What Does a Bar Puller Do?
Dunham Tool manufactures high quality lathe bar pullers and bar puller kits to enhance bar stock puller applications. Dunham bar pullers are most frequently used as a CNC bar puller, but are also used in 'pick and place' applications. These tools are sometimes referred to as pull up bars.
The Dunham bar puller line of low cost bar pull grippers for CNC Lathes are available from 1/8" to 2" diameters in 1/16" increments, from 2" to 2 1/2" diameters in 1/8" increments, and from 3MM to 34MM in 1MM increments. Dunham bar pull grippers mount directly to the Dunham bar pull shank or you can use a Dunham bar pull adapter to mount to the shank for select sizes.
The lightweight and self-activating Dunham bar puller has no moving parts, mounts in 60 seconds, changes grips in about 30 seconds, and does not interfere with other tools or cause turret imbalance. When a bar puller is used, the lathe turret no longer acts as a stock stop, reducing turret degradation and eliminating expensive, space-consuming, high maintenance bar feeds.
Employing a Dunham bar pull shank (available in 9 diameters--See Bar Pull Adapters) which is clamped in the lathe turret in the same manner as a boring bar, the grippers are hand turned onto the shank thread or onto adapters that attach to the shank to accept smaller diameter grippers. These self-activated grippers are slotted like standard collets and, as they advance over the bar to be pulled, are forced open to firmly grasp the bar for pulling out of the spindle to a programmed length. Only 1/4" bar engagement is needed. Gripping and release of the bar are automatic when the turret is advanced and retracted. CNC bar pull components are available individually or in kits. Bar pull shanks should be specified to the size of the boring tool holders.
How it works:
1. Mount shank in turret; screw on adapter (if required) and gripper.
2. Insert bar through back of spindle and clamp with collet or chuck.
3. Face off minimum 1/4" projection using parting off command in CNC program.
4. Index turret to bar pull and traverse turret toward spindle for programmed distance, sliding gripper over stock.
5. Release clamping pressure on bar.
6. Retract turret programmed distance.
7. Re-clamp Bar.
8. Retract turret sufficiently to clear gripper from bar.
9. Begin programmed machining cycle.
10. Repeat until all of the bar is used.
Features and benefits
- Bar Pull Shanks Fit in Most Boring Tool Holders
- Low Cost Bar Pull Gripper Replacements
- Pull Bar to Last Usable Part Length
- Pull Positions Bar +/- 0.001"
- Works Close to Chuck or Collet Nose
- Does Not Interfere With Adjacent Tools or Turret Movement
- Only 1/4" Bar Engagement Required