon and press it up against the drive mat.

All are much quicker and easier than it is to describe them. The first allows you to sand in situ, the other two leave a small stub to seperate off and finish by hand.

All of them need to be used at low speed, with gentle cuts from a sharp gouge, but straightforwards and very effective.

Hope that helps !

Cheers, Paul

 

[nev]

another lo cost/ no cost option for removing the foot is a home made donut chuck
https://www.google.com/search?q=donut+c ... =633&dpr=1

 

[Mr Finch]

Oh, I Like that! Nice and secure. Thanks Nev.

Coll

 

[sue denim]

I have had a similar incident. I chucked oak in the same way , didn't go too deep but as the jaws of the chuck were on a mortice (rather than gripping a tenon) the outward force of the chuck split the bowl in half. I always use the jaws in compression now.

 

[Random Orbital Bob]

Brilliant! The only method I've come across from that whole list is the cole jaws. That's really useful. Thanks.

So Paul, you can really use a piece of MDF plus tailstock and the friction of the pressure will hold the reverse mounted bowl? I love that idea, really simple. You can just turn the tenon to a dimple then sand the stub. Could you glue a piece of rubbery kitchen material to the MDF to improve its holding properties. Sort of a compromise between your final two options.

Out of interest, which method do you use most frequently? (I don't own cole jaws yet but they do seem a pretty useful approach). My problem with recesses is the marks the chuck leaves inside the dovetail. It always seems to leave a black stain no matter how much I clean the jaws. Also I have cracked a thin walled bowl due to the pressure as mentioned by other folks.

What I like about the recess is it requires less thickness in the blank so your stock goes further.

My sense from my turning club is that recesses are a frowned upon finish for a bowl (despite being on the underside). Would you agree that is true? At first I thought it rather turning snobbery-ish. But I'm coming round to it myself now. The recesses don't look as well presented.

 

[paulm]

I had planned to add some non-slip router mat type material to the mdf Rob but I tried it without and seemed fine so didn't bother ! No harm in adding it though, it would probably increase the speed possibility a bit.

Haven't used the cylinder with the sponge/mat end much recently but it is especially good where the bowl rim is uneven/natural edge and wouldn't sit flat on the mdf disc or cole jaws.

So probably prefer the cole jaws now I've got the extra adjustment potential on the Goliath chuck that reduces the need to faff around moving the buttons, but before that I guess I probably used the mdf disc most, as long as you keep the speed low and use a sharp gouge with light cuts it works really well, and if I hadn't already bought the cole jaws years ago I probably wouldn't bother with them these days.

I too think nice clean lines flowing through and across the bottom of bowls tend to make them look more elegant and flowing than the recesses I used to use early days, but I suspect it's mainly us turners that worry about it, not sure others generally tend to notice much?

Cheers, Paul

 

[Random Orbital Bob]

Great advice. Thanks mate. I shall try that on my next bowl. Presumably the mdf is screwed to a faceplate?

 

[paulm]

Could do Rob, I just turned a short cylinder that would sit in the chuck jaws and then glued and screwed the mdf to that. A faceplate would probably run truer though and flex less...

Cheers, Paul

 

[CHJ]

........So probably prefer the cole jaws now I've got the extra adjustment potential on the Goliath chuck that reduces the need to faff around moving the buttons, ....

One way to speed up the standard button position changing is to use a hex bit in a small slow speed drill driver.
Using the torque setting also keeps things even and flexible on the driver timing.

Obviously care is needed not to cross the threads but I now use machine cut stainless screws which have better thread start than rolled threads which reduce this risk.

Changing a set of 8 buttons can be reduced to less than a minute by retaining the button Assembly on the hex bit for immediate re-inserting, just a flick of the direction switch with the thumb as you move locations.

I have an older model small Bosch drill driver (minus battery) adapted to run off a mains powered power pack that is used for this and slow speed rotary sanding.

 

[Random Orbital Bob]

Thanks Chaps

 

[CHJ]

......My sense from my turning club is that recesses are a frowned upon finish for a bowl (despite being on the underside). Would you agree that is true? At first I thought it rather turning snobbery-ish. But I'm coming round to it myself now. The recesses don't look as well presented.

I too think nice clean lines flowing through and across the bottom of bowls tend to make them look more elegant and flowing than the recesses I used to use early days, but I suspect it's mainly us turners that worry about it, not sure others generally tend to notice much?
...

One of the main drivers for cleaning up the bottom of my work is that after comments about the finish, remarks concerning the way they are finished off on the bases is nearly always made.
"unlike most of the stuff we've seen on craft stalls" being a common expression.

Some folks go to the trouble of decorating the sockets with tool marks etc. why? its just as quick to clean up the socket and blend it into the base form.

One turner marketing at Westonbirt a couple of years ago told me that he did not have time to do such a thing as he "had to make a living at it".
My reply was "and I decline to buy unfinished pieces"

 

[Random Orbital Bob]

Interesting perspective....thanks Chas