Metal lathe chucks a la Bill Jones

[QuarkVI]

I have been spending a few very enjoyable days reading Bill Jones' books (https://www.amazon.com/Bill-Jones-Notes-Turning-Shop/dp/1861080174 and https://www.amazon.com/Bill-Jones-Further-Notes-Turning/dp/1861080360) and it seems that a four jaw self centering metal lathe chuck makes quite a bit of sense for smaller scale work.

Now I am not suggesting it is appropriate or can replace woodturning chucks for larger scale work as they simply aren't designed with that kind of workholding in mind.

There doesn't seem to be a better option for holding stock in the 0-40mm range - only other option is a collet chuck which requires round stock. Also using the inside jaws means you could comfortably hold small boxes including some rubber to prevent damage from the jaws.

Holding the smaller stock in a jacobs chuck means you have a lower upper limit (16mm in my case) and pin jaws seem to be a real compromise as they aren't really made for holding and you will still be using four corners since unlikely that your stock will match the internal diameter.

As for attaching to the lathe: it seems Axminister still makes a backing plate (Backplates for Super Precision Chuck - Chuck Accessories - Woodturning Chucks - Lathe Accessories - Machinery Accessories - Accessories | Axminster Tools & Machinery (http://www.axminster.co.uk/backplates-for-super-precision-chuck-ax23301?sel=900077))for their old super precision chuck (which was a K12 100mm) which will mean a relatively simple attachment and no need for special engineering if I go with a K12 100mm.

So am I missing something in the above analysis? or do you reckon it is the best option for those parameters?

cheers
Robin

[Sawdust Maker]

Can't comment on the metal work chuck

but would the teknatool mini jaws on a SN2 do what you want? Link (http://www.teknatool.com/products/Chuck_Accessories/Mini_jaw_set.htm)

[hughie]

The design on metal lathe chucks are minimal contact and maximum pressure. Which is darn near the opposite of wood turning chucks, plus the mass is significantly greater.
So what does all this mean? Well some folks do turn with these chucks and do a fine job of it. As long as you remember the limitations such as small contact and pressure then you should be ok.
Its no accident that Teknatool , one of the first to make wood turning chucks. Designed a lighter chuck with a less aggressive scroll and wide corrugated jaws.

[turnerted]

I use a set of long nose jaws on my VM120 chuck .This will take anything from about 10mm up to what will what will fit in my VM90 chuck . You dont get much contact once the diameter goes up a bit, but you can make a very long dovetail for more contact .
Ted

[Old Croc]

Robin, the other consideration to remember is that most metalworking chucks are made of cast iron and are not rated for the speed of woodlathes, read they can explode from centrifugal force.
Rgds,
Crocy

[NeilS]

We used metal lathe chucks before Teknatool introduced their woodturning chuck. They have their limitations; no dovetail jaws, so not very useful for faceplate/bowl work, and they have nasty projecting jaws that will kill your knuckles.

I still have mine, but only use them for working soft metal like brass for ferrules.

I can't believe that you can't find some Vicmarc jaws to meet your requirements

Vicmarc - Woodturning Lathes, Chucks, Jaws and Accessories - Jaw range (http://www.vicmarc.com/default.asp?contentID=592)

[Mobyturns]

Robin, When we read older books on woodturning techniques we always have to be mindful of what tooling was available to the writer in the era that the book was written. Woodturners four jaw scroll chucks are a relatively recent invention in the context of woodturning history dating back to the early - mid 1980's. Even though the books were compiled in 1998 the articles date from a much earlier period in Bill's career. Bill also turned a lot of ivory and harder timbers which would work well with a conventional metal machinists chuck and he did a lot of hand chasing of threads at slower speeds..

I have been using Vermec's ER25 & ER32 Collett chuck bodies & collett nuts for probably over ten years now. I can say without reservation that they are the best option hands down for small spindle work. The ER32 will handle up to 20.5mm round stock and both can handle reasonably well dimensioned square stock with out issue. There are larger ER collett systems but no manufacturers adapting them to suit woodturning applications.

At last years Proserpine Turnout I used the Vermec ER25 collett chuck to turn about fifty 2mm dia ebony pins from random lengths (50 - 150 mm) of ebony recovered from odd slices given to me by another turner. They were sawn to about 3.5 - 4mm square on a cheap small GMC band saw with a very fine tooth saw band and fed through the collett chuck body. No significant issues, but if you want real precision square stock is essential.

Hughie & Crocy make some very good safety points - most wood turners believe fine spindle turning typically requires very high spindle rpm's - metal lathe chucks are not designed for those spindle speeds. However fine spindle turning can be achieved at relatively low spindle rpm's if the turner has sufficient skill.

There are quite a few good choices available with pin jaws on Nova and Vicmarc chucks but be cautious of using (25mm) pin jaws that have only one screw into the backing slides in compression mode. If you hold the work piece in only the nose of the jaws you will place quite a bit of strain on the jaws and backing slides. I have found Jacobs chucks to be very unreliable for runout accuracy of the work piece unless using quite hard timbers.

