Turning a bowl tenon for chuck

[Chris Barnett]

Forgot what tool is suitable to turn a tenon Have only turned a few and they were a piece of cake, but my bowl gouge or parting tool do not seem to fit into root, unless a parting tool can be used flat, and a bit worried to use skew...they are looking so promising though. Had changed my bowl gouge from fingernail back to basic grind since I could not seem to duplicate the fingernail, so think I may have changed the tool profile that worked so well. You-Tube has been less than helpful on this one. Am embarassed to ask for help on something so simple...

[John Keeton]

Chris, I think you will get varied responses to this question. I normally use a 1/2" bowl gouge with deeply swept back wings, and a small working bevel of about 1/8" - 3/16". However, it would seem a parting tool would work fine.

You don't say what kind of chuck you have, but Nova (Teknatool) does not recommend a dovetail shaped tenon. For the Nova chucks, you need a tenon that is square edged, and not over 1/4" long for most purposes. In fact, the dovetail "crushing" action of the jaws really require about a 3/16" tenon.

[Hilel Salomon]

Hi Chris,
It depends on the chuck you are going to use. If it's a Oneway, then a straight tenon can be achieved with a parting tool, bedan or a finger nail bowl gouge. The Vicmarcs and Novas use an angled tenon and I've seen these cut using all of the above tools w/a turn at the end for the bedan and parting tools. I am going to get a lot of grief but I do use an angled skew almost all the time. I don't use the skew for much else and it works for me. I now don't cut too big of a tenon (depth wise or circumference) so a light plunging cut with the skew (when I've gotten to the right circumference) as the finishing cut to achieve the angle works just fine.

Hilel

[Chris Barnett]

Yes, I use only Nova II and Titan chucks but did not know not to cut a dovetail. Class I took had us cutting a dovetail on their Nova chucks. But if that is the case, I already have the square tenon cut. I could not get the tool into the corner without taking out the rear flat to support the chuck face, and thought the parting tool would maybe break or bend or catch if I used in flat, although it seems the perfect tool to use in that application. Will go ahead and chuck it up then see how it goes. The long sweptback wings is what I ground off.... I need to rethink my action. A reground bowl gouge to a point tool might be the ticket. Hilel, I can easily see how well a skew would work. I have three skews, two from a set, but have mastered none; I have used a skew but a few times...very carefully. Last time I used the larger skew...actually trying to cut the dovetail, I had a catch and it went back to the rack for a few more months.
Thanks.

[Jim Burr]

You can try a dovetail gouge...included in the CSUSA set I bought 10 years ago.

[John Keeton]

Hi Chris,
The Vicmarcs and Novas use an angled tenon....

Hilel

This topic has come up several times, and while I have no knowledge of the Vicmarc chuck, the Teknatool manual is explicit on the formation of a spigot tenon - quote from page 13 -

Make the spigot as parallel as possible to maximise the efficiency of the clamping action. Only approximate sizing of the spigot is necessary, as the jaws will accommodate a wide range of spigot diameters within the spigot limits stated above. 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.

When forming a "recess" (vs. a spigot), the process does require a dovetail recess, and that process is covered on pages 12-13 of the SN2 manual.

Again, other chucks may require a dovetail spigot/tenon, but the whole premise behind the interior dovetail on the Nova jaws is to compress the wood to achieve a "bite".

[Prashun Patel]

I just bought a 1/4" detail gouge that is perfect for this.

I use a 1/2" or 3/8" bowl gouge to get the rough depth of the tenon, then the 1/4" detail to sneak up on the fit.

Prior to this, I DID use a skew but only at the end, after I did as much possible work with the gouges.

[Sean Hughto]

For my one-way (straight NOT dovetail) chucks, I shape the square sides and small flat at the base of the bowl with a scraper (several shapes are suitable from spear point to square to slightly curved).

[Scott Hackler]

I might start the tenon with a gouge, just to remove some surrounding stock.... but.... 95% of the time I use a parting tool for the whole thing. Either coming in from the tail stock side (more difficult because the tail stock is kinda in the way) or if it's a spindle type turning I just part the end into a tenon.

I will also meantion that I made a crude gauge out of wood to see when I am at the correct diameter on my tenon. It doesnt look professional (I made it in 30 seconds on the band saw) but it works good and it was free!

[Jamie Donaldson]

Just whip out the parting tool and do it! Make sure that the tenon shoulders that meet the chuck jaws are square, and that the tenon is not so long that it bottoms out on the chuck. Don't get too confident with a short tenon either- it produces projectiles and other bad effects!

[Reed Gray]

A bedan, or sizing/beading and parting tool (wide parting tool actually) will work. A specialized dove tailed scraper will do if you need a dove tail. You can rough it in with standard gouges, and then clean it up with a spindle/detail type gouge which tends to be more pointy. You can use a skew like a scraper to clean it up. You do want the final cut to be clean, the bowl bottom to be square to the tenon, and the angles to match. I do tend to make a feather light cut, just barely touching the wood to remove most of the run out/bumps so when I reverse, it will mount more truly.

robo hippy

[Kyle Iwamoto]

Wow, I have Novas, and I've been cuttng a dovetail tenon for years...... I guess I better stop.

Who reads instructions anyways?

Oh, for ME, that's one of the uses for a skew. BUT since I no longer should cut a dovetail, I'd use a parting tool, and make a square shoulder. I guess I can retire my skews, since I can't think of another reason to use them... LOL

[Michael Mills]

I made my own dovetail tool but Nova does sell one. I made mine from an old bench chisel but a stout flat-tip screwdriver which has been ground on the side to the 15* angle works just as well. When and If a dovetail is suggested, I cut the tenon or recess with a parting tool. Once open a slight side movement (scrape) cuts the dovetail. You are removing a very small amount of wood.
That said, here are Nova instructions for forming a dovetail with a skew (when a dovetail is required). “The jaw dovetail has been designed for use with a standard skew scraper.” You will note they state also “Before scraping out the recess…”
Forming Recess http://www.teknatool.com/products/Chucks/SuperNova2/Downloads/SuperNova2 Manual Sheet_Jun07.pdf

As far as length/depth of a tenon/spigot… and Jamie D.’s comment above … “Don't get too confident with a short tenon either- it produces projectiles and other bad effects!

I agree…
If you go to Nova’s jaw manual which John K. referenced above http://www.teknatool.com/products/chuck_accessories/General/downloads/Accessory Jaw Manual_Nov07.pdf

Page 20 for the 50mm Jaw Set also states for a spigot
“Spigot Depth: The length of the spigot area must not be less than 16mm (5/8”).”

Page 36 for the Powergrip Jaws states for REVERSE Dovetails
“Spigot Depth: Always use the maximum spigot depth which is 12.5mm. ”At one time they gave the spigot depth in SPIGOT operation (not Reverse Dovetail operation) as a minimum of about 1-1/4” with the Powergips. They no longer list this data. However, on page 39 for the Titan Powergrip Jaws they state…” Always use the maximum spigot depth of 40mm (1.57”).”
You also do not cut a dovetail in the Spigot mode, only in the Reverse Dovetail mode with these jaws.

[Jon Nuckles]

+1 on Prashun's method. A quick rough size with a bowl gouge followed by a pass or two with a detail gouge from both directions toward the 90 degree corner of the tenon and bottom of the piece (along the side of the tenon and along the base of the piece) leaves a much cleaner seat than I can achieve with a parting tool.

[Jamie Donaldson]

Kyle- skews make great negative rake scrapers!