FAQ: BIG-PLUS Dual Contact

Can I use BIG-PLUS tool holders in a machine that is not BIG-PLUS?

Yes. BIG-PLUS tool holders will fit into any machine no matter if it is made to the BIG-PLUS or standard specification. The gage plane of a BIG-PLUS tool holder is the same as standard tool holders and therefore seats in the spindle taper only. For this reason, BIG DAISHOWA has standardized almost all of the tool holders produced with BIG-PLUS.
 

The tolerances of BIG-PLUS are very tight, but it does not seem possible to achieve dual contact unless the spindle and tool holders are nearly perfect. How is BIG-PLUS able to work on any machine and in any environment for dual contact?

All BIG-PLUS tool holders are made to the same tolerance and specification. However, there is a known and repeatable elastic deformation that occurs to the spindle due to clamping. Every machine will see an axial movement during clamping of approximately .0005”-.001”. We use this movement to secure taper contact first, followed by face contact second, all within the elastic deformation of clamping. As a result of BIG-PLUS achieving face contact with the spindle, BIG-PLUS is able to control tool offset better than standard tool holders.

 

How does BIG-PLUS compare to HSK? Which is better?

HSK is a dual-contact spindle system that relies on tool holder expansion during clamping. This is made possible by very high clamping forces but also the tool holder itself is a thin-walled short taper that can expand elastically during clamping. Extensive testing at BIG DAISHOWA of both systems revealed that the longer the tool holder is, BIG-PLUS has the advantage and better rigidity compared to HSK. Also, due to the internal construction of HSK, tool overhang is longer and BIG-PLUS has better tool holder taper engagement in the spindle. However, for high-speed operations, HSK should be considered the better option.


 Is it possible to rebuild BIG-PLUS spindles to original factory specifications?

Yes, there are several companies who specialize in spindle repair who have obtained the license and gages for BIG-PLUS. Also, these companies can convert a standard spindle to BIG-PLUS by replacing the spindle shaft during the rebuild process at their company.

Do I need to acquire BIG-PLUS adapters for my tool presetter or tightening fixtures?

No, if your presetter is already equipped with CAT or BT adapters, BIG-PLUS tool holders will fit and measure like a standard tool holder.