Genuine 75mm dovetail bowl jaws?

[NeilS]

Some time ago I bought a set of 75mm dovetail bowl jaws for my Nova chucks, but was disappointed to find that they were closer to 85mm external diameter when I went to use them. Nice sturdy jaws, but not 75mm.

I mostly use my jaws in expansion mode on the finished foot while completing the inside of bowls, so need a close fit to avoid marking the completed foot. I rarely re-turn the foot.

I like to have a distinct foot on my bowls and the proportion of the foot to the remainder of the bowl is important for the overall aesthetics of the piece. So I'm after some jaws halfway between 50mm and 100mm.

I know that 50mm jaws will open to 75mm, but they tend to mark the foot and are more inclined to break out at pressure points when more fully expanded.

Spoke to Jim Caroll at WWW Show and he agreed that the so-called 75mm jaws were more like 85mm and couldn't suggest an alternative.

Does anyone have a genuine set of 75mm dovetail jaws?

Thanks

Neil

[Taffsmania]

Could you make your own using the Nova Soft Jaws from Jim.
Keith

[Skew ChiDAMN!!]

You'll probably find that the 75mm refers to the inside diameter, not the outside, so what you want is more likely to be called a set of 65mm jaws. Somehow I doubt that you'll find such a set "off the shelf."

Have you given any thought to making up a set from neoprene blocks?

A cheap, neoprene chopping board would do the job... just score lines in an X though the middle and then place an ordinary set of jaws in position along the lines. This would allow you to mark the holes for the grub-screws for drilling, before cutting along the scribed lines to separate each new "jaw." Mount these on the chuck and then you can turn them to suit whatever shape/diameter you desire...

Don't know how strong they'd be in expansion mode, although they work well in compression.

[NeilS]

Hi Keith and Skew


Could you make your own using the Nova Soft Jaws from Jim.
Keith



..... Somehow I doubt that you'll find such a set "off the shelf."

Have you given any thought to making up a set from neoprene blocks?

...snip useful methodology....

Don't know how strong they'd be in expansion mode, although they work well in compression.

Thanks for your helpful suggestions.

I'm also not sure that those softer materials are going to be firm enough to hold in expansion mode, but not much loss in at least having a go with an old neoprene chopping board. Perhaps aluminium is another option that I could have a go at if the neoprene doesn't do the job.

Did think about turning down the so-called 75mm jaws as they have plenty of meat to do so, but not sure how the metal in the jaws would work with handheld HSS turning tools. Certainly have had no trouble in nicking the jaws accidentally with HSS. Anyone had any experience with 'adjusting' jaws in this way?

Thanks

Neil

[Sawdust Maker]

I was a bit disappointed in these jaws as well - they didn't really add anything to my kit in terms of holding in contraction mode

[Jim Carroll]

When these jaws originally came out they were 75mm outside diameter and 48mm inside diameter.
Some one in their wisdom at teknatool increased the outside diameter to 80mm without actually making any changes to the description on the packaging.

We also have the same problem with the step jaws which were always 75mm od now are 85mm od.

The only advantage the 75mm bowl jaws have over the standard 50mm jaws that come with the chuck is a deeper recess so allowing for a bit longer spigot.

As indicated you may need to make your own jaws out of aluminium or use the plastic jaws.

[Sawdust Maker]

When these jaws originally came out they were 75mm outside diameter and 48mm inside diameter.
Some one in their wisdom at teknatool increased the outside diameter to 80mm without actually making any changes to the description on the packaging.

We also have the same problem with the step jaws which were always 75mm od now are 85mm od.

...


One wonders whether when they went to PRC for manufacture, the new manufacturer changed specs without our kiwi friends noticing

[rsser]

Vicmarc do a set of 70mm jaws for their 90/100 chuck. With the jaw adaptors from Vermec they might work for you Neil. Do you want me to estimate the expansion range?

I've used the adaptors now with two sets of VM jaws fitted to an SN2 and they work fine. You have to drill out the jaw mounting holes to 6mm which is no drama.

[NeilS]

Vicmarc do a set of 70mm jaws for their 90/100 chuck. With the jaw adaptors from Vermec they might work for you Neil. Do you want me to estimate the expansion range?

I've used the adaptors now with two sets of VM jaws fitted to an SN2 and they work fine. You have to drill out the jaw mounting holes to 6mm which is no drama.

Good thinking Ern.... I keep forgetting about those adaptors for the Vicmarc jaws.

It would be useful to get an estimate of the minimum O/S diameter on those Vicmarc jaws.

Thanks

Neil

[rsser]

Neil, it's 70mm.

You might also consider the range of VM Shark jaws which IMO are more versatile and will stand up to some heavy treatment. They don't have the beveled outside face of the Nova Spigot jaws that I own so you can use them equally well in expand and contract mode.

The range has been expanded since I got my first set some time ago so you'd need to research them on the VM website. FWIW, my first (small) set have a min OD of 45 mm, and a set subsequently acquired (which I think were the 3rd in the range of 4 but don't quote me) are 70 mm too. I went for that size since it overlapped the travel range of the small set nicely.

Hope this helps.

[NeilS]

Neil, it's 70mm.

You might also consider the range of VM Shark jaws which IMO are more versatile and will stand up to some heavy treatment. They don't have the beveled outside face of the Nova Spigot jaws that I own so you can use them equally well in expand and contract mode.

The range has been expanded since I got my first set some time ago so you'd need to research them on the VM website. FWIW, my first (small) set have a min OD of 45 mm, and a set subsequently acquired (which I think were the 3rd in the range of 4 but don't quote me) are 70 mm too. I went for that size since it overlapped the travel range of the small set nicely.

Hope this helps.

Thanks for that Ern.

Yes, that got me having a closer look at the VM range and also having another think about the gaps in my chuck/jaw kit. Well, a few genuine gaps (like 75mm and 200mm) but mostly just wants. Regularly changing jaw sets was never my favourite thing and it seems that you can never have enough chucks, but it is always a shock when you calculate the extra cost of having a chuck for each regularly used jaw set...:o... and you have to sell a lot of bowls to pay for such a luxury... :C

Neil

[robyn2839]

i have a set of 70 vm jaws and adaptors for the teknatool chuck so it can take the vm jaws ,if your interested

[NeilS]

i have a set of 70 vm jaws and adaptors for the teknatool chuck so it can take the vm jaws ,if your interested

Hi Robyn - PM sent, Neil