Dovetail jaws vs. Straight jaws

[Roy Turbett]

A while back Oneway started to offer the Stronghold chuck with a choice of either dovetail or straight jaws. Then VicMarc did the same. For those of you who have both styles, which do you prefer and why?

[Thom Sturgill]

While I do not own either a Oneway or Vicmark, I have had both jaw types. My first chucks were PSI with straight serrated jaws. Not as aggressive as either OneWay or Vicmark by a long shot, so probably not a good comparison. Launched many pieces. PSI came out with dovetail jaws for the same chuck and problems with the piece walking out of the chuck ended. Probably my techniques improved too, but the change was dramatic.

The ONLY time I have had a piece leave dovetail jaws in either expansion or contraction was when a tenon sheared off (punky wood). All newer chcucks have been Novas (one G3 and 5 SN2s) all with dovetail jaws.

[Jeff Gilfor]

But the Novas are only dovetailed in expansion mode. For tenons, they require straight cut sides. I wonder if the chuck jaws that are dovetail on the contraction side are even more grippy. Anyone?

[Thom Sturgill]

But the Novas are only dovetailed in expansion mode. For tenons, they require straight cut sides. I wonder if the chuck jaws that are dovetail on the contraction side are even more grippy. Anyone?

I rarely use the standard jaws. Almost all of the other nova jaws are true dovetails on the inside.

[Joe Meirhaeghe]

My 1st chuck way a One Way Strong hold with straight serrated jaws. I didn't care for them and quickly changed them to dovetail jaws. I now have three different brands of chucks & use dovetail jaws in all of them.

[Jeff Gilfor]

Oh my goodness!!!!! You are correct sir! I have been (ignorantly) using straight sides for contraction gripping with my super grip jaws. A quick read over the manual confirms that, except for the 50 mm bowl jaws, contraction modes use a "reverse dovetail". Wow.

One question though, that I cannot find the answer to: expanding mode dovetail is 15 degrees; is the contracting mode dovetail the same? Thom?

[John King]

Dovetail jaws only way to go. My opinion. Just sayin'. - John

[Thom Sturgill]

One question though, that I cannot find the answer to: expanding mode dovetail is 15 degrees; is the contracting mode dovetail the same? Thom?

I believe so. While I do not have one, from the pictures the nova dovetail scraper looks symetrical as do the 4" jaws. The 3" bowl jaws look more aggressive though and they have serrations lower down.

[Dennis Nagle]

My first chuck had straight jaws and my HTC125 has dovetails. I use to launch off my old chuck often. Doesn't happen with the dovetails.

[Michael Mills]

I have seven Novas with different jaw sets. Until you get to the 100mm none that I have ever seen have an interior dovetail.

With the 100mm powergrips you have expanding dovetail, reverse dovetail, or spigot. Using the 100mm powergrips with a spigot you do not cut a dovetail, the spigot is 1+ inches long for hollowing. For a reverse dovetail the maximum is ½” long and you do cut a dovetail.

The others are serrated (spigot jaws); smooth like the smaller Pin, 25mm or 35mm bowl; or have a “lip” like the 50mm bowl and others. Below is a pic of the 50mm; notice most of the inside is straight, only the top 4mm or so have a profile and the width of the “lip” is only about 1mm (or the gap at the bottom between the square and the jaw).

The other jaw is the 100mm powergrips.

[Kyle Iwamoto]

Interesting. I thought my SN2 jaws were dovetails on the inside...... Maybe just at the top? I did buy a set of serrated jaws for the SN2, and only used them once. I prefer the dovetails, mainly since I re-turn at least 2 times. Easy to re-align the chuck to where it was.

I would have thought with so many Oneway chuck fans, this would be one of those hot topics......

[Robert Henrickson]

I would have thought with so many Oneway chuck fans, this would be one of those hot topics......

OK -- "you asked for it" -- I use my Stronghold 90% of the time, almost always with the standard serrated jaws, for almost anything but the smallest stuff. I have G3s which I use almost entirely for small stuff and spindle turning. I much prefer serrated to dovetail jaws.

[Jeffrey J Smith]

All my chucks (6 OneWays 3 strongholds and 3 talons) are setup with dovetail jaws - gave up on serrated jaws a long time ago. The only exception is when I want/need to use the tower jaws. With them I use a short dovetailed tenon that avoids the serrated section altogether. Haven't lost a piece yet...

[Roger Chandler]

I have seven Novas with different jaw sets. Until you get to the 100mm none that I have ever seen have an interior dovetail.

With the 100mm powergrips you have expanding dovetail, reverse dovetail, or spigot. Using the 100mm powergrips with a spigot you do not cut a dovetail, the spigot is 1+ inches long for hollowing. For a reverse dovetail the maximum is ½” long and you do cut a dovetail.

The others are serrated (spigot jaws); smooth like the smaller Pin, 25mm or 35mm bowl; or have a “lip” like the 50mm bowl and others. Below is a pic of the 50mm; notice most of the inside is straight, only the top 4mm or so have a profile and the width of the “lip” is only about 1mm (or the gap at the bottom between the square and the jaw).

The other jaw is the 100mm powergrips.


After reading this thread........I went out to the shop this evening and I used my SN2 chuck with the powergrip jaws.........mine do have a dovetail on them......both inside and out....compression and expansion. I took a good look at it to make sure, and mine are definitely dovetail. Now, my 50mm standard jaws that came with the chuck are not dovetail in contraction mode.....so that set uses a straight tenon. My 100mm bowl jaws for the SN2 does have a dovetail as well.

