Insert vs. Direct Thread Chucks

[Tom Hansen]

I have a couple of nova chucks both of which are insert type. One uses an 1.5" insert and the other uses closer to a 3" (and very heavy duty) collar type insert. They work fine enough until it's time to change chucks. Then half of the time they inserts want to come out of the chuck instead of off my drive threads. All set screws are tightened but it's kind of a janky fit. Sometimes after loosening the insert set screw i have to use huge channel locks to get the insert to unscrew from the drive threads.

I'm pretty much over it. I've been looking at buying a Vicmarc 120 and just assumed I'd buy a direct thread type instead of an insert type to avoid this issue. But I got to thinking, if for any reason I want to sell the chuck, will I have a harder time getting rid of an 1 1/4"-8tpi direct chuck vs. the insert type? I would assume If I bought a different lathe without the 1 1/4"-8 threads I could just buy an adapter for the direct chuck but now I'm not sure.

Any of you with more experience shed any light on this for me?

Thanks in advance for your input.

 

[Mike Johnson]

A thin brass, aluminum or polymer washer installed between the insert thread and the spindle mount will keep the insert adapter from locking onto the spindle thread.
The hardened steel thread of the insert tends to tighten down against the spindle thread each time you start the lathe and get a catch on the lathe locks the two threads
together over time. Having a softer metal to cushion the two thread mating surfaces makes it easier to break the threads apart when removing the chuck. Having a chuck
with the threads of your lathe spindle will eliminate some of the headache, but you can still seize the threads together if the chuck threads locks onto to the spindle threads
and requires some brute force to remove the chuck.

 

[Curt Fuller]

I wasn't aware you could buy a direct thread Vicmarc chuck but I learn something new every day. I have 5 Vicmarcs and all use an insert. That said, I think part of your problem could be that you're tightening your chuck to tight to begin with. I've never had that happen in almost 20 years of using Vicmarc chucks. Also, my chucks use a short "tommy bar" that inserts in a hole in the insert to loosen them. So the torque of loosening is on the insert rather than the chuck itself. But I never use the tommy bar to tighten them. I just thread them on until they're about a quarter turn from tight and then just give them a little spin by hand so they snap tight. I have never had a Nova chuck though so that advice many not be relevant.
As for buying a direct thread chuck, odds are the new lathe you buy in the future would be the same 1 1/8" x 8tpi spindle. That seems to be almost standard anymore. You can even order the Vics and Oneways with that spindle.

 

[Dean Center]

Oddly, I've never had any problem with my Nova chucks coming off the insert. Did you put the little gasket/cushion dot down into the set screw hole before tightening the set screw? I clearly recall having no idea what that little dot was when I got my first chuck, and concluded it was a paper punch like bit of debris from the packaging. I ended up making a new one out of some auto gasket material to replace it.

 

[Tom Hansen]

I do have a couple of nylon washers but they get wonky when the insert is screwed up against them then i get a wiggle and it doesn't center. maybe i'm just tightening down too much.

Hah, the dot was used for something? It goes between the screw and the headstock? I've tried 3 different inserts and the same with all of them.

Couple other things about the nova chucks i dont like are how jaws wiggle if not torqued down onto a tenon and I'm unable to get my steb or screw center to align properly in the jaws. At first it was ok and now it's impossible. Possibly I've cranked them down too hard and marred the receiving end? I ended up buying a morse taper steb center which works perfectly.

Side note, can anyone confirm my nova jaws will fit on the vicmarc chuck? I've been told yes but further confirmation would be nice.

 

[RichColvin]

I have the Vicmarc 120 that does not have an adapter (as you called it, direct threads). I really like it and have considered getting more of those.

Rich

 

[Roger Wiegand]

The Vicmarc I got recently has a grub screw to anchor the insert in place.

 

[john lucas]

Just put loctite on the insert threads. It will stay on but can be removed if necessary.

 

[Bill Blasic]

I have never had a problem with my Novas inserts coming loose. I have the Nova wrench which works quite well. John's answer is a good one as Loctite will keep it nicely in place if you have a problem.

 

[Mark Jundanian]

I think 1 1/4 x 8 tpi is the most common spindle size in hobby workshops, but there are plenty of lathes using other sizes.

I would think that a spindle adapter would not be a superior mounting method to an insert.

So I think an insert chuck has some advantages.

Not to dissuade you from Vicmarc, but here is my experience with my two Super Nova II's with inserts. I can't recall either insert ever loosening. The inserts are secured with the dot and grub screw. I have gone back and forth with the nylon spindle washer, and currently don't use one. I always put a drop of machine oil on the lathe spindle threads when mounting a chuck. I'm pretty sure I read to do that in the manual, but it's what I do. I have and use the Nova wrench, which I think is worth the money. It would cost just as much to buy a regular wrench that size, but a regular wrench is harder to store. The wrench fits directly on the insert, so the insert is never going to loosen, and it's way easier to put on the wrench than try to get purchase on the chuck body or the work when removing the chuck.

 

[Tom Hansen]

loctite, so obvious it went directly under the radar. that's what I'll do. I'm still wondering about the proper placement of the "dot" that goes with the grub screw. it goes between the screw and the spindle? what exactly does it do?

 

[Mark Jundanian]

It goes between the grub screw and the outer threads of the insert. It protects the insert's threaded surface and improves the hold of the grub screw.

 

[Tom Hansen]

excellent, thanks

 

[Dave Landers]

I had occasional problems with the insert backing out of my chucks. What I did was to drill a bit where the grub screw seats. Not really a hole, but just a bit of a detent. That's been enough to keep things in place.

Also, I have this wrench https://www.amazon.com/gp/product/B000TDGHF0 which is great for removing chucks from the spindle. It's adjustable (so it fits all my chucks and things) and narrow enough to get between the headstock bearings (or whatever is there in the way) and the chuck body.

 

[William Rogers]

I doubt you would have any trouble selling a direct thread 1 1/4 - 8 tpi Vicmarc chuck. It would be different if your spindle was 1 - 8 tpi. For that size, an insert would be more practical. I prefer direct thread chucks, one less piece with tolerances to deal with. I have never seen where the Nova jaws fit a Vicmarc chuck. They do fit a Sorby or Record chuck. I do not like the washer solution to the chuck sticking. When John Jordan did a demo for our club he said never spent the chuck against the spindle. You should bring the chuck to the spindle and hand tighten it. It would not take any more torque to remove it. I use to spin the chuck on and had difficulty on occasion removing it. I have been following John’s suggestion for the past 18 months and have zero problem removing the chuck and I have had a few catches. I ended up selling all my Nova and Record chucks and bought two Axminister direct thread chucks. The SK100 has a spanner wrench that fits for installation and removal, however there was no provision for the SK114. I had an adjustable spanner that fits the SK114 and use that.

 

[Timothy White]

I have 2 lathes one each 1”X8 and 1/14”X 8 I have 2 adapters and 3 Nova chucks. I install the adapters on the lathes and change the chucks as I please no need to change inserts.
Using Loctite on the inserts isn’t a good idea as it makes taking the Chuck apart to clean or service a real pain.