Mini-lathe chucks are they located?

[WobblyHand]

Being effectively a rank beginner, I question a lot of things that might be trivial. But, I'd rather ask than do something dumb and regret it. Obviously, as time goes on, I'll get more adventurous, and perhaps more knowledgeable.

When I bought my mini lathe I also got a 4 jaw chuck. It was packed in a box with no instructions. It came with screws, and a chuck key. The jaws were pre installed.
Also in my order, there are some studs and nuts, that look to be about the same size as the screws. Just a bag of parts, no instructions. Assuming they fit, they are to mount the chuck? The 3 jaw is mounted with studs and nuts.

So how do I install the 4 (or re-install the 3) jaw chuck and get it true? Is there a feature which locates the chuck center to the spindle? The parts diagram doesn't seem to indicate there is anything. So just install it and check if moderately true?

 

[matthewsx]

Hi and welcome,

Since I don't have a mini-lathe I can't answer the question about how it mounts. Littlemachineshop.com has a lot of info on the mini machines if you can't find the answer on here.

As for a 4 jaw, having it perfectly centered isn't as critical as the 3 jaw though because you will use an indicator to center the work by adjusting the jaws. Personally I wouldn't be afraid to mount it the same way the 3 jaw is mounted and use an indicator to see how close to concentric it is. If it's way off figure out what has to be changed, otherwise give it a try.

Others may have better info but that's what I'd do.

Cheers,

John

 

[WobblyHand]

Been cruising their website. Seems they have a lot of info there, but my initial questions are below their baseline competency assumptions.

I wasn't worried at all about the 4J, since I'll use an indicator anyways. I was wondering more about getting the 3J back in position. Guess I'll use an indicator on the outer body and adjust if necessary.

John, thanks for your suggestion. It's helpful.

I'm trying to mount my indicator to a QCTP, but I don't seem to have the right adapter pieces. I'll have to make an adapter to my QCTP holder. My new QCTP holder is expecting a dovetail or a post. My crummy Harbor Freight indicator has a hole. I have a new indicator with dovetails coming, but it's not here yet. Maybe Monday.

 

[jaek]

There is a raised registration surface on the spindle matching a recess on the chuck. Swapping chucks takes minutes at most, less than a minute if you’ve done it a few times.

 

[mikey]

There should be a register on the face of the spindle that fits into a similarly sized recess in the back of the chuck. This is what should locate the chuck accurately. The bolts only hold the chuck in place.

 

[matthewsx]

Both of my indicators have magnetic bases.

 

[Larry42]

Before you take the 3J off magic mark it and the spindle so you can put it back on the same way it came. You may also want to try it in several different bolt locations to see if one gives you better concentricity. Once found center punch it and the spindle. Note that you can rarely take work out of a 3J and put it back expecting it to be dead on center. You don't need to mark the 4 jaw as it doesn't matter which bolt holes it uses. Get yourself a mag base for your indicators. They range in price from dirt cheap Chinese to very nice Noga. Your adventure will require lots of "stuff" in addition to the lathe. HSS tool bits that you can grind on your bench grinder to make whatever you need. Way oil, cutting fluid, WD40 for aluminum (cheap & works well.) A caliper works fine for non-critical measurements, micrometers and bore gages for better measuring. Have fun.

 

[Mitch Alsup]

Before you take the 3J off magic mark it and the spindle so you can put it back on the same way it came.

Can I suggest you make a more permanent mark--exacto blade, punch, scribe line,...--on both the chuck and on the spindle.

 

[WobblyHand]

There should be a register on the face of the spindle that fits into a similarly sized recess in the back of the chuck. This is what should locate the chuck accurately. The bolts only hold the chuck in place.

That's what I was hoping for, but I didn't see. I did mark the 3J chuck before removing it. So I can put it back the same way. Perhaps I missed it or plain didn't recognize it. When looking at the 4J I was hoping to see something as well. I didn't recognize anything. I'll take a pic of the back of the 3J.

 

[mikey]

There has to be a register, a step, on the nose of the spindle. That step fits into a recess in the back of the chuck. Take a pic of your spindle and let's see what you're dealing with.