[Reed Gray]

The dove tail joint has been used in woodworking forever and then some. Main reason is strength. It is a locking wedged joint. It has far greater holding power than a finger (straight) joint. This is why I prefer it, both for recess (my main attachment) and for tenons. I measured my Vicmark jaws once a long time ago, and found them to be at 7 degrees, which is the 'accepted' angle for hard wood joinery. Only real trick is getting the angle to match, which is simplified by the specialized dove tail tools. You can get close with a detail gouge or a skew, but you can get it exact with the dove tail scrapers. Straight plunge cut in, and it moves to the side at the angle all by itself. Just line up your blade with the ways as you cut.

robo hippy

[Michael Mills]

After reading this thread........I went out to the shop this evening and I used my SN2 chuck with the powergrip jaws.........mine do have a dovetail on them......both inside and out....compression and expansion. I took a good look at it to make sure, and mine are definitely dovetail. Now, my 50mm standard jaws that came with the chuck are not dovetail in contraction mode.....so that set uses a straight tenon. My 100mm bowl jaws for the SN2 does have a dovetail as well.

Sorry I took it off topic from the original.
Roger,
I may had stated it unclear. As far as I know only the 100mm or larger have an internal dovetail. So yes your powergrips do as shown in the picture with the steel square.
The little pamphlet that comes with your chuck from Nova probably states either a “bowl mount” meaning side grain, or a “spigot mount” meaning end grain. The full jaw manual states the same but adds a caveat/disclaimer that many bowl turner prefer a spigot/tenon on side grain.

So with your 100mm power grips you can expand with a dovetail into side grain.
Or use the reverse dovetail with side grain in contraction with a maximum ½” spigot/tenon.
Or mount end grain using the serrations and they suggest to be maximum length (about 1 ¼?); the same way they suggest for the 35mm or 45mm spigot jaws.

So there are three mounting options with the powergrips.

[Dan Forman]

I have Oneway Talon and Stronghold chucks with serrated jaws, and Vicmark chucks in corresponding sizes with dovetail jaws. The Oneways see a lot more use than the Vic's because I like the serrated jaws much better. i find them quite sturdy, and have never launched a bowl from them as far as I can recall, though have launched a few from dovetail jaws. The design of the Oneway jaws provide for greater surface area of grip, which one can see on the tenon when the piece is released. I tend to use a pretty thick tenon, near the 1/2" capacity most of the time, and find it very secure, and don't have to worry about matching the dovetail of the tenon to the jaw.

Dan

[Bill Blasic]

Every Nova chuck except the Titan comes standard with the 2" (50mm) jaws. I have at least 14 sets of these 2" jaws and every one of them has dovetails inside and outside. They may only be 3/16 deep but they are there and the tenon I use for them is also 3/16 proud dovetail and I have no problem holding the pieces I turn with this combination.

[Michael Mills]

Every Nova chuck except the Titan comes standard with the 2" (50mm) jaws. I have at least 14 sets of these 2" jaws and every one of them has dovetails inside and outside. They may only be 3/16 deep but they are there and the tenon I use for them is also 3/16 proud dovetail and I have no problem holding the pieces I turn with this combination.

Can’t say you're wrong, I only have seven sets. :( They all look like the pic in my prior post where the inside is straight except for 4mm at the top. The bottom gap between the straight section and the machinist square is only 1 to 1.5mm so that is all the lip can bite into the wood.

From the manual from Teknatool (at least all manuals that I have)
"FORMING SPIGOT:.....
The 50mm standard jaw has a thin lip or shoulder at the front face. This is designed to bite into the timber as the jaws are tightened. DO NOT CUT A RECESS FOR THE LIP TO FIT INTO, AS THIS WILL REDUCE GRIPPING POWER."

[John Keeton]

Michael, perhaps you and Bill are saying the same thing in different terms. Bill may be referring to the small "biting" area as a dovetail - I often do that, as well. Certainly, it is different from the full dovetail on the exterior of the jaws, but many would say a dovetail nonetheless.

[Roy Turbett]

I am surprised by the preference for the dovetail jaws because of the long popularity of the Oneway Stronghold with straight jaws. I posed the question because I currently have two Vicmarc 120's but will soon be in the market for at least one more chuck and was wondering if there was any advantage to having at least one chuck with serrated jaws. Since I'm comfortable with dovetails, I'm going to stick with them and will probably buy another Vicmarc dispite the cost. Thanks for all the replys.

[Reed Gray]

The only real reason I can see for having the serrated jaws would be if I was going to do a lot of deep hollow forms, and I would want the biggest tenon possible for the extra grip, and a little depth on the end grain would help. To me, any grip on side grain more than 1/4 inch at most is a waste and no gain in holding power at all.

robo hippy

[Mike Cruz]

I used to have Strongholds with the profiled serrated jaws. I liked them just fine. I now have Hurricane HTCs with dovetailed jaws and like them just fine, too.

I think the secret to either is a cutting a good tenon. Do a good job, and either will work. I've also found that dovetail jaws do not necessarily require a dovetail tenon...if you cut it straight or close...maybe a little dovetailed, the jaws will grip quite well. Maybe a perfectly matching tenon is ideal, but it is certainly not necessary. On serrated jaws, however, a straight tenon is much more "necessary". At least that is what I found.