Thread: Bowl jaws

Michael, on the Woodfast web page you linked to, it says 'The Bowl Jaws have eight plastic holding jaws for both internal and external clamping.'

Going by that, it sounds to me like it's OK to use them in expansion mode.

I didn't see it at first - just below the pic of the bowl jaws there's also a chart showing the range of diameters for each of the 3 sizes of bowl jaws, in both contraction and expansion modes.:

Woodfast Bowl Jaws.JPG

One possible problem with using the jaws in expansion mode inside a box. It won't take much pressure to split the box. Been there, done that. A pine or other soft wood jam chuck (recess), with the box being a tenon is safer, and I use a tailstock with a softer wood point to keep it from popping out.

robo hippy

Originally Posted by robo hippy

One possible problem with using the jaws in expansion mode inside a box. It won't take much pressure to split the box. Been there, done that. A pine or other soft wood jam chuck (recess), with the box being a tenon is safer, and I use a tailstock with a softer wood point to keep it from popping out.

robo hippy

& use some low tack painters masking tape as extra security. The shape of the box determines holding choices for reversing. Straight sided is easy, deeply convex makes it a little more difficult to get good registration i.e. running true. Next is to remember to modify your cutting tool presenation so that cuts are towards the jamb chuck or bowl jaws forcing the work piece onto the jamb chuck and are not dragging the piece away from the chuck / jaws as you cut. Simple changes in cutting style and using bevel support to your advantage greatly help to prevent the box from going AWOL.

Originally Posted by Hermit

Michael, on the Woodfast web page you linked to, it says 'The Bowl Jaws have eight plastic holding jaws for both internal and external clamping.'

Going by that, it sounds to me like it's OK to use them in expansion mode.

I didn't see it at first - just below the pic of the bowl jaws there's also a chart showing the range of diameters for each of the 3 sizes of bowl jaws, in both contraction and expansion modes.:

Woodfast Bowl Jaws.JPG

I read this also that it could be used but I was asking the forum members that have done it to get the pro's and con's
regards Michael

Originally Posted by Mobyturns

& use some low tack painters masking tape as extra security. The shape of the box determines holding choices for reversing. Straight sided is easy, deeply convex makes it a little more difficult to get good registration i.e. running true. Next is to remember to modify your cutting tool presenation so that cuts are towards the jamb chuck or bowl jaws forcing the work piece onto the jamb chuck and are not dragging the piece away from the chuck / jaws as you cut. Simple changes in cutting style and using bevel support to your advantage greatly help to prevent the box from going AWOL.

mobyturn & hippy
I thank you guys for your answers
when I reverse my boxes on my scroll chuck I also bring my tailstock into the back of the box to assist the chuck and this also stops the box going for a walk across the workshop
it also reduces the amount of pressure exerted by the chuck on the box sides while cutting. I remove the tail stock at the last possible time to reduce the amount of pressure on the boxes sides
Regards Michael

I have done internal mounting often with the cole/bowl jaws even with the Gary Pye ext jaws on as has been said the shape of the internal area has much to do with holding as does the shape/size of the buttons.

thanks for the replys guys
regards Michael

Originally Posted by wheelinround

the Gary Pye ext jaws

I just got one of those yesterday by special delivery, my beloved brought one back from her holidays, and it's a really good piece of kit. Thick plastic and well machined and three types of different buttons as well as a long extension handle for the chuck.

Have to make it a bit smaller to fit the lathe well but the instructions for it are on PSI website.

Peter.

Btw it would have helped Ern out with his special platter.

You could knock up some jaws out of MDF, to match your expansion diameters. If the box walls slant out from the top it's a lay-down misere. The jaws can match both top and side with a keyed joint.

How tight is a good question. You can creep up on this. Wind out to beginning grip, and then wrench the box by hand. Movement? wind out a bit more, etc.

Best if your MDF jaws closely match the circumference of the box.

For insurance you can always add a wrap of tape crossing jaws and walls.

HTH. Let us know how you go.

Originally Posted by Hermit

Michael, on the Woodfast web page you linked to, it says 'The Bowl Jaws have eight plastic holding jaws for both internal and external clamping.'

Going by that, it sounds to me like it's OK to use them in expansion mode.

