At that awkward size... one is too big the other too small...

[Barry Larson]

Another question for the membership. I'm trying to use my newly acquired Oneway jumbo jaws to reverse a small bowl and finish off the base. When I set the jaws up with the buttons I can't seem to find a spacing to allow the bowl to be clamped in place. With the buttons in one set of holes the jaws can't open enough to get the bowl in place and the next set out the jaws close together before the buttons clamp on the bowl rim. Either I'm missing something obvious (wouldn't be the first time) or I need to consider either turned jaws or I need to turn a set of wooden buttons to allow the bowl to be clamped in place. Any and all advice is appreciated. Thanks. Be safe and stay well.
Barry W. Larson
Calgary, Alberta, Canada eh!

 

[Kevin Jesequel]

Oneway chucks have a wide opening range. It sounds to me like something must be preventing them from opening all the way. Do the jumbo jaws have a pin on the back of one jaw? If they do you might need to swap your jaws in positions 2 & 4 to get that pin in the longer slot in the chuck body.

 

[Barry Larson]

Oneway chucks have a wide opening range. It sounds to me like something must be preventing them from opening all the way. Do the jumbo jaws have a pin on the back of one jaw? If they do you might need to swap your jaws in positions 2 & 4 to get that pin in the longer slot in the chuck body.

Thanks Kevin. That's what I thought, and I thought the range was pretty much continuous. I have the pin in the longer of the two slots - first attempt it was in the short slot. I'm thinking I'm missing something obvious, just can't seem to see what it might be. I'll just have to keep at it until I figure it out.
Cheers.
Barry

 

[Brian Gustin]

Well, to figure it out, I'd probably put original jaws on the chuck and then measure (in a linear fashion from center along the line of one jaw) the full travel from closed to max open, and note that down, and then remove original jaws and flip over to compare mounting surfaces of them with the accessory jaws (and check relationship of the screw holes to inside edge of jaws?) to see if I could spot any differences, and if none, and cole jaws will not open /close for the same travel distance, I'd be wondering at how much difference in countersink the mounting screws might have between originals and coles (Perhaps seat a screw and measure exposed thread) with the thought that there could be some interference internally if the screws went in just a touch too far. (or if that seems possible how do the jaws travel if the screws are not fully tightened in?)

 

[Leo Van Der Loo]

The chuck moves 25mm from closed to open, and the screw holes are about 12 mm apart (12.5 maybe ?).

So yes the buttons can move just the right amount, however I have run into the problem where for the shape of the piece I could not clamp it tight and if I moved the buttons, it could not put the piece in, for the buttons, as they were to close for that.

This here was the kind of shape that would give me trouble if it was just the right/wrong size , it would not go through the narrower front of the buttons, but could not get held if opened larger.

So what I would do was remove 3 or 4 buttons stick the piece in and then install the buttons back on the jumbo jaws.



Can you see the problem with a shape like this ?, as the edge is too large to go in, but when the buttons are set wider, it can go in, but then the back of the buttons are too wide to hold it because of the taper of the buttons, they are approx. 3 mm wider in the back than the front.

 

[Barry Larson]

The chuck moves 25mm from closed to open, and the screw holes are about 12 mm apart (12.5 maybe ?).

So yes the buttons can move just the right amount, however I have run into the problem where for the shape of the piece I could not clamp it tight and if I moved the buttons, it could not put the piece in, for the buttons, as they were to close for that.

This here was the kind of shape that would give me trouble if it was just the right/wrong size , it would not go through the narrower front of the buttons, but could not get held if opened larger.

So what I would do was remove 3 or 4 buttons stick the piece in and then install the buttons back on the jumbo jaws.

View attachment 50248

Can you see the problem with a shape like this ?, as the edge is too large to go in, but when the buttons are set wider, it can go in, but then the back of the buttons are too wide to hold it because of the taper of the buttons, they are approx. 3 mm wider in the back than the front.

