Lathe chucks which one and why (3 vs 4 jaw vs grip tru)

Just watched a video on someone converting a standard 3 jaw chuck into a grip tru type. Whilst i appreciate on a commercial shop basis time is money and a few minuets spent dialing in a work piece is "dead" time especially where concentisity doesnt matter as it will be achieved by turning the work piece down. In the home shop why use a 3 jaw at all. time doesnt matter to the same extent why use a three jaw at all.

what is the benefit of the grip tru type why spend 600 pounds up to get what amounts to a 4 jaw with less adjustment?

there must be a reason otherwise they wouldnt make them just wondering what it is

Angular alignment in addition to positional alignment. With a 4-jaw, you can adjust the x and y position to your requirement, but you have no control beyond the z position of the clamping surface. with a tru type, you can adjust the angle , to affect the z some distance away from the chuck face.

Some of these home shop guys are also professionals. Having used industrial grade equipment at work, it can be difficult and frustrating to make concessions at home. After all, most of us in the trades, are home only at the will and whim of our employers. So if you have a spare 30 minutes while the kids are at soccer, and the wife’s getting her hair done, you don’t want to lose any of it to less capable machinery than you use all day at work.

Honestly, there is work I can get done on my lunch break at work, that would take me 6 hours at home. Assuming the boss is in a good mood or absent…

mfendley said:

Angular alignment in addition to positional alignment. With a 4-jaw, you can adjust the x and y position to your requirement, but you have no control beyond the z position of the clamping surface. with a tru type, you can adjust the angle , to affect the z some distance away from the chuck face.

Click to expand...

Please explain.

Tom

When I prep’d the backplate for my 5” 3-Jaw I used slightly oversized clearance holes for the hex-head screws that secure the backplate to the chuck so that if needed I could reduce the boss & bump the chuck into better concentricity (not needed as it turned out).

https://www.hobby-machinist.com/threads/accusize-5-3-jaw-chuck-fitting.112194/post-1129737

If I had:

• A larger lathe
• Quality 3- & 4-Jaw chucks for the lathe
• Unlimited funds

I would get a Bison/Buck/etc. Set-Tru (or equivalent) 6-Jaw: I still remember the joy that the Department Machinist (a retired Tool & Die Maker) experienced when he was allowed to buy one for his Monarch. He seldom used the 5C adapter/drawtube afterwards.

He was almost this happy when he got a surplus BP (so he could stop mounting the vertical head on the B&S horizontal mill).

jwmay said:

Some of these home shop guys are also professionals. Having used industrial grade equipment at work, it can be difficult and frustrating to make concessions at home. After all, most of us in the trades, are home only at the will and whim of our employers. So if you have a spare 30 minutes while the kids are at soccer, and the wife’s getting her hair done, you don’t want to lose any of it to less capable machinery than you use all day at work.

Click to expand...

Once you own a Jag , it's hard to go back to a Yugo . To the OP . True , a 4 jaw will do anything that a 3 jaw will do , and more . But at a point , time becomes an issue .

The 3-jaw chuck fills the need for a quick method of workholding where the job can be completed as a first operation
or multiple operations if the runout is acceptable
6-jaw chucks are used for thin materials where there is risk of collapse or there is a need for additional grip

higgite said:

Please explain.

Tom

Click to expand...

Gavin @ Ultimate Reloader did a review and explains it here:

The time element is less important to a hobbyist, but I wouldn't say it is unimportant. 3 jaw chucks are a quick and easy solution for many tasks, quick and easy is always appreciated so long as it results in good parts.

Ooooh...you just made a slip up there.

Either you just revealed your membership of the small group of immortal human beings existing on earth, or you just admitted to being a sentient true AI!

Of course time matters. Everything takes some amount of time and whilst hobbyists aren't under commercial pressure, we can't spend 24/7 in the workshop and have other demands on our time.

Also eventually we get to the stage where, if we're lucky we, as Mr Pete so charmingly says, 'take a dirt nap', or we get decrepit enough that we can't use our workshops anymore.

You use a four jaw chuck where you either need to ensure concentricity if you have to remove the workpiece from the chuck, or you need absolute assurance that you have absolute minimum runout that a standard three jaw can't offer, or you need to hold a square part in the chuck (you can square up a piece of stock in a lathe with a four jaw chuck, if you don't have a mill), or you need to turn a feature that is eccentric to the lathe's spindle axis.

You'll use a three jaw chuck for pretty much the rest.

People say "If I was on a desert island and I could take only one chuck it would be a four jaw" and what they're actually saying is that a three jaw has limitations and just having a three jaw chuck is not enough.

And that's correct; everyone should have a four jaw chuck as a basic part of lathe tooling.

But no hobbyist, least of all beginners like thee and me, should be punishing themselves by having to dial in a workpiece in a four jaw chuck, every time they need to do a set of operations on a cylindrical workpiece where it can remain in place throughout those operations.