Originally Posted by robo hippy

One possible problem with using the jaws in expansion mode inside a box. It won't take much pressure to split the box. Been there, done that. A pine or other soft wood jam chuck (recess), with the box being a tenon is safer, and I use a tailstock with a softer wood point to keep it from popping out.

Just expanding on this...

...if your bowl/box has thin, constant width walls all the way up to the rim then mounting the rim in expansion mode on any jaws includes a risk of splitting.

However, if you're in the habit of doing forms with wide rims, eg. 'Saturn' boxes, etc. where the rim is much wider than the wall sides, then this risk is mitigated somewhat.

Hence the claim that "for both internal and external clamping" is true, although it is NOT true to say "for ALL internal & external clamping."

The ability to proficiently use Jam Chucks is yet another woodturning skill that takes time and effort to learn... but it is a skill that is well worth as Jam Chucks can hold pieces that no standard chuck can ever hope to hold! Especially when combined with tailstock support.


Personally, the only time I use Cole Jaws such as under discussion is after I've cleaned up the outside and simply want to clean up the foot where the tailstock may've left a mark!

Originally Posted by Sturdee

I just got one of those yesterday by special delivery, my beloved brought one back from her holidays, and it's a really good piece of kit. Thick plastic and well machined and three types of different buttons as well as a long extension handle for the chuck.

Have to make it a bit smaller to fit the lathe well but the instructions for it are on PSI website.

Peter.

Btw it would have helped Ern out with his special platter.

Why do you need to reduce them?? did you get the 10" not the 8" ones. is this for the mini lathe or the big one?

Originally Posted by wheelinround

Why do you need to reduce them?? did you get the 10" not the 8" ones. is this for the mini lathe or the big one?

Ray, as you know I have a mini lathe with a turning diameter of 260 mm and the Hafco WL 18 with a turning diam of 310 mm which are both used for spindle work and small stuff. For these I have both a Gary Pye 185 mm and a Vicmarc 285 mm Colejaws on their own chucks.

Recently I installed Michelle's lathe in the workshop as well, being a Hafco WL 20 with a turning diam of 370 mm, as a dedicated bowl lathe. This is installed on a bench diagonally through the wall with only the end of the lathe bed being in the workshop and used. I can turn on this from the front and the end without any problems.

For this one I needed the Cole jaw extension to fit onto the small Colejaw when needed. The extension is 365 mm which doesn't allow for adjustments. Cheaper to buy the extensions then another larger Vicmarc one.

Of course they are only a small part of my reverse chucking options as I have 3 doughnut chucks, small, medium and the recently made large one to fit the bowl turning lathe, as well as a 300 mm Longworth and 3 adapters (75 mm, 105 mm and 130 mm) for my vacuum chuck.

Depending on the type of turning, I'm rather eclectic rather then doing the same all the time, each gets its use, and I'm still building more. Remember the old saying, he who passes on the most tools and jigs to their offspring wins.


Peter

Originally Posted by Sturdee

Ray, as you know I have a mini lathe with a turning diameter of 260 mm and the Hafco WL 18 with a turning diam of 310 mm which are both used for spindle work and small stuff. For these I have both a Gary Pye 185 mm and a Vicmarc 285 mm Colejaws on their own chucks.

Recently I installed Michelle's lathe in the workshop as well, being a Hafco WL 20 with a turning diam of 370 mm, as a dedicated bowl lathe. This is installed on a bench diagonally through the wall with only the end of the lathe bed being in the workshop and used. I can turn on this from the front and the end without any problems.

For this one I needed the Cole jaw extension to fit onto the small Colejaw when needed. The extension is 365 mm which doesn't allow for adjustments. Cheaper to buy the extensions then another larger Vicmarc one.

Of course they are only a small part of my reverse chucking options as I have 3 doughnut chucks, small, medium and the recently made large one to fit the bowl turning lathe, as well as a 300 mm Longworth and 3 adapters (75 mm, 105 mm and 130 mm) for my vacuum chuck.

Depending on the type of turning, I'm rather eclectic rather then doing the same all the time, each gets its use, and I'm still building more. Remember the old saying, he who passes on the most tools and jigs to their offspring wins.


Peter

Where are the pics of this new set up eh come on Peter your slacking here

thanks for the info I made a jam chuck & used a 25 mm spacer on the tail stock to hold it in place going to glue some 19mm mdf into blocks to make future jam chucks for the boxes
regards Michael