Thanks Leo. That may well be my problem. I'm thinking I can turn some wood buttons that are a slightly different size/shape and use those. My bowl shape is actually similar to yours with sharp flared edge on top. I suppose I could also use some spacers to raise the rim off the jaws, but this wouldn't be as stable. I'll also test your idea of removing some buttons first, then place the bowl and replace the buttons, to see if this is a solution here. Cheers. Be safe and stay well.
Barry

 

[Charlie Knighton]

well, u need to learn to jam chuck....there are probably lots of viedoes for sale or check on u tube......hf or different size bowls, strange shapes, all are possible with the tailstock ....sort of rite of passage

 

[Mike Novak]

I had same problem with my Nova cole jaws. I bought 1” rubber bottle stoppers from the local Ace hardware and drilled holes in them. The larger diameter covers that blank spot.

 

[Leo Van Der Loo]

Thanks Leo. That may well be my problem. I'm thinking I can turn some wood buttons that are a slightly different size/shape and use those. My bowl shape is actually similar to yours with sharp flared edge on top. I suppose I could also use some spacers to raise the rim off the jaws, but this wouldn't be as stable. I'll also test your idea of removing some buttons first, then place the bowl and replace the buttons, to see if this is a solution here. Cheers. Be safe and stay well.
Barry

Yes Barry it does hardly ever happen, but with just the right shape and size, it can.

I use the Jumbo jaws all the time with large pieces, as my big lathe has no tailstock on the outboard side, of course it is also nice to not have the tailstock in your way when removing the tenon or reshaping a recess.

There is nothing that works for everything all of the time

 

[Barry Larson]

Yes Barry it does hardly ever happen, but with just the right shape and size, it can.

I use the Jumbo jaws all the time with large pieces, as my big lathe has no tailstock on the outboard side, of course it is also nice to not have the tailstock in your way when removing the tenon or reshaping a recess.

There is nothing that works for everything all of the time

Thanks Leo. Trust me to find this out on the first try - I'm a good problem finder; just have to keep working on the problem solving. I'm just about to go out and try your suggestion on mounting the piece. If that fails I'll get some bottle stoppers and try Mike's suggestion. Failing these two suggestions I'll mount up some wood on the jaws and practice turning a modified jam chuck on the jaws. One of these should work! Thanks again to all who have responded. Cheers,
Barry

 

[Leo Van Der Loo]

Thanks Leo. Trust me to find this out on the first try - I'm a good problem finder; just have to keep working on the problem solving. I'm just about to go out and try your suggestion on mounting the piece. If that fails I'll get some bottle stoppers and try Mike's suggestion. Failing these two suggestions I'll mount up some wood on the jaws and practice turning a modified jam chuck on the jaws. One of these should work! Thanks again to all who have responded. Cheers,
Barry

Barry don't forget that the all rubber stoppers will not hold as well, like the Oneway ones, as those have a tapered metal core with the harder rubber tire around it, be careful if you use the rubber bottle stoppers.

 

[Mike Novak]

Barry don't forget that the all rubber stoppers will not hold as well, like the Oneway ones, as those have a tapered metal core with the harder rubber tire around it, be careful if you use the rubber bottle stoppers.

That’s a very good point. I installed them narrow end against the chuck so they grip better, and use the Tailstock as much as possible.

Because they are tapered towards the chuck, they seem to hold better.

 

[Tom Gall]

Another question for the membership. I'm trying to use my newly acquired Oneway jumbo jaws to reverse a small bowl and finish off the base. When I set the jaws up with the buttons I can't seem to find a spacing to allow the bowl to be clamped in place. With the buttons in one set of holes the jaws can't open enough to get the bowl in place and the next set out the jaws close together before the buttons clamp on the bowl rim. Either I'm missing something obvious (wouldn't be the first time) or I need to consider either turned jaws or I need to turn a set of wooden buttons to allow the bowl to be clamped in place. Any and all advice is appreciated. Thanks. Be safe and stay well.
Barry W. Larson
Calgary, Alberta, Canada eh!