[BobL]

Hughie & Crocy make some very good safety points - most wood turners believe fine spindle turning typically requires very high spindle rpm's - metal lathe chucks are not designed for those spindle speeds. However fine spindle turning can be achieved at relatively low spindle rpm's if the turner has sufficient skill. .

Modern small MW chucks can run at much higher speeds than required by WW.

Even cheap chinese chucks can run at over 4500 rpm
e.g. this 100 mm (http://www.machineryhouse.com.au/C230) can run at 4800 rpm and this 160 mm chuck (http://www.machineryhouse.com.au/C203) can run at 3600 rpm.

If you are prepared to pay ($1000+) for quality then there are small (100 mm) Bison forged steel MW chucks (http://www.bison-bial.com/public/data/resource/upload/00199/198037/technical-data-de.pdf)that can turn at 6300 rpm
Even their 100mm cast iron can do 4500 rpm

If your budget stretches to paying as much for a chuck as a WW lathe then there are always these with quick change (seconds) jaws (http://www.forkardt.com/usa/us-us/products/power-chucks/fnc/)
These also come with jaw inserts just like those used for WW lathes.

Buck USA make some really nice 6 jaw chucks but their smallest is a 6" and it is cast iron and it does have a max RPM of 1600.

[wheelinround]

Robin, the other consideration to remember is that most metalworking chucks are made of cast iron and are not rated for the speed of woodlathes, read they can explode from centrifugal force.
Rgds,
Crocy

You seen the speed new lathes do Old Croc and some of the new 4 jaw metal lathe chucks time you went shopping at H&F for some gear newer than 100yr old :q

I agree with what you say but a hunk of 6" dia steel turning at 600rpm+ compared to a chunk of wood 600mm dia turning at 600rpm :oo:

[Mobyturns]

Bob makes a good point about the newer MW chucks but as turners are frugal they are more likely to resurect an old chuck or purchase a cheapie that is certainly not rated to those rpm. For some unknown reason I have been asked about "grand dads wood turning gear" and to give an opinion on what it is worth by quite a few people in the last couple of years. Most of what I have seen is pretty low quality in the chuck department with modified 3 jaw MW chucks..

[BobL]

Bob makes a good point about the newer MW chucks but as turners are frugal they are more likely to resurect an old chuck or purchase a cheapie that is certainly not rated to those rpm.

The same would apply to any cheap or old WW lathe chuck spun at much higher RPM than its rating.

One thing to remember is the RPM ratings on MW chucks take into account the much greater clamping forces needed to hold metal.
The reaction to these high clamping forces along with the centrifugal forces is what tries to tear the chuck apart and is is one reason why 6 jaw chucks generally have lower RPM.
The other reason is that there is less metal between the 6 jaws to counteract these forces.

If the same clamping force as used on metal is use on wood, it would be crushed.
This probably means when MW chucks are used on wood they safer in terms of RPM than they would when used on metal.

Conversely the use of a WW chuck to hold metal (I know some of you are doing that) suggests the WW chucks should be derated in terms of their RPM in these situations

However I won't be doing any testing of these assumptions. :)

[Mobyturns]

Don't worry there are wood turners that apply that sort of pressure to wood turning scroll chucks. :rolleyes: I've seen a few Vicmarc VM90 / 100's with broken leading edges to the scrolls and dings in the scroll that could have only come from mistreatment.

[Mobyturns]

Modern small MW chucks can run at much higher speeds than required by WW.

Even cheap chinese chucks can run at over 4500 rpm
e.g. this 100 mm (http://www.machineryhouse.com.au/C230) can run at 4800 rpm and this 160 mm chuck (http://www.machineryhouse.com.au/C203) can run at 3600 rpm.

If you are prepared to pay ($1000+) for quality then there are small (100 mm) Bison forged steel MW chucks (http://www.bison-bial.com/public/data/resource/upload/00199/198037/technical-data-de.pdf)that can turn at 6300 rpm
Even their 100mm cast iron can do 4500 rpm

If your budget stretches to paying as much for a chuck as a WW lathe then there are always these with quick change (seconds) jaws (http://www.forkardt.com/usa/us-us/products/power-chucks/fnc/)
These also come with jaw inserts just like those used for WW lathes.

Buck USA make some really nice 6 jaw chucks but their smallest is a 6" and it is cast iron and it does have a max RPM of 1600.

That Forkardt looks pretty!

Bob, Have you seen any backing plates made up to convert MW chucks for use on WT lathe spindle threads?

[BobL]

That Forkardt looks pretty!

Bob, Have you seen any backing plates made up to convert MW chucks for use on WT lathe spindle threads?

I haven't seen any but I haven't looked that hard either. I would not be that big of a task to make one.