My Haas VF-2 threw a tool holder right into the door last Friday

I was running a 3/4 inch end mill at 6500 rpm on a steel part and the retention knob sheared clean off. The whole holder shot out of the spindle and put a huge dent in the safety glass. I think the knob was from a cheap batch we bought online about six months ago. Has anyone else had a retention knob fail like that, and what brand do you trust now?

3 comments

3 Comments

hollym822mo ago

Check the torque on your drawbar, because a weak grip can put extra stress on the knob. We switched to only using genuine Haas retention knobs after a similar scare, even though they cost more. The cheap ones often have bad heat treatment and can snap right at the thread root.

finley_craig532mo ago

Hold up, buying the super expensive brand name knobs is just feeding the machine tool tax. We ran generic knobs from a decent supplier for years in a high mix job shop, no issues. You just have to know your source and maybe do a quick hardness check when they come in. Blaming the part ignores other factors like a worn spindle or an operator over-torquing the drawbar. Throwing money at the Haas brand doesn't fix a maintenance problem.

matthewgonzalez1mo ago

Yeah but @finley_craig53 I've snapped enough cheap tools to know my luck with generic parts is about as good as my aim on a Monday morning. My bank account definitely feels the tax though.