Get the Most Out of Your Tool Holders

BIG-PLUS BT Hydraulic Chuck Super Slim

It should go without saying that the first thing you need to do after taking your tool holder out of the box is to read the manual. Manuals are written for a reason. This is too much to ask for many people, so the following is a quick list of tips that can help improve tool life and performance before you even start cutting. However, it must be stressed that there is no substitute for the manual included with your holder.

Always follow proper clamping procedures outlined in the manuals. Sometimes this means tightening clamping nuts to the proper position, using torque values that are included, or even using the proper wrench. It's a common misconception that tighter is better. It is certainly possible to over-tighten a screw or collet nut, for example. The tightening torque is usually sufficient when the fit feels "snug." Any tighter than the suggested torque and you will induce internal stresses in the tool and holder, decreasing tool life. In some cases, you may actually cause greater runout as well. Ideally, you will have a torque wrench or other such tool to accurately measure your tightening torque. BIG KAISER has a wide variety of torque measuring devices to suit your needs.

For hydraulic holders, shrink fit holders and similar high-precision holders, be sure that your tool shank diameter is as close to nominal size as possible. These types of holders are particularly sensitive to the tool shank diameter. For example, a Ø6mm hydraulic chuck with an h6 cutter will have about half the gripping force when the shank size is at the low end of the tolerance range (-h6), compared to the same holder with an exact (0) shank size. While we're on the topic, always be sure that your cutter shank meets or exceeds the minimum clamping length for your holder. When part of the the gripping portion of the bore doesn't have anything to grip onto, you will increase runout, decrease gripping strength, and may cause irreversible deformation.

In general, overall gripping strength increases as you increase the size of the holder (when looking at the same type of holder).  So, if for whatever reason you require more gripping force, it may be possible to use the next-size-up holder and reduce down with a collet. For instance, our Ø32mm Hi-Power Milling chuck with a Ø32-20mm reduction collet will have 1.5x more gripping force than an exact fit Ø20mm Hi-Power Milling chuck. Nevertheless, keep in mind that using a collet will also increase the runout.

If you are unsure about proper clamping procedures for your holder, don't hesitate to contact the BIG KAISER engineering department at (224) 770-2999 ext. 254 or

Jack Kerlin

By Jack Kerlin
Applications Engineer

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Mon, 07/05/2021 - 02:22

Some questions to ask ,any torque number to recommend for CNC lathe , turret unit M8 screw tightening for axis rolls head

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