[How-To] 7x12 - compound removal / 4-jaw chuck

[Nates]

I'll ask these two questions together because I'm horrible at rabbit trailing. The current goal is to remove my compound. I need the adapter and don't have a mill. I do have a drill press, and my next door neighbor has a mini mill. I can use it but probably not 40 hrs worth of machining.

I'm considering using this to justify a 4-jaw chuck as I don't have one. One thing I see about the 5-inch chucks is that the jaws will stick out enough to hit the ways. But does it actually hold bigger work than a 4" opened to its max? Does anyone just sell the part? (Not that I've seen).

Is removal substantially better than just locking it down? (another common mod) Does an 0XA QCTP negate the benefit of "solid tool post?"

 

[WobblyHand]

For a mini-lathe, I doubt you could find a 5 jaw, or 6 jaw chuck. I don't believe a 5 jaw exists, and all the 6 jaw chucks that I know of are much larger than a mini can handle. It's unclear what you are trying to do. What adapter are you talking about? What are you trying to improve?

Are you thinking of removing the compound and replacing it with a plinth (solid block)? That could help. However, I suggest you adjust and tighten your gibs, as that will give you a lot of benefit, for zero expense. A mini-lathe can do some decent work, as long as you don't push it too hard. Having a plinth does improve rigidity, if that is what you are after. Tightening up your lathe can help as well.

A four jaw chuck is quite handy. It has nothing to do with tightening gibs, or adjusting your lathe. It is useful for secondary operations, so that you can have a previously turned part exactly centered. Most 3 jaw chucks cannot do this.

A solid plinth can help improve rigidity. However, try adjusting your lathe. Most are shipped and have not been adjusted properly. If you have specific questions on how to do that, ask away, because we can help you make it better. Perhaps well enough that you don't need to make a plinth. I haven't bothered making one for my mini.

 

[Nates]

Sorry that was a typo. I meant 5-inch 4-jaw vs 4-inch 4-jaw.

 

[WobblyHand]

Sorry that was a typo. I meant 5-inch 4-jaw vs 4-inch 4-jaw.

Think a 5 inch chuck is kind of large on a mini-lathe. I have a 4", really 100mm, 4 jaw chuck. Are you really going to turn something large enough to need a 5" chuck? That's rather large stuff for a mini, in my opinion. The 4" is cheaper and will probably suit you for a long time.

 

[Nates]

That's what I was trying to be sure of. I just wasn't looking to start collecting chucks for their own sake.

 

[WobblyHand]

Why are you considering removing your compound? Is it not rigid enough?

Might just need tightening of the gibs everywhere. There's plates for the cross slide on the front and back, and the gib screws on the cross slide and compound, they all need adjustment to work decently. Snug, but allowing free movement through out their full range. The little gib screws may have retaining nuts, they need to be loosened first, then the screws can be adjusted to slightly tighten up the system. It's easy to go overboard, but then, all you do is back it off some, until things are snug, but they allow smooth linear movement with a slight drag.

 

[Nates]

It definitely has room for improvement on setup, but as I was reading I was seeing tons and tons of folks saying these 7x lathes can really benefit from it and just put it back on if you want to do tapers.

 

[WobblyHand]

I'd bet a plinth would be an improvement, but adjusting your gibs has immediate benefit all the time, so why not start with that first? If you do that and still want to make a plinth, by all means, try it.

For me, just making the adjustments made a huge improvement, so much so, that I didn't feel that much need for a plinth. I get reasonable performance out of my mini lathe, given it's size and rigidity. In full disclosure, I didn't have access to a mill at the time, and making a plinth was out of reach. Now I have a small mill, and I could make a plinth, but I haven't bothered, since the mini lathe works well enough once adjusted.

 

[D.sebens]

I'd bet a plinth would be an improvement, but adjusting your gibs has immediate benefit all the time, so why not start with that first? If you do that and still want to make a plinth, by all means, try it.

For me, just making the adjustments made a huge improvement, so much so, that I didn't feel that much need for a plinth. I get reasonable performance out of my mini lathe, given it's size and rigidity. In full disclosure, I didn't have access to a mill at the time, and making a plinth was out of reach. Now I have a small mill, and I could make a plinth, but I haven't bothered, since the mini lathe works well enough once adjusted.

I think part of it is being able to center the tool over the cross slide to do that with the compound you have to back out of its dove tails pretty far.

 

[WobblyHand]

I think part of it is being able to center the tool over the cross slide to do that with the compound you have to back out of its dove tails pretty far.

I don't ever remember centering the tool over the cross slide while using the mini lathe. I try to have at least two thirds or more of engagement with the gibs, otherwise there's all sorts of trouble. If you don't have a large engagement, and adjusted gibs, the setup will be floppy.

In my experience, if you can easily and effortlessly spin the handles, it's way too loose. Of course, if you scrape everything, you can achieve that, but on a standard mini lathe without that effort, one needs some drag on the handles to get to the required tightness. You don't want excess drag, but there's more than one would like. This is the price we pay for these lathes at the low end of the cost continuum. The fit and finish is to a price point. They need effort to improve their performance. Part of that is constant fiddling and adjustment in the beginning to get them to perform to their potential. Once they are set up, they are decent for their rigidity class.

Don't think I've ever seen a plinth setup centered either. It's always off to the edge of the cross slide not on center. If you have made something like that, please post a picture or two. I have made a rear plinth for my knurler which I love. Made the knurler as well. They work great on my mini lathe.