These 3-jaw self-centering scroll chucks are popular workholding devices used on machine tools such as lathes, grinders, deep-hole borers etc.. Also they can be used on drilling machines, milling machines etc. by being mounted on indexing devices. Also they can be designed to have large bore to be installed on pipe processing machines such as welding positioners. Our 3-jaw self-centering scroll chucks can always be custom made to meet customers specifical needs. We have ever supplied a 2600mm 3-jaw self-centering scroll chuck which was intalled on a vertical lathe.

These 3-jaw self-centering chucks are available with steel made bases, one-piece or two-piece construction jaws, hard jaws and soft jaws to offer ease-to-operate and quick clamping. Their centering accuracy is high, conforming to ISO, DIN which are worldly recognized. Chuck mounts are available as below:

(1) Short-cylinder indirect mount: This mount is also called as plain back for the chucks. Chucks with this mount have on it a short cylindrical recess which fits with the outer cylindrical surface of the overhang on an adapting backplate. This backplate has on its other end an internal short tapered surface which fits with the spindle nose on the machine. Then the bolts for tightening the chuck onto the spindle nose pass through from the front of the chuck to fasten the chuck on the spindle nose. The adapting backplate will be supplied together with the chuck by us, matching with the spindle nose specifications, so that the chuck's installation will not cost extra re-work on adapting it to the spindle nose.

(2) Short-taper direct mount: Chucks with this mount has on its hack a tapered hole which directly fits with the lathe's spindle nose. Depending on the patterns on how the chuck is tightened onto the spindle nose, this mount includes four types: A1, A2, C, D.

A1 type short-taper directmount have both an inner bolt circle and an outer bolt circle where bolts pass through from the front of the chuck and fasten it onto the spindle nose.

A2 type short-taper directmount is same to A1 mount except that A2 mount has only the outer bolt circle and doesn't have the inner bolt circle. Therefore, all chucks with A1 mount can be installed on the A1 spindle only, and all chucks with A2 mount can be installed on either the A1 spindle nose or the A2 spindle nose. 

C type short-taper direct mount is also called bayonet type mount. Chucks with this mount have latch-pin type studs with one end studded into the back of chuck and the other end passing through the plain holes evenly spread on the spindle nose's flange, then llocking-nuts are tightened onto these studs to fix the chuck onto the spindle nose. 

D type short-taper direct mount is also called cam-lock type mount. Chucks with this mount have connecting rods with one end threaded into the chuck base and the other end, which has a concave cam surface, inserted in the plain hole spread evenly on the spindle nose's flange. Then cams, each with a driving socket on one of its ends, are inserted from outside of the spindle nose's flange into the plain holes which are located in the spindle nose's flange and have their centerline vertical to the spindle centerline, then each cam is driven via the socket on its end to turn to a certain angle where the cam and the connect rod match to reach a "dead-lock" position to fix the chuck onto the spindle noses.

For other types of mounts, please specify it and we can customize them as per your requirements.

Short-cylindrical indirect mount (plain back) 3-jaw self-centering chucks:

Note: 

• In parameters of D in below tabulate, postfix A means the 2-piece jaws conform to ISO 3442 Standard, and postfix Cmeans the 2-piece jaws conform to China traditional Standards. Parameters of D without a postfix mean that those chucks have the solid type top jaws;
• If the chucks you need are larger than 1250mm, please specify its OD and we will provide you its parameters.