[viroy]

I am having a heck of a time figuring out anything about the chuck on my 4th axis rotary... it's 4" in diameter, no id#'s on it, just a chinese logo.
I'd like to change it out to a 4-jaw, but dont have a clue what is on there now or what type of 4jaw I should look for.
The jaws on mine go all the way to the backside, but everything I see for sale is way way thicker (jaws like 3" from backside).
I have to use 2 hand-tools to tighten it, one to hold the chuck still, and another to rotate the black ring just behind the chuck which closes/open the jaws.
Please, any info on this type of chuck or what I can replace it with is greatly appreciated!

The worm gear is a NMRV050

[atomarc]

It's a mini lathe chuck, typically used for turning pens or very small wood items. https://www.grizzly.com/products/gri...xoCgQsQAvD_BwE

Stuart

[viroy]

So it looks like it simply screws on to a shaft... No set screws or keyways?
I tried forcing it to unscrew, but the gear system moves too.
Theres nothing to pry against... there is an allen screw on the other side of the shaft (backside of the gear system) which rotates with the chuck
If it requires rotational force only to unscrew, should I wedge the hand tool used for tightening the jaws and energize the motor to break it loose?
Or should I remove that back allen screw and maybe the shaft slides out and see whats going on?
I really dont want to damage anything... first time attempting this

[atomarc]

That gear reducer is a typical right angle unit which has a keyed shaft out of the side your chuck is attached to. If your setup was built/assembled by a hobbyist, the connection between chuck and reducer could be anything. The threaded version of those chucks come in two different sizes, and If you look into the bore of your chuck, you can see internal threads...but they're isn't anything threaded into them, so that's not how the chuck is apparently connected to the reducer. Your pictures show 3 socket head cap screws through the body of the chuck, and those are not typical of these small chucks. Have you tried removing them to see if the chuck comes off...my bets are that it will. Keep us posted.

Stuart

[viroy]

Hey it was as simple as that!
I cant find a 4-Jaw that has that 3-bolt pattern though.
I purchased it from SaleCNC.com in 2011 and just emailed them.

[atomarc]

That style chuck doesn't come with the mounting bolts, they were added to attach to the gear reducer adapter plate (home made, it appears). The funky scroll system allows that chuck to be very low profile, and cost effective for the hobbyist. There are 4 jaw chucks out there of that same design, and they too are low profile, but be aware, they are not independent 4 jaw units, all the jaws adjust together because of the funky scroll system. I think mounting it will have to be something of your own creation unless 'SaleCNC' has something on the shelf.

https://www.amazon.com/Reversible-Self-Centering-Thread-Milling-Drilling/dp/B07JG2GSXH


Stuart

[joeavaerage]

Hi,
can you see any manufacturers markings on the drive?

I have a couple of Atlanta Drive System servo reducers and are vey good quality with <2 arc min backlash.

Really the chuck is not the important bit but how rigid, accurate and how much lash the worm drive has. Good quality units are worth a fortune.

Craig

[viroy]

The worm gear is a NMRV050
I came across a silly video of a guy making custom fittings for an NMRV040 so he could take off tire lugnuts with a hand drill lol
Anyways I learned about the input/output shaft fittings from that video.

I removed the back bolt and tapped out the shaft... It's a custom shaft for this chuck.
So now I need to find a 4-jaw chuck mated to a 0.985" dia shaft that has a 0.312" wide keyway, roughly 3.5" to 4" long with a tapped end

[atomarc]

Had the original pictures shown the back of the reducer it would have been apparent that it was a hollow shaft unit and removing that shaft, along with the attached chuck, would have been even easier than taking out the SHCS's and popping the chuck off. As was noted above, that reducer is not a zero-backlash unit, which would be fine for its intended use with wood, but not so for precision machining in metal. I'm pretty confident you or someone else is going to have to custom machine any lash-up to mate a 4 jaw to that gear reducer, which shouldn't be a big deal at all if you have the tools to do so.

I have the tools and skill to do the job if all else fails you.

Stuart

[joeavaerage]

Hi,
my three jaw chuck has three cap screws that retain the chuck to the shaft adapter. The shaft adapter has a 72mm boss to centre the chuck.

