Pros/Cons of Vicmarc Direct Thread Chuck vs. Using Insert

[Paul Heely]

I'm getting ready to add another VM120 chuck to my collection and just realized there is a direct thready option for these chucks that do not require an insert adapter. Can anyone shed some light on the pros and cons of going with the direct thread chuck vs. using the insert adapter. I turn on a PM3520 now, any other lathe I would ever go to would have the same 1-1/4 x 8 spindle size so I'm not worried about being able to change thread size for a new lathe if that ever happened.

[Greg Parrish]

Less chance for adapter induced wobble or out of round. I have one of each for my laguna and prefer the direct but can’t tell much real difference in use.

[tom lucas]

I own one. It's really nice but there is no grub screw. So you have to watch it when using in reverse. It has also come unspun going forward a couple of times. I was working on small parts at high speeds and just turned the lathe off. It kept on spinning and came off. I don't know if the same is more or less likely to happen with an adapter version (don't own one). Several things affect this that are not all in the chuck. I also don't know if the adapter version has a grub screw. My other big chuck is a Nova Titan with adapter. It has never unspun on me...... yet.

As for adapter vs. not w.r.t. using it on smaller lathes, I think the VM120 is a bit large for smaller spindle lathes anyway. I would think its weight would be detrimental to the machine. So I don't see the advantage of the adapter from that perspective. If I were to get a smaller lathe, I'd just use smaller chucks with it.

One advantage of the adapter is that it is easily replaced should the threads get damaged (unlikely).

The VM120 is outstanding quality. But it's best suited for larger turnings. It grips like crazy with really thick jaws, but is heavy. I think that is why a lot of folks like the One-Ways: big strong chuck but lighter due to open back. I now mostly use a Supernova2 for smaller workpieces, with plans to add another or two when I can afford them. I would love to have a VM100....just to pricey for me.

[Alex Zeller]

Unless Vicmark charges more for the chuck there's a cost savings by not having to buy an adapter. The downside is if you get a different lathe with bigger threads. Going from larger chuck thread to smaller is much simpler than stepping up in size as far as the adapter goes. 1 1/4" seams to be the US standard now for larger chucks. Of course that's not to say you will not come across a great deal on an American Beauty with the metric spindle and your 1 1/4"x 8 chuck isn't going to work without an adapter.

[John K Jordan]

I don't have a Vicmark so I don't know how it's made. The direct-threaded Nova Titan I have has one "liability" compared to the Nova insert models - it doesn't allow using the chuck wrench to remove the chuck. I tighten a chuck with a wrist "flick" and loosen with the Nova chuck wrench. I might machine flats on the back of the chuck to fit the wrench.

This may not matter to those who don't use a wrench.

Another advantage to the insert was mentioned - changing inserts for different lathes. I keep inserts to fit a mini lathe. When a friend got a new lathe I was able to loan a couple of chucks to fit.

JKJ

[John Beaver]

I believe the direct threads don't go as deep as the insert. This could be an issue where the chuck will bottom out on the end of the lathe spindle before seating properly. I would check this out before committing.

[tom lucas]

I believe the direct threads don't go as deep as the insert. This could be an issue where the chuck will bottom out on the end of the lathe spindle before seating properly. I would check this out before committing.

nop. seats all the way.

[Mick Fagan]

If you have a Vicmarc lathe, then direct thread is probably the better unit. My reasoning is because you can use the Vicmarc safety collar to keep the chuck on the lathe, no matter which way you turn.

https://vicmarc.com/index.php?option...=21&Itemid=528

If you don't have a Vicmarc chuck then having an insert with a grub screw that locks onto the spindle is far better for any reverse turning. It can certainly help when turning large heavy stuff and you switch the lathe off and the lathe brake works; you may find your chuck is starting to unwind.

I have both and all of my lathe work is done on one thread, but when I visit a friend I take an insert chuck so I can run an insert for his lathe.

Mick.

[Paul Heely]

Thank you all for your inputs. Sounds like switching to a different size lathe is the biggest potential con of the direct thread. Didn't see anyone mentions any cons to the using the insert. All my current VM120s use an insert, so I think I may stay with that style, my OCD likes consistency

I also just realized that I can drill and tap the adapter for a grub screw to prevent the check from coming off in reverse, though I've never had that problem to date. I'm getting ready to start turning and coring some much larger bowls, so having the grub screw could be a good piece of mind.

Paul

[Pat Scott]

Paul I have five VM120's, four with inserts and one direct thread. The main reason I was given for getting a direct thread is reduced vibration since the chuck is closer to the headstock. I use the direct thread chuck with 5" jaws (maybe it's my 6" jaws) as that's the chuck I use most often when coring. There is a lot of stress and vibration when coring and sometimes my lathe let's me know it's not happy. I think the direct thread might help with this?

As mentioned already since there isn't an insert with flat spots or with a hole for the tommy bar, you must use the T-wrench to remove the chuck. I asked if this is harmful to the chuck in any way and was told no. Also I have never had any of my VM100's or VM120's come off or come loose when turning in reverse. I have never used a grub screw in 15 years of turning. The direct thread seats fully on my 3520B spinde.

So while the chuck being closer to the headstock can be an advantage, it can also be a disadvantage depending on how you turn. If you need access to the back of the piece there isn't as much room. With an adapter the work is a couple inches farther away from the headstock. Being concerned about spindle size for a future lathe would not even be a consideration to me as 1-1/4 x 8 seems the standard for 99% of the full size lathes out there. If you need something different then you can buy an insert.

[Paul Heely]

Ended up sticking with the insert style VM120, just ordered 2 more with the 173mm and 223mm jaws. Was going to order the direct thread model when I realized that the distance from the back of the chuck's threaded part to the face of the jaws would be different between the insert style and direct thread. I have spacers made up to quickly position my Oneway Easy Core base and having different distances would mean making an other set of templates and then keeping track of them, and then using the correct one based on which chuck I was using.