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Diaphragm Chucks

Custom Diaphragm Chucks from Skill-Craft Company Inc.

Diaphragm Chucks from Skill-Craft Company Inc are ideal for high precision turning, grinding, milling, boring, hard turning, inspection. By using one piece construction allows for clamping on O.D., I.D., or pitch-line, thin-walled parts: No metal-on-metal moving parts, causing no wear for long-life. These chucks ensure flexibility to engineers or tool designers and will mount in existing machine envelope (jaw height, locator, and jaw inserts identical). 3, 4 or 6 jaw standard designs, or custom designs available and uniform, variable clamping forces provide a rigid design without part distortion.

Custom Diaphragm Chuck Features

Sealed Design

  • One piece construction eliminates contaminants and costly down time.
  • Maintenance free, no lubrication required

Pull Down

  • Pulls work piece tight against part stop


  • Quick change jaws allows for quick turnover
  • No grinding necessary on replacement jaws – part turnover within minutes, not hours
  • Accommodates different sizes using a single diaphragm


  • Air actuation or push-pull clamping
  • Uniform clamping pressures


  • Repeatability of less than .0002
  • Quick change jaws do not affect TIR

Custom Diaphragm Chuck Examples

4 Jaw O.D. Diaphragm Chuck

This is a (4) jaw – 6 inch O.D. diaphragm chuck that was used to hard turn the I.D. of bearing caps. This chuck accommodated (3) different sizes of the bearing caps, where change over was as simple as removing (1) screw from each jaw. This chuck had a positive part stop with a part ejector that was used in a system with robotic load.

There was also a built in air cylinder which incorporated push-pull capabilities. The chuck was built with stir- around screws where the chuck was proven to repeat within .0001 TIR. This particular chuck was used to replace a (3) jaw sliding chuck where performance and maintenance was timely and not cost effective.

Being this chuck was used in a grinding application, the previous chucks were having to be taken off the machine and disassembled every month due to the nature of the grinding process. With the one-piece construction of the diaphragm, the chuck has currently been in use for over 1.5 years with continuous cycle times of 7 seconds.

6 Jaw I.D. Diaphragm Chuck

This chuck is a 9 inch, 6-jaw I.D. diaphragm chuck. Our customer needed a way to perform an audit on their production ring gears they were machining. This chuck was used and developed to hold on the I.D. of the ring gear so various dimensions could be checked.

This chuck had to repeat within .0002 in order to assure proper readings from the audit machine. There were (2) different sized ring gears, so all that was necessary for part change over was replacing the (6) top jaws that has (2) bolts per jaw to hold it in place. Even with part change over, the chuck repeated within .0002.

12 Inch 9 Ears O.D.

Diaphragm Chuck This chuck is a 12 inch O.D. diaphragm chuck with 9 ears. There is no grinding of the jaws at part change over and the chuck still repeats within .0002 TIR.

12 Inch 12 Ears O.D. Diaphragm Chuck

This chuck is a 12 inch O.D. diaphragm chuck with 12 ears. This chuck is a push-pull chuck that allows the user to vary chucking pressure depending on part geometry. The slots are sealed to eliminate any swarf to hinder chucks application. The chuck comes with 12 replaceable jaws that can chuck any part from 10 inches an below.

I.D. Diaphragm Chuck

This chuck was used to hold the I.D. of 5 different parts, all having different bores. With having (10) ears on the chuck, there were (10) different inserts that we replaceable, where part change over could be done in less than 15 minutes. With changing each set of inserts, the chuck was repeating within .0002 on each part.