I've just checked with the manufacturer (Vertex) and the four jaw chuck of the same size has four cap screws, on the same pitch circle and the same diameter boss.
So to fit a four jaw in place of my three jaw I just need to drill some new holes, I do not have to make another shaft adapter. Maybe you can do the same.

Craig

[viroy]

so ones like this ebay 4-jaw just use the 4 bolt holes on the back to mount?
I figure if that one mounts with the 4-bolt holes on the back, I can simply make a 4-bolt adapter for my existing 3-bolt shaft



That is the best one I can find as far as ease of mounting to my machine.
All the others have a threaded hole or a tapered shaft, or a pipe

[joeavaerage]

Hi,
yes....they are called Backplate Mount. The one you have pictured has the screws going through the backplate and thread into the chuck. My one is the other way around,
the screws pass through the chuck from the front and are intended to thread into the backplate. Note also the recessed area in the back of the chuck. The backplate is intended
to have a matching diameter boss so that the backplate and chuck remain concentric without having to rely on the screws to do so.

As I say I have a Vertex 3 jaw chuck. The 4 jaw has identical dimensions, but just requires four holes rather than three. Simple enough to re-drill.

You might get lucky and find that the manufacturer of your existing 3 jaw might have a matching 4 jaw. That would save you having to make a new shaft adapter.....although
that's not that hard either.

Craig

[joeavaerage]

Hi,
I needed to remove the chuck so that I could get a little extra room for a piece of steel I'm working on.

You can see the shaft adapter with the central boss and the three threaded holes usually occupied by the cap screws retaining the chuck.
If it had four holes rather than three I could bolt on a 4 jaw chuck from the same manufacturer.

Craig

[viroy]

That is the problem I mentioned earlier and posted pics of the only identifying mark, a chinese logo with 2x characters which I cannot interpret.. not a clue of the manufacturer.
Can you post links to the manufacturers product page of the chuck you are talking about, both 3 & 4 jaw.

[joeavaerage]

Hi,
the company is called Vertex, a Taiwanese company. It has been a long time favorite of mine. They use Meehanite, a really top TOP grade of cast iron, silky smooth like a steel,
but still cast iron..Easily as well made as a lot of US and Japanese stuff but much better priced. Do not expect it to be as cheap as Chinese, its not, not by a long chalk.

https://www.vertex.co.com/

Craig

[joeavaerage]

Hi,
actually that site is not much good, it doesn't seem to have chucks, this one does though:

Detail

Craig

- - - Updated - - -

Hi,
actually that site is not much good, it doesn't seem to have chucks, this one does though:

Detail

Craig

[viroy]

Looks like an incomplete website, hardly anything works

[joeavaerage]

Hi,
they are all over Ebay.

Craig

[viroy]

There is only one 4-jaw vertex on ebay, but it's an 8" which wont clear my base and costs $900!!!
I'm not seeing this as any type of solution.... even the 3-bolt pattern doesnt match up to my shaft much less the 4-bolt.
I would be trading one problem for a far more expensive one.

Unless someone knows of a better 4-jaw chuck option which can utilize my current 3-bolt pattern, or comes with a new shaft matching the shaft/keyway... the only solution I see is to order that 4-jaw I listed above and make an adapter for my existing shaft.
Otherwise it's a very expensive overhaul

I did find a cheat..... I would really like to avoid using these though.
https://www.ebay.com/itm/364262001116

[joeavaerage]

Hi,
why not just make a new shaft...its not that hard. I made the adapter that you see pictured. a 150mm piece of 104mm diameter 4140 shaft cost $175NZD ($105USD) and about 2 hours in the lathe.
I milled the keyway on my CNC machine, 15minutes or so.

The company I bought my 100mm Vertex 3 jaw off has ceased listing them but I paid $157NZD ($94USD) about five months ago, and I can get a 100mm Vertex 4 jaw for $147AUD($100USD) from an Australian
company. Vertex is good, much cheaper than Bison, Gator, or Pratt and Burnerd, but quite a step up from Chinese.

Craig