Why You Need This Even If You Don't Turn Natural Edge Bowls

Cole Jaws, Longworth Chucks, and Doughnut Chucks are wonderful devices. However, you always lose 2" of holding capacity to allow for the gripper buttons or bolts. If you are using a 12" lathe, you can only hold a 10" project to finish the bottom. Using the Natural Edge Jamb Chuck you avoid that limitation and can hold projects up to the full size of your lathe! Turn 12" bowls on a 12" lathe, 14" salad bowls and platters on a 14" lathe and a full 16" platter or salad bowl on a 16" lathe.

Patent Pending 29/790,019

Natural Edge Jamb Chuck with 4" Extension Tube and Drawbolt. Includes 3 endplates: 3", 4", 6" Diameter

OPTIONAL 8" Extension Tube and 8" Drawbolt available at an additional charge

What is in the package:

1 @ Faceplate Assembly factory installed (1x8 and 1-1/4x8 available)

1 @ 2” dia x 4” long PVC Stand-Off Tube

1 @ 3” Chuck Plate ½” thick HDPE

1 @ 4” Chuck Plate ½” thick HDPE

1 @ 6” Chuck Plate ½” thick HDPE

1 @ 3/8” x 16 tpi special draw bolt with center chamfer

1 @ 3/8” washer

1 @ 8” x 8” Anti-Slip Friction mat

1 @ Instructions

1) What

a) The NEJC serves as a stand-off Jamb Chuck for use with any bowl, plate, or platter that has an irregular rim. The irregular rim makes it incompatible with conventional Longworth type or Cole Jaw type bottom finishing chucks. We often find this condition in Natural Edge and rough-turned vessels.

2) Who

a) Anyone who turns natural edge bowls.

b) Anyone who rough turns regular bowls that go oval during drying, including the tenon.

c) Anyone working with a vessel too large for their Longworth Chuck or Cole Jaws. If you are working with a 12” vessel on a 12” lathe, it will clear the bed ways, but you can’t hold it in Cole Jaws or a regular Longworth Chuck. You can easily hold it with the tailstock against the NEJC.


3) How

a) Threaded directly onto the lathe spindle, various sized disks are fitted onto the outermost end of the NEJC and the vessel is placed against the disk. The tailstock and live center are brought to bear against the vessel to hold it in place. The tenon can then be removed except a small nub which is subsequently removed and finished by hand.

4) Why

a) Jamb chucks have long been used in this manner. Each of the chuck plates provides a more reliable uniform bearing surface for less breakage, less marking on a finished interior surface, a more secure hold, and supplied in 3 diameters, will hold an almost endless range of vessels with irregular rims.

b) The issue we are addressing is having jamb chucks of the correct sizes and shape on hand that hasn’t gone oval, cracked, or split since the previous use. The tenon on the jamb chuck itself often goes oval due to drying between uses. Then you face the same concentricity issues you do with a twice-turned bowl such as the 4 jaw scroll chuck failing to grip the tenon securely unless trued up before use.

5) Where

a) The vessel is placed open-side toward the headstock against the disk (usually with a rubber mat for cushioning) and held in place with pressure from a live center in the tailstock. The stand-off is approximately 4” from the headstock housing.

6) When

a) For use whenever the bottom of a vessel requires turning and there is no other convenient holding method available because of the irregular rim.

Note: It is dramatically easier to re-center your vessel if you will leave a divot in the tenon. We always recommend that you mark the center of your vessel on the tenon even if you didn’t use a live center when you initially turned the vessel and created the tenon.


How to use

Off the lathe, select the appropriate size chuck plate, 3, 4, or 6” diameter.

Loosley, assemble your NEJC in the following order:

Faceplate assembly, PVC stand-off tube, HDPE chuck disk, drawbolt, and washer.

Firmly seat the PVC stand-off tube in the grove of the HDPE disk on the faceplate assembly.

Firmly seat the HDPE chuck plate into the PVC stand-off tube.

Insert the drawbolt and tighten the assembly together. Don’t over tighten!

Thread the completed NEJC assembly onto your lathe spindle and run at low rpm to check that is running true.

Place the non-slip matting in the bottom of your vessel.

Our good friend, Sam Angelo, has posted a 24-minute video on how he makes a natural edge bowl. Sam uses our new Natural Edge Jamb Chuck in the video. I think you will find his remarks helpful.


From: Eddie Castelin [mailto:capneddiecastelin@gmail.com]

Sent: Monday, August 16, 2021 6:53 PM
To: ronbrown@coolhammers.com
Subject: Chuck,


Thank you, Ron, Oh by the way tell Janice hi, this is one fantastic gizmo. I have almost given up on Natural edge pieces because of the time I have to spend to make a jam Chuck. This is a great idea it’s well-machined looks like it works fantastic and it’s versatile.

As I sit in the shop this afternoon I’m thinking about 1 million things and ways I can hold them and it’s just natural edges I can also hold what you’ve described as footballs and get the base correct it. Must be a pretty good Woodturning around your house to develop the stuff.


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Natural Edge Jamb Chuck

  • Product Code: Natural Edge Jamb Chuck
  • Availability: In Stock
  • $119.99
  • $99.99

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