Jacobs #100 Armature Chuck For Metal Lathe

This is a very rare, special purpose, Jacobs Chuck. This is a #100 Jacobs chuck 1/4 to 3/4 its mounted with a #2 Morse taper to a #33jacobs taper arbor with brass/bronze jaws.




This is a shaft centering chuck for turning generator and starter armatures that are not drilled for normal centers. The correct name for it is centerless armature turning chuck.

Nice piece and not to common as only automotive shops bought them. It is used by having an armature locked in the large Jacobs drill chuck that threads on to the spindle in place of one of the turning chucks and then the centerless chuck is used in the tailstock by easily tightening the chuck until the armature runs true and smooth, and then lock the ring down and oil the jaws good and go to work turning the comuntator.

This chuck is also designed for holding the end of a shaft at the tail stock end that has a finished diameter and allow it to turn...like a bushing.

It's a "tailstock steady rest" in effect, used when turning precision shaft mounted items such as generator or motor commutators, or anything that you want to turn without center drilling. You close the jaws to a nice sliding fit, oil heavily, and turn.

Category:

Howto & Style

Tags:

• Jacobs
• chuck
• drill
• metal
• lathe
• mini
• lathemaster
• workshop
• electric
• motor
• generator
• classic
• car
• rebuilding
• machine
• atlas
• south
• bend

[MGARestoration]

I learned something today! Thank you for sharing..

[johnrob281]

@MGARestoration

Thanks for your comment, glad you enjoyed the video.

---John---

[Guds777]

i thought a steady rest is for this kinda thing.

[johnrob281]

@Guds777 -- You're right! I think today we would use the steady reat for the same thing. This tool was popular with the electric motor repair folks. For some reason they did not use a steady rest. ---John---

[djzupzup]

THE BRASS WILL WARE ALOT?

[johnrob281]

@djzupzup You are correct, the brass will wear. However the speeds are relatively slow and the brass is softer than the shaft. Replacing the brass inserts (after years of use) is much easier and less expensive than replacing a motor shaft or armature shaft..

---John---

[stivep1]

It is very nice to have ham radio amateur involved in mechanics as well. Jacobs chuck is really interesting device.

[Guds777]

@johnrob281 , but nice tool.

[Mainer1945]

Thanks for sharing

[frtgghy]

i work in the electric motor industry, and was surprised to see a jacobs 100,i own one myself, i hardly ever use it, but its a cool tool to have.