Barry, here is another option I posted several years ago. Turn your jumbo jaws into a giant set of "flat jaws". No fiddling with buttons & bolts and quick to adjust to different sizes. Also grips at near 360º - not just 8 points.

 

[Barry Larson]

Barry don't forget that the all rubber stoppers will not hold as well, like the Oneway ones, as those have a tapered metal core with the harder rubber tire around it, be careful if you use the rubber bottle stoppers.

Good point, thanks Leo! I wonder how hard it would be to turn a set down to a smaller diameter? Maybe freeze then first? Has anyone tried this? Thanks.
Barry

 

[Barry Larson]

Barry, here is another option I posted several years ago. Turn your jumbo jaws into a giant set of "flat jaws". No fiddling with buttons & bolts and quick to adjust to different sizes. Also grips at near 360º - not just 8 points.

Thanks Tom: This is what I plan to do as a last resort. I thought of smaller jaws turned to fit the object being held, but your way allows for more flexibility. Do you use the tailstock for added security? - I note you don't picture it in use. I only plan to finish the bottoms of objects, so no heavy cuts - well at least not intentionally anyway!
Cheers. Be safe and stay well.
Barry

 

[Dennis Weiner]

Oneway sells an inexpensive pair of flat jaws(approx 40-50 bucks) that you can use for this purpose.

 

[Barry Larson]

Problem solved! Using Leo's suggestion of leaving a few buttons off, placing the bowl and then placing the remaining buttons and extending the jaws a wee bit further I had success. Not much wiggle-room, but success nonetheless. I got the jaws to extend a hair further - I think the safety pin might have been hanging up in the groove on the chuck body and that prevented the jaws from fully extending. Thanks again to all who responded with advice. Be safe and stay well.
Barry W. Larson
Calgary, Alberta, Canada eh!

 

[Tom Gall]

Thanks Tom: This is what I plan to do as a last resort. I thought of smaller jaws turned to fit the object being held, but your way allows for more flexibility. Do you use the tailstock for added security? - I note you don't picture it in use. I only plan to finish the bottoms of objects, so no heavy cuts - well at least not intentionally anyway!
Cheers. Be safe and stay well.
Barry

Yes, always use the tailstock no matter the holding method (even vacuum) until the final cuts & sanding.
"I note you don't picture it in use." ??? The advantage of this chuck is that it perfectly centers the piece even if you didn't have a center dimple in the wasteblock to then bring up the tailstock with no fuss ... and have 360º holding. The bowl in the photos has an undercut rim so the groove is cut with a slight dovetail on the inside and is held by expanding the jaws. If I ever finish the piece shown (started about 2004?) I will mount it as shown with tailstock pressure and either part off or saw off the rather large tenon/wasteblock and then proceed as above.

 

[Tom Gall]

Oneway sells an inexpensive pair of flat jaws(approx 40-50 bucks) that you can use for this purpose.

I have those flat jaws, but they are under 3" each. I was reluctant to add larger waste wood jaws to it. The one I have with the jumbo jaws is 18"Ø (20" swing on my lathe). I never wanted, liked, or trusted Cole jaws but when I saw them for a good price at an estate sale I saw that as my opportunity to make a larger version of "flat jaws".

 

[hughie]

Barry, here is another option I posted several years ago. Turn your jumbo jaws into a giant set of "flat jaws". No fiddling with buttons & bolts and quick to adjust to different sizes. Also grips at near 360º - not just 8 points.

Something I found at times also, that what I wanted to turn wouldnt fit any of my chucks or chuck jaws. So I have a series 0f wooden and plastic jaws to meet this problem. They screw onto the 100 and 130mm Nova jaws as Nova drilled tapped each jaw with two m